diff --git a/lib/tsc.js b/lib/tsc.js
index a1b2d54c54c..8f42c687429 100644
--- a/lib/tsc.js
+++ b/lib/tsc.js
@@ -4659,6 +4659,8 @@ var ts;
         Parameter_0_of_accessor_has_or_is_using_private_name_1: diag(4106, ts.DiagnosticCategory.Error, "Parameter_0_of_accessor_has_or_is_using_private_name_1_4106", "Parameter '{0}' of accessor has or is using private name '{1}'."),
         Parameter_0_of_accessor_has_or_is_using_name_1_from_private_module_2: diag(4107, ts.DiagnosticCategory.Error, "Parameter_0_of_accessor_has_or_is_using_name_1_from_private_module_2_4107", "Parameter '{0}' of accessor has or is using name '{1}' from private module '{2}'."),
         Parameter_0_of_accessor_has_or_is_using_name_1_from_external_module_2_but_cannot_be_named: diag(4108, ts.DiagnosticCategory.Error, "Parameter_0_of_accessor_has_or_is_using_name_1_from_external_module_2_but_cannot_be_named_4108", "Parameter '{0}' of accessor has or is using name '{1}' from external module '{2}' but cannot be named."),
+        Type_arguments_for_0_circularly_reference_themselves: diag(4109, ts.DiagnosticCategory.Error, "Type_arguments_for_0_circularly_reference_themselves_4109", "Type arguments for '{0}' circularly reference themselves."),
+        Tuple_type_arguments_circularly_reference_themselves: diag(4110, ts.DiagnosticCategory.Error, "Tuple_type_arguments_circularly_reference_themselves_4110", "Tuple type arguments circularly reference themselves."),
         The_current_host_does_not_support_the_0_option: diag(5001, ts.DiagnosticCategory.Error, "The_current_host_does_not_support_the_0_option_5001", "The current host does not support the '{0}' option."),
         Cannot_find_the_common_subdirectory_path_for_the_input_files: diag(5009, ts.DiagnosticCategory.Error, "Cannot_find_the_common_subdirectory_path_for_the_input_files_5009", "Cannot find the common subdirectory path for the input files."),
         File_specification_cannot_end_in_a_recursive_directory_wildcard_Asterisk_Asterisk_Colon_0: diag(5010, ts.DiagnosticCategory.Error, "File_specification_cannot_end_in_a_recursive_directory_wildcard_Asterisk_Asterisk_Colon_0_5010", "File specification cannot end in a recursive directory wildcard ('**'): '{0}'."),
@@ -30734,7 +30736,7 @@ var ts;
                 var visitedSymbols = ts.createMap();
                 var deferredPrivates;
                 var oldcontext = context;
-                context = __assign(__assign({}, oldcontext), { usedSymbolNames: ts.mapMap(symbolTable, function (_symbol, name) { return [ts.unescapeLeadingUnderscores(name), true]; }), remappedSymbolNames: ts.createMap(), tracker: __assign(__assign({}, oldcontext.tracker), { trackSymbol: function (sym, decl, meaning) {
+                context = __assign(__assign({}, oldcontext), { usedSymbolNames: ts.createMap(), remappedSymbolNames: ts.createMap(), tracker: __assign(__assign({}, oldcontext.tracker), { trackSymbol: function (sym, decl, meaning) {
                             var accessibleResult = isSymbolAccessible(sym, decl, meaning, false);
                             if (accessibleResult.accessibility === 0) {
                                 var chain = lookupSymbolChainWorker(sym, context, meaning);
@@ -30751,6 +30753,10 @@ var ts;
                         context.usedSymbolNames.set(name, true);
                     });
                 }
+                ts.forEachEntry(symbolTable, function (symbol, name) {
+                    var baseName = ts.unescapeLeadingUnderscores(name);
+                    void getInternalSymbolName(symbol, baseName);
+                });
                 var addingDeclare = !bundled;
                 var exportEquals = symbolTable.get("export=");
                 if (exportEquals && symbolTable.size > 1 && exportEquals.flags & 2097152) {
@@ -30903,7 +30909,11 @@ var ts;
                         isPrivate = true;
                     }
                     var modifierFlags = (!isPrivate ? 1 : 0) | (isDefault && !needsPostExportDefault ? 512 : 0);
-                    if (symbol.flags & 16) {
+                    var isConstMergedWithNS = symbol.flags & 1536 &&
+                        symbol.flags & (2 | 1 | 4) &&
+                        symbol.escapedName !== "export=";
+                    var isConstMergedWithNSPrintableAsSignatureMerge = isConstMergedWithNS && isTypeRepresentableAsFunctionNamespaceMerge(getTypeOfSymbol(symbol), symbol);
+                    if (symbol.flags & 16 || isConstMergedWithNSPrintableAsSignatureMerge) {
                         serializeAsFunctionNamespaceMerge(getTypeOfSymbol(symbol), symbol, getInternalSymbolName(symbol, symbolName), modifierFlags);
                     }
                     if (symbol.flags & 524288) {
@@ -30912,7 +30922,8 @@ var ts;
                     if (symbol.flags & (2 | 1 | 4)
                         && symbol.escapedName !== "export="
                         && !(symbol.flags & 4194304)
-                        && !(symbol.flags & 32)) {
+                        && !(symbol.flags & 32)
+                        && !isConstMergedWithNSPrintableAsSignatureMerge) {
                         serializeVariableOrProperty(symbol, symbolName, isPrivate, needsPostExportDefault, propertyAsAlias, modifierFlags);
                     }
                     if (symbol.flags & 384) {
@@ -30926,7 +30937,7 @@ var ts;
                             serializeAsClass(symbol, getInternalSymbolName(symbol, symbolName), modifierFlags);
                         }
                     }
-                    if (symbol.flags & (512 | 1024)) {
+                    if ((symbol.flags & (512 | 1024) && (!isConstMergedWithNS || isTypeOnlyNamespace(symbol))) || isConstMergedWithNSPrintableAsSignatureMerge) {
                         serializeModule(symbol, symbolName, modifierFlags);
                     }
                     if (symbol.flags & 64) {
@@ -30952,7 +30963,10 @@ var ts;
                     }
                 }
                 function includePrivateSymbol(symbol) {
+                    if (ts.some(symbol.declarations, ts.isParameterDeclaration))
+                        return;
                     ts.Debug.assertDefined(deferredPrivates);
+                    getUnusedName(ts.unescapeLeadingUnderscores(symbol.escapedName), symbol);
                     deferredPrivates.set("" + getSymbolId(symbol), symbol);
                 }
                 function isExportingScope(enclosingDeclaration) {
@@ -31005,22 +31019,31 @@ var ts;
                     var heritageClauses = !ts.length(baseTypes) ? undefined : [ts.createHeritageClause(89, ts.mapDefined(baseTypes, function (b) { return trySerializeAsTypeReference(b); }))];
                     addResult(ts.createInterfaceDeclaration(undefined, undefined, getInternalSymbolName(symbol, symbolName), typeParamDecls, heritageClauses, __spreadArrays(indexSignatures, constructSignatures, callSignatures, members)), modifierFlags);
                 }
+                function getNamespaceMembersForSerialization(symbol) {
+                    return !symbol.exports ? [] : ts.filter(ts.arrayFrom((symbol.exports).values()), function (p) { return !((p.flags & 4194304) || (p.escapedName === "prototype")); });
+                }
+                function isTypeOnlyNamespace(symbol) {
+                    return ts.every(getNamespaceMembersForSerialization(symbol), function (m) { return !(resolveSymbol(m).flags & 111551); });
+                }
                 function serializeModule(symbol, symbolName, modifierFlags) {
-                    var members = !symbol.exports ? [] : ts.filter(ts.arrayFrom((symbol.exports).values()), function (p) { return !((p.flags & 4194304) || (p.escapedName === "prototype")); });
+                    var members = getNamespaceMembersForSerialization(symbol);
                     var locationMap = ts.arrayToMultiMap(members, function (m) { return m.parent && m.parent === symbol ? "real" : "merged"; });
                     var realMembers = locationMap.get("real") || ts.emptyArray;
                     var mergedMembers = locationMap.get("merged") || ts.emptyArray;
                     if (ts.length(realMembers)) {
                         var localName = getInternalSymbolName(symbol, symbolName);
-                        serializeAsNamespaceDeclaration(realMembers, localName, modifierFlags, !!(symbol.flags & 16));
+                        serializeAsNamespaceDeclaration(realMembers, localName, modifierFlags, !!(symbol.flags & (16 | 67108864)));
                     }
                     if (ts.length(mergedMembers)) {
                         var localName = getInternalSymbolName(symbol, symbolName);
-                        ts.forEach(mergedMembers, includePrivateSymbol);
                         var nsBody = ts.createModuleBlock([ts.createExportDeclaration(undefined, undefined, ts.createNamedExports(ts.map(ts.filter(mergedMembers, function (n) { return n.escapedName !== "export="; }), function (s) {
                                 var name = ts.unescapeLeadingUnderscores(s.escapedName);
                                 var localName = getInternalSymbolName(s, name);
-                                return ts.createExportSpecifier(name === localName ? undefined : localName, name);
+                                var aliasDecl = s.declarations && getDeclarationOfAliasSymbol(s);
+                                var target = aliasDecl && getTargetOfAliasDeclaration(aliasDecl, true);
+                                includePrivateSymbol(target || s);
+                                var targetName = target ? getInternalSymbolName(target, ts.unescapeLeadingUnderscores(target.escapedName)) : localName;
+                                return ts.createExportSpecifier(name === targetName ? undefined : targetName, name);
                             })))]);
                         addResult(ts.createModuleDeclaration(undefined, undefined, ts.createIdentifier(localName), nsBody, 16), 0);
                     }
@@ -31170,6 +31193,7 @@ var ts;
                             serializeMaybeAliasAssignment(symbol);
                             break;
                         case 208:
+                        case 193:
                             if (symbol.escapedName === "default" || symbol.escapedName === "export=") {
                                 serializeMaybeAliasAssignment(symbol);
                             }
@@ -31177,8 +31201,6 @@ var ts;
                                 serializeExportSpecifier(localName, targetName);
                             }
                             break;
-                        case 193:
-                            break;
                         default:
                             return ts.Debug.failBadSyntaxKind(node, "Unhandled alias declaration kind in symbol serializer!");
                     }
@@ -31196,7 +31218,7 @@ var ts;
                     var isExportAssignment = isExportEquals || isDefault;
                     var aliasDecl = symbol.declarations && getDeclarationOfAliasSymbol(symbol);
                     var target = aliasDecl && getTargetOfAliasDeclaration(aliasDecl, true);
-                    if (target) {
+                    if (target && ts.length(target.declarations) && ts.some(target.declarations, function (d) { return ts.getSourceFileOfNode(d) === ts.getSourceFileOfNode(enclosingDeclaration); })) {
                         var expr = isExportAssignment ? ts.getExportAssignmentExpression(aliasDecl) : ts.getPropertyAssignmentAliasLikeExpression(aliasDecl);
                         var first_1 = ts.isEntityNameExpression(expr) ? getFirstNonModuleExportsIdentifier(expr) : undefined;
                         var referenced = first_1 && resolveEntityName(first_1, 67108863, true, true, enclosingDeclaration);
@@ -31248,6 +31270,7 @@ var ts;
                     return ts.getObjectFlags(typeToSerialize) & (16 | 32) &&
                         !getIndexInfoOfType(typeToSerialize, 0) &&
                         !getIndexInfoOfType(typeToSerialize, 1) &&
+                        !!(ts.length(getPropertiesOfType(typeToSerialize)) || ts.length(getSignaturesOfType(typeToSerialize, 0))) &&
                         !ts.length(getSignaturesOfType(typeToSerialize, 1)) &&
                         !getDeclarationWithTypeAnnotation(hostSymbol) &&
                         !(typeToSerialize.symbol && ts.some(typeToSerialize.symbol.declarations, function (d) { return ts.getSourceFileOfNode(d) !== ctxSrc; })) &&
@@ -31482,11 +31505,8 @@ var ts;
                             return context.remappedSymbolNames.get("" + getSymbolId(symbol));
                         }
                     }
-                    if (input === "default") {
-                        input = "_default";
-                    }
-                    else if (input === "export=") {
-                        input = "_exports";
+                    if (symbol) {
+                        input = getNameCandidateWorker(symbol, input);
                     }
                     var i = 0;
                     var original = input;
@@ -31500,17 +31520,28 @@ var ts;
                     }
                     return input;
                 }
-                function getInternalSymbolName(symbol, localName) {
-                    if (context.remappedSymbolNames.has("" + getSymbolId(symbol))) {
-                        return context.remappedSymbolNames.get("" + getSymbolId(symbol));
-                    }
+                function getNameCandidateWorker(symbol, localName) {
                     if (localName === "default" || localName === "__class" || localName === "__function") {
                         var flags = context.flags;
                         context.flags |= 16777216;
                         var nameCandidate = getNameOfSymbolAsWritten(symbol, context);
                         context.flags = flags;
-                        localName = ts.isIdentifierText(nameCandidate, languageVersion) && !ts.isStringANonContextualKeyword(nameCandidate) ? nameCandidate : getUnusedName("_default", symbol);
+                        localName = nameCandidate.length > 0 && ts.isSingleOrDoubleQuote(nameCandidate.charCodeAt(0)) ? ts.stripQuotes(nameCandidate) : nameCandidate;
                     }
+                    if (localName === "default") {
+                        localName = "_default";
+                    }
+                    else if (localName === "export=") {
+                        localName = "_exports";
+                    }
+                    localName = ts.isIdentifierText(localName, languageVersion) && !ts.isStringANonContextualKeyword(localName) ? localName : "_" + localName.replace(/[^a-zA-Z0-9]/g, "_");
+                    return localName;
+                }
+                function getInternalSymbolName(symbol, localName) {
+                    if (context.remappedSymbolNames.has("" + getSymbolId(symbol))) {
+                        return context.remappedSymbolNames.get("" + getSymbolId(symbol));
+                    }
+                    localName = getNameCandidateWorker(symbol, localName);
                     context.remappedSymbolNames.set("" + getSymbolId(symbol), localName);
                     return localName;
                 }
@@ -31797,6 +31828,8 @@ var ts;
                     return !!target.immediateBaseConstraint;
                 case 6:
                     return !!getSymbolLinks(target).resolvedJSDocType;
+                case 7:
+                    return !!target.resolvedTypeArguments;
             }
             return ts.Debug.assertNever(propertyName);
         }
@@ -35128,13 +35161,25 @@ var ts;
             return type;
         }
         function getTypeArguments(type) {
+            var _a, _b;
             if (!type.resolvedTypeArguments) {
+                if (!pushTypeResolution(type, 7)) {
+                    return ((_a = type.target.localTypeParameters) === null || _a === void 0 ? void 0 : _a.map(function () { return errorType; })) || ts.emptyArray;
+                }
                 var node = type.node;
                 var typeArguments = !node ? ts.emptyArray :
                     node.kind === 168 ? ts.concatenate(type.target.outerTypeParameters, getEffectiveTypeArguments(node, type.target.localTypeParameters)) :
                         node.kind === 173 ? [getTypeFromTypeNode(node.elementType)] :
                             ts.map(node.elementTypes, getTypeFromTypeNode);
-                type.resolvedTypeArguments = type.mapper ? instantiateTypes(typeArguments, type.mapper) : typeArguments;
+                if (popTypeResolution()) {
+                    type.resolvedTypeArguments = type.mapper ? instantiateTypes(typeArguments, type.mapper) : typeArguments;
+                }
+                else {
+                    type.resolvedTypeArguments = ((_b = type.target.localTypeParameters) === null || _b === void 0 ? void 0 : _b.map(function () { return errorType; })) || ts.emptyArray;
+                    error(type.node || currentNode, type.target.symbol
+                        ? ts.Diagnostics.Type_arguments_for_0_circularly_reference_themselves
+                        : ts.Diagnostics.Tuple_type_arguments_circularly_reference_themselves, type.target.symbol && symbolToString(type.target.symbol));
+                }
             }
             return type.resolvedTypeArguments;
         }
@@ -35251,14 +35296,16 @@ var ts;
             var typeType = valueType;
             if (symbol.valueDeclaration) {
                 var decl = ts.getRootDeclaration(symbol.valueDeclaration);
-                var isRequireAlias = ts.isVariableDeclaration(decl)
-                    && decl.initializer
-                    && ts.isCallExpression(decl.initializer)
-                    && ts.isRequireCall(decl.initializer, true)
-                    && valueType.symbol;
-                var isImportType = node.kind === 187;
+                var isRequireAlias = false;
+                if (ts.isVariableDeclaration(decl) && decl.initializer) {
+                    var expr = decl.initializer;
+                    while (ts.isPropertyAccessExpression(expr)) {
+                        expr = expr.expression;
+                    }
+                    isRequireAlias = ts.isCallExpression(expr) && ts.isRequireCall(expr, true) && !!valueType.symbol;
+                }
                 var isDelayedMergeClass = symbol !== valueType.symbol && getMergedSymbol(symbol) === valueType.symbol;
-                if (isRequireAlias || isImportType || isDelayedMergeClass) {
+                if (isRequireAlias || node.kind === 187 || isDelayedMergeClass) {
                     typeType = getTypeReferenceType(node, valueType.symbol);
                 }
             }
@@ -38066,7 +38113,7 @@ var ts;
                 return true;
             }
             if (source.flags & 524288 && target.flags & 524288) {
-                var related = relation.get(getRelationKey(source, target, relation));
+                var related = relation.get(getRelationKey(source, target, false, relation));
                 if (related !== undefined) {
                     return !!(related & 1);
                 }
@@ -38383,7 +38430,7 @@ var ts;
                 var isIntersectionConstituent = !!isApparentIntersectionConstituent;
                 if (source.flags & 1048576) {
                     result = relation === comparableRelation ?
