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fix(eslint-plugin): [no-unnecessary-condition] don't flag optional chaining for union types with an unconstrained type parameters #10602

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Merged
merged 1 commit into from
Jan 13, 2025
Merged

fix(eslint-plugin): [no-unnecessary-condition] don't flag optional chaining for union types with an unconstrained type parameters #10602

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28 changes: 15 additions & 13 deletions packages/eslint-plugin/src/rules/no-unnecessary-condition.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -304,6 +304,19 @@ export default createRule<Options, MessageId>({
);
}

// Conditional is always necessary if it involves:
// `any` or `unknown` or a naked type variable
function isConditionalAlwaysNecessary(type: ts.Type): boolean {
return tsutils
.unionTypeParts(type)
.some(
part =>
isTypeAnyType(part) ||
isTypeUnknownType(part) ||
isTypeFlagSet(part, ts.TypeFlags.TypeVariable),
);
}

function isNullableMemberExpression(
node: TSESTree.MemberExpression,
): boolean {
Expand Down Expand Up @@ -370,18 +383,7 @@ export default createRule<Options, MessageId>({

const type = getConstrainedTypeAtLocation(services, expression);

// Conditional is always necessary if it involves:
// `any` or `unknown` or a naked type variable
if (
tsutils
.unionTypeParts(type)
.some(
part =>
isTypeAnyType(part) ||
isTypeUnknownType(part) ||
isTypeFlagSet(part, ts.TypeFlags.TypeVariable),
)
) {
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[Praise] Heh, yeah, this was getting a little hard to read inline even before...

if (isConditionalAlwaysNecessary(type)) {
return;
}
let messageId: MessageId | null = null;
Expand Down Expand Up @@ -813,7 +815,7 @@ export default createRule<Options, MessageId>({
: true;

return (
isTypeFlagSet(type, ts.TypeFlags.Any | ts.TypeFlags.Unknown) ||
isConditionalAlwaysNecessary(type) ||
(isOwnNullable && isNullableType(type))
);
}
Expand Down
18 changes: 18 additions & 0 deletions packages/eslint-plugin/tests/rules/no-unnecessary-condition.test.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -143,6 +143,24 @@ function test<T>(t: T | []) {
return t ? 'yes' : 'no';
}
`,
`
function test<T>(arg: T, key: keyof T) {
if (arg[key]?.toString()) {
}
}
`,
`
function test<T>(arg: T, key: keyof T) {
if (arg?.toString()) {
}
}
`,
`
function test<T>(arg: T | { value: string }) {
if (arg?.value) {
}
}
`,

// Boolean expressions
`
Expand Down
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