Fix empty block generation in using declaration for-of loops and remove obsolete comment

Copilot · weswigham · Copilot · commit 0b3bf33a8eaa · 2025-06-25T20:46:24.000Z
Co-authored-by: weswigham &lt;2932786+weswigham@users.noreply.github.com&gt;
diff --git a/src/compiler/transformers/esnext.ts b/src/compiler/transformers/esnext.ts
@@ -292,11 +292,6 @@ export function transformESNext(context: TransformationContext): (x: SourceFile
         return visitEachChild(node, visitor, context);
     }
 
-    /**
-     * Collects all variable declarations that shadow a given identifier name in a statement.
-     */
-
-
     function visitForOfStatement(node: ForOfStatement) {
         if (isUsingVariableDeclarationList(node.initializer)) {
             // given:
@@ -322,9 +317,17 @@ export function transformESNext(context: TransformationContext): (x: SourceFile
             const usingVarStatement = factory.createVariableStatement(/*modifiers*/ undefined, usingVarList);
             
             // Wrap the original loop body in an additional block scope to handle shadowing
-            const wrappedStatement = isBlock(node.statement) ? 
-                node.statement : 
-                factory.createBlock([node.statement], /*multiLine*/ true);
+            // Don't create an extra block if the original statement is empty
+            const isEmptyBlock = isBlock(node.statement) && node.statement.statements.length === 0;
+            const shouldWrapInBlock = !isEmptyBlock;
+            
+            const statements: Statement[] = [usingVarStatement];
+            if (shouldWrapInBlock) {
+                const wrappedStatement = isBlock(node.statement) ? 
+                    node.statement : 
+                    factory.createBlock([node.statement], /*multiLine*/ true);
+                statements.push(wrappedStatement);
+            }
             