-                        someTypeRelatedToType(source, target, reportErrors && !(source.flags & 131068), isIntersectionConstituent) :
+                        someTypeRelatedToType(source, target, reportErrors && !(source.flags & 131068)) :
                         eachTypeRelatedToType(source, target, reportErrors && !(source.flags & 131068));
                 }
                 else {
@@ -38406,7 +38453,7 @@ var ts;
                         }
                     }
                     else if (source.flags & 2097152) {
-                        result = someTypeRelatedToType(source, target, false, true);
+                        result = someTypeRelatedToType(source, target, false);
                     }
                     if (!result && (source.flags & 66846720 || target.flags & 66846720)) {
                         if (result = recursiveTypeRelatedTo(source, target, reportErrors, isIntersectionConstituent)) {
@@ -38657,14 +38704,14 @@ var ts;
                 }
                 return result;
             }
-            function someTypeRelatedToType(source, target, reportErrors, isIntersectionConstituent) {
+            function someTypeRelatedToType(source, target, reportErrors) {
                 var sourceTypes = source.types;
                 if (source.flags & 1048576 && containsType(sourceTypes, target)) {
                     return -1;
                 }
                 var len = sourceTypes.length;
                 for (var i = 0; i < len; i++) {
-                    var related = isRelatedTo(sourceTypes[i], target, reportErrors && i === len - 1, undefined, isIntersectionConstituent);
+                    var related = isRelatedTo(sourceTypes[i], target, reportErrors && i === len - 1);
                     if (related) {
                         return related;
                     }
@@ -38733,7 +38780,7 @@ var ts;
                 if (overflow) {
                     return 0;
                 }
-                var id = getRelationKey(source, target, relation);
+                var id = getRelationKey(source, target, isIntersectionConstituent, relation);
                 var entry = relation.get(id);
                 if (entry !== undefined) {
                     if (reportErrors && entry & 2 && !(entry & 4)) {
@@ -39747,17 +39794,18 @@ var ts;
             }
             return result;
         }
-        function getRelationKey(source, target, relation) {
+        function getRelationKey(source, target, isIntersectionConstituent, relation) {
             if (relation === identityRelation && source.id > target.id) {
                 var temp = source;
                 source = target;
                 target = temp;
             }
+            var intersection = isIntersectionConstituent ? "&" : "";
             if (isTypeReferenceWithGenericArguments(source) && isTypeReferenceWithGenericArguments(target)) {
                 var typeParameters = [];
-                return getTypeReferenceId(source, typeParameters) + "," + getTypeReferenceId(target, typeParameters);
+                return getTypeReferenceId(source, typeParameters) + "," + getTypeReferenceId(target, typeParameters) + intersection;
             }
-            return source.id + "," + target.id;
+            return source.id + "," + target.id + intersection;
         }
         function forEachProperty(prop, callback) {
             if (ts.getCheckFlags(prop) & 6) {
diff --git a/lib/tsserver.js b/lib/tsserver.js
index e56b826b3fd..0dcbf6ac917 100644
--- a/lib/tsserver.js
+++ b/lib/tsserver.js
@@ -7026,6 +7026,8 @@ var ts;
         Parameter_0_of_accessor_has_or_is_using_private_name_1: diag(4106, ts.DiagnosticCategory.Error, "Parameter_0_of_accessor_has_or_is_using_private_name_1_4106", "Parameter '{0}' of accessor has or is using private name '{1}'."),
         Parameter_0_of_accessor_has_or_is_using_name_1_from_private_module_2: diag(4107, ts.DiagnosticCategory.Error, "Parameter_0_of_accessor_has_or_is_using_name_1_from_private_module_2_4107", "Parameter '{0}' of accessor has or is using name '{1}' from private module '{2}'."),
         Parameter_0_of_accessor_has_or_is_using_name_1_from_external_module_2_but_cannot_be_named: diag(4108, ts.DiagnosticCategory.Error, "Parameter_0_of_accessor_has_or_is_using_name_1_from_external_module_2_but_cannot_be_named_4108", "Parameter '{0}' of accessor has or is using name '{1}' from external module '{2}' but cannot be named."),
+        Type_arguments_for_0_circularly_reference_themselves: diag(4109, ts.DiagnosticCategory.Error, "Type_arguments_for_0_circularly_reference_themselves_4109", "Type arguments for '{0}' circularly reference themselves."),
+        Tuple_type_arguments_circularly_reference_themselves: diag(4110, ts.DiagnosticCategory.Error, "Tuple_type_arguments_circularly_reference_themselves_4110", "Tuple type arguments circularly reference themselves."),
         The_current_host_does_not_support_the_0_option: diag(5001, ts.DiagnosticCategory.Error, "The_current_host_does_not_support_the_0_option_5001", "The current host does not support the '{0}' option."),
         Cannot_find_the_common_subdirectory_path_for_the_input_files: diag(5009, ts.DiagnosticCategory.Error, "Cannot_find_the_common_subdirectory_path_for_the_input_files_5009", "Cannot find the common subdirectory path for the input files."),
         File_specification_cannot_end_in_a_recursive_directory_wildcard_Asterisk_Asterisk_Colon_0: diag(5010, ts.DiagnosticCategory.Error, "File_specification_cannot_end_in_a_recursive_directory_wildcard_Asterisk_Asterisk_Colon_0_5010", "File specification cannot end in a recursive directory wildcard ('**'): '{0}'."),
@@ -32952,6 +32954,7 @@ var ts;
         TypeSystemPropertyName[TypeSystemPropertyName["ImmediateBaseConstraint"] = 4] = "ImmediateBaseConstraint";
         TypeSystemPropertyName[TypeSystemPropertyName["EnumTagType"] = 5] = "EnumTagType";
         TypeSystemPropertyName[TypeSystemPropertyName["JSDocTypeReference"] = 6] = "JSDocTypeReference";
+        TypeSystemPropertyName[TypeSystemPropertyName["ResolvedTypeArguments"] = 7] = "ResolvedTypeArguments";
     })(TypeSystemPropertyName || (TypeSystemPropertyName = {}));
     var CheckMode;
     (function (CheckMode) {
@@ -37348,7 +37351,7 @@ var ts;
                 var visitedSymbols = ts.createMap();
                 var deferredPrivates;
                 var oldcontext = context;
-                context = __assign(__assign({}, oldcontext), { usedSymbolNames: ts.mapMap(symbolTable, function (_symbol, name) { return [ts.unescapeLeadingUnderscores(name), true]; }), remappedSymbolNames: ts.createMap(), tracker: __assign(__assign({}, oldcontext.tracker), { trackSymbol: function (sym, decl, meaning) {
+                context = __assign(__assign({}, oldcontext), { usedSymbolNames: ts.createMap(), remappedSymbolNames: ts.createMap(), tracker: __assign(__assign({}, oldcontext.tracker), { trackSymbol: function (sym, decl, meaning) {
                             var accessibleResult = isSymbolAccessible(sym, decl, meaning, /*computeALiases*/ false);
                             if (accessibleResult.accessibility === 0 /* Accessible */) {
                                 // Lookup the root symbol of the chain of refs we'll use to access it and serialize it
@@ -37366,6 +37369,10 @@ var ts;
                         context.usedSymbolNames.set(name, true);
                     });
                 }
+                ts.forEachEntry(symbolTable, function (symbol, name) {
+                    var baseName = ts.unescapeLeadingUnderscores(name);
+                    void getInternalSymbolName(symbol, baseName); // Called to cache values into `usedSymbolNames` and `remappedSymbolNames`
+                });
                 var addingDeclare = !bundled;
                 var exportEquals = symbolTable.get("export=" /* ExportEquals */);
                 if (exportEquals && symbolTable.size > 1 && exportEquals.flags & 2097152 /* Alias */) {
@@ -37557,7 +37564,11 @@ var ts;
                         isPrivate = true;
                     }
                     var modifierFlags = (!isPrivate ? 1 /* Export */ : 0) | (isDefault && !needsPostExportDefault ? 512 /* Default */ : 0);
-                    if (symbol.flags & 16 /* Function */) {
+                    var isConstMergedWithNS = symbol.flags & 1536 /* Module */ &&
+                        symbol.flags & (2 /* BlockScopedVariable */ | 1 /* FunctionScopedVariable */ | 4 /* Property */) &&
+                        symbol.escapedName !== "export=" /* ExportEquals */;
+                    var isConstMergedWithNSPrintableAsSignatureMerge = isConstMergedWithNS && isTypeRepresentableAsFunctionNamespaceMerge(getTypeOfSymbol(symbol), symbol);
+                    if (symbol.flags & 16 /* Function */ || isConstMergedWithNSPrintableAsSignatureMerge) {
                         serializeAsFunctionNamespaceMerge(getTypeOfSymbol(symbol), symbol, getInternalSymbolName(symbol, symbolName), modifierFlags);
                     }
                     if (symbol.flags & 524288 /* TypeAlias */) {
@@ -37568,7 +37579,8 @@ var ts;
                     if (symbol.flags & (2 /* BlockScopedVariable */ | 1 /* FunctionScopedVariable */ | 4 /* Property */)
                         && symbol.escapedName !== "export=" /* ExportEquals */
                         && !(symbol.flags & 4194304 /* Prototype */)
-                        && !(symbol.flags & 32 /* Class */)) {
+                        && !(symbol.flags & 32 /* Class */)
+                        && !isConstMergedWithNSPrintableAsSignatureMerge) {
                         serializeVariableOrProperty(symbol, symbolName, isPrivate, needsPostExportDefault, propertyAsAlias, modifierFlags);
                     }
                     if (symbol.flags & 384 /* Enum */) {
@@ -37585,7 +37597,7 @@ var ts;
                             serializeAsClass(symbol, getInternalSymbolName(symbol, symbolName), modifierFlags);
                         }
                     }
-                    if (symbol.flags & (512 /* ValueModule */ | 1024 /* NamespaceModule */)) {
+                    if ((symbol.flags & (512 /* ValueModule */ | 1024 /* NamespaceModule */) && (!isConstMergedWithNS || isTypeOnlyNamespace(symbol))) || isConstMergedWithNSPrintableAsSignatureMerge) {
                         serializeModule(symbol, symbolName, modifierFlags);
                     }
                     if (symbol.flags & 64 /* Interface */) {
@@ -37613,7 +37625,10 @@ var ts;
                     }
                 }
                 function includePrivateSymbol(symbol) {
+                    if (ts.some(symbol.declarations, ts.isParameterDeclaration))
+                        return;
                     ts.Debug.assertDefined(deferredPrivates);
+                    getUnusedName(ts.unescapeLeadingUnderscores(symbol.escapedName), symbol); // Call to cache unique name for symbol
                     deferredPrivates.set("" + getSymbolId(symbol), symbol);
                 }
                 function isExportingScope(enclosingDeclaration) {
@@ -37672,8 +37687,14 @@ var ts;
                     /*decorators*/ undefined, 
                     /*modifiers*/ undefined, getInternalSymbolName(symbol, symbolName), typeParamDecls, heritageClauses, __spreadArrays(indexSignatures, constructSignatures, callSignatures, members)), modifierFlags);
                 }
+                function getNamespaceMembersForSerialization(symbol) {
+                    return !symbol.exports ? [] : ts.filter(ts.arrayFrom((symbol.exports).values()), function (p) { return !((p.flags & 4194304 /* Prototype */) || (p.escapedName === "prototype")); });
+                }
+                function isTypeOnlyNamespace(symbol) {
+                    return ts.every(getNamespaceMembersForSerialization(symbol), function (m) { return !(resolveSymbol(m).flags & 111551 /* Value */); });
+                }
                 function serializeModule(symbol, symbolName, modifierFlags) {
-                    var members = !symbol.exports ? [] : ts.filter(ts.arrayFrom((symbol.exports).values()), function (p) { return !((p.flags & 4194304 /* Prototype */) || (p.escapedName === "prototype")); });
+                    var members = getNamespaceMembersForSerialization(symbol);
                     // Split NS members up by declaration - members whose parent symbol is the ns symbol vs those whose is not (but were added in later via merging)
                     var locationMap = ts.arrayToMultiMap(members, function (m) { return m.parent && m.parent === symbol ? "real" : "merged"; });
                     var realMembers = locationMap.get("real") || ts.emptyArray;
@@ -37683,17 +37704,20 @@ var ts;
                     // so we don't even have placeholders to fill in.
