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feat(parser): add ts error 1257 for TSTupleElement #18146

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Merged
graphite-app merged 1 commit into from
Jan 18, 2026
Merged

feat(parser): add ts error 1257 for TSTupleElement #18146

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12 changes: 12 additions & 0 deletions crates/oxc_parser/src/diagnostics.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -343,6 +343,18 @@ pub fn const_class_member(span: Span) -> OxcDiagnostic {
.with_label(span)
}

// A required element cannot follow an optional element. ts(1257)
#[cold]
pub fn required_element_cannot_follow_optional_element(
span: Span,
optional_span: Span,
) -> OxcDiagnostic {
ts_error("1257", "A required element cannot follow an optional element.").with_labels([
span.label("Required element here"),
optional_span.label("Optional element seen here"),
])
}

/// A rest element cannot follow another rest element. ts(1265)
#[cold]
pub fn rest_element_cannot_follow_another_rest_element(
Expand Down
28 changes: 21 additions & 7 deletions crates/oxc_parser/src/ts/types.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -899,7 +899,8 @@ impl<'a> ParserImpl<'a> {
let opening_span = self.cur_token().span();
self.expect(Kind::LBrack);

let mut seen_type_span: Option<Span> = None;
let mut seen_rest_span: Option<Span> = None;
let mut seen_optional_span: Option<Span> = None;
let (elements, _) =
self.parse_delimited_list(Kind::RBrack, Kind::Comma, opening_span, |me| {
let tuple = me.parse_tuple_element();
Expand All @@ -918,23 +919,36 @@ impl<'a> ParserImpl<'a> {
_ => false,
}
{
if let Some(seen_span) = seen_type_span {
if let Some(seen_span) = seen_rest_span {
me.error(diagnostics::rest_element_cannot_follow_another_rest_element(
seen_span,
tuple.span(),
));
}
seen_type_span = Some(tuple.span());
seen_rest_span = Some(tuple.span());
}

if let Some(seen_rest_span) = seen_type_span
&& matches!(tuple, TSTupleElement::TSOptionalType(_))
if !matches!(
tuple,
TSTupleElement::TSOptionalType(_) | TSTupleElement::TSRestType(_)
) && let Some(seen_optional_span) = seen_optional_span
{
me.error(diagnostics::optional_element_cannot_follow_rest_element(
me.error(diagnostics::required_element_cannot_follow_optional_element(
tuple.span(),
seen_rest_span,
seen_optional_span,
));
}

if matches!(tuple, TSTupleElement::TSOptionalType(_)) {
if let Some(seen_rest_span) = seen_rest_span {
me.error(diagnostics::optional_element_cannot_follow_rest_element(
tuple.span(),
seen_rest_span,
));
}
seen_optional_span = Some(tuple.span());
}

tuple
});
self.expect(Kind::RBrack);
Expand Down
12 changes: 9 additions & 3 deletions tasks/coverage/snapshots/parser_babel.snap
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Expand Up @@ -3,7 +3,7 @@ commit: fc58af40
parser_babel Summary:
AST Parsed : 2224/2230 (99.73%)
Positive Passed: 2207/2230 (98.97%)
Negative Passed: 1649/1697 (97.17%)
Negative Passed: 1650/1697 (97.23%)
Expect Syntax Error: tasks/coverage/babel/packages/babel-parser/test/fixtures/es2026/explicit-resource-management/invalid-for-using-of-no-initializer/input.js

Expect Syntax Error: tasks/coverage/babel/packages/babel-parser/test/fixtures/estree/class-private-property/typescript-invalid-abstract/input.ts
Expand Down Expand Up @@ -96,8 +96,6 @@ Expect Syntax Error: tasks/coverage/babel/packages/babel-parser/test/fixtures/ty

Expect Syntax Error: tasks/coverage/babel/packages/babel-parser/test/fixtures/typescript/types/invalid-import-type-options-with-spread-element/input.ts

Expect Syntax Error: tasks/coverage/babel/packages/babel-parser/test/fixtures/typescript/types/tuple-optional-invalid/input.ts

Expect Syntax Error: tasks/coverage/babel/packages/babel-parser/test/fixtures/typescript/types/tuple-required-after-labeled-optional/input.ts

Expect to Parse: tasks/coverage/babel/packages/babel-parser/test/fixtures/core/opts/allowNewTargetOutsideFunction-true/input.js
Expand Down Expand Up @@ -14373,6 +14371,14 @@ Expect to Parse: tasks/coverage/babel/packages/babel-parser/test/fixtures/typesc
· ──
╰────