             return visitNode(
                 factory.updateForOfStatement(
@@ -334,10 +337,7 @@ export function transformESNext(context: TransformationContext): (x: SourceFile
                         factory.createVariableDeclaration(temp),
                     ], NodeFlags.Const),
                     node.expression,
-                    factory.createBlock([
-                        usingVarStatement,
-                        wrappedStatement,
-                    ], /*multiLine*/ true),
+                    factory.createBlock(statements, /*multiLine*/ true),
                 ),
                 visitor,
                 isStatement,
diff --git a/tests/baselines/reference/awaitUsingDeclarationsInForAwaitOf(target=es2015).js b/tests/baselines/reference/awaitUsingDeclarationsInForAwaitOf(target=es2015).js
@@ -88,8 +88,6 @@ function main() {
                 const env_1 = { stack: [], error: void 0, hasError: false };
                 try {
                     const d1 = __addDisposableResource(env_1, d1_1, true);
-                    {
-                    }
                 }
                 catch (e_2) {
                     env_1.error = e_2;
diff --git a/tests/baselines/reference/awaitUsingDeclarationsInForAwaitOf(target=es2017).js b/tests/baselines/reference/awaitUsingDeclarationsInForAwaitOf(target=es2017).js
@@ -76,8 +76,6 @@ async function main() {
             const env_1 = { stack: [], error: void 0, hasError: false };
             try {
                 const d1 = __addDisposableResource(env_1, d1_1, true);
-                {
-                }
             }
             catch (e_2) {
                 env_1.error = e_2;
diff --git a/tests/baselines/reference/awaitUsingDeclarationsInForAwaitOf(target=es2022).js b/tests/baselines/reference/awaitUsingDeclarationsInForAwaitOf(target=es2022).js
@@ -64,8 +64,6 @@ async function main() {
         const env_1 = { stack: [], error: void 0, hasError: false };
         try {
             const d1 = __addDisposableResource(env_1, d1_1, true);
-            {
-            }
         }
         catch (e_1) {
             env_1.error = e_1;
diff --git a/tests/baselines/reference/awaitUsingDeclarationsInForAwaitOf(target=es5).js b/tests/baselines/reference/awaitUsingDeclarationsInForAwaitOf(target=es5).js
@@ -128,8 +128,6 @@ function main() {
                 case 3:
                     _j.trys.push([3, 4, 5, 8]);
                     d1 = __addDisposableResource(env_1, d1_1, true);
-                    {
-                    }
                     return [3 /*break*/, 8];
                 case 4:
                     e_1 = _j.sent();
diff --git a/tests/baselines/reference/awaitUsingDeclarationsInForOf.1(target=es2015).js b/tests/baselines/reference/awaitUsingDeclarationsInForOf.1(target=es2015).js
@@ -77,8 +77,6 @@ function main() {
             const env_1 = { stack: [], error: void 0, hasError: false };
             try {
                 const d1 = __addDisposableResource(env_1, d1_1, true);
-                {
-                }
             }
             catch (e_1) {
                 env_1.error = e_1;
diff --git a/tests/baselines/reference/awaitUsingDeclarationsInForOf.1(target=es2017).js b/tests/baselines/reference/awaitUsingDeclarationsInForOf.1(target=es2017).js
@@ -65,8 +65,6 @@ async function main() {
         const env_1 = { stack: [], error: void 0, hasError: false };
         try {
             const d1 = __addDisposableResource(env_1, d1_1, true);
-            {
-            }
         }
         catch (e_1) {
             env_1.error = e_1;
diff --git a/tests/baselines/reference/awaitUsingDeclarationsInForOf.1(target=es2022).js b/tests/baselines/reference/awaitUsingDeclarationsInForOf.1(target=es2022).js
@@ -65,8 +65,6 @@ async function main() {
         const env_1 = { stack: [], error: void 0, hasError: false };
         try {
             const d1 = __addDisposableResource(env_1, d1_1, true);
-            {
-            }
         }
         catch (e_1) {
             env_1.error = e_1;
diff --git a/tests/baselines/reference/awaitUsingDeclarationsInForOf.1(target=es5).js b/tests/baselines/reference/awaitUsingDeclarationsInForOf.1(target=es5).js
@@ -117,8 +117,6 @@ function main() {
                 case 2:
                     _d.trys.push([2, 3, 4, 7]);
                     d1 = __addDisposableResource(env_1, d1_1, true);
-                    {
-                    }
                     return [3 /*break*/, 7];
                 case 3:
                     e_1 = _d.sent();
diff --git a/tests/baselines/reference/usingDeclarationsInForAwaitOf(target=es2015).js b/tests/baselines/reference/usingDeclarationsInForAwaitOf(target=es2015).js
@@ -87,8 +87,6 @@ function main() {
                 const env_1 = { stack: [], error: void 0, hasError: false };
                 try {
                     const d1 = __addDisposableResource(env_1, d1_1, false);
-                    {
-                    }
                 }
                 catch (e_2) {
                     env_1.error = e_2;
diff --git a/tests/baselines/reference/usingDeclarationsInForAwaitOf(target=es2017).js b/tests/baselines/reference/usingDeclarationsInForAwaitOf(target=es2017).js
@@ -77,8 +77,6 @@ async function main() {
             const env_1 = { stack: [], error: void 0, hasError: false };
             try {
                 const d1 = __addDisposableResource(env_1, d1_1, false);
-                {
-                }
             }
             catch (e_2) {
                 env_1.error = e_2;
diff --git a/tests/baselines/reference/usingDeclarationsInForAwaitOf(target=es2022).js b/tests/baselines/reference/usingDeclarationsInForAwaitOf(target=es2022).js
@@ -65,8 +65,6 @@ async function main() {
         const env_1 = { stack: [], error: void 0, hasError: false };
         try {
             const d1 = __addDisposableResource(env_1, d1_1, false);
-            {
-            }
         }
         catch (e_1) {
             env_1.error = e_1;
diff --git a/tests/baselines/reference/usingDeclarationsInForAwaitOf(target=es5).js b/tests/baselines/reference/usingDeclarationsInForAwaitOf(target=es5).js
@@ -123,8 +123,6 @@ function main() {
                     env_1 = { stack: [], error: void 0, hasError: false };
                     try {
                         d1 = __addDisposableResource(env_1, d1_1, false);
-                        {
-                        }
                     }
                     catch (e_2) {
                         env_1.error = e_2;
diff --git a/tests/baselines/reference/usingDeclarationsInForOf.1(target=es2015).js b/tests/baselines/reference/usingDeclarationsInForOf.1(target=es2015).js
@@ -62,8 +62,6 @@ for (const d1_1 of [{ [Symbol.dispose]() { } }, null, undefined]) {
     const env_1 = { stack: [], error: void 0, hasError: false };
     try {
         const d1 = __addDisposableResource(env_1, d1_1, false);
-        {
-        }
     }
     catch (e_1) {
         env_1.error = e_1;
diff --git a/tests/baselines/reference/usingDeclarationsInForOf.1(target=es2017).js b/tests/baselines/reference/usingDeclarationsInForOf.1(target=es2017).js
@@ -62,8 +62,6 @@ for (const d1_1 of [{ [Symbol.dispose]() { } }, null, undefined]) {
     const env_1 = { stack: [], error: void 0, hasError: false };
     try {
         const d1 = __addDisposableResource(env_1, d1_1, false);
-        {
-        }
     }
     catch (e_1) {
         env_1.error = e_1;
diff --git a/tests/baselines/reference/usingDeclarationsInForOf.1(target=es2022).js b/tests/baselines/reference/usingDeclarationsInForOf.1(target=es2022).js
@@ -62,8 +62,6 @@ for (const d1_1 of [{ [Symbol.dispose]() { } }, null, undefined]) {
     const env_1 = { stack: [], error: void 0, hasError: false };
     try {
         const d1 = __addDisposableResource(env_1, d1_1, false);
-        {
-        }
     }
     catch (e_1) {
         env_1.error = e_1;
diff --git a/tests/baselines/reference/usingDeclarationsInForOf.1(target=es5).js b/tests/baselines/reference/usingDeclarationsInForOf.1(target=es5).js
@@ -64,8 +64,6 @@ for (var _i = 0, _b = [(_a = {}, _a[Symbol.dispose] = function () { }, _a), null
     var env_1 = { stack: [], error: void 0, hasError: false };
     try {
         var d1 = __addDisposableResource(env_1, d1_1, false);
-        {
-        }
     }
     catch (e_1) {
         env_1.error = e_1;