                     if (ts.length(realMembers)) {
                         var localName = getInternalSymbolName(symbol, symbolName);
-                        serializeAsNamespaceDeclaration(realMembers, localName, modifierFlags, !!(symbol.flags & 16 /* Function */));
+                        serializeAsNamespaceDeclaration(realMembers, localName, modifierFlags, !!(symbol.flags & (16 /* Function */ | 67108864 /* Assignment */)));
                     }
                     if (ts.length(mergedMembers)) {
                         var localName = getInternalSymbolName(symbol, symbolName);
-                        ts.forEach(mergedMembers, includePrivateSymbol);
                         var nsBody = ts.createModuleBlock([ts.createExportDeclaration(
                             /*decorators*/ undefined, 
                             /*modifiers*/ undefined, ts.createNamedExports(ts.map(ts.filter(mergedMembers, function (n) { return n.escapedName !== "export=" /* ExportEquals */; }), function (s) {
                                 var name = ts.unescapeLeadingUnderscores(s.escapedName);
                                 var localName = getInternalSymbolName(s, name);
-                                return ts.createExportSpecifier(name === localName ? undefined : localName, name);
+                                var aliasDecl = s.declarations && getDeclarationOfAliasSymbol(s);
+                                var target = aliasDecl && getTargetOfAliasDeclaration(aliasDecl, /*dontRecursivelyResolve*/ true);
+                                includePrivateSymbol(target || s);
+                                var targetName = target ? getInternalSymbolName(target, ts.unescapeLeadingUnderscores(target.escapedName)) : localName;
+                                return ts.createExportSpecifier(name === targetName ? undefined : targetName, name);
                             })))]);
                         addResult(ts.createModuleDeclaration(
                         /*decorators*/ undefined, 
@@ -37924,6 +37948,7 @@ var ts;
                             serializeMaybeAliasAssignment(symbol);
                             break;
                         case 208 /* BinaryExpression */:
+                        case 193 /* PropertyAccessExpression */:
                             // Could be best encoded as though an export specifier or as though an export assignment
                             // If name is default or export=, do an export assignment
                             // Otherwise do an export specifier
@@ -37934,10 +37959,6 @@ var ts;
                                 serializeExportSpecifier(localName, targetName);
                             }
                             break;
-                        case 193 /* PropertyAccessExpression */:
-                            // A PAE alias is _always_ going to exist as an append to a top-level export, where our top level
-                            // handling should always be sufficient to encode the export action itself
-                            break;
                         default:
                             return ts.Debug.failBadSyntaxKind(node, "Unhandled alias declaration kind in symbol serializer!");
                     }
@@ -37961,7 +37982,8 @@ var ts;
                     var aliasDecl = symbol.declarations && getDeclarationOfAliasSymbol(symbol);
                     // serialize what the alias points to, preserve the declaration's initializer
                     var target = aliasDecl && getTargetOfAliasDeclaration(aliasDecl, /*dontRecursivelyResolve*/ true);
-                    if (target) {
+                    // If the target resolves and resolves to a thing defined in this file, emit as an alias, otherwise emit as a const
+                    if (target && ts.length(target.declarations) && ts.some(target.declarations, function (d) { return ts.getSourceFileOfNode(d) === ts.getSourceFileOfNode(enclosingDeclaration); })) {
                         // In case `target` refers to a namespace member, look at the declaration and serialize the leftmost symbol in it
                         // eg, `namespace A { export class B {} }; exports = A.B;`
                         // Technically, this is all that's required in the case where the assignment is an entity name expression
@@ -38036,6 +38058,7 @@ var ts;
                     return ts.getObjectFlags(typeToSerialize) & (16 /* Anonymous */ | 32 /* Mapped */) &&
                         !getIndexInfoOfType(typeToSerialize, 0 /* String */) &&
                         !getIndexInfoOfType(typeToSerialize, 1 /* Number */) &&
+                        !!(ts.length(getPropertiesOfType(typeToSerialize)) || ts.length(getSignaturesOfType(typeToSerialize, 0 /* Call */))) &&
                         !ts.length(getSignaturesOfType(typeToSerialize, 1 /* Construct */)) && // TODO: could probably serialize as function + ns + class, now that that's OK
                         !getDeclarationWithTypeAnnotation(hostSymbol) &&
                         !(typeToSerialize.symbol && ts.some(typeToSerialize.symbol.declarations, function (d) { return ts.getSourceFileOfNode(d) !== ctxSrc; })) &&
@@ -38309,11 +38332,8 @@ var ts;
                             return context.remappedSymbolNames.get("" + getSymbolId(symbol));
                         }
                     }
-                    if (input === "default" /* Default */) {
-                        input = "_default";
-                    }
-                    else if (input === "export=" /* ExportEquals */) {
-                        input = "_exports";
+                    if (symbol) {
+                        input = getNameCandidateWorker(symbol, input);
                     }
                     var i = 0;
                     var original = input;
@@ -38327,17 +38347,28 @@ var ts;
                     }
                     return input;
                 }
-                function getInternalSymbolName(symbol, localName) {
-                    if (context.remappedSymbolNames.has("" + getSymbolId(symbol))) {
-                        return context.remappedSymbolNames.get("" + getSymbolId(symbol));
-                    }
+                function getNameCandidateWorker(symbol, localName) {
                     if (localName === "default" /* Default */ || localName === "__class" /* Class */ || localName === "__function" /* Function */) {
                         var flags = context.flags;
                         context.flags |= 16777216 /* InInitialEntityName */;
                         var nameCandidate = getNameOfSymbolAsWritten(symbol, context);
                         context.flags = flags;
-                        localName = ts.isIdentifierText(nameCandidate, languageVersion) && !ts.isStringANonContextualKeyword(nameCandidate) ? nameCandidate : getUnusedName("_default", symbol);
+                        localName = nameCandidate.length > 0 && ts.isSingleOrDoubleQuote(nameCandidate.charCodeAt(0)) ? ts.stripQuotes(nameCandidate) : nameCandidate;
                     }
+                    if (localName === "default" /* Default */) {
+                        localName = "_default";
+                    }
+                    else if (localName === "export=" /* ExportEquals */) {
+                        localName = "_exports";
+                    }
+                    localName = ts.isIdentifierText(localName, languageVersion) && !ts.isStringANonContextualKeyword(localName) ? localName : "_" + localName.replace(/[^a-zA-Z0-9]/g, "_");
+                    return localName;
+                }
+                function getInternalSymbolName(symbol, localName) {
+                    if (context.remappedSymbolNames.has("" + getSymbolId(symbol))) {
+                        return context.remappedSymbolNames.get("" + getSymbolId(symbol));
+                    }
+                    localName = getNameCandidateWorker(symbol, localName);
                     // The result of this is going to be used as the symbol's name - lock it in, so `getUnusedName` will also pick it up
                     context.remappedSymbolNames.set("" + getSymbolId(symbol), localName);
                     return localName;
@@ -38666,6 +38697,8 @@ var ts;
                     return !!target.immediateBaseConstraint;
                 case 6 /* JSDocTypeReference */:
                     return !!getSymbolLinks(target).resolvedJSDocType;
+                case 7 /* ResolvedTypeArguments */:
+                    return !!target.resolvedTypeArguments;
             }
             return ts.Debug.assertNever(propertyName);
         }
@@ -42472,13 +42505,25 @@ var ts;
             return type;
         }
         function getTypeArguments(type) {
+            var _a, _b;
             if (!type.resolvedTypeArguments) {
+                if (!pushTypeResolution(type, 7 /* ResolvedTypeArguments */)) {
+                    return ((_a = type.target.localTypeParameters) === null || _a === void 0 ? void 0 : _a.map(function () { return errorType; })) || ts.emptyArray;
+                }
                 var node = type.node;
                 var typeArguments = !node ? ts.emptyArray :
                     node.kind === 168 /* TypeReference */ ? ts.concatenate(type.target.outerTypeParameters, getEffectiveTypeArguments(node, type.target.localTypeParameters)) :
                         node.kind === 173 /* ArrayType */ ? [getTypeFromTypeNode(node.elementType)] :
                             ts.map(node.elementTypes, getTypeFromTypeNode);
-                type.resolvedTypeArguments = type.mapper ? instantiateTypes(typeArguments, type.mapper) : typeArguments;
+                if (popTypeResolution()) {
+                    type.resolvedTypeArguments = type.mapper ? instantiateTypes(typeArguments, type.mapper) : typeArguments;
+                }
+                else {
+                    type.resolvedTypeArguments = ((_b = type.target.localTypeParameters) === null || _b === void 0 ? void 0 : _b.map(function () { return errorType; })) || ts.emptyArray;
+                    error(type.node || currentNode, type.target.symbol
+                        ? ts.Diagnostics.Type_arguments_for_0_circularly_reference_themselves
+                        : ts.Diagnostics.Tuple_type_arguments_circularly_reference_themselves, type.target.symbol && symbolToString(type.target.symbol));
+                }
             }
             return type.resolvedTypeArguments;
         }
@@ -42617,14 +42662,17 @@ var ts;
             var typeType = valueType;
             if (symbol.valueDeclaration) {
                 var decl = ts.getRootDeclaration(symbol.valueDeclaration);
-                var isRequireAlias = ts.isVariableDeclaration(decl)
-                    && decl.initializer
-                    && ts.isCallExpression(decl.initializer)
-                    && ts.isRequireCall(decl.initializer, /*requireStringLiteralLikeArgument*/ true)
-                    && valueType.symbol;
-                var isImportType = node.kind === 187 /* ImportType */;
+                var isRequireAlias = false;
+                if (ts.isVariableDeclaration(decl) && decl.initializer) {
+                    var expr = decl.initializer;
+                    // skip past entity names, eg `require("x").a.b.c`
+                    while (ts.isPropertyAccessExpression(expr)) {
+                        expr = expr.expression;
+                    }
+                    isRequireAlias = ts.isCallExpression(expr) && ts.isRequireCall(expr, /*requireStringLiteralLikeArgument*/ true) && !!valueType.symbol;
+                }
                 var isDelayedMergeClass = symbol !== valueType.symbol && getMergedSymbol(symbol) === valueType.symbol;
-                if (isRequireAlias || isImportType || isDelayedMergeClass) {
+                if (isRequireAlias || node.kind === 187 /* ImportType */ || isDelayedMergeClass) {
                     typeType = getTypeReferenceType(node, valueType.symbol);
                 }
             }
@@ -45747,7 +45795,7 @@ var ts;
                 return true;
             }
             if (source.flags & 524288 /* Object */ && target.flags & 524288 /* Object */) {
-                var related = relation.get(getRelationKey(source, target, relation));
+                var related = relation.get(getRelationKey(source, target, /*isIntersectionConstituent*/ false, relation));
                 if (related !== undefined) {
                     return !!(related & 1 /* Succeeded */);
                 }
@@ -46118,7 +46166,7 @@ var ts;
                 // and we need to handle "each" relations before "some" relations for the same kind of type.
                 if (source.flags & 1048576 /* Union */) {
                     result = relation === comparableRelation ?
-                        someTypeRelatedToType(source, target, reportErrors && !(source.flags & 131068 /* Primitive */), isIntersectionConstituent) :
+                        someTypeRelatedToType(source, target, reportErrors && !(source.flags & 131068 /* Primitive */)) :
                         eachTypeRelatedToType(source, target, reportErrors && !(source.flags & 131068 /* Primitive */));
                 }
                 else {
@@ -46156,7 +46204,7 @@ var ts;
                         //
                         //    - For a primitive type or type parameter (such as 'number = A & B') there is no point in
                         //          breaking the intersection apart.
-                        result = someTypeRelatedToType(source, target, /*reportErrors*/ false, /*isIntersectionConstituent*/ true);
+                        result = someTypeRelatedToType(source, target, /*reportErrors*/ false);
                     }
                     if (!result && (source.flags & 66846720 /* StructuredOrInstantiable */ || target.flags & 66846720 /* StructuredOrInstantiable */)) {
                         if (result = recursiveTypeRelatedTo(source, target, reportErrors, isIntersectionConstituent)) {
@@ -46440,14 +46488,14 @@ var ts;
                 }
                 return result;
             }
-            function someTypeRelatedToType(source, target, reportErrors, isIntersectionConstituent) {
+            function someTypeRelatedToType(source, target, reportErrors) {
                 var sourceTypes = source.types;
                 if (source.flags & 1048576 /* Union */ && containsType(sourceTypes, target)) {
                     return -1 /* True */;
                 }
                 var len = sourceTypes.length;
                 for (var i = 0; i < len; i++) {
-                    var related = isRelatedTo(sourceTypes[i], target, reportErrors && i === len - 1, /*headMessage*/ undefined, isIntersectionConstituent);
+                    var related = isRelatedTo(sourceTypes[i], target, reportErrors && i === len - 1);
                     if (related) {
                         return related;
                     }
@@ -46535,7 +46583,7 @@ var ts;
                 if (overflow) {
                     return 0 /* False */;
                 }
-                var id = getRelationKey(source, target, relation);
+                var id = getRelationKey(source, target, isIntersectionConstituent, relation);
                 var entry = relation.get(id);
                 if (entry !== undefined) {
                     if (reportErrors && entry & 2 /* Failed */ && !(entry & 4 /* Reported */)) {
@@ -47721,17 +47769,18 @@ var ts;
          * To improve caching, the relation key for two generic types uses the target's id plus ids of the type parameters.
          * For other cases, the types ids are used.
          */
-        function getRelationKey(source, target, relation) {
+        function getRelationKey(source, target, isIntersectionConstituent, relation) {
             if (relation === identityRelation && source.id > target.id) {
                 var temp = source;
                 source = target;
                 target = temp;
             }
+            var intersection = isIntersectionConstituent ? "&" : "";
             if (isTypeReferenceWithGenericArguments(source) && isTypeReferenceWithGenericArguments(target)) {
                 var typeParameters = [];
-                return getTypeReferenceId(source, typeParameters) + "," + getTypeReferenceId(target, typeParameters);
+                return getTypeReferenceId(source, typeParameters) + "," + getTypeReferenceId(target, typeParameters) + intersection;
             }
-            return source.id + "," + target.id;
+            return source.id + "," + target.id + intersection;
         }
         // Invoke the callback for each underlying property symbol of the given symbol and return the first
         // value that isn't undefined.
diff --git a/lib/tsserverlibrary.js b/lib/tsserverlibrary.js
index 8b63ee9abd8..ecaed3c11ad 100644
--- a/lib/tsserverlibrary.js
+++ b/lib/tsserverlibrary.js
@@ -7176,6 +7176,8 @@ var ts;
         Parameter_0_of_accessor_has_or_is_using_private_name_1: diag(4106, ts.DiagnosticCategory.Error, "Parameter_0_of_accessor_has_or_is_using_private_name_1_4106", "Parameter '{0}' of accessor has or is using private name '{1}'."),
         Parameter_0_of_accessor_has_or_is_using_name_1_from_private_module_2: diag(4107, ts.DiagnosticCategory.Error, "Parameter_0_of_accessor_has_or_is_using_name_1_from_private_module_2_4107", "Parameter '{0}' of accessor has or is using name '{1}' from private module '{2}'."),
         Parameter_0_of_accessor_has_or_is_using_name_1_from_external_module_2_but_cannot_be_named: diag(4108, ts.DiagnosticCategory.Error, "Parameter_0_of_accessor_has_or_is_using_name_1_from_external_module_2_but_cannot_be_named_4108", "Parameter '{0}' of accessor has or is using name '{1}' from external module '{2}' but cannot be named."),
+        Type_arguments_for_0_circularly_reference_themselves: diag(4109, ts.DiagnosticCategory.Error, "Type_arguments_for_0_circularly_reference_themselves_4109", "Type arguments for '{0}' circularly reference themselves."),
+        Tuple_type_arguments_circularly_reference_themselves: diag(4110, ts.DiagnosticCategory.Error, "Tuple_type_arguments_circularly_reference_themselves_4110", "Tuple type arguments circularly reference themselves."),
         The_current_host_does_not_support_the_0_option: diag(5001, ts.DiagnosticCategory.Error, "The_current_host_does_not_support_the_0_option_5001", "The current host does not support the '{0}' option."),
         Cannot_find_the_common_subdirectory_path_for_the_input_files: diag(5009, ts.DiagnosticCategory.Error, "Cannot_find_the_common_subdirectory_path_for_the_input_files_5009", "Cannot find the common subdirectory path for the input files."),
         File_specification_cannot_end_in_a_recursive_directory_wildcard_Asterisk_Asterisk_Colon_0: diag(5010, ts.DiagnosticCategory.Error, "File_specification_cannot_end_in_a_recursive_directory_wildcard_Asterisk_Asterisk_Colon_0_5010", "File specification cannot end in a recursive directory wildcard ('**'): '{0}'."),
@@ -33102,6 +33104,7 @@ var ts;
         TypeSystemPropertyName[TypeSystemPropertyName["ImmediateBaseConstraint"] = 4] = "ImmediateBaseConstraint";
         TypeSystemPropertyName[TypeSystemPropertyName["EnumTagType"] = 5] = "EnumTagType";
         TypeSystemPropertyName[TypeSystemPropertyName["JSDocTypeReference"] = 6] = "JSDocTypeReference";
+        TypeSystemPropertyName[TypeSystemPropertyName["ResolvedTypeArguments"] = 7] = "ResolvedTypeArguments";
     })(TypeSystemPropertyName || (TypeSystemPropertyName = {}));
     var CheckMode;
     (function (CheckMode) {
@@ -37498,7 +37501,7 @@ var ts;
                 var visitedSymbols = ts.createMap();
                 var deferredPrivates;
                 var oldcontext = context;
-                context = __assign(__assign({}, oldcontext), { usedSymbolNames: ts.mapMap(symbolTable, function (_symbol, name) { return [ts.unescapeLeadingUnderscores(name), true]; }), remappedSymbolNames: ts.createMap(), tracker: __assign(__assign({}, oldcontext.tracker), { trackSymbol: function (sym, decl, meaning) {
+                context = __assign(__assign({}, oldcontext), { usedSymbolNames: ts.createMap(), remappedSymbolNames: ts.createMap(), tracker: __assign(__assign({}, oldcontext.tracker), { trackSymbol: function (sym, decl, meaning) {
                             var accessibleResult = isSymbolAccessible(sym, decl, meaning, /*computeALiases*/ false);
                             if (accessibleResult.accessibility === 0 /* Accessible */) {
                                 // Lookup the root symbol of the chain of refs we'll use to access it and serialize it
@@ -37516,6 +37519,10 @@ var ts;
                         context.usedSymbolNames.set(name, true);
                     });
                 }
+                ts.forEachEntry(symbolTable, function (symbol, name) {
+                    var baseName = ts.unescapeLeadingUnderscores(name);
+                    void getInternalSymbolName(symbol, baseName); // Called to cache values into `usedSymbolNames` and `remappedSymbolNames`
+                });
                 var addingDeclare = !bundled;
                 var exportEquals = symbolTable.get("export=" /* ExportEquals */);
                 if (exportEquals && symbolTable.size > 1 && exportEquals.flags & 2097152 /* Alias */) {
@@ -37707,7 +37714,11 @@ var ts;
                         isPrivate = true;
                     }
                     var modifierFlags = (!isPrivate ? 1 /* Export */ : 0) | (isDefault && !needsPostExportDefault ? 512 /* Default */ : 0);
-                    if (symbol.flags & 16 /* Function */) {
+                    var isConstMergedWithNS = symbol.flags & 1536 /* Module */ &&
+                        symbol.flags & (2 /* BlockScopedVariable */ | 1 /* FunctionScopedVariable */ | 4 /* Property */) &&
+                        symbol.escapedName !== "export=" /* ExportEquals */;
+                    var isConstMergedWithNSPrintableAsSignatureMerge = isConstMergedWithNS && isTypeRepresentableAsFunctionNamespaceMerge(getTypeOfSymbol(symbol), symbol);
+                    if (symbol.flags & 16 /* Function */ || isConstMergedWithNSPrintableAsSignatureMerge) {
                         serializeAsFunctionNamespaceMerge(getTypeOfSymbol(symbol), symbol, getInternalSymbolName(symbol, symbolName), modifierFlags);
                     }
                     if (symbol.flags & 524288 /* TypeAlias */) {
@@ -37718,7 +37729,8 @@ var ts;
                     if (symbol.flags & (2 /* BlockScopedVariable */ | 1 /* FunctionScopedVariable */ | 4 /* Property */)
                         && symbol.escapedName !== "export=" /* ExportEquals */
                         && !(symbol.flags & 4194304 /* Prototype */)
-                        && !(symbol.flags & 32 /* Class */)) {
+                        && !(symbol.flags & 32 /* Class */)
+                        && !isConstMergedWithNSPrintableAsSignatureMerge) {
                         serializeVariableOrProperty(symbol, symbolName, isPrivate, needsPostExportDefault, propertyAsAlias, modifierFlags);
                     }
                     if (symbol.flags & 384 /* Enum */) {
@@ -37735,7 +37747,7 @@ var ts;
                             serializeAsClass(symbol, getInternalSymbolName(symbol, symbolName), modifierFlags);
                         }
                     }
-                    if (symbol.flags & (512 /* ValueModule */ | 1024 /* NamespaceModule */)) {
+                    if ((symbol.flags & (512 /* ValueModule */ | 1024 /* NamespaceModule */) && (!isConstMergedWithNS || isTypeOnlyNamespace(symbol))) || isConstMergedWithNSPrintableAsSignatureMerge) {
                         serializeModule(symbol, symbolName, modifierFlags);
                     }
                     if (symbol.flags & 64 /* Interface */) {
@@ -37763,7 +37775,10 @@ var ts;
                     }
                 }
                 function includePrivateSymbol(symbol) {
+                    if (ts.some(symbol.declarations, ts.isParameterDeclaration))
+                        return;
                     ts.Debug.assertDefined(deferredPrivates);
+                    getUnusedName(ts.unescapeLeadingUnderscores(symbol.escapedName), symbol); // Call to cache unique name for symbol
                     deferredPrivates.set("" + getSymbolId(symbol), symbol);
                 }
                 function isExportingScope(enclosingDeclaration) {
@@ -37822,8 +37837,14 @@ var ts;
                     /*decorators*/ undefined, 
                     /*modifiers*/ undefined, getInternalSymbolName(symbol, symbolName), typeParamDecls, heritageClauses, __spreadArrays(indexSignatures, constructSignatures, callSignatures, members)), modifierFlags);
                 }
+                function getNamespaceMembersForSerialization(symbol) {
+                    return !symbol.exports ? [] : ts.filter(ts.arrayFrom((symbol.exports).values()), function (p) { return !((p.flags & 4194304 /* Prototype */) || (p.escapedName === "prototype")); });
+                }
+                function isTypeOnlyNamespace(symbol) {
+                    return ts.every(getNamespaceMembersForSerialization(symbol), function (m) { return !(resolveSymbol(m).flags & 111551 /* Value */); });
+                }
                 function serializeModule(symbol, symbolName, modifierFlags) {
-                    var members = !symbol.exports ? [] : ts.filter(ts.arrayFrom((symbol.exports).values()), function (p) { return !((p.flags & 4194304 /* Prototype */) || (p.escapedName === "prototype")); });
+                    var members = getNamespaceMembersForSerialization(symbol);
                     // Split NS members up by declaration - members whose parent symbol is the ns symbol vs those whose is not (but were added in later via merging)
                     var locationMap = ts.arrayToMultiMap(members, function (m) { return m.parent && m.parent === symbol ? "real" : "merged"; });
                     var realMembers = locationMap.get("real") || ts.emptyArray;
@@ -37833,17 +37854,20 @@ var ts;
                     // so we don't even have placeholders to fill in.
