fix(semantic): report TS18019 for abstract modifier with private identifier

crates/oxc_semantic/src/checker/mod.rs

@@ -87,6 +87,9 @@ pub fn check<'a>(kind: AstKind<'a>, ctx: &SemanticBuilder<'a>) {
         AstKind::MethodDefinition(method) => {
             ts::check_method_definition(method, ctx);
         }
+        AstKind::PropertyDefinition(prop) => {
+            ts::check_property_definition(prop, ctx);
+        }
         AstKind::ObjectProperty(prop) => {
             ts::check_object_property(prop, ctx);
         }

crates/oxc_semantic/src/checker/typescript.rs

@@ -271,6 +271,12 @@ pub fn check_method_definition<'a>(method: &MethodDefinition<'a>, ctx: &Semantic
         if method.kind.is_constructor() {
             ctx.error(diagnostics::illegal_abstract_modifier(method.key.span()));
         }
+        // abstract cannot be used with private identifiers
+        if method.key.is_private_identifier() {
+            ctx.error(diagnostics::abstract_cannot_be_used_with_private_identifier(
+                method.key.span(),
+            ));
+        }
     }
 
     let is_empty_body = method.value.r#type == FunctionType::TSEmptyBodyFunctionExpression;
@@ -289,6 +295,13 @@ pub fn check_method_definition<'a>(method: &MethodDefinition<'a>, ctx: &Semantic
     }
 }
 
+pub fn check_property_definition(prop: &PropertyDefinition, ctx: &SemanticBuilder<'_>) {
+    // abstract cannot be used with private identifiers
+    if prop.r#type.is_abstract() && prop.key.is_private_identifier() {
+        ctx.error(diagnostics::abstract_cannot_be_used_with_private_identifier(prop.key.span()));
+    }
+}
+
 pub fn check_object_property(prop: &ObjectProperty, ctx: &SemanticBuilder<'_>) {
     if let Expression::FunctionExpression(func) = &prop.value
         && prop.kind.is_accessor()

crates/oxc_semantic/src/diagnostics.rs

@@ -375,6 +375,13 @@ pub fn illegal_abstract_modifier(span: Span) -> OxcDiagnostic {
     .with_label(span)
 }
 
+/// 'abstract' modifier cannot be used with a private identifier. (18019)
+#[cold]
+pub fn abstract_cannot_be_used_with_private_identifier(span: Span) -> OxcDiagnostic {
+    ts_error("18019", "'abstract' modifier cannot be used with a private identifier.")
+        .with_label(span)
+}
+
 /// A parameter property is only allowed in a constructor implementation.ts(2369)
 #[cold]
 pub fn parameter_property_only_in_constructor_impl(span: Span) -> OxcDiagnostic {

tasks/coverage/snapshots/parser_babel.snap

@@ -2,12 +2,10 @@ commit: fc58af40
 
 parser_babel Summary:
 AST Parsed     : 2221/2227 (99.73%)
-Positive Passed: 2206/2227 (99.06%)
-Negative Passed: 1647/1689 (97.51%)
+Positive Passed: 2205/2227 (99.01%)
+Negative Passed: 1649/1689 (97.63%)
 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
-
 Expect Syntax Error: tasks/coverage/babel/packages/babel-parser/test/fixtures/typescript/cast/unparenthesized-assert-and-assign/input.ts
 
 Expect Syntax Error: tasks/coverage/babel/packages/babel-parser/test/fixtures/typescript/cast/unparenthesized-type-assertion-and-assign/input.ts
@@ -30,8 +28,6 @@ Expect Syntax Error: tasks/coverage/babel/packages/babel-parser/test/fixtures/ty
 
 Expect Syntax Error: tasks/coverage/babel/packages/babel-parser/test/fixtures/typescript/class/modifiers-invalid-order/input.ts
 
-Expect Syntax Error: tasks/coverage/babel/packages/babel-parser/test/fixtures/typescript/class/private-fields-modifier-abstract/input.ts
-
 Expect Syntax Error: tasks/coverage/babel/packages/babel-parser/test/fixtures/typescript/declare/invalid-namespace-var/input.ts
 
