Fix loop variables incorrectly being made global (#1641)

Perryvw · web-flow · commit 45fb7eb6e487 · 2025-06-08T16:38:46.000+02:00
diff --git a/src/transformation/visitors/loops/for.ts b/src/transformation/visitors/loops/for.ts
@@ -4,10 +4,13 @@ import { FunctionVisitor } from "../../context";
 import { transformInPrecedingStatementScope } from "../../utils/preceding-statements";
 import { checkVariableDeclarationList, transformVariableDeclaration } from "../variable-declaration";
 import { invertCondition, transformLoopBody } from "./utils";
+import { ScopeType } from "../../utils/scope";
 
 export const transformForStatement: FunctionVisitor<ts.ForStatement> = (statement, context) => {
     const result: lua.Statement[] = [];
 
+    context.pushScope(ScopeType.Loop);
+
     if (statement.initializer) {
         if (ts.isVariableDeclarationList(statement.initializer)) {
             checkVariableDeclarationList(context, statement.initializer);
@@ -61,5 +64,7 @@ export const transformForStatement: FunctionVisitor<ts.ForStatement> = (statemen
     // while (condition) do ... end
     result.push(lua.createWhileStatement(lua.createBlock(body), condition, statement));
 
+    context.popScope();
+
     return lua.createDoStatement(result, statement);
 };
diff --git a/test/unit/loops.spec.ts b/test/unit/loops.spec.ts
@@ -540,10 +540,10 @@ for (const testCase of [
     "for (const a of []) { continue; }",
 ]) {
     const expectContinueVariable: util.TapCallback = builder =>
-        expect(builder.getMainLuaCodeChunk()).toMatch("local __continue2");
+        expect(builder.getMainLuaCodeChunk()).toMatch(/local __continue\d+/);
 
     const expectContinueGotoLabel: util.TapCallback = builder =>
-        expect(builder.getMainLuaCodeChunk()).toMatch("::__continue2::");
+        expect(builder.getMainLuaCodeChunk()).toMatch(/::__continue\d+::/);
 
     const expectContinueStatement: util.TapCallback = builder =>
         expect(builder.getMainLuaCodeChunk()).toMatch("continue;");
@@ -638,3 +638,12 @@ test("for...in with pre-defined variable keeps last value", () => {
     // Need custom matcher because order is not guaranteed in neither JS nor Lua
     expect([keyX, keyFoo]).toContain(result);
 });
+
+// https://github.com/TypeScriptToLua/TypeScriptToLua/issues/1631
+test("loop variables should not be global (#1631)", () => {
+    const code = util.testModule`
+        for (let val = 0; val < 2; ++val) {}
+    `.getMainLuaCodeChunk();
+
+    expect(code).toContain("local val");
+});