                     if (ts.length(realMembers)) {
                         var localName = getInternalSymbolName(symbol, symbolName);
-                        serializeAsNamespaceDeclaration(realMembers, localName, modifierFlags, !!(symbol.flags & 16 /* Function */));
+                        serializeAsNamespaceDeclaration(realMembers, localName, modifierFlags, !!(symbol.flags & (16 /* Function */ | 67108864 /* Assignment */)));
                     }
                     if (ts.length(mergedMembers)) {
                         var localName = getInternalSymbolName(symbol, symbolName);
-                        ts.forEach(mergedMembers, includePrivateSymbol);
                         var nsBody = ts.createModuleBlock([ts.createExportDeclaration(
                             /*decorators*/ undefined, 
                             /*modifiers*/ undefined, ts.createNamedExports(ts.map(ts.filter(mergedMembers, function (n) { return n.escapedName !== "export=" /* ExportEquals */; }), function (s) {
                                 var name = ts.unescapeLeadingUnderscores(s.escapedName);
                                 var localName = getInternalSymbolName(s, name);
-                                return ts.createExportSpecifier(name === localName ? undefined : localName, name);
+                                var aliasDecl = s.declarations && getDeclarationOfAliasSymbol(s);
+                                var target = aliasDecl && getTargetOfAliasDeclaration(aliasDecl, /*dontRecursivelyResolve*/ true);
+                                includePrivateSymbol(target || s);
+                                var targetName = target ? getInternalSymbolName(target, ts.unescapeLeadingUnderscores(target.escapedName)) : localName;
+                                return ts.createExportSpecifier(name === targetName ? undefined : targetName, name);
                             })))]);
                         addResult(ts.createModuleDeclaration(
                         /*decorators*/ undefined, 
@@ -38074,6 +38098,7 @@ var ts;
                             serializeMaybeAliasAssignment(symbol);
                             break;
                         case 208 /* BinaryExpression */:
+                        case 193 /* PropertyAccessExpression */:
                             // Could be best encoded as though an export specifier or as though an export assignment
                             // If name is default or export=, do an export assignment
                             // Otherwise do an export specifier
@@ -38084,10 +38109,6 @@ var ts;
                                 serializeExportSpecifier(localName, targetName);
                             }
                             break;
-                        case 193 /* PropertyAccessExpression */:
-                            // A PAE alias is _always_ going to exist as an append to a top-level export, where our top level
-                            // handling should always be sufficient to encode the export action itself
-                            break;
                         default:
                             return ts.Debug.failBadSyntaxKind(node, "Unhandled alias declaration kind in symbol serializer!");
                     }
@@ -38111,7 +38132,8 @@ var ts;
                     var aliasDecl = symbol.declarations && getDeclarationOfAliasSymbol(symbol);
                     // serialize what the alias points to, preserve the declaration's initializer
                     var target = aliasDecl && getTargetOfAliasDeclaration(aliasDecl, /*dontRecursivelyResolve*/ true);
-                    if (target) {
+                    // If the target resolves and resolves to a thing defined in this file, emit as an alias, otherwise emit as a const
+                    if (target && ts.length(target.declarations) && ts.some(target.declarations, function (d) { return ts.getSourceFileOfNode(d) === ts.getSourceFileOfNode(enclosingDeclaration); })) {
                         // In case `target` refers to a namespace member, look at the declaration and serialize the leftmost symbol in it
                         // eg, `namespace A { export class B {} }; exports = A.B;`
                         // Technically, this is all that's required in the case where the assignment is an entity name expression
@@ -38186,6 +38208,7 @@ var ts;
                     return ts.getObjectFlags(typeToSerialize) & (16 /* Anonymous */ | 32 /* Mapped */) &&
                         !getIndexInfoOfType(typeToSerialize, 0 /* String */) &&
                         !getIndexInfoOfType(typeToSerialize, 1 /* Number */) &&
+                        !!(ts.length(getPropertiesOfType(typeToSerialize)) || ts.length(getSignaturesOfType(typeToSerialize, 0 /* Call */))) &&
                         !ts.length(getSignaturesOfType(typeToSerialize, 1 /* Construct */)) && // TODO: could probably serialize as function + ns + class, now that that's OK
                         !getDeclarationWithTypeAnnotation(hostSymbol) &&
                         !(typeToSerialize.symbol && ts.some(typeToSerialize.symbol.declarations, function (d) { return ts.getSourceFileOfNode(d) !== ctxSrc; })) &&
@@ -38459,11 +38482,8 @@ var ts;
                             return context.remappedSymbolNames.get("" + getSymbolId(symbol));
                         }
                     }
-                    if (input === "default" /* Default */) {
-                        input = "_default";
-                    }
-                    else if (input === "export=" /* ExportEquals */) {
-                        input = "_exports";
+                    if (symbol) {
+                        input = getNameCandidateWorker(symbol, input);
                     }
                     var i = 0;
                     var original = input;
@@ -38477,17 +38497,28 @@ var ts;
                     }
                     return input;
                 }
-                function getInternalSymbolName(symbol, localName) {
-                    if (context.remappedSymbolNames.has("" + getSymbolId(symbol))) {
-                        return context.remappedSymbolNames.get("" + getSymbolId(symbol));
-                    }
+                function getNameCandidateWorker(symbol, localName) {
                     if (localName === "default" /* Default */ || localName === "__class" /* Class */ || localName === "__function" /* Function */) {
                         var flags = context.flags;
                         context.flags |= 16777216 /* InInitialEntityName */;
                         var nameCandidate = getNameOfSymbolAsWritten(symbol, context);
                         context.flags = flags;
-                        localName = ts.isIdentifierText(nameCandidate, languageVersion) && !ts.isStringANonContextualKeyword(nameCandidate) ? nameCandidate : getUnusedName("_default", symbol);
+                        localName = nameCandidate.length > 0 && ts.isSingleOrDoubleQuote(nameCandidate.charCodeAt(0)) ? ts.stripQuotes(nameCandidate) : nameCandidate;
                     }
+                    if (localName === "default" /* Default */) {
+                        localName = "_default";
+                    }
+                    else if (localName === "export=" /* ExportEquals */) {
+                        localName = "_exports";
+                    }
+                    localName = ts.isIdentifierText(localName, languageVersion) && !ts.isStringANonContextualKeyword(localName) ? localName : "_" + localName.replace(/[^a-zA-Z0-9]/g, "_");
+                    return localName;
+                }
+                function getInternalSymbolName(symbol, localName) {
+                    if (context.remappedSymbolNames.has("" + getSymbolId(symbol))) {
+                        return context.remappedSymbolNames.get("" + getSymbolId(symbol));
+                    }
+                    localName = getNameCandidateWorker(symbol, localName);
                     // The result of this is going to be used as the symbol's name - lock it in, so `getUnusedName` will also pick it up
                     context.remappedSymbolNames.set("" + getSymbolId(symbol), localName);
                     return localName;
@@ -38816,6 +38847,8 @@ var ts;
                     return !!target.immediateBaseConstraint;
                 case 6 /* JSDocTypeReference */:
                     return !!getSymbolLinks(target).resolvedJSDocType;
+                case 7 /* ResolvedTypeArguments */:
+                    return !!target.resolvedTypeArguments;
             }
             return ts.Debug.assertNever(propertyName);
         }
@@ -42622,13 +42655,25 @@ var ts;
             return type;
         }
         function getTypeArguments(type) {
+            var _a, _b;
             if (!type.resolvedTypeArguments) {
+                if (!pushTypeResolution(type, 7 /* ResolvedTypeArguments */)) {
+                    return ((_a = type.target.localTypeParameters) === null || _a === void 0 ? void 0 : _a.map(function () { return errorType; })) || ts.emptyArray;
+                }
                 var node = type.node;
                 var typeArguments = !node ? ts.emptyArray :
                     node.kind === 168 /* TypeReference */ ? ts.concatenate(type.target.outerTypeParameters, getEffectiveTypeArguments(node, type.target.localTypeParameters)) :
                         node.kind === 173 /* ArrayType */ ? [getTypeFromTypeNode(node.elementType)] :
                             ts.map(node.elementTypes, getTypeFromTypeNode);
-                type.resolvedTypeArguments = type.mapper ? instantiateTypes(typeArguments, type.mapper) : typeArguments;
+                if (popTypeResolution()) {
+                    type.resolvedTypeArguments = type.mapper ? instantiateTypes(typeArguments, type.mapper) : typeArguments;
+                }
+                else {
+                    type.resolvedTypeArguments = ((_b = type.target.localTypeParameters) === null || _b === void 0 ? void 0 : _b.map(function () { return errorType; })) || ts.emptyArray;
+                    error(type.node || currentNode, type.target.symbol
+                        ? ts.Diagnostics.Type_arguments_for_0_circularly_reference_themselves
+                        : ts.Diagnostics.Tuple_type_arguments_circularly_reference_themselves, type.target.symbol && symbolToString(type.target.symbol));
+                }
             }
             return type.resolvedTypeArguments;
         }
@@ -42767,14 +42812,17 @@ var ts;
             var typeType = valueType;
             if (symbol.valueDeclaration) {
                 var decl = ts.getRootDeclaration(symbol.valueDeclaration);
-                var isRequireAlias = ts.isVariableDeclaration(decl)
-                    && decl.initializer
-                    && ts.isCallExpression(decl.initializer)
-                    && ts.isRequireCall(decl.initializer, /*requireStringLiteralLikeArgument*/ true)
-                    && valueType.symbol;
-                var isImportType = node.kind === 187 /* ImportType */;
+                var isRequireAlias = false;
+                if (ts.isVariableDeclaration(decl) && decl.initializer) {
+                    var expr = decl.initializer;
+                    // skip past entity names, eg `require("x").a.b.c`
+                    while (ts.isPropertyAccessExpression(expr)) {
+                        expr = expr.expression;
+                    }
+                    isRequireAlias = ts.isCallExpression(expr) && ts.isRequireCall(expr, /*requireStringLiteralLikeArgument*/ true) && !!valueType.symbol;
+                }
                 var isDelayedMergeClass = symbol !== valueType.symbol && getMergedSymbol(symbol) === valueType.symbol;
-                if (isRequireAlias || isImportType || isDelayedMergeClass) {
+                if (isRequireAlias || node.kind === 187 /* ImportType */ || isDelayedMergeClass) {
                     typeType = getTypeReferenceType(node, valueType.symbol);
                 }
             }
@@ -45897,7 +45945,7 @@ var ts;
                 return true;
             }
             if (source.flags & 524288 /* Object */ && target.flags & 524288 /* Object */) {
-                var related = relation.get(getRelationKey(source, target, relation));
+                var related = relation.get(getRelationKey(source, target, /*isIntersectionConstituent*/ false, relation));
                 if (related !== undefined) {
                     return !!(related & 1 /* Succeeded */);
                 }
@@ -46268,7 +46316,7 @@ var ts;
                 // and we need to handle "each" relations before "some" relations for the same kind of type.
                 if (source.flags & 1048576 /* Union */) {
                     result = relation === comparableRelation ?
-                        someTypeRelatedToType(source, target, reportErrors && !(source.flags & 131068 /* Primitive */), isIntersectionConstituent) :
+                        someTypeRelatedToType(source, target, reportErrors && !(source.flags & 131068 /* Primitive */)) :
                         eachTypeRelatedToType(source, target, reportErrors && !(source.flags & 131068 /* Primitive */));
                 }
                 else {
@@ -46306,7 +46354,7 @@ var ts;
                         //
                         //    - For a primitive type or type parameter (such as 'number = A & B') there is no point in
                         //          breaking the intersection apart.
-                        result = someTypeRelatedToType(source, target, /*reportErrors*/ false, /*isIntersectionConstituent*/ true);
+                        result = someTypeRelatedToType(source, target, /*reportErrors*/ false);
                     }
                     if (!result && (source.flags & 66846720 /* StructuredOrInstantiable */ || target.flags & 66846720 /* StructuredOrInstantiable */)) {
                         if (result = recursiveTypeRelatedTo(source, target, reportErrors, isIntersectionConstituent)) {
@@ -46590,14 +46638,14 @@ var ts;
                 }
                 return result;
             }
-            function someTypeRelatedToType(source, target, reportErrors, isIntersectionConstituent) {
+            function someTypeRelatedToType(source, target, reportErrors) {
                 var sourceTypes = source.types;
                 if (source.flags & 1048576 /* Union */ && containsType(sourceTypes, target)) {
                     return -1 /* True */;
                 }
                 var len = sourceTypes.length;
                 for (var i = 0; i < len; i++) {
-                    var related = isRelatedTo(sourceTypes[i], target, reportErrors && i === len - 1, /*headMessage*/ undefined, isIntersectionConstituent);
+                    var related = isRelatedTo(sourceTypes[i], target, reportErrors && i === len - 1);
                     if (related) {
                         return related;
                     }
@@ -46685,7 +46733,7 @@ var ts;
                 if (overflow) {
                     return 0 /* False */;
                 }
-                var id = getRelationKey(source, target, relation);
+                var id = getRelationKey(source, target, isIntersectionConstituent, relation);
                 var entry = relation.get(id);
                 if (entry !== undefined) {
                     if (reportErrors && entry & 2 /* Failed */ && !(entry & 4 /* Reported */)) {
@@ -47871,17 +47919,18 @@ var ts;
          * To improve caching, the relation key for two generic types uses the target's id plus ids of the type parameters.
          * For other cases, the types ids are used.