 Expect Syntax Error: tasks/coverage/babel/packages/babel-parser/test/fixtures/typescript/declare/module-class/input.ts
@@ -218,6 +214,16 @@ Expect to Parse: tasks/coverage/babel/packages/babel-parser/test/fixtures/es2026
    ·     ╰── Opened here
    ╰────
 
+Expect to Parse: tasks/coverage/babel/packages/babel-parser/test/fixtures/estree/class-private-method/typescript-invalid-abstract/input.ts
+
+  × TS(18019): 'abstract' modifier cannot be used with a private identifier.
+   ╭─[babel/packages/babel-parser/test/fixtures/estree/class-private-method/typescript-invalid-abstract/input.ts:2:12]
+ 1 │ abstract class TSAbstractClass {
+ 2 │   abstract #foo(name: string): boolean;
+   ·            ────
+ 3 │ }
+   ╰────
+
 Expect to Parse: tasks/coverage/babel/packages/babel-parser/test/fixtures/typescript/class/constructor-with-modifier-names/input.ts
 
   × Multiple constructor implementations are not allowed.
@@ -12170,6 +12176,14 @@ Expect to Parse: tasks/coverage/babel/packages/babel-parser/test/fixtures/typesc
    ╰────
   help: Add an initializer (e.g. ` = undefined`) here
 
+  × TS(18019): 'abstract' modifier cannot be used with a private identifier.
+   ╭─[babel/packages/babel-parser/test/fixtures/estree/class-private-property/typescript-invalid-abstract/input.ts:2:12]
+ 1 │ abstract class TSAbstractClass {
+ 2 │   abstract #foo: boolean;
+   ·            ────
+ 3 │ }
+   ╰────
+
   × A 'set' accessor must have exactly one parameter.
    ╭─[babel/packages/babel-parser/test/fixtures/estree/typescript/getter-setter/input.ts:3:9]
  2 │ ({ get x() { return 1 } });
@@ -13053,6 +13067,14 @@ Expect to Parse: tasks/coverage/babel/packages/babel-parser/test/fixtures/typesc
  8 │         // Also works on AssignmentPattern
    ╰────
 
+  × TS(18019): 'abstract' modifier cannot be used with a private identifier.
+   ╭─[babel/packages/babel-parser/test/fixtures/typescript/class/private-fields-modifier-abstract/input.ts:2:12]
+ 1 │ abstract class A {
+ 2 │   abstract #a;
+   ·            ──
+ 3 │ }
+   ╰────
+
   × TS(18010): An accessibility modifier cannot be used with a private identifier.
    ╭─[babel/packages/babel-parser/test/fixtures/typescript/class/private-fields-modifier-private/input.ts:2:3]
  1 │ class A {

tasks/coverage/snapshots/parser_typescript.snap

@@ -14772,6 +14772,14 @@ Expect to Parse: tasks/coverage/typescript/tests/cases/conformance/statements/Va
  27 │     async get #asyncProp() { return 1; }         // Error
     ╰────
 
+  × TS(18019): 'abstract' modifier cannot be used with a private identifier.
+    ╭─[typescript/tests/cases/conformance/classes/members/privateNames/privateNamesIncompatibleModifiers.ts:32:14]
+ 31 │ abstract class B {
+ 32 │     abstract #quux = 3;      // Error
+    ·              ─────
+ 33 │ }
+    ╰────
+
   × Private identifier '#prop' is not allowed outside class bodies
     ╭─[typescript/tests/cases/conformance/classes/members/privateNames/privateNamesInterfaceExtendingClass.ts:10:7]
   9 │ function func(x: I) {

tasks/coverage/snapshots/semantic_babel.snap

@@ -195,9 +195,7 @@ after transform: ScopeId(1): [ScopeId(2)]
 rebuilt        : ScopeId(1): []
 
 semantic Error: tasks/coverage/babel/packages/babel-parser/test/fixtures/estree/class-private-method/typescript-invalid-abstract/input.ts
-Scope children mismatch:
-after transform: ScopeId(1): [ScopeId(2)]
-rebuilt        : ScopeId(1): []
+'abstract' modifier cannot be used with a private identifier.
 
 semantic Error: tasks/coverage/babel/packages/babel-parser/test/fixtures/estree/class-private-property/typescript/input.js
 Unresolved references mismatch: