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Fix/try finally rethrow #1690

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RealColdFry wants to merge 2 commits into from
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Fix/try finally rethrow #1690

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9e25767
fix try/finally not re-throwing errors when there is no catch clause …
RealColdFry Mar 18, 2026
1afe73b
Nicer test return values
RealColdFry Mar 18, 2026
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20 changes: 20 additions & 0 deletions src/transformation/visitors/errors.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -146,6 +146,10 @@ export const transformTryStatement: FunctionVisitor<ts.TryStatement> = (statemen
returnedIdentifier,
lua.SyntaxKind.AndOperator
);
} else if (statement.finallyBlock) {
// try without catch, but with finally — need to capture error for re-throw
const errorIdentifier = lua.createIdentifier("____error");
result.push(lua.createVariableDeclarationStatement([tryResultIdentifier, errorIdentifier], tryCall));
} else {
// try without return or catch
result.push(lua.createExpressionStatement(tryCall));
Expand All @@ -155,6 +159,22 @@ export const transformTryStatement: FunctionVisitor<ts.TryStatement> = (statemen
result.push(...context.transformStatements(statement.finallyBlock));
}

// Re-throw error if try had no catch but had a finally
if (!statement.catchClause && statement.finallyBlock) {
const notTryCondition = lua.createUnaryExpression(
lua.cloneIdentifier(tryResultIdentifier),
lua.SyntaxKind.NotOperator
);
const errorIdentifier = lua.createIdentifier("____error");
const rethrow = lua.createExpressionStatement(
lua.createCallExpression(lua.createIdentifier("error"), [
lua.cloneIdentifier(errorIdentifier),
lua.createNumericLiteral(0),
])
);
result.push(lua.createIfStatement(notTryCondition, lua.createBlock([rethrow])));
}

if (returnCondition && returnedIdentifier) {
const returnValues: lua.Expression[] = [];

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22 changes: 22 additions & 0 deletions test/unit/error.spec.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -256,6 +256,28 @@ test("multi return from catch->finally", () => {
.expectToMatchJsResult();
});

test("throw propagates through finally to outer catch", () => {
util.testFunction`
function thrower() {
try {
throw "Error";
} finally {
}
}

function caller() {
try {
thrower();
return "NoCatch";
} catch (e) {
return e;
}
}

return caller();
`.expectToMatchJsResult();
});

test("return from nested finally", () => {
util.testFunction`
let x = "";
Expand Down