          */
-        function getRelationKey(source, target, relation) {
+        function getRelationKey(source, target, isIntersectionConstituent, relation) {
             if (relation === identityRelation && source.id > target.id) {
                 var temp = source;
                 source = target;
                 target = temp;
             }
+            var intersection = isIntersectionConstituent ? "&" : "";
             if (isTypeReferenceWithGenericArguments(source) && isTypeReferenceWithGenericArguments(target)) {
                 var typeParameters = [];
-                return getTypeReferenceId(source, typeParameters) + "," + getTypeReferenceId(target, typeParameters);
+                return getTypeReferenceId(source, typeParameters) + "," + getTypeReferenceId(target, typeParameters) + intersection;
             }
-            return source.id + "," + target.id;
+            return source.id + "," + target.id + intersection;
         }
         // Invoke the callback for each underlying property symbol of the given symbol and return the first
         // value that isn't undefined.
diff --git a/lib/typescript.js b/lib/typescript.js
index 9be4787be27..7d9452c7b39 100644
--- a/lib/typescript.js
+++ b/lib/typescript.js
@@ -7165,6 +7165,8 @@ var ts;
         Parameter_0_of_accessor_has_or_is_using_private_name_1: diag(4106, ts.DiagnosticCategory.Error, "Parameter_0_of_accessor_has_or_is_using_private_name_1_4106", "Parameter '{0}' of accessor has or is using private name '{1}'."),
         Parameter_0_of_accessor_has_or_is_using_name_1_from_private_module_2: diag(4107, ts.DiagnosticCategory.Error, "Parameter_0_of_accessor_has_or_is_using_name_1_from_private_module_2_4107", "Parameter '{0}' of accessor has or is using name '{1}' from private module '{2}'."),
         Parameter_0_of_accessor_has_or_is_using_name_1_from_external_module_2_but_cannot_be_named: diag(4108, ts.DiagnosticCategory.Error, "Parameter_0_of_accessor_has_or_is_using_name_1_from_external_module_2_but_cannot_be_named_4108", "Parameter '{0}' of accessor has or is using name '{1}' from external module '{2}' but cannot be named."),
+        Type_arguments_for_0_circularly_reference_themselves: diag(4109, ts.DiagnosticCategory.Error, "Type_arguments_for_0_circularly_reference_themselves_4109", "Type arguments for '{0}' circularly reference themselves."),
+        Tuple_type_arguments_circularly_reference_themselves: diag(4110, ts.DiagnosticCategory.Error, "Tuple_type_arguments_circularly_reference_themselves_4110", "Tuple type arguments circularly reference themselves."),
         The_current_host_does_not_support_the_0_option: diag(5001, ts.DiagnosticCategory.Error, "The_current_host_does_not_support_the_0_option_5001", "The current host does not support the '{0}' option."),
         Cannot_find_the_common_subdirectory_path_for_the_input_files: diag(5009, ts.DiagnosticCategory.Error, "Cannot_find_the_common_subdirectory_path_for_the_input_files_5009", "Cannot find the common subdirectory path for the input files."),
         File_specification_cannot_end_in_a_recursive_directory_wildcard_Asterisk_Asterisk_Colon_0: diag(5010, ts.DiagnosticCategory.Error, "File_specification_cannot_end_in_a_recursive_directory_wildcard_Asterisk_Asterisk_Colon_0_5010", "File specification cannot end in a recursive directory wildcard ('**'): '{0}'."),
@@ -33091,6 +33093,7 @@ var ts;
         TypeSystemPropertyName[TypeSystemPropertyName["ImmediateBaseConstraint"] = 4] = "ImmediateBaseConstraint";
         TypeSystemPropertyName[TypeSystemPropertyName["EnumTagType"] = 5] = "EnumTagType";
         TypeSystemPropertyName[TypeSystemPropertyName["JSDocTypeReference"] = 6] = "JSDocTypeReference";
+        TypeSystemPropertyName[TypeSystemPropertyName["ResolvedTypeArguments"] = 7] = "ResolvedTypeArguments";
     })(TypeSystemPropertyName || (TypeSystemPropertyName = {}));
     var CheckMode;
     (function (CheckMode) {
@@ -37487,7 +37490,7 @@ var ts;
                 var visitedSymbols = ts.createMap();
                 var deferredPrivates;
                 var oldcontext = context;
-                context = __assign(__assign({}, oldcontext), { usedSymbolNames: ts.mapMap(symbolTable, function (_symbol, name) { return [ts.unescapeLeadingUnderscores(name), true]; }), remappedSymbolNames: ts.createMap(), tracker: __assign(__assign({}, oldcontext.tracker), { trackSymbol: function (sym, decl, meaning) {
+                context = __assign(__assign({}, oldcontext), { usedSymbolNames: ts.createMap(), remappedSymbolNames: ts.createMap(), tracker: __assign(__assign({}, oldcontext.tracker), { trackSymbol: function (sym, decl, meaning) {
                             var accessibleResult = isSymbolAccessible(sym, decl, meaning, /*computeALiases*/ false);
                             if (accessibleResult.accessibility === 0 /* Accessible */) {
                                 // Lookup the root symbol of the chain of refs we'll use to access it and serialize it
@@ -37505,6 +37508,10 @@ var ts;
                         context.usedSymbolNames.set(name, true);
                     });
                 }
+                ts.forEachEntry(symbolTable, function (symbol, name) {
+                    var baseName = ts.unescapeLeadingUnderscores(name);
+                    void getInternalSymbolName(symbol, baseName); // Called to cache values into `usedSymbolNames` and `remappedSymbolNames`
+                });
                 var addingDeclare = !bundled;
                 var exportEquals = symbolTable.get("export=" /* ExportEquals */);
                 if (exportEquals && symbolTable.size > 1 && exportEquals.flags & 2097152 /* Alias */) {
@@ -37696,7 +37703,11 @@ var ts;
                         isPrivate = true;
                     }
                     var modifierFlags = (!isPrivate ? 1 /* Export */ : 0) | (isDefault && !needsPostExportDefault ? 512 /* Default */ : 0);
-                    if (symbol.flags & 16 /* Function */) {
+                    var isConstMergedWithNS = symbol.flags & 1536 /* Module */ &&
+                        symbol.flags & (2 /* BlockScopedVariable */ | 1 /* FunctionScopedVariable */ | 4 /* Property */) &&
+                        symbol.escapedName !== "export=" /* ExportEquals */;
+                    var isConstMergedWithNSPrintableAsSignatureMerge = isConstMergedWithNS && isTypeRepresentableAsFunctionNamespaceMerge(getTypeOfSymbol(symbol), symbol);
+                    if (symbol.flags & 16 /* Function */ || isConstMergedWithNSPrintableAsSignatureMerge) {
                         serializeAsFunctionNamespaceMerge(getTypeOfSymbol(symbol), symbol, getInternalSymbolName(symbol, symbolName), modifierFlags);
                     }
                     if (symbol.flags & 524288 /* TypeAlias */) {
@@ -37707,7 +37718,8 @@ var ts;
                     if (symbol.flags & (2 /* BlockScopedVariable */ | 1 /* FunctionScopedVariable */ | 4 /* Property */)
                         && symbol.escapedName !== "export=" /* ExportEquals */
                         && !(symbol.flags & 4194304 /* Prototype */)
-                        && !(symbol.flags & 32 /* Class */)) {
+                        && !(symbol.flags & 32 /* Class */)
+                        && !isConstMergedWithNSPrintableAsSignatureMerge) {
                         serializeVariableOrProperty(symbol, symbolName, isPrivate, needsPostExportDefault, propertyAsAlias, modifierFlags);
                     }
                     if (symbol.flags & 384 /* Enum */) {
@@ -37724,7 +37736,7 @@ var ts;
                             serializeAsClass(symbol, getInternalSymbolName(symbol, symbolName), modifierFlags);
                         }
                     }
-                    if (symbol.flags & (512 /* ValueModule */ | 1024 /* NamespaceModule */)) {
+                    if ((symbol.flags & (512 /* ValueModule */ | 1024 /* NamespaceModule */) && (!isConstMergedWithNS || isTypeOnlyNamespace(symbol))) || isConstMergedWithNSPrintableAsSignatureMerge) {
                         serializeModule(symbol, symbolName, modifierFlags);
                     }
                     if (symbol.flags & 64 /* Interface */) {
@@ -37752,7 +37764,10 @@ var ts;
                     }
                 }
                 function includePrivateSymbol(symbol) {
+                    if (ts.some(symbol.declarations, ts.isParameterDeclaration))
+                        return;
                     ts.Debug.assertDefined(deferredPrivates);
+                    getUnusedName(ts.unescapeLeadingUnderscores(symbol.escapedName), symbol); // Call to cache unique name for symbol
                     deferredPrivates.set("" + getSymbolId(symbol), symbol);
                 }
                 function isExportingScope(enclosingDeclaration) {
@@ -37811,8 +37826,14 @@ var ts;
                     /*decorators*/ undefined, 
                     /*modifiers*/ undefined, getInternalSymbolName(symbol, symbolName), typeParamDecls, heritageClauses, __spreadArrays(indexSignatures, constructSignatures, callSignatures, members)), modifierFlags);
                 }
+                function getNamespaceMembersForSerialization(symbol) {
+                    return !symbol.exports ? [] : ts.filter(ts.arrayFrom((symbol.exports).values()), function (p) { return !((p.flags & 4194304 /* Prototype */) || (p.escapedName === "prototype")); });
+                }
+                function isTypeOnlyNamespace(symbol) {
+                    return ts.every(getNamespaceMembersForSerialization(symbol), function (m) { return !(resolveSymbol(m).flags & 111551 /* Value */); });
+                }
                 function serializeModule(symbol, symbolName, modifierFlags) {
-                    var members = !symbol.exports ? [] : ts.filter(ts.arrayFrom((symbol.exports).values()), function (p) { return !((p.flags & 4194304 /* Prototype */) || (p.escapedName === "prototype")); });
+                    var members = getNamespaceMembersForSerialization(symbol);
                     // Split NS members up by declaration - members whose parent symbol is the ns symbol vs those whose is not (but were added in later via merging)
                     var locationMap = ts.arrayToMultiMap(members, function (m) { return m.parent && m.parent === symbol ? "real" : "merged"; });
                     var realMembers = locationMap.get("real") || ts.emptyArray;
@@ -37822,17 +37843,20 @@ var ts;
                     // so we don't even have placeholders to fill in.
                     if (ts.length(realMembers)) {
                         var localName = getInternalSymbolName(symbol, symbolName);
-                        serializeAsNamespaceDeclaration(realMembers, localName, modifierFlags, !!(symbol.flags & 16 /* Function */));
+                        serializeAsNamespaceDeclaration(realMembers, localName, modifierFlags, !!(symbol.flags & (16 /* Function */ | 67108864 /* Assignment */)));
                     }
                     if (ts.length(mergedMembers)) {
                         var localName = getInternalSymbolName(symbol, symbolName);
-                        ts.forEach(mergedMembers, includePrivateSymbol);
                         var nsBody = ts.createModuleBlock([ts.createExportDeclaration(
                             /*decorators*/ undefined, 
                             /*modifiers*/ undefined, ts.createNamedExports(ts.map(ts.filter(mergedMembers, function (n) { return n.escapedName !== "export=" /* ExportEquals */; }), function (s) {
                                 var name = ts.unescapeLeadingUnderscores(s.escapedName);
                                 var localName = getInternalSymbolName(s, name);
-                                return ts.createExportSpecifier(name === localName ? undefined : localName, name);
+                                var aliasDecl = s.declarations && getDeclarationOfAliasSymbol(s);
+                                var target = aliasDecl && getTargetOfAliasDeclaration(aliasDecl, /*dontRecursivelyResolve*/ true);
+                                includePrivateSymbol(target || s);
+                                var targetName = target ? getInternalSymbolName(target, ts.unescapeLeadingUnderscores(target.escapedName)) : localName;
+                                return ts.createExportSpecifier(name === targetName ? undefined : targetName, name);
                             })))]);
                         addResult(ts.createModuleDeclaration(
                         /*decorators*/ undefined, 
@@ -38063,6 +38087,7 @@ var ts;
                             serializeMaybeAliasAssignment(symbol);
                             break;
                         case 208 /* BinaryExpression */:
+                        case 193 /* PropertyAccessExpression */:
                             // Could be best encoded as though an export specifier or as though an export assignment
                             // If name is default or export=, do an export assignment
                             // Otherwise do an export specifier
@@ -38073,10 +38098,6 @@ var ts;
                                 serializeExportSpecifier(localName, targetName);
                             }
                             break;
-                        case 193 /* PropertyAccessExpression */:
-                            // A PAE alias is _always_ going to exist as an append to a top-level export, where our top level
-                            // handling should always be sufficient to encode the export action itself
-                            break;
                         default:
                             return ts.Debug.failBadSyntaxKind(node, "Unhandled alias declaration kind in symbol serializer!");
                     }
@@ -38100,7 +38121,8 @@ var ts;
                     var aliasDecl = symbol.declarations && getDeclarationOfAliasSymbol(symbol);
                     // serialize what the alias points to, preserve the declaration's initializer
                     var target = aliasDecl && getTargetOfAliasDeclaration(aliasDecl, /*dontRecursivelyResolve*/ true);
-                    if (target) {
+                    // If the target resolves and resolves to a thing defined in this file, emit as an alias, otherwise emit as a const
+                    if (target && ts.length(target.declarations) && ts.some(target.declarations, function (d) { return ts.getSourceFileOfNode(d) === ts.getSourceFileOfNode(enclosingDeclaration); })) {
                         // In case `target` refers to a namespace member, look at the declaration and serialize the leftmost symbol in it
                         // eg, `namespace A { export class B {} }; exports = A.B;`
                         // Technically, this is all that's required in the case where the assignment is an entity name expression
@@ -38175,6 +38197,7 @@ var ts;
                     return ts.getObjectFlags(typeToSerialize) & (16 /* Anonymous */ | 32 /* Mapped */) &&
                         !getIndexInfoOfType(typeToSerialize, 0 /* String */) &&
                         !getIndexInfoOfType(typeToSerialize, 1 /* Number */) &&
+                        !!(ts.length(getPropertiesOfType(typeToSerialize)) || ts.length(getSignaturesOfType(typeToSerialize, 0 /* Call */))) &&
                         !ts.length(getSignaturesOfType(typeToSerialize, 1 /* Construct */)) && // TODO: could probably serialize as function + ns + class, now that that's OK
                         !getDeclarationWithTypeAnnotation(hostSymbol) &&
                         !(typeToSerialize.symbol && ts.some(typeToSerialize.symbol.declarations, function (d) { return ts.getSourceFileOfNode(d) !== ctxSrc; })) &&
@@ -38448,11 +38471,8 @@ var ts;
                             return context.remappedSymbolNames.get("" + getSymbolId(symbol));
                         }
                     }
-                    if (input === "default" /* Default */) {
-                        input = "_default";
-                    }
-                    else if (input === "export=" /* ExportEquals */) {
-                        input = "_exports";
+                    if (symbol) {
+                        input = getNameCandidateWorker(symbol, input);
                     }
                     var i = 0;
                     var original = input;
@@ -38466,17 +38486,28 @@ var ts;
                     }
                     return input;
                 }
-                function getInternalSymbolName(symbol, localName) {
-                    if (context.remappedSymbolNames.has("" + getSymbolId(symbol))) {
-                        return context.remappedSymbolNames.get("" + getSymbolId(symbol));
-                    }
+                function getNameCandidateWorker(symbol, localName) {
                     if (localName === "default" /* Default */ || localName === "__class" /* Class */ || localName === "__function" /* Function */) {
                         var flags = context.flags;
                         context.flags |= 16777216 /* InInitialEntityName */;
                         var nameCandidate = getNameOfSymbolAsWritten(symbol, context);
                         context.flags = flags;
-                        localName = ts.isIdentifierText(nameCandidate, languageVersion) && !ts.isStringANonContextualKeyword(nameCandidate) ? nameCandidate : getUnusedName("_default", symbol);
+                        localName = nameCandidate.length > 0 && ts.isSingleOrDoubleQuote(nameCandidate.charCodeAt(0)) ? ts.stripQuotes(nameCandidate) : nameCandidate;
                     }
+                    if (localName === "default" /* Default */) {
+                        localName = "_default";
+                    }
+                    else if (localName === "export=" /* ExportEquals */) {
+                        localName = "_exports";
+                    }
+                    localName = ts.isIdentifierText(localName, languageVersion) && !ts.isStringANonContextualKeyword(localName) ? localName : "_" + localName.replace(/[^a-zA-Z0-9]/g, "_");
+                    return localName;
+                }
+                function getInternalSymbolName(symbol, localName) {
+                    if (context.remappedSymbolNames.has("" + getSymbolId(symbol))) {
+                        return context.remappedSymbolNames.get("" + getSymbolId(symbol));
+                    }
+                    localName = getNameCandidateWorker(symbol, localName);
                     // The result of this is going to be used as the symbol's name - lock it in, so `getUnusedName` will also pick it up
                     context.remappedSymbolNames.set("" + getSymbolId(symbol), localName);
                     return localName;
@@ -38805,6 +38836,8 @@ var ts;
                     return !!target.immediateBaseConstraint;
                 case 6 /* JSDocTypeReference */:
                     return !!getSymbolLinks(target).resolvedJSDocType;
+                case 7 /* ResolvedTypeArguments */:
+                    return !!target.resolvedTypeArguments;
             }
             return ts.Debug.assertNever(propertyName);
         }
@@ -42611,13 +42644,25 @@ var ts;
             return type;
         }
         function getTypeArguments(type) {
+            var _a, _b;
             if (!type.resolvedTypeArguments) {
+                if (!pushTypeResolution(type, 7 /* ResolvedTypeArguments */)) {
+                    return ((_a = type.target.localTypeParameters) === null || _a === void 0 ? void 0 : _a.map(function () { return errorType; })) || ts.emptyArray;
+                }
                 var node = type.node;
                 var typeArguments = !node ? ts.emptyArray :
                     node.kind === 168 /* TypeReference */ ? ts.concatenate(type.target.outerTypeParameters, getEffectiveTypeArguments(node, type.target.localTypeParameters)) :
                         node.kind === 173 /* ArrayType */ ? [getTypeFromTypeNode(node.elementType)] :
                             ts.map(node.elementTypes, getTypeFromTypeNode);
-                type.resolvedTypeArguments = type.mapper ? instantiateTypes(typeArguments, type.mapper) : typeArguments;
+                if (popTypeResolution()) {
+                    type.resolvedTypeArguments = type.mapper ? instantiateTypes(typeArguments, type.mapper) : typeArguments;
+                }
+                else {
+                    type.resolvedTypeArguments = ((_b = type.target.localTypeParameters) === null || _b === void 0 ? void 0 : _b.map(function () { return errorType; })) || ts.emptyArray;
+                    error(type.node || currentNode, type.target.symbol
+                        ? ts.Diagnostics.Type_arguments_for_0_circularly_reference_themselves
+                        : ts.Diagnostics.Tuple_type_arguments_circularly_reference_themselves, type.target.symbol && symbolToString(type.target.symbol));
+                }
             }
             return type.resolvedTypeArguments;
         }
@@ -42756,14 +42801,17 @@ var ts;
             var typeType = valueType;
             if (symbol.valueDeclaration) {
                 var decl = ts.getRootDeclaration(symbol.valueDeclaration);
-                var isRequireAlias = ts.isVariableDeclaration(decl)
-                    && decl.initializer
-                    && ts.isCallExpression(decl.initializer)
-                    && ts.isRequireCall(decl.initializer, /*requireStringLiteralLikeArgument*/ true)
-                    && valueType.symbol;
-                var isImportType = node.kind === 187 /* ImportType */;
+                var isRequireAlias = false;
+                if (ts.isVariableDeclaration(decl) && decl.initializer) {
+                    var expr = decl.initializer;
+                    // skip past entity names, eg `require("x").a.b.c`
+                    while (ts.isPropertyAccessExpression(expr)) {
+                        expr = expr.expression;
+                    }
+                    isRequireAlias = ts.isCallExpression(expr) && ts.isRequireCall(expr, /*requireStringLiteralLikeArgument*/ true) && !!valueType.symbol;
+                }
                 var isDelayedMergeClass = symbol !== valueType.symbol && getMergedSymbol(symbol) === valueType.symbol;
-                if (isRequireAlias || isImportType || isDelayedMergeClass) {
+                if (isRequireAlias || node.kind === 187 /* ImportType */ || isDelayedMergeClass) {
                     typeType = getTypeReferenceType(node, valueType.symbol);
                 }
             }
@@ -45886,7 +45934,7 @@ var ts;
                 return true;
             }
             if (source.flags & 524288 /* Object */ && target.flags & 524288 /* Object */) {
-                var related = relation.get(getRelationKey(source, target, relation));
+                var related = relation.get(getRelationKey(source, target, /*isIntersectionConstituent*/ false, relation));
                 if (related !== undefined) {
                     return !!(related & 1 /* Succeeded */);
                 }
@@ -46257,7 +46305,7 @@ var ts;
                 // and we need to handle "each" relations before "some" relations for the same kind of type.
                 if (source.flags & 1048576 /* Union */) {
                     result = relation === comparableRelation ?
