fix: Parse of class specifiers in defining type ids

Author: robertoraggi

src/parser/cxx/parser.cc

@@ -3529,7 +3529,8 @@ auto Parser::parse_alias_declaration(
 
   TypeIdAST* typeId = nullptr;
 
-  if (!parse_defining_type_id(typeId)) parse_error("expected a type id");
+  if (!parse_defining_type_id(typeId, templateDeclarations))
+    parse_error("expected a type id");
 
   SourceLocation semicolonLoc;
 
@@ -5232,10 +5233,12 @@ auto Parser::parse_type_id(TypeIdAST*& yyast) -> bool {
   return true;
 }
 
-auto Parser::parse_defining_type_id(TypeIdAST*& yyast) -> bool {
+auto Parser::parse_defining_type_id(
+    TypeIdAST*& yyast,
+    const std::vector<TemplateDeclarationAST*>& templateDeclarations) -> bool {
   DeclSpecs specs;
 
-  specs.no_class_or_enum_specs = true;
+  if (!templateDeclarations.empty()) specs.no_class_or_enum_specs = true;
 
   List<SpecifierAST*>* typeSpecifierList = nullptr;
 

src/parser/cxx/parser.h

@@ -411,7 +411,9 @@ class Parser final {
   [[nodiscard]] auto parse_ref_qualifier(SourceLocation& refLoc) -> bool;
   [[nodiscard]] auto parse_declarator_id(CoreDeclaratorAST*& yyast) -> bool;
   [[nodiscard]] auto parse_type_id(TypeIdAST*& yyast) -> bool;
-  [[nodiscard]] auto parse_defining_type_id(TypeIdAST*& yyast) -> bool;
+  [[nodiscard]] auto parse_defining_type_id(
+      TypeIdAST*& yyast,
+      const std::vector<TemplateDeclarationAST*>& templateDeclarations) -> bool;
   [[nodiscard]] auto parse_abstract_declarator(DeclaratorAST*& yyast) -> bool;
   [[nodiscard]] auto parse_ptr_abstract_declarator(DeclaratorAST*& yyast)
       -> bool;

tests/unit_tests/ast/struct_alias_01.cc

@@ -0,0 +1,33 @@
+// RUN: %cxx -verify -ast-dump %s | %filecheck %s --match-full-lines
+
+using Pair = struct {
+  int a, b;
+};
+// clang-format off
+//      CHECK:translation-unit
+// CHECK-NEXT:  declaration-list
+// CHECK-NEXT:    alias-declaration
+// CHECK-NEXT:      identifier: Pair
+// CHECK-NEXT:      type-id: type-id
+// CHECK-NEXT:        type-specifier-list
+// CHECK-NEXT:          class-specifier
+// CHECK-NEXT:            class-key: struct
+// CHECK-NEXT:            declaration-list
+// CHECK-NEXT:              simple-declaration
+// CHECK-NEXT:                decl-specifier-list
+// CHECK-NEXT:                  integral-type-specifier
+// CHECK-NEXT:                    specifier: int
+// CHECK-NEXT:                init-declarator-list
+// CHECK-NEXT:                  init-declarator
+// CHECK-NEXT:                    declarator: declarator
+// CHECK-NEXT:                      core-declarator: id-declarator
+// CHECK-NEXT:                        declarator-id: id-expression
+// CHECK-NEXT:                          unqualified-id: name-id
+// CHECK-NEXT:                            identifier: a
+// CHECK-NEXT:                  init-declarator
+// CHECK-NEXT:                    declarator: declarator
+// CHECK-NEXT:                      core-declarator: id-declarator
+// CHECK-NEXT:                        declarator-id: id-expression
+// CHECK-NEXT:                          unqualified-id: name-id
+// CHECK-NEXT:                            identifier: b
+// CHECK-NEXT:        declarator: declarator