feat(parser): add ts error 1266 for TSTupleElement

crates/oxc_parser/src/diagnostics.rs

@@ -353,6 +353,15 @@ pub fn rest_element_cannot_follow_another_rest_element(
         .with_labels([span.label("Second rest element here"), seen_span.label("First seen here")])
 }
 
+/// An optional element cannot follow a rest element. ts(1266)
+#[cold]
+pub fn optional_element_cannot_follow_rest_element(span: Span, rest_span: Span) -> OxcDiagnostic {
+    ts_error("1266", "An optional element cannot follow a rest element.").with_labels([
+        span.label("Optional element here"),
+        rest_span.label("Rest element seen here"),
+    ])
+}
+
 // A type-only import can specify a default import or named bindings, but not both. ts(1363)
 #[cold]
 pub fn type_only_import_default_and_named(specifier_span: Span) -> OxcDiagnostic {

crates/oxc_parser/src/ts/types.rs

@@ -926,6 +926,15 @@ impl<'a> ParserImpl<'a> {
                     }
                     seen_type_span = Some(tuple.span());
                 }
+
+                if let Some(seen_rest_span) = seen_type_span
+                    && matches!(tuple, TSTupleElement::TSOptionalType(_))
+                {
+                    me.error(diagnostics::optional_element_cannot_follow_rest_element(
+                        tuple.span(),
+                        seen_rest_span,
+                    ));
+                }
                 tuple
             });
         self.expect(Kind::RBrack);

tasks/coverage/snapshots/parser_typescript.snap

@@ -26514,6 +26514,16 @@ Expect to Parse: tasks/coverage/typescript/tests/cases/conformance/statements/Va
  8 │ type V11 = [number, ...string[], boolean?];  // Error
    ╰────
 
+  × TS(1266): An optional element cannot follow a rest element.
+   ╭─[typescript/tests/cases/conformance/types/tuple/variadicTuples2.ts:8:21]
+ 7 │ type V10 = [number, ...string[], ...boolean[]];  // Error
+ 8 │ type V11 = [number, ...string[], boolean?];  // Error
+   ·                     ─────┬─────  ────┬───
+   ·                          │           ╰── Optional element here
+   ·                          ╰── Rest element seen here
+ 9 │ type V12 = [number, string?, boolean];  // Error
+   ╰────
+
   × TS(1265): A rest element cannot follow another rest element.
     ╭─[typescript/tests/cases/conformance/types/tuple/variadicTuples2.ts:11:13]
  10 │