-                        someTypeRelatedToType(source, target, reportErrors && !(source.flags & 131068 /* Primitive */), isIntersectionConstituent) :
+                        someTypeRelatedToType(source, target, reportErrors && !(source.flags & 131068 /* Primitive */)) :
                         eachTypeRelatedToType(source, target, reportErrors && !(source.flags & 131068 /* Primitive */));
                 }
                 else {
@@ -46295,7 +46343,7 @@ var ts;
                         //
                         //    - For a primitive type or type parameter (such as 'number = A & B') there is no point in
                         //          breaking the intersection apart.
-                        result = someTypeRelatedToType(source, target, /*reportErrors*/ false, /*isIntersectionConstituent*/ true);
+                        result = someTypeRelatedToType(source, target, /*reportErrors*/ false);
                     }
                     if (!result && (source.flags & 66846720 /* StructuredOrInstantiable */ || target.flags & 66846720 /* StructuredOrInstantiable */)) {
                         if (result = recursiveTypeRelatedTo(source, target, reportErrors, isIntersectionConstituent)) {
@@ -46579,14 +46627,14 @@ var ts;
                 }
                 return result;
             }
-            function someTypeRelatedToType(source, target, reportErrors, isIntersectionConstituent) {
+            function someTypeRelatedToType(source, target, reportErrors) {
                 var sourceTypes = source.types;
                 if (source.flags & 1048576 /* Union */ && containsType(sourceTypes, target)) {
                     return -1 /* True */;
                 }
                 var len = sourceTypes.length;
                 for (var i = 0; i < len; i++) {
-                    var related = isRelatedTo(sourceTypes[i], target, reportErrors && i === len - 1, /*headMessage*/ undefined, isIntersectionConstituent);
+                    var related = isRelatedTo(sourceTypes[i], target, reportErrors && i === len - 1);
                     if (related) {
                         return related;
                     }
@@ -46674,7 +46722,7 @@ var ts;
                 if (overflow) {
                     return 0 /* False */;
                 }
-                var id = getRelationKey(source, target, relation);
+                var id = getRelationKey(source, target, isIntersectionConstituent, relation);
                 var entry = relation.get(id);
                 if (entry !== undefined) {
                     if (reportErrors && entry & 2 /* Failed */ && !(entry & 4 /* Reported */)) {
@@ -47860,17 +47908,18 @@ var ts;
          * To improve caching, the relation key for two generic types uses the target's id plus ids of the type parameters.
          * For other cases, the types ids are used.
          */
-        function getRelationKey(source, target, relation) {
+        function getRelationKey(source, target, isIntersectionConstituent, relation) {
             if (relation === identityRelation && source.id > target.id) {
                 var temp = source;
                 source = target;
                 target = temp;
             }
+            var intersection = isIntersectionConstituent ? "&" : "";
             if (isTypeReferenceWithGenericArguments(source) && isTypeReferenceWithGenericArguments(target)) {
                 var typeParameters = [];
-                return getTypeReferenceId(source, typeParameters) + "," + getTypeReferenceId(target, typeParameters);
+                return getTypeReferenceId(source, typeParameters) + "," + getTypeReferenceId(target, typeParameters) + intersection;
             }
-            return source.id + "," + target.id;
+            return source.id + "," + target.id + intersection;
         }
         // Invoke the callback for each underlying property symbol of the given symbol and return the first
         // value that isn't undefined.
diff --git a/lib/typescriptServices.js b/lib/typescriptServices.js
index 30080900e66..cdab461b914 100644
--- a/lib/typescriptServices.js
+++ b/lib/typescriptServices.js
@@ -7165,6 +7165,8 @@ var ts;
         Parameter_0_of_accessor_has_or_is_using_private_name_1: diag(4106, ts.DiagnosticCategory.Error, "Parameter_0_of_accessor_has_or_is_using_private_name_1_4106", "Parameter '{0}' of accessor has or is using private name '{1}'."),
         Parameter_0_of_accessor_has_or_is_using_name_1_from_private_module_2: diag(4107, ts.DiagnosticCategory.Error, "Parameter_0_of_accessor_has_or_is_using_name_1_from_private_module_2_4107", "Parameter '{0}' of accessor has or is using name '{1}' from private module '{2}'."),
         Parameter_0_of_accessor_has_or_is_using_name_1_from_external_module_2_but_cannot_be_named: diag(4108, ts.DiagnosticCategory.Error, "Parameter_0_of_accessor_has_or_is_using_name_1_from_external_module_2_but_cannot_be_named_4108", "Parameter '{0}' of accessor has or is using name '{1}' from external module '{2}' but cannot be named."),
+        Type_arguments_for_0_circularly_reference_themselves: diag(4109, ts.DiagnosticCategory.Error, "Type_arguments_for_0_circularly_reference_themselves_4109", "Type arguments for '{0}' circularly reference themselves."),
+        Tuple_type_arguments_circularly_reference_themselves: diag(4110, ts.DiagnosticCategory.Error, "Tuple_type_arguments_circularly_reference_themselves_4110", "Tuple type arguments circularly reference themselves."),
         The_current_host_does_not_support_the_0_option: diag(5001, ts.DiagnosticCategory.Error, "The_current_host_does_not_support_the_0_option_5001", "The current host does not support the '{0}' option."),
         Cannot_find_the_common_subdirectory_path_for_the_input_files: diag(5009, ts.DiagnosticCategory.Error, "Cannot_find_the_common_subdirectory_path_for_the_input_files_5009", "Cannot find the common subdirectory path for the input files."),
         File_specification_cannot_end_in_a_recursive_directory_wildcard_Asterisk_Asterisk_Colon_0: diag(5010, ts.DiagnosticCategory.Error, "File_specification_cannot_end_in_a_recursive_directory_wildcard_Asterisk_Asterisk_Colon_0_5010", "File specification cannot end in a recursive directory wildcard ('**'): '{0}'."),
@@ -33091,6 +33093,7 @@ var ts;
         TypeSystemPropertyName[TypeSystemPropertyName["ImmediateBaseConstraint"] = 4] = "ImmediateBaseConstraint";
         TypeSystemPropertyName[TypeSystemPropertyName["EnumTagType"] = 5] = "EnumTagType";
         TypeSystemPropertyName[TypeSystemPropertyName["JSDocTypeReference"] = 6] = "JSDocTypeReference";
+        TypeSystemPropertyName[TypeSystemPropertyName["ResolvedTypeArguments"] = 7] = "ResolvedTypeArguments";
     })(TypeSystemPropertyName || (TypeSystemPropertyName = {}));
     var CheckMode;
     (function (CheckMode) {
@@ -37487,7 +37490,7 @@ var ts;
                 var visitedSymbols = ts.createMap();
                 var deferredPrivates;
                 var oldcontext = context;
-                context = __assign(__assign({}, oldcontext), { usedSymbolNames: ts.mapMap(symbolTable, function (_symbol, name) { return [ts.unescapeLeadingUnderscores(name), true]; }), remappedSymbolNames: ts.createMap(), tracker: __assign(__assign({}, oldcontext.tracker), { trackSymbol: function (sym, decl, meaning) {
+                context = __assign(__assign({}, oldcontext), { usedSymbolNames: ts.createMap(), remappedSymbolNames: ts.createMap(), tracker: __assign(__assign({}, oldcontext.tracker), { trackSymbol: function (sym, decl, meaning) {
                             var accessibleResult = isSymbolAccessible(sym, decl, meaning, /*computeALiases*/ false);
                             if (accessibleResult.accessibility === 0 /* Accessible */) {
                                 // Lookup the root symbol of the chain of refs we'll use to access it and serialize it
@@ -37505,6 +37508,10 @@ var ts;
                         context.usedSymbolNames.set(name, true);
                     });
                 }
+                ts.forEachEntry(symbolTable, function (symbol, name) {
+                    var baseName = ts.unescapeLeadingUnderscores(name);
+                    void getInternalSymbolName(symbol, baseName); // Called to cache values into `usedSymbolNames` and `remappedSymbolNames`
+                });
                 var addingDeclare = !bundled;
                 var exportEquals = symbolTable.get("export=" /* ExportEquals */);
                 if (exportEquals && symbolTable.size > 1 && exportEquals.flags & 2097152 /* Alias */) {
@@ -37696,7 +37703,11 @@ var ts;
                         isPrivate = true;
                     }
                     var modifierFlags = (!isPrivate ? 1 /* Export */ : 0) | (isDefault && !needsPostExportDefault ? 512 /* Default */ : 0);
-                    if (symbol.flags & 16 /* Function */) {
+                    var isConstMergedWithNS = symbol.flags & 1536 /* Module */ &&
+                        symbol.flags & (2 /* BlockScopedVariable */ | 1 /* FunctionScopedVariable */ | 4 /* Property */) &&
+                        symbol.escapedName !== "export=" /* ExportEquals */;
+                    var isConstMergedWithNSPrintableAsSignatureMerge = isConstMergedWithNS && isTypeRepresentableAsFunctionNamespaceMerge(getTypeOfSymbol(symbol), symbol);
+                    if (symbol.flags & 16 /* Function */ || isConstMergedWithNSPrintableAsSignatureMerge) {
                         serializeAsFunctionNamespaceMerge(getTypeOfSymbol(symbol), symbol, getInternalSymbolName(symbol, symbolName), modifierFlags);
                     }
                     if (symbol.flags & 524288 /* TypeAlias */) {
@@ -37707,7 +37718,8 @@ var ts;
                     if (symbol.flags & (2 /* BlockScopedVariable */ | 1 /* FunctionScopedVariable */ | 4 /* Property */)
                         && symbol.escapedName !== "export=" /* ExportEquals */
                         && !(symbol.flags & 4194304 /* Prototype */)
-                        && !(symbol.flags & 32 /* Class */)) {
+                        && !(symbol.flags & 32 /* Class */)
+                        && !isConstMergedWithNSPrintableAsSignatureMerge) {
                         serializeVariableOrProperty(symbol, symbolName, isPrivate, needsPostExportDefault, propertyAsAlias, modifierFlags);
                     }
                     if (symbol.flags & 384 /* Enum */) {
@@ -37724,7 +37736,7 @@ var ts;
                             serializeAsClass(symbol, getInternalSymbolName(symbol, symbolName), modifierFlags);
                         }
                     }
-                    if (symbol.flags & (512 /* ValueModule */ | 1024 /* NamespaceModule */)) {
+                    if ((symbol.flags & (512 /* ValueModule */ | 1024 /* NamespaceModule */) && (!isConstMergedWithNS || isTypeOnlyNamespace(symbol))) || isConstMergedWithNSPrintableAsSignatureMerge) {
                         serializeModule(symbol, symbolName, modifierFlags);
                     }
                     if (symbol.flags & 64 /* Interface */) {
@@ -37752,7 +37764,10 @@ var ts;
                     }
                 }
                 function includePrivateSymbol(symbol) {
+                    if (ts.some(symbol.declarations, ts.isParameterDeclaration))
+                        return;
                     ts.Debug.assertDefined(deferredPrivates);
+                    getUnusedName(ts.unescapeLeadingUnderscores(symbol.escapedName), symbol); // Call to cache unique name for symbol
                     deferredPrivates.set("" + getSymbolId(symbol), symbol);
                 }
                 function isExportingScope(enclosingDeclaration) {
@@ -37811,8 +37826,14 @@ var ts;
                     /*decorators*/ undefined, 
                     /*modifiers*/ undefined, getInternalSymbolName(symbol, symbolName), typeParamDecls, heritageClauses, __spreadArrays(indexSignatures, constructSignatures, callSignatures, members)), modifierFlags);
                 }
+                function getNamespaceMembersForSerialization(symbol) {
+                    return !symbol.exports ? [] : ts.filter(ts.arrayFrom((symbol.exports).values()), function (p) { return !((p.flags & 4194304 /* Prototype */) || (p.escapedName === "prototype")); });
+                }
+                function isTypeOnlyNamespace(symbol) {
+                    return ts.every(getNamespaceMembersForSerialization(symbol), function (m) { return !(resolveSymbol(m).flags & 111551 /* Value */); });
+                }
                 function serializeModule(symbol, symbolName, modifierFlags) {
-                    var members = !symbol.exports ? [] : ts.filter(ts.arrayFrom((symbol.exports).values()), function (p) { return !((p.flags & 4194304 /* Prototype */) || (p.escapedName === "prototype")); });
+                    var members = getNamespaceMembersForSerialization(symbol);
                     // Split NS members up by declaration - members whose parent symbol is the ns symbol vs those whose is not (but were added in later via merging)
                     var locationMap = ts.arrayToMultiMap(members, function (m) { return m.parent && m.parent === symbol ? "real" : "merged"; });
                     var realMembers = locationMap.get("real") || ts.emptyArray;
@@ -37822,17 +37843,20 @@ var ts;
                     // so we don't even have placeholders to fill in.
