[clang] Add cxx scope if needed for requires clause.

Fixes issue #55216.

Patch by Luke Nihlen! (luken@google.com, luken-google@)

Reviewed By: #clang-language-wg, aaron.ballman

Differential Revision: https://reviews.llvm.org/D132503

clang/docs/ReleaseNotes.rst

@@ -171,6 +171,8 @@ C++20 Feature Support
   Note: The handling of deleted functions is not yet compliant, as Clang
   does not implement `DR1496 <https://www.open-std.org/jtc1/sc22/wg21/docs/cwg_defects.html#1496>`_
   and `DR1734 <https://www.open-std.org/jtc1/sc22/wg21/docs/cwg_defects.html#1734>`_.
+- Class member variables are now in scope when parsing requires clauses. Fixes
+  `GH55216 <https://github.com/llvm/llvm-project/issues/55216>`_.
 
 
 

clang/lib/Parse/ParseTemplate.cpp

@@