× TS(1257): A required element cannot follow an optional element.
╭─[babel/packages/babel-parser/test/fixtures/typescript/types/tuple-optional-invalid/input.ts:1:9]
1 │ let x: [string?, number]
· ───┬─── ───┬──
· │ ╰── Required element here
· ╰── Optional element seen here
╰────

× TS(1273): 'public' modifier cannot be used on a type parameter.
╭─[babel/packages/babel-parser/test/fixtures/typescript/types/variance-annotations/input.ts:95:10]
94 │
Expand Down
36 changes: 31 additions & 5 deletions tasks/coverage/snapshots/parser_typescript.snap
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Original file line number Diff line number Diff line change
Expand Up @@ -3,7 +3,7 @@ commit: f5ccf434
parser_typescript Summary:
AST Parsed : 9844/9845 (99.99%)
Positive Passed: 9836/9845 (99.91%)
Negative Passed: 1496/2549 (58.69%)
Negative Passed: 1498/2549 (58.77%)
Expect Syntax Error: tasks/coverage/typescript/tests/cases/compiler/FunctionDeclaration3.ts

Expect Syntax Error: tasks/coverage/typescript/tests/cases/compiler/FunctionDeclaration4.ts
Expand Down Expand Up @@ -2070,10 +2070,6 @@ Expect Syntax Error: tasks/coverage/typescript/tests/cases/conformance/types/thi

Expect Syntax Error: tasks/coverage/typescript/tests/cases/conformance/types/tuple/contextualTypeTupleEnd.ts

Expect Syntax Error: tasks/coverage/typescript/tests/cases/conformance/types/tuple/optionalTupleElements1.ts

Expect Syntax Error: tasks/coverage/typescript/tests/cases/conformance/types/tuple/restTupleElements1.ts

Expect Syntax Error: tasks/coverage/typescript/tests/cases/conformance/types/tuple/unionsOfTupleTypes1.ts

Expect Syntax Error: tasks/coverage/typescript/tests/cases/conformance/types/typeAliases/intrinsicKeyword.ts
Expand Down Expand Up @@ -26472,6 +26468,16 @@ Expect to Parse: tasks/coverage/typescript/tests/cases/conformance/statements/Va
17 │
╰────

× TS(1257): A required element cannot follow an optional element.
╭─[typescript/tests/cases/conformance/types/tuple/optionalTupleElements1.ts:11:20]
10 │
11 │ type T5 = [number, string?, boolean]; // Error
· ───┬─── ───┬───
· │ ╰── Required element here
· ╰── Optional element seen here
12 │
╰────

× TS(1354): 'readonly' type modifier is only permitted on array and tuple literal types.
╭─[typescript/tests/cases/conformance/types/tuple/readonlyArraysAndTuples.ts:9:12]
8 │
Expand Down Expand Up @@ -26504,6 +26510,16 @@ Expect to Parse: tasks/coverage/typescript/tests/cases/conformance/statements/Va
13 │
╰────

× TS(1257): A required element cannot follow an optional element.
╭─[typescript/tests/cases/conformance/types/tuple/restTupleElements1.ts:3:13]
2 │ type T01 = [string, string?];
3 │ type T02 = [string?, string]; // Error
· ───┬─── ───┬──
· │ ╰── Required element here
· ╰── Optional element seen here
4 │ type T03 = [...string[]];
╰────

× TS(1265): A rest element cannot follow another rest element.
╭─[typescript/tests/cases/conformance/types/tuple/variadicTuples2.ts:7:21]
6 │
Expand All @@ -26524,6 +26540,16 @@ Expect to Parse: tasks/coverage/typescript/tests/cases/conformance/statements/Va
9 │ type V12 = [number, string?, boolean]; // Error
╰────

× TS(1257): A required element cannot follow an optional element.
╭─[typescript/tests/cases/conformance/types/tuple/variadicTuples2.ts:9:21]
8 │ type V11 = [number, ...string[], boolean?]; // Error
9 │ type V12 = [number, string?, boolean]; // Error
· ───┬─── ───┬───
· │ ╰── Required element here
· ╰── Optional element seen here
10 │
╰────

× TS(1265): A rest element cannot follow another rest element.
╭─[typescript/tests/cases/conformance/types/tuple/variadicTuples2.ts:11:13]
10 │
Expand Down
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