                     if (ts.length(realMembers)) {
                         var localName = getInternalSymbolName(symbol, symbolName);
-                        serializeAsNamespaceDeclaration(realMembers, localName, modifierFlags, !!(symbol.flags & 16 /* Function */));
+                        serializeAsNamespaceDeclaration(realMembers, localName, modifierFlags, !!(symbol.flags & (16 /* Function */ | 67108864 /* Assignment */)));
                     }
                     if (ts.length(mergedMembers)) {
                         var localName = getInternalSymbolName(symbol, symbolName);
-                        ts.forEach(mergedMembers, includePrivateSymbol);
                         var nsBody = ts.createModuleBlock([ts.createExportDeclaration(
                             /*decorators*/ undefined, 
                             /*modifiers*/ undefined, ts.createNamedExports(ts.map(ts.filter(mergedMembers, function (n) { return n.escapedName !== "export=" /* ExportEquals */; }), function (s) {
                                 var name = ts.unescapeLeadingUnderscores(s.escapedName);
                                 var localName = getInternalSymbolName(s, name);
-                                return ts.createExportSpecifier(name === localName ? undefined : localName, name);
+                                var aliasDecl = s.declarations && getDeclarationOfAliasSymbol(s);
+                                var target = aliasDecl && getTargetOfAliasDeclaration(aliasDecl, /*dontRecursivelyResolve*/ true);
+                                includePrivateSymbol(target || s);
+                                var targetName = target ? getInternalSymbolName(target, ts.unescapeLeadingUnderscores(target.escapedName)) : localName;
+                                return ts.createExportSpecifier(name === targetName ? undefined : targetName, name);
                             })))]);
                         addResult(ts.createModuleDeclaration(
                         /*decorators*/ undefined, 
@@ -38063,6 +38087,7 @@ var ts;
                             serializeMaybeAliasAssignment(symbol);
                             break;
                         case 208 /* BinaryExpression */:
+                        case 193 /* PropertyAccessExpression */:
                             // Could be best encoded as though an export specifier or as though an export assignment
                             // If name is default or export=, do an export assignment
                             // Otherwise do an export specifier
@@ -38073,10 +38098,6 @@ var ts;
                                 serializeExportSpecifier(localName, targetName);
                             }
                             break;
-                        case 193 /* PropertyAccessExpression */:
-                            // A PAE alias is _always_ going to exist as an append to a top-level export, where our top level
-                            // handling should always be sufficient to encode the export action itself
-                            break;
                         default:
                             return ts.Debug.failBadSyntaxKind(node, "Unhandled alias declaration kind in symbol serializer!");
                     }
@@ -38100,7 +38121,8 @@ var ts;
                     var aliasDecl = symbol.declarations && getDeclarationOfAliasSymbol(symbol);
                     // serialize what the alias points to, preserve the declaration's initializer
                     var target = aliasDecl && getTargetOfAliasDeclaration(aliasDecl, /*dontRecursivelyResolve*/ true);
-                    if (target) {
+                    // If the target resolves and resolves to a thing defined in this file, emit as an alias, otherwise emit as a const
+                    if (target && ts.length(target.declarations) && ts.some(target.declarations, function (d) { return ts.getSourceFileOfNode(d) === ts.getSourceFileOfNode(enclosingDeclaration); })) {
                         // In case `target` refers to a namespace member, look at the declaration and serialize the leftmost symbol in it
                         // eg, `namespace A { export class B {} }; exports = A.B;`
                         // Technically, this is all that's required in the case where the assignment is an entity name expression
@@ -38175,6 +38197,7 @@ var ts;
                     return ts.getObjectFlags(typeToSerialize) & (16 /* Anonymous */ | 32 /* Mapped */) &&
                         !getIndexInfoOfType(typeToSerialize, 0 /* String */) &&
                         !getIndexInfoOfType(typeToSerialize, 1 /* Number */) &&
+                        !!(ts.length(getPropertiesOfType(typeToSerialize)) || ts.length(getSignaturesOfType(typeToSerialize, 0 /* Call */))) &&
                         !ts.length(getSignaturesOfType(typeToSerialize, 1 /* Construct */)) && // TODO: could probably serialize as function + ns + class, now that that's OK
                         !getDeclarationWithTypeAnnotation(hostSymbol) &&
                         !(typeToSerialize.symbol && ts.some(typeToSerialize.symbol.declarations, function (d) { return ts.getSourceFileOfNode(d) !== ctxSrc; })) &&
@@ -38448,11 +38471,8 @@ var ts;
                             return context.remappedSymbolNames.get("" + getSymbolId(symbol));
                         }
                     }
-                    if (input === "default" /* Default */) {
-                        input = "_default";
-                    }
-                    else if (input === "export=" /* ExportEquals */) {
-                        input = "_exports";
+                    if (symbol) {
+                        input = getNameCandidateWorker(symbol, input);
                     }
                     var i = 0;
                     var original = input;
@@ -38466,17 +38486,28 @@ var ts;
                     }
                     return input;
                 }
-                function getInternalSymbolName(symbol, localName) {
-                    if (context.remappedSymbolNames.has("" + getSymbolId(symbol))) {
-                        return context.remappedSymbolNames.get("" + getSymbolId(symbol));
-                    }
+                function getNameCandidateWorker(symbol, localName) {
                     if (localName === "default" /* Default */ || localName === "__class" /* Class */ || localName === "__function" /* Function */) {
                         var flags = context.flags;
                         context.flags |= 16777216 /* InInitialEntityName */;
                         var nameCandidate = getNameOfSymbolAsWritten(symbol, context);
                         context.flags = flags;
-                        localName = ts.isIdentifierText(nameCandidate, languageVersion) && !ts.isStringANonContextualKeyword(nameCandidate) ? nameCandidate : getUnusedName("_default", symbol);
+                        localName = nameCandidate.length > 0 && ts.isSingleOrDoubleQuote(nameCandidate.charCodeAt(0)) ? ts.stripQuotes(nameCandidate) : nameCandidate;
                     }
+                    if (localName === "default" /* Default */) {
+                        localName = "_default";
+                    }
+                    else if (localName === "export=" /* ExportEquals */) {
+                        localName = "_exports";
+                    }
+                    localName = ts.isIdentifierText(localName, languageVersion) && !ts.isStringANonContextualKeyword(localName) ? localName : "_" + localName.replace(/[^a-zA-Z0-9]/g, "_");
+                    return localName;
+                }
+                function getInternalSymbolName(symbol, localName) {
+                    if (context.remappedSymbolNames.has("" + getSymbolId(symbol))) {
+                        return context.remappedSymbolNames.get("" + getSymbolId(symbol));
+                    }
+                    localName = getNameCandidateWorker(symbol, localName);
                     // The result of this is going to be used as the symbol's name - lock it in, so `getUnusedName` will also pick it up
                     context.remappedSymbolNames.set("" + getSymbolId(symbol), localName);
                     return localName;
@@ -38805,6 +38836,8 @@ var ts;
                     return !!target.immediateBaseConstraint;
                 case 6 /* JSDocTypeReference */:
                     return !!getSymbolLinks(target).resolvedJSDocType;
+                case 7 /* ResolvedTypeArguments */:
+                    return !!target.resolvedTypeArguments;
             }
             return ts.Debug.assertNever(propertyName);
         }
@@ -42611,13 +42644,25 @@ var ts;
             return type;
         }
         function getTypeArguments(type) {
+            var _a, _b;
             if (!type.resolvedTypeArguments) {
+                if (!pushTypeResolution(type, 7 /* ResolvedTypeArguments */)) {
+                    return ((_a = type.target.localTypeParameters) === null || _a === void 0 ? void 0 : _a.map(function () { return errorType; })) || ts.emptyArray;
+                }
                 var node = type.node;
                 var typeArguments = !node ? ts.emptyArray :
                     node.kind === 168 /* TypeReference */ ? ts.concatenate(type.target.outerTypeParameters, getEffectiveTypeArguments(node, type.target.localTypeParameters)) :
                         node.kind === 173 /* ArrayType */ ? [getTypeFromTypeNode(node.elementType)] :
                             ts.map(node.elementTypes, getTypeFromTypeNode);
-                type.resolvedTypeArguments = type.mapper ? instantiateTypes(typeArguments, type.mapper) : typeArguments;
+                if (popTypeResolution()) {
+                    type.resolvedTypeArguments = type.mapper ? instantiateTypes(typeArguments, type.mapper) : typeArguments;
+                }
+                else {
+                    type.resolvedTypeArguments = ((_b = type.target.localTypeParameters) === null || _b === void 0 ? void 0 : _b.map(function () { return errorType; })) || ts.emptyArray;
+                    error(type.node || currentNode, type.target.symbol
+                        ? ts.Diagnostics.Type_arguments_for_0_circularly_reference_themselves
+                        : ts.Diagnostics.Tuple_type_arguments_circularly_reference_themselves, type.target.symbol && symbolToString(type.target.symbol));
+                }
             }
             return type.resolvedTypeArguments;
         }
@@ -42756,14 +42801,17 @@ var ts;
             var typeType = valueType;
             if (symbol.valueDeclaration) {
                 var decl = ts.getRootDeclaration(symbol.valueDeclaration);
-                var isRequireAlias = ts.isVariableDeclaration(decl)
-                    && decl.initializer
-                    && ts.isCallExpression(decl.initializer)
-                    && ts.isRequireCall(decl.initializer, /*requireStringLiteralLikeArgument*/ true)
-                    && valueType.symbol;
-                var isImportType = node.kind === 187 /* ImportType */;
+                var isRequireAlias = false;
+                if (ts.isVariableDeclaration(decl) && decl.initializer) {
+                    var expr = decl.initializer;
+                    // skip past entity names, eg `require("x").a.b.c`
+                    while (ts.isPropertyAccessExpression(expr)) {
+                        expr = expr.expression;
+                    }
+                    isRequireAlias = ts.isCallExpression(expr) && ts.isRequireCall(expr, /*requireStringLiteralLikeArgument*/ true) && !!valueType.symbol;
+                }
                 var isDelayedMergeClass = symbol !== valueType.symbol && getMergedSymbol(symbol) === valueType.symbol;
-                if (isRequireAlias || isImportType || isDelayedMergeClass) {
+                if (isRequireAlias || node.kind === 187 /* ImportType */ || isDelayedMergeClass) {
                     typeType = getTypeReferenceType(node, valueType.symbol);
                 }
             }
@@ -45886,7 +45934,7 @@ var ts;
                 return true;
             }
             if (source.flags & 524288 /* Object */ && target.flags & 524288 /* Object */) {
-                var related = relation.get(getRelationKey(source, target, relation));
+                var related = relation.get(getRelationKey(source, target, /*isIntersectionConstituent*/ false, relation));
                 if (related !== undefined) {
                     return !!(related & 1 /* Succeeded */);
                 }
@@ -46257,7 +46305,7 @@ var ts;
                 // and we need to handle "each" relations before "some" relations for the same kind of type.
                 if (source.flags & 1048576 /* Union */) {
                     result = relation === comparableRelation ?
-                        someTypeRelatedToType(source, target, reportErrors && !(source.flags & 131068 /* Primitive */), isIntersectionConstituent) :
+                        someTypeRelatedToType(source, target, reportErrors && !(source.flags & 131068 /* Primitive */)) :
                         eachTypeRelatedToType(source, target, reportErrors && !(source.flags & 131068 /* Primitive */));
                 }
                 else {
@@ -46295,7 +46343,7 @@ var ts;
                         //
                         //    - For a primitive type or type parameter (such as 'number = A & B') there is no point in
                         //          breaking the intersection apart.
-                        result = someTypeRelatedToType(source, target, /*reportErrors*/ false, /*isIntersectionConstituent*/ true);
+                        result = someTypeRelatedToType(source, target, /*reportErrors*/ false);
                     }
                     if (!result && (source.flags & 66846720 /* StructuredOrInstantiable */ || target.flags & 66846720 /* StructuredOrInstantiable */)) {
                         if (result = recursiveTypeRelatedTo(source, target, reportErrors, isIntersectionConstituent)) {
@@ -46579,14 +46627,14 @@ var ts;
                 }
                 return result;
             }
-            function someTypeRelatedToType(source, target, reportErrors, isIntersectionConstituent) {
+            function someTypeRelatedToType(source, target, reportErrors) {
                 var sourceTypes = source.types;
                 if (source.flags & 1048576 /* Union */ && containsType(sourceTypes, target)) {
                     return -1 /* True */;
                 }
                 var len = sourceTypes.length;
                 for (var i = 0; i < len; i++) {
-                    var related = isRelatedTo(sourceTypes[i], target, reportErrors && i === len - 1, /*headMessage*/ undefined, isIntersectionConstituent);
+                    var related = isRelatedTo(sourceTypes[i], target, reportErrors && i === len - 1);
                     if (related) {
                         return related;
                     }
@@ -46674,7 +46722,7 @@ var ts;
                 if (overflow) {
                     return 0 /* False */;
                 }
-                var id = getRelationKey(source, target, relation);
+                var id = getRelationKey(source, target, isIntersectionConstituent, relation);
                 var entry = relation.get(id);
                 if (entry !== undefined) {
                     if (reportErrors && entry & 2 /* Failed */ && !(entry & 4 /* Reported */)) {
@@ -47860,17 +47908,18 @@ var ts;
          * To improve caching, the relation key for two generic types uses the target's id plus ids of the type parameters.
          * For other cases, the types ids are used.
          */
-        function getRelationKey(source, target, relation) {
+        function getRelationKey(source, target, isIntersectionConstituent, relation) {
             if (relation === identityRelation && source.id > target.id) {
                 var temp = source;
                 source = target;
                 target = temp;
             }
+            var intersection = isIntersectionConstituent ? "&" : "";
             if (isTypeReferenceWithGenericArguments(source) && isTypeReferenceWithGenericArguments(target)) {
                 var typeParameters = [];
-                return getTypeReferenceId(source, typeParameters) + "," + getTypeReferenceId(target, typeParameters);
+                return getTypeReferenceId(source, typeParameters) + "," + getTypeReferenceId(target, typeParameters) + intersection;
             }
-            return source.id + "," + target.id;
+            return source.id + "," + target.id + intersection;
         }
         // Invoke the callback for each underlying property symbol of the given symbol and return the first
         // value that isn't undefined.
diff --git a/lib/typingsInstaller.js b/lib/typingsInstaller.js
index 0a539b4fc66..ad34e548d6c 100644
--- a/lib/typingsInstaller.js
+++ b/lib/typingsInstaller.js
@@ -7015,6 +7015,8 @@ var ts;
         Parameter_0_of_accessor_has_or_is_using_private_name_1: diag(4106, ts.DiagnosticCategory.Error, "Parameter_0_of_accessor_has_or_is_using_private_name_1_4106", "Parameter '{0}' of accessor has or is using private name '{1}'."),
         Parameter_0_of_accessor_has_or_is_using_name_1_from_private_module_2: diag(4107, ts.DiagnosticCategory.Error, "Parameter_0_of_accessor_has_or_is_using_name_1_from_private_module_2_4107", "Parameter '{0}' of accessor has or is using name '{1}' from private module '{2}'."),
         Parameter_0_of_accessor_has_or_is_using_name_1_from_external_module_2_but_cannot_be_named: diag(4108, ts.DiagnosticCategory.Error, "Parameter_0_of_accessor_has_or_is_using_name_1_from_external_module_2_but_cannot_be_named_4108", "Parameter '{0}' of accessor has or is using name '{1}' from external module '{2}' but cannot be named."),
+        Type_arguments_for_0_circularly_reference_themselves: diag(4109, ts.DiagnosticCategory.Error, "Type_arguments_for_0_circularly_reference_themselves_4109", "Type arguments for '{0}' circularly reference themselves."),
+        Tuple_type_arguments_circularly_reference_themselves: diag(4110, ts.DiagnosticCategory.Error, "Tuple_type_arguments_circularly_reference_themselves_4110", "Tuple type arguments circularly reference themselves."),
         The_current_host_does_not_support_the_0_option: diag(5001, ts.DiagnosticCategory.Error, "The_current_host_does_not_support_the_0_option_5001", "The current host does not support the '{0}' option."),
         Cannot_find_the_common_subdirectory_path_for_the_input_files: diag(5009, ts.DiagnosticCategory.Error, "Cannot_find_the_common_subdirectory_path_for_the_input_files_5009", "Cannot find the common subdirectory path for the input files."),
         File_specification_cannot_end_in_a_recursive_directory_wildcard_Asterisk_Asterisk_Colon_0: diag(5010, ts.DiagnosticCategory.Error, "File_specification_cannot_end_in_a_recursive_directory_wildcard_Asterisk_Asterisk_Colon_0_5010", "File specification cannot end in a recursive directory wildcard ('**'): '{0}'."),
@@ -32941,6 +32943,7 @@ var ts;
         TypeSystemPropertyName[TypeSystemPropertyName["ImmediateBaseConstraint"] = 4] = "ImmediateBaseConstraint";
         TypeSystemPropertyName[TypeSystemPropertyName["EnumTagType"] = 5] = "EnumTagType";
         TypeSystemPropertyName[TypeSystemPropertyName["JSDocTypeReference"] = 6] = "JSDocTypeReference";
+        TypeSystemPropertyName[TypeSystemPropertyName["ResolvedTypeArguments"] = 7] = "ResolvedTypeArguments";
     })(TypeSystemPropertyName || (TypeSystemPropertyName = {}));
     var CheckMode;
     (function (CheckMode) {
@@ -37337,7 +37340,7 @@ var ts;
                 var visitedSymbols = ts.createMap();
                 var deferredPrivates;
                 var oldcontext = context;
-                context = __assign(__assign({}, oldcontext), { usedSymbolNames: ts.mapMap(symbolTable, function (_symbol, name) { return [ts.unescapeLeadingUnderscores(name), true]; }), remappedSymbolNames: ts.createMap(), tracker: __assign(__assign({}, oldcontext.tracker), { trackSymbol: function (sym, decl, meaning) {
+                context = __assign(__assign({}, oldcontext), { usedSymbolNames: ts.createMap(), remappedSymbolNames: ts.createMap(), tracker: __assign(__assign({}, oldcontext.tracker), { trackSymbol: function (sym, decl, meaning) {
                             var accessibleResult = isSymbolAccessible(sym, decl, meaning, /*computeALiases*/ false);
                             if (accessibleResult.accessibility === 0 /* Accessible */) {
                                 // Lookup the root symbol of the chain of refs we'll use to access it and serialize it
@@ -37355,6 +37358,10 @@ var ts;
                         context.usedSymbolNames.set(name, true);
                     });
                 }
+                ts.forEachEntry(symbolTable, function (symbol, name) {
+                    var baseName = ts.unescapeLeadingUnderscores(name);
+                    void getInternalSymbolName(symbol, baseName); // Called to cache values into `usedSymbolNames` and `remappedSymbolNames`
+                });
                 var addingDeclare = !bundled;
                 var exportEquals = symbolTable.get("export=" /* ExportEquals */);
                 if (exportEquals && symbolTable.size > 1 && exportEquals.flags & 2097152 /* Alias */) {
@@ -37546,7 +37553,11 @@ var ts;
                         isPrivate = true;
                     }
                     var modifierFlags = (!isPrivate ? 1 /* Export */ : 0) | (isDefault && !needsPostExportDefault ? 512 /* Default */ : 0);
-                    if (symbol.flags & 16 /* Function */) {
+                    var isConstMergedWithNS = symbol.flags & 1536 /* Module */ &&
+                        symbol.flags & (2 /* BlockScopedVariable */ | 1 /* FunctionScopedVariable */ | 4 /* Property */) &&
+                        symbol.escapedName !== "export=" /* ExportEquals */;
+                    var isConstMergedWithNSPrintableAsSignatureMerge = isConstMergedWithNS && isTypeRepresentableAsFunctionNamespaceMerge(getTypeOfSymbol(symbol), symbol);
+                    if (symbol.flags & 16 /* Function */ || isConstMergedWithNSPrintableAsSignatureMerge) {
                         serializeAsFunctionNamespaceMerge(getTypeOfSymbol(symbol), symbol, getInternalSymbolName(symbol, symbolName), modifierFlags);
                     }
                     if (symbol.flags & 524288 /* TypeAlias */) {
@@ -37557,7 +37568,8 @@ var ts;
                     if (symbol.flags & (2 /* BlockScopedVariable */ | 1 /* FunctionScopedVariable */ | 4 /* Property */)
                         && symbol.escapedName !== "export=" /* ExportEquals */
                         && !(symbol.flags & 4194304 /* Prototype */)
-                        && !(symbol.flags & 32 /* Class */)) {
+                        && !(symbol.flags & 32 /* Class */)
+                        && !isConstMergedWithNSPrintableAsSignatureMerge) {
                         serializeVariableOrProperty(symbol, symbolName, isPrivate, needsPostExportDefault, propertyAsAlias, modifierFlags);
                     }
                     if (symbol.flags & 384 /* Enum */) {
@@ -37574,7 +37586,7 @@ var ts;
                             serializeAsClass(symbol, getInternalSymbolName(symbol, symbolName), modifierFlags);
                         }
                     }
-                    if (symbol.flags & (512 /* ValueModule */ | 1024 /* NamespaceModule */)) {
+                    if ((symbol.flags & (512 /* ValueModule */ | 1024 /* NamespaceModule */) && (!isConstMergedWithNS || isTypeOnlyNamespace(symbol))) || isConstMergedWithNSPrintableAsSignatureMerge) {
                         serializeModule(symbol, symbolName, modifierFlags);
                     }
                     if (symbol.flags & 64 /* Interface */) {
@@ -37602,7 +37614,10 @@ var ts;
                     }
                 }
                 function includePrivateSymbol(symbol) {
+                    if (ts.some(symbol.declarations, ts.isParameterDeclaration))
+                        return;
                     ts.Debug.assertDefined(deferredPrivates);
+                    getUnusedName(ts.unescapeLeadingUnderscores(symbol.escapedName), symbol); // Call to cache unique name for symbol
                     deferredPrivates.set("" + getSymbolId(symbol), symbol);
                 }
                 function isExportingScope(enclosingDeclaration) {
@@ -37661,8 +37676,14 @@ var ts;
                     /*decorators*/ undefined, 
                     /*modifiers*/ undefined, getInternalSymbolName(symbol, symbolName), typeParamDecls, heritageClauses, __spreadArrays(indexSignatures, constructSignatures, callSignatures, members)), modifierFlags);
                 }
+                function getNamespaceMembersForSerialization(symbol) {
+                    return !symbol.exports ? [] : ts.filter(ts.arrayFrom((symbol.exports).values()), function (p) { return !((p.flags & 4194304 /* Prototype */) || (p.escapedName === "prototype")); });
+                }
+                function isTypeOnlyNamespace(symbol) {
+                    return ts.every(getNamespaceMembersForSerialization(symbol), function (m) { return !(resolveSymbol(m).flags & 111551 /* Value */); });
+                }
                 function serializeModule(symbol, symbolName, modifierFlags) {
-                    var members = !symbol.exports ? [] : ts.filter(ts.arrayFrom((symbol.exports).values()), function (p) { return !((p.flags & 4194304 /* Prototype */) || (p.escapedName === "prototype")); });
+                    var members = getNamespaceMembersForSerialization(symbol);
                     // Split NS members up by declaration - members whose parent symbol is the ns symbol vs those whose is not (but were added in later via merging)
                     var locationMap = ts.arrayToMultiMap(members, function (m) { return m.parent && m.parent === symbol ? "real" : "merged"; });
                     var realMembers = locationMap.get("real") || ts.emptyArray;
@@ -37672,17 +37693,20 @@ var ts;
                     // so we don't even have placeholders to fill in.
