Fix spurious circularity caused by removeOptionalityFromDeclaredType, cache result (#52696)

src/compiler/checker.ts

@@ -1233,6 +1233,7 @@ const enum TypeSystemPropertyName {
     ResolvedTypeArguments,
     ResolvedBaseTypes,
     WriteType,
+    ParameterInitializerContainsUndefined,
 }
 
 /** @internal */
@@ -9983,6 +9984,8 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
                 return !!(target as InterfaceType).baseTypesResolved;
             case TypeSystemPropertyName.WriteType:
                 return !!getSymbolLinks(target as Symbol).writeType;
+            case TypeSystemPropertyName.ParameterInitializerContainsUndefined:
+                return getNodeLinks(target as ParameterDeclaration).parameterInitializerContainsUndefined !== undefined;
         }
         return Debug.assertNever(propertyName);
     }
@@ -27295,22 +27298,37 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
         return symbol.flags & SymbolFlags.Variable && (getDeclarationNodeFlagsFromSymbol(symbol) & NodeFlags.Const) !== 0;
     }
 
+    function parameterInitializerContainsUndefined(declaration: ParameterDeclaration): boolean {
+        const links = getNodeLinks(declaration);
+
+        if (links.parameterInitializerContainsUndefined === undefined) {
+            if (!pushTypeResolution(declaration, TypeSystemPropertyName.ParameterInitializerContainsUndefined)) {
+                reportCircularityError(declaration.symbol);
+                return true;
+            }
+
+            const containsUndefined = !!(getTypeFacts(checkDeclarationInitializer(declaration, CheckMode.Normal)) & TypeFacts.IsUndefined);
+
+            if (!popTypeResolution()) {
+                reportCircularityError(declaration.symbol);
+                return true;
+            }
+
+            links.parameterInitializerContainsUndefined = containsUndefined;
+        }
+
+        return links.parameterInitializerContainsUndefined;
+    }
+
     /** remove undefined from the annotated type of a parameter when there is an initializer (that doesn't include undefined) */
     function removeOptionalityFromDeclaredType(declaredType: Type, declaration: VariableLikeDeclaration): Type {
-        if (pushTypeResolution(declaration.symbol, TypeSystemPropertyName.DeclaredType)) {
-            const annotationIncludesUndefined = strictNullChecks &&
-                declaration.kind === SyntaxKind.Parameter &&
-                declaration.initializer &&
-                getTypeFacts(declaredType) & TypeFacts.IsUndefined &&
-                !(getTypeFacts(checkExpression(declaration.initializer)) & TypeFacts.IsUndefined);
-            popTypeResolution();
+        const removeUndefined = strictNullChecks &&
+            declaration.kind === SyntaxKind.Parameter &&
+            declaration.initializer &&
+            getTypeFacts(declaredType) & TypeFacts.IsUndefined &&
+            !parameterInitializerContainsUndefined(declaration);
 
-            return annotationIncludesUndefined ? getTypeWithFacts(declaredType, TypeFacts.NEUndefined) : declaredType;
-        }
-        else {
-            reportCircularityError(declaration.symbol);
-            return declaredType;
-        }
+        return removeUndefined ? getTypeWithFacts(declaredType, TypeFacts.NEUndefined) : declaredType;
     }
 
     function isConstraintPosition(type: Type, node: Node) {

src/compiler/types.ts

@@ -5997,6 +5997,7 @@ export interface NodeLinks {
     declarationRequiresScopeChange?: boolean; // Set by `useOuterVariableScopeInParameter` in checker when downlevel emit would change the name resolution scope inside of a parameter.
     serializedTypes?: Map<string, SerializedTypeEntry>; // Collection of types serialized at this location
     decoratorSignature?: Signature;     // Signature for decorator as if invoked by the runtime.
+    parameterInitializerContainsUndefined?: boolean; // True if this is a parameter declaration whose type annotation contains "undefined".
 }
 
 /** @internal */

src/testRunner/unittests/tsserver/inconsistentErrorInEditor.ts

@@ -38,4 +38,36 @@ describe("unittests:: tsserver:: inconsistentErrorInEditor", () => {
         verifyGetErrRequest({ session, host, files: ["^/untitled/ts-nul-authority/Untitled-1"] });
         baselineTsserverLogs("inconsistentErrorInEditor", "should not error", session);
     });
-});
+});
+
+describe("unittests:: tsserver:: inconsistentErrorInEditor2", () => {
+    it("should not error", () => {
+        const host = createServerHost([]);
+        const session = createSession(host, { canUseEvents: true, noGetErrOnBackgroundUpdate: true, logger: createLoggerWithInMemoryLogs(host) });
+        session.executeCommandSeq<ts.server.protocol.UpdateOpenRequest>({
+            command: ts.server.protocol.CommandTypes.UpdateOpen,
+            arguments: {
+                changedFiles: [],
+                closedFiles: [],
+                openFiles: [
+                    {
+                        file: "^/untitled/ts-nul-authority/Untitled-1",
+                        fileContent: "function fn(Foo: number) {\r\n     type Foo = typeof Foo;\r\n    return 0 as any as {x: Foo};\r\n}",
+                        scriptKindName: "TS"
+                    }
+                ]
+            }
+        });
+        session.executeCommandSeq<ts.server.protocol.EncodedSemanticClassificationsRequest>({
+            command: ts.server.protocol.CommandTypes.EncodedSemanticClassificationsFull,
+            arguments: {
+                file: "^/untitled/ts-nul-authority/Untitled-1",
+                start: 0,
+                length: 128,
+                format: "2020"
+            }
+        });
+        verifyGetErrRequest({ session, host, files: ["^/untitled/ts-nul-authority/Untitled-1"] });
+        baselineTsserverLogs("inconsistentErrorInEditor2", "should not error", session);
+    });
+});