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Fix crash when trying to assign to an optional chain #1045

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Merged
Perryvw merged 1 commit into from
Aug 3, 2021
Merged

Fix crash when trying to assign to an optional chain #1045

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4 changes: 4 additions & 0 deletions src/transformation/utils/diagnostics.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -143,3 +143,7 @@ export const annotationDeprecated = createWarningDiagnosticFactory(
`'@${kind}' is deprecated and will be removed in a future update. Please update your code before upgrading to the next release, otherwise your project will no longer compile. ` +
`See https://typescripttolua.github.io/docs/advanced/compiler-annotations#${kind.toLowerCase()} for more information.`
);

export const notAllowedOptionalAssignment = createErrorDiagnosticFactory(
"The left-hand side of an assignment expression may not be an optional property access."
);
6 changes: 6 additions & 0 deletions src/transformation/visitors/binary-expression/assignments.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -16,6 +16,7 @@ import {
ImmediatelyInvokedFunctionParameters,
transformToImmediatelyInvokedFunctionExpression,
} from "../../utils/transform";
import { notAllowedOptionalAssignment } from "../../utils/diagnostics";

export function transformAssignmentLeftHandSideExpression(
context: TransformationContext,
Expand All @@ -36,6 +37,11 @@ export function transformAssignment(
right: lua.Expression,
parent?: ts.Expression
): lua.Statement[] {
if (ts.isOptionalChain(lhs)) {
context.diagnostics.push(notAllowedOptionalAssignment(lhs));
return [];
}

if (isArrayLength(context, lhs)) {
const arrayLengthAssignment = lua.createExpressionStatement(
transformLuaLibFunction(
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10 changes: 10 additions & 0 deletions test/unit/optionalChaining.spec.ts
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Original file line number Diff line number Diff line change
@@ -1,3 +1,4 @@
import { notAllowedOptionalAssignment } from "../../src/transformation/utils/diagnostics";
import * as util from "../util";

test.each(["null", "undefined", '{ foo: "foo" }'])("optional chaining (%p)", value => {
Expand Down Expand Up @@ -97,6 +98,15 @@ test("no side effects", () => {
`.expectToMatchJsResult();
});

// Test for https://github.com/TypeScriptToLua/TypeScriptToLua/issues/1044
test("does not crash when incorrectly used in assignment (#1044)", () => {
const { diagnostics } = util.testFunction`
foo?.bar = "foo";
`.getLuaResult();

expect(diagnostics.find(d => d.code === notAllowedOptionalAssignment.code)).toBeDefined();
});

describe("optional chaining function calls", () => {
test.each(["() => 4", "undefined"])("stand-alone optional function (%p)", value => {
util.testFunction`
Expand Down