                     if (ts.length(realMembers)) {
                         var localName = getInternalSymbolName(symbol, symbolName);
-                        serializeAsNamespaceDeclaration(realMembers, localName, modifierFlags, !!(symbol.flags & 16 /* Function */));
+                        serializeAsNamespaceDeclaration(realMembers, localName, modifierFlags, !!(symbol.flags & (16 /* Function */ | 67108864 /* Assignment */)));
                     }
                     if (ts.length(mergedMembers)) {
                         var localName = getInternalSymbolName(symbol, symbolName);
-                        ts.forEach(mergedMembers, includePrivateSymbol);
                         var nsBody = ts.createModuleBlock([ts.createExportDeclaration(
                             /*decorators*/ undefined, 
                             /*modifiers*/ undefined, ts.createNamedExports(ts.map(ts.filter(mergedMembers, function (n) { return n.escapedName !== "export=" /* ExportEquals */; }), function (s) {
                                 var name = ts.unescapeLeadingUnderscores(s.escapedName);
                                 var localName = getInternalSymbolName(s, name);
-                                return ts.createExportSpecifier(name === localName ? undefined : localName, name);
+                                var aliasDecl = s.declarations && getDeclarationOfAliasSymbol(s);
+                                var target = aliasDecl && getTargetOfAliasDeclaration(aliasDecl, /*dontRecursivelyResolve*/ true);
+                                includePrivateSymbol(target || s);
+                                var targetName = target ? getInternalSymbolName(target, ts.unescapeLeadingUnderscores(target.escapedName)) : localName;
+                                return ts.createExportSpecifier(name === targetName ? undefined : targetName, name);
                             })))]);
                         addResult(ts.createModuleDeclaration(
                         /*decorators*/ undefined, 
@@ -37913,6 +37937,7 @@ var ts;
                             serializeMaybeAliasAssignment(symbol);
                             break;
                         case 208 /* BinaryExpression */:
+                        case 193 /* PropertyAccessExpression */:
                             // Could be best encoded as though an export specifier or as though an export assignment
                             // If name is default or export=, do an export assignment
                             // Otherwise do an export specifier
@@ -37923,10 +37948,6 @@ var ts;
                                 serializeExportSpecifier(localName, targetName);
                             }
                             break;
-                        case 193 /* PropertyAccessExpression */:
-                            // A PAE alias is _always_ going to exist as an append to a top-level export, where our top level
-                            // handling should always be sufficient to encode the export action itself
-                            break;
                         default:
                             return ts.Debug.failBadSyntaxKind(node, "Unhandled alias declaration kind in symbol serializer!");
                     }
@@ -37950,7 +37971,8 @@ var ts;
                     var aliasDecl = symbol.declarations && getDeclarationOfAliasSymbol(symbol);
                     // serialize what the alias points to, preserve the declaration's initializer
                     var target = aliasDecl && getTargetOfAliasDeclaration(aliasDecl, /*dontRecursivelyResolve*/ true);
-                    if (target) {
+                    // If the target resolves and resolves to a thing defined in this file, emit as an alias, otherwise emit as a const
+                    if (target && ts.length(target.declarations) && ts.some(target.declarations, function (d) { return ts.getSourceFileOfNode(d) === ts.getSourceFileOfNode(enclosingDeclaration); })) {
                         // In case `target` refers to a namespace member, look at the declaration and serialize the leftmost symbol in it
                         // eg, `namespace A { export class B {} }; exports = A.B;`
                         // Technically, this is all that's required in the case where the assignment is an entity name expression
@@ -38025,6 +38047,7 @@ var ts;
                     return ts.getObjectFlags(typeToSerialize) & (16 /* Anonymous */ | 32 /* Mapped */) &&
                         !getIndexInfoOfType(typeToSerialize, 0 /* String */) &&
                         !getIndexInfoOfType(typeToSerialize, 1 /* Number */) &&
+                        !!(ts.length(getPropertiesOfType(typeToSerialize)) || ts.length(getSignaturesOfType(typeToSerialize, 0 /* Call */))) &&
                         !ts.length(getSignaturesOfType(typeToSerialize, 1 /* Construct */)) && // TODO: could probably serialize as function + ns + class, now that that's OK
                         !getDeclarationWithTypeAnnotation(hostSymbol) &&
                         !(typeToSerialize.symbol && ts.some(typeToSerialize.symbol.declarations, function (d) { return ts.getSourceFileOfNode(d) !== ctxSrc; })) &&
@@ -38298,11 +38321,8 @@ var ts;
                             return context.remappedSymbolNames.get("" + getSymbolId(symbol));
                         }
                     }
-                    if (input === "default" /* Default */) {
-                        input = "_default";
-                    }
-                    else if (input === "export=" /* ExportEquals */) {
-                        input = "_exports";
+                    if (symbol) {
+                        input = getNameCandidateWorker(symbol, input);
                     }
                     var i = 0;
                     var original = input;
@@ -38316,17 +38336,28 @@ var ts;
                     }
                     return input;
                 }
-                function getInternalSymbolName(symbol, localName) {
-                    if (context.remappedSymbolNames.has("" + getSymbolId(symbol))) {
-                        return context.remappedSymbolNames.get("" + getSymbolId(symbol));
-                    }
+                function getNameCandidateWorker(symbol, localName) {
                     if (localName === "default" /* Default */ || localName === "__class" /* Class */ || localName === "__function" /* Function */) {
                         var flags = context.flags;
                         context.flags |= 16777216 /* InInitialEntityName */;
                         var nameCandidate = getNameOfSymbolAsWritten(symbol, context);
                         context.flags = flags;
-                        localName = ts.isIdentifierText(nameCandidate, languageVersion) && !ts.isStringANonContextualKeyword(nameCandidate) ? nameCandidate : getUnusedName("_default", symbol);
+                        localName = nameCandidate.length > 0 && ts.isSingleOrDoubleQuote(nameCandidate.charCodeAt(0)) ? ts.stripQuotes(nameCandidate) : nameCandidate;
                     }
+                    if (localName === "default" /* Default */) {
+                        localName = "_default";
+                    }
+                    else if (localName === "export=" /* ExportEquals */) {
+                        localName = "_exports";
+                    }
+                    localName = ts.isIdentifierText(localName, languageVersion) && !ts.isStringANonContextualKeyword(localName) ? localName : "_" + localName.replace(/[^a-zA-Z0-9]/g, "_");
+                    return localName;
+                }
+                function getInternalSymbolName(symbol, localName) {
+                    if (context.remappedSymbolNames.has("" + getSymbolId(symbol))) {
+                        return context.remappedSymbolNames.get("" + getSymbolId(symbol));
+                    }
+                    localName = getNameCandidateWorker(symbol, localName);
                     // The result of this is going to be used as the symbol's name - lock it in, so `getUnusedName` will also pick it up
                     context.remappedSymbolNames.set("" + getSymbolId(symbol), localName);
                     return localName;
@@ -38655,6 +38686,8 @@ var ts;
                     return !!target.immediateBaseConstraint;
                 case 6 /* JSDocTypeReference */:
                     return !!getSymbolLinks(target).resolvedJSDocType;
+                case 7 /* ResolvedTypeArguments */:
+                    return !!target.resolvedTypeArguments;
             }
             return ts.Debug.assertNever(propertyName);
         }
@@ -42461,13 +42494,25 @@ var ts;
             return type;
         }
         function getTypeArguments(type) {
+            var _a, _b;
             if (!type.resolvedTypeArguments) {
+                if (!pushTypeResolution(type, 7 /* ResolvedTypeArguments */)) {
+                    return ((_a = type.target.localTypeParameters) === null || _a === void 0 ? void 0 : _a.map(function () { return errorType; })) || ts.emptyArray;
+                }
                 var node = type.node;
                 var typeArguments = !node ? ts.emptyArray :
                     node.kind === 168 /* TypeReference */ ? ts.concatenate(type.target.outerTypeParameters, getEffectiveTypeArguments(node, type.target.localTypeParameters)) :
                         node.kind === 173 /* ArrayType */ ? [getTypeFromTypeNode(node.elementType)] :
                             ts.map(node.elementTypes, getTypeFromTypeNode);
-                type.resolvedTypeArguments = type.mapper ? instantiateTypes(typeArguments, type.mapper) : typeArguments;
+                if (popTypeResolution()) {
+                    type.resolvedTypeArguments = type.mapper ? instantiateTypes(typeArguments, type.mapper) : typeArguments;
+                }
+                else {
+                    type.resolvedTypeArguments = ((_b = type.target.localTypeParameters) === null || _b === void 0 ? void 0 : _b.map(function () { return errorType; })) || ts.emptyArray;
+                    error(type.node || currentNode, type.target.symbol
+                        ? ts.Diagnostics.Type_arguments_for_0_circularly_reference_themselves
+                        : ts.Diagnostics.Tuple_type_arguments_circularly_reference_themselves, type.target.symbol && symbolToString(type.target.symbol));
+                }
             }
             return type.resolvedTypeArguments;
         }
@@ -42606,14 +42651,17 @@ var ts;
             var typeType = valueType;
             if (symbol.valueDeclaration) {
                 var decl = ts.getRootDeclaration(symbol.valueDeclaration);
-                var isRequireAlias = ts.isVariableDeclaration(decl)
-                    && decl.initializer
-                    && ts.isCallExpression(decl.initializer)
-                    && ts.isRequireCall(decl.initializer, /*requireStringLiteralLikeArgument*/ true)
-                    && valueType.symbol;
-                var isImportType = node.kind === 187 /* ImportType */;
+                var isRequireAlias = false;
+                if (ts.isVariableDeclaration(decl) && decl.initializer) {
+                    var expr = decl.initializer;
+                    // skip past entity names, eg `require("x").a.b.c`
+                    while (ts.isPropertyAccessExpression(expr)) {
+                        expr = expr.expression;
+                    }
+                    isRequireAlias = ts.isCallExpression(expr) && ts.isRequireCall(expr, /*requireStringLiteralLikeArgument*/ true) && !!valueType.symbol;
+                }
                 var isDelayedMergeClass = symbol !== valueType.symbol && getMergedSymbol(symbol) === valueType.symbol;
-                if (isRequireAlias || isImportType || isDelayedMergeClass) {
+                if (isRequireAlias || node.kind === 187 /* ImportType */ || isDelayedMergeClass) {
                     typeType = getTypeReferenceType(node, valueType.symbol);
                 }
             }
@@ -45736,7 +45784,7 @@ var ts;
                 return true;
             }
             if (source.flags & 524288 /* Object */ && target.flags & 524288 /* Object */) {
-                var related = relation.get(getRelationKey(source, target, relation));
+                var related = relation.get(getRelationKey(source, target, /*isIntersectionConstituent*/ false, relation));
                 if (related !== undefined) {
                     return !!(related & 1 /* Succeeded */);
                 }
@@ -46107,7 +46155,7 @@ var ts;
                 // and we need to handle "each" relations before "some" relations for the same kind of type.
                 if (source.flags & 1048576 /* Union */) {
                     result = relation === comparableRelation ?
-                        someTypeRelatedToType(source, target, reportErrors && !(source.flags & 131068 /* Primitive */), isIntersectionConstituent) :
+                        someTypeRelatedToType(source, target, reportErrors && !(source.flags & 131068 /* Primitive */)) :
                         eachTypeRelatedToType(source, target, reportErrors && !(source.flags & 131068 /* Primitive */));
                 }
                 else {
@@ -46145,7 +46193,7 @@ var ts;
                         //
                         //    - For a primitive type or type parameter (such as 'number = A & B') there is no point in
                         //          breaking the intersection apart.
-                        result = someTypeRelatedToType(source, target, /*reportErrors*/ false, /*isIntersectionConstituent*/ true);
+                        result = someTypeRelatedToType(source, target, /*reportErrors*/ false);
                     }
                     if (!result && (source.flags & 66846720 /* StructuredOrInstantiable */ || target.flags & 66846720 /* StructuredOrInstantiable */)) {
                         if (result = recursiveTypeRelatedTo(source, target, reportErrors, isIntersectionConstituent)) {
@@ -46429,14 +46477,14 @@ var ts;
                 }
                 return result;
             }
-            function someTypeRelatedToType(source, target, reportErrors, isIntersectionConstituent) {
+            function someTypeRelatedToType(source, target, reportErrors) {
                 var sourceTypes = source.types;
                 if (source.flags & 1048576 /* Union */ && containsType(sourceTypes, target)) {
                     return -1 /* True */;
                 }
                 var len = sourceTypes.length;
                 for (var i = 0; i < len; i++) {
-                    var related = isRelatedTo(sourceTypes[i], target, reportErrors && i === len - 1, /*headMessage*/ undefined, isIntersectionConstituent);
+                    var related = isRelatedTo(sourceTypes[i], target, reportErrors && i === len - 1);
                     if (related) {
                         return related;
                     }
@@ -46524,7 +46572,7 @@ var ts;
                 if (overflow) {
                     return 0 /* False */;
                 }
-                var id = getRelationKey(source, target, relation);
+                var id = getRelationKey(source, target, isIntersectionConstituent, relation);
                 var entry = relation.get(id);
                 if (entry !== undefined) {
                     if (reportErrors && entry & 2 /* Failed */ && !(entry & 4 /* Reported */)) {
@@ -47710,17 +47758,18 @@ var ts;
          * To improve caching, the relation key for two generic types uses the target's id plus ids of the type parameters.
          * For other cases, the types ids are used.
          */
-        function getRelationKey(source, target, relation) {
+        function getRelationKey(source, target, isIntersectionConstituent, relation) {
             if (relation === identityRelation && source.id > target.id) {
                 var temp = source;
                 source = target;
                 target = temp;
             }
+            var intersection = isIntersectionConstituent ? "&" : "";
             if (isTypeReferenceWithGenericArguments(source) && isTypeReferenceWithGenericArguments(target)) {
                 var typeParameters = [];
-                return getTypeReferenceId(source, typeParameters) + "," + getTypeReferenceId(target, typeParameters);
+                return getTypeReferenceId(source, typeParameters) + "," + getTypeReferenceId(target, typeParameters) + intersection;
             }
-            return source.id + "," + target.id;
+            return source.id + "," + target.id + intersection;
         }
         // Invoke the callback for each underlying property symbol of the given symbol and return the first
         // value that isn't undefined.