From 77965450f24da5e027579db689be59f483c8da42 Mon Sep 17 00:00:00 2001
From: "Matthew \"strager\" Glazar" <strager.nds@gmail.com>
Date: Thu, 25 Jan 2024 01:40:37 -0500
Subject: [PATCH] fix(fe): parse decorators on abstract classes

---
 docs/CHANGELOG.md                        |  2 ++
 src/quick-lint-js/fe/parse-class.cpp     | 14 ++++++++++++++
 src/quick-lint-js/fe/parse-statement.cpp |  1 +
 test/test-parse-decorator.cpp            | 11 +++++++++++
 4 files changed, 28 insertions(+)

diff --git a/docs/CHANGELOG.md b/docs/CHANGELOG.md
index df78615f44..edd93b8219 100644
--- a/docs/CHANGELOG.md
+++ b/docs/CHANGELOG.md
@@ -13,6 +13,7 @@ Semantic Versioning.
 * VS Code: You can now make quick-lint-js messages fun and insulting with the
   `quick-lint-js.snarky` setting (disabled by default). (Implemented by
   [vegerot][].)
+* TypeScript: Decorators on abstract classes are now parsed. ([#1194][])
 
 ### Fixed
 
@@ -1415,6 +1416,7 @@ Beta release.
 [#1168]: https://github.com/quick-lint/quick-lint-js/pull/1168
 [#1171]: https://github.com/quick-lint/quick-lint-js/issues/1171
 [#1180]: https://github.com/quick-lint/quick-lint-js/issues/1180
+[#1194]: https://github.com/quick-lint/quick-lint-js/issues/1194
 
 [E0001]: https://quick-lint-js.com/errors/E0001/
 [E0003]: https://quick-lint-js.com/errors/E0003/
diff --git a/src/quick-lint-js/fe/parse-class.cpp b/src/quick-lint-js/fe/parse-class.cpp
index b8251db7ea..18e676dd82 100644
--- a/src/quick-lint-js/fe/parse-class.cpp
+++ b/src/quick-lint-js/fe/parse-class.cpp
@@ -25,6 +25,20 @@
 namespace quick_lint_js {
 void Parser::parse_and_visit_class(Parse_Visitor_Base &v,
                                    Parse_Class_Options options) {
+  if (this->peek().type == Token_Type::kw_abstract) {
+    if (options.abstract_keyword_span.has_value()) {
+      // abstract abstract class???
+      QLJS_PARSER_UNIMPLEMENTED();
+    }
+    options.abstract_keyword_span = this->peek().span();
+    this->skip();
+    if (this->peek().has_leading_newline) {
+      this->diag_reporter_->report(
+          Diag_Newline_Not_Allowed_After_Abstract_Keyword{
+              .abstract_keyword = *options.abstract_keyword_span,
+          });
+    }
+  }
   QLJS_ASSERT(this->peek().type == Token_Type::kw_class);
   Source_Code_Span class_keyword_span = this->peek().span();
 
diff --git a/src/quick-lint-js/fe/parse-statement.cpp b/src/quick-lint-js/fe/parse-statement.cpp
index df3c959349..740a82f04b 100644
--- a/src/quick-lint-js/fe/parse-statement.cpp
+++ b/src/quick-lint-js/fe/parse-statement.cpp
@@ -2999,6 +2999,7 @@ void Parser::parse_and_visit_decorator_statement(Parse_Visitor_Base &v) {
   this->parse_and_visit_one_or_more_decorators(decorator_visits.visitor());
 
   switch (this->peek().type) {
+  case Token_Type::kw_abstract:
   case Token_Type::kw_class:
     this->parse_and_visit_class(
         v, Parse_Class_Options{
diff --git a/test/test-parse-decorator.cpp b/test/test-parse-decorator.cpp
index 543cfc4b4c..48050329aa 100644
--- a/test/test-parse-decorator.cpp
+++ b/test/test-parse-decorator.cpp
@@ -456,6 +456,17 @@ TEST_F(Test_Parse_Decorator,
       typescript_options);
 }
 
+TEST_F(Test_Parse_Decorator, decorator_on_typescript_abstract_class) {
+  test_parse_and_visit_module(
+      u8"@decorator abstract class C { abstract m(); }"_sv, no_diags,
+      typescript_options);
+
+  test_parse_and_visit_module(
+      u8"@decorator abstract\nclass C { abstract m(); }"_sv,  //
+      u8"           ^^^^^^^^ Diag_Newline_Not_Allowed_After_Abstract_Keyword.abstract_keyword"_diag,
+      typescript_options);
+}
+
 TEST_F(Test_Parse_Decorator, typescript_parameter_decorator) {
   {
     Spy_Visitor p = test_parse_and_visit_statement(