Ensure that emitter calls callbacks for empty blocks (#18547) (#18550)

* Ensure that emitter calls callbacks for empty blocks (#18547)

* Fix action description

src/compiler/emitter.ts

@@ -1440,29 +1440,18 @@ namespace ts {
         //
 
         function emitBlock(node: Block) {
-            if (isSingleLineEmptyBlock(node)) {
-                writeToken(SyntaxKind.OpenBraceToken, node.pos, /*contextNode*/ node);
-                write(" ");
-                writeToken(SyntaxKind.CloseBraceToken, node.statements.end, /*contextNode*/ node);
-            }
-            else {
-                writeToken(SyntaxKind.OpenBraceToken, node.pos, /*contextNode*/ node);
-                emitBlockStatements(node);
-                // We have to call emitLeadingComments explicitly here because otherwise leading comments of the close brace token will not be emitted
-                increaseIndent();
-                emitLeadingCommentsOfPosition(node.statements.end);
-                decreaseIndent();
-                writeToken(SyntaxKind.CloseBraceToken, node.statements.end, /*contextNode*/ node);
-            }
+            writeToken(SyntaxKind.OpenBraceToken, node.pos, /*contextNode*/ node);
+            emitBlockStatements(node, /*forceSingleLine*/ !node.multiLine && isEmptyBlock(node));
+            // We have to call emitLeadingComments explicitly here because otherwise leading comments of the close brace token will not be emitted
+            increaseIndent();
+            emitLeadingCommentsOfPosition(node.statements.end);
+            decreaseIndent();
+            writeToken(SyntaxKind.CloseBraceToken, node.statements.end, /*contextNode*/ node);
         }
 
-        function emitBlockStatements(node: BlockLike) {
-            if (getEmitFlags(node) & EmitFlags.SingleLine) {
-                emitList(node, node.statements, ListFormat.SingleLineBlockStatements);
-            }
-            else {
-                emitList(node, node.statements, ListFormat.MultiLineBlockStatements);
-            }
+        function emitBlockStatements(node: BlockLike, forceSingleLine: boolean) {
+            const format = forceSingleLine || getEmitFlags(node) & EmitFlags.SingleLine ? ListFormat.SingleLineBlockStatements : ListFormat.MultiLineBlockStatements;
+            emitList(node, node.statements, format);
         }
 
         function emitVariableStatement(node: VariableStatement) {
@@ -1889,16 +1878,11 @@ namespace ts {
         }
 
         function emitModuleBlock(node: ModuleBlock) {
-            if (isEmptyBlock(node)) {
-                write("{ }");
-            }
-            else {
-                pushNameGenerationScope();
-                write("{");
-                emitBlockStatements(node);
-                write("}");
-                popNameGenerationScope();
-            }
+            pushNameGenerationScope();
+            write("{");
+            emitBlockStatements(node, /*forceSingleLine*/ isEmptyBlock(node));
+            write("}");
+            popNameGenerationScope();
         }
 
         function emitCaseBlock(node: CaseBlock) {
@@ -2762,11 +2746,6 @@ namespace ts {
                 && !rangeEndIsOnSameLineAsRangeStart(node1, node2, currentSourceFile);
         }
 
-        function isSingleLineEmptyBlock(block: Block) {
-            return !block.multiLine
-                && isEmptyBlock(block);
-        }
-
         function isEmptyBlock(block: BlockLike) {
             return block.statements.length === 0
                 && rangeEndIsOnSameLineAsRangeStart(block, block, currentSourceFile);

tests/cases/fourslash/convertToEs6Class_emptyCatchClause.ts

@@ -0,0 +1,20 @@
+/// <reference path='fourslash.ts' />
+
+// @allowNonTsExtensions: true
+// @Filename: /a.js
+////function /**/MyClass() {}
+////MyClass.prototype.foo = function() {
+////    try {} catch() {}
+////}
+
+verify.applicableRefactorAvailableAtMarker("");
+verify.fileAfterApplyingRefactorAtMarker("",
+`class MyClass {
+    constructor() { }
+    foo() {
+        try { }
+        catch () { }
+    }
+}
+`,
+'Convert to ES2015 class', 'convert');

tests/cases/fourslash/extract-method-empty-namespace.ts

@@ -0,0 +1,22 @@
+/// <reference path='fourslash.ts' />
+
+// TODO: GH#18546
+// For now this tests that at least we don't crash.
+
+////function f() {
+////    /*start*/namespace N {}/*end*/
+////}
+
+goTo.select('start', 'end')
+edit.applyRefactor({
+    refactorName: "Extract Method",
+    actionName: "scope_1",
+    actionDescription: "Extract function into global scope",
+    newContent: `function f() {
+    /*RENAME*/newFunction(N);
+}
+function newFunction(N: any) {
+    namespace N { }
+}
+`
+});