Original file line number	Diff line number	Diff line change
`@@ -88,8 +88,6 @@ function main() {`
`88`	`88`	`const env_1 = { stack: [], error: void 0, hasError: false };`
`89`	`89`	`try {`
`90`	`90`	`const d1 = __addDisposableResource(env_1, d1_1, true);`
`91`		`- {`
`92`		`- }`
`93`	`91`	`}`
`94`	`92`	`catch (e_2) {`
`95`	`93`	`env_1.error = e_2;`
Original file line number	Diff line number	Diff line change
`@@ -76,8 +76,6 @@ async function main() {`
`76`	`76`	`const env_1 = { stack: [], error: void 0, hasError: false };`
`77`	`77`	`try {`
`78`	`78`	`const d1 = __addDisposableResource(env_1, d1_1, true);`
`79`		`- {`
`80`		`- }`
`81`	`79`	`}`
`82`	`80`	`catch (e_2) {`
`83`	`81`	`env_1.error = e_2;`
Original file line number	Diff line number	Diff line change
`@@ -64,8 +64,6 @@ async function main() {`
`64`	`64`	`const env_1 = { stack: [], error: void 0, hasError: false };`
`65`	`65`	`try {`
`66`	`66`	`const d1 = __addDisposableResource(env_1, d1_1, true);`
`67`		`- {`
`68`		`- }`
`69`	`67`	`}`
`70`	`68`	`catch (e_1) {`
`71`	`69`	`env_1.error = e_1;`
Original file line number	Diff line number	Diff line change
`@@ -77,8 +77,6 @@ function main() {`
`77`	`77`	`const env_1 = { stack: [], error: void 0, hasError: false };`
`78`	`78`	`try {`
`79`	`79`	`const d1 = __addDisposableResource(env_1, d1_1, true);`
`80`		`- {`
`81`		`- }`
`82`	`80`	`}`
`83`	`81`	`catch (e_1) {`
`84`	`82`	`env_1.error = e_1;`
Original file line number	Diff line number	Diff line change
`@@ -65,8 +65,6 @@ async function main() {`
`65`	`65`	`const env_1 = { stack: [], error: void 0, hasError: false };`
`66`	`66`	`try {`
`67`	`67`	`const d1 = __addDisposableResource(env_1, d1_1, true);`
`68`		`- {`
`69`		`- }`
`70`	`68`	`}`
`71`	`69`	`catch (e_1) {`
`72`	`70`	`env_1.error = e_1;`
Original file line number	Diff line number	Diff line change
`@@ -87,8 +87,6 @@ function main() {`
`87`	`87`	`const env_1 = { stack: [], error: void 0, hasError: false };`
`88`	`88`	`try {`
`89`	`89`	`const d1 = __addDisposableResource(env_1, d1_1, false);`
`90`		`- {`
`91`		`- }`
`92`	`90`	`}`
`93`	`91`	`catch (e_2) {`
`94`	`92`	`env_1.error = e_2;`