feat(parser): add diagnostic for parameters with question mark and initializer

crates/oxc_parser/src/diagnostics.rs

@@ -818,6 +818,11 @@ pub fn cannot_appear_on_a_type_parameter(
         .with_allowed_modifier_help(allowed)
 }
 
+#[cold]
+pub fn a_parameter_cannot_have_question_mark_and_initializer(span: Span) -> OxcDiagnostic {
+    ts_error("1015", "A parameter cannot have a question mark and an initializer.").with_label(span)
+}
+
 #[cold]
 pub fn can_only_appear_on_a_type_parameter_of_a_class_interface_or_type_alias(
     modifier: ModifierKind,

crates/oxc_parser/src/js/function.rs

@@ -169,6 +169,11 @@ impl<'a> ParserImpl<'a> {
         let init = if self.eat(Kind::Eq) {
             let init =
                 self.context_add(Context::In, ParserImpl::parse_assignment_expression_or_higher);
+            if optional {
+                self.error(diagnostics::a_parameter_cannot_have_question_mark_and_initializer(
+                    pattern.span(),
+                ));
+            }
             Some(init)
         } else {
             None

tasks/coverage/snapshots/parser_babel.snap

@@ -464,6 +464,14 @@ Expect to Parse: tasks/coverage/babel/packages/babel-parser/test/fixtures/typesc
 
 Expect to Parse: tasks/coverage/babel/packages/babel-parser/test/fixtures/typescript/class/parameter-properties/input.ts
 
+  × TS(1015): A parameter cannot have a question mark and an initializer.
+    ╭─[babel/packages/babel-parser/test/fixtures/typescript/class/parameter-properties/input.ts:10:16]
+  9 │         readonly x = 0,
+ 10 │         public y?: number = 0) {}
+    ·                ─
+ 11 │ }
+    ╰────
+
   × TS(1016): A required parameter cannot follow an optional parameter.
    ╭─[babel/packages/babel-parser/test/fixtures/typescript/class/parameter-properties/input.ts:7:9]
  6 │         private pi?: number,
@@ -13177,6 +13185,14 @@ Expect to Parse: tasks/coverage/babel/packages/babel-parser/test/fixtures/typesc
     ╰────
   help: No modifiers are allowed here.
 
+  × TS(1015): A parameter cannot have a question mark and an initializer.
+    ╭─[babel/packages/babel-parser/test/fixtures/typescript/class/parameter-properties-not-constructor/input.ts:10:16]
+  9 │         readonly x = 0,
+ 10 │         public y?: number = 0) {}
+    ·                ─
+ 11 │ }
+    ╰────
+
   × TS(1016): A required parameter cannot follow an optional parameter.
    ╭─[babel/packages/babel-parser/test/fixtures/typescript/class/parameter-properties-not-constructor/input.ts:7:9]
  6 │         private pi?: number,
@@ -13453,6 +13469,14 @@ Expect to Parse: tasks/coverage/babel/packages/babel-parser/test/fixtures/typesc
    ╰────
   help: No modifiers are allowed here.
 
+  × TS(1015): A parameter cannot have a question mark and an initializer.
+   ╭─[babel/packages/babel-parser/test/fixtures/typescript/function/parameter-properties/input.ts:8:10]
+ 7 │   readonly x = 0,
+ 8 │   public y?: number = 0
+   ·          ─
+ 9 │ ) {}
+   ╰────
+
   × TS(1016): A required parameter cannot follow an optional parameter.
    ╭─[babel/packages/babel-parser/test/fixtures/typescript/function/parameter-properties/input.ts:6:3]
  5 │   private pi?: number,