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Fix loop variables incorrectly being made global #1641

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Merged
merged 1 commit into from
Jun 8, 2025
Merged

Fix loop variables incorrectly being made global #1641

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5 changes: 5 additions & 0 deletions src/transformation/visitors/loops/for.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -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);
Expand Down Expand Up @@ -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);
};
13 changes: 11 additions & 2 deletions test/unit/loops.spec.ts
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Expand Up @@ -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;");
Expand Down Expand Up @@ -624,3 +624,12 @@ 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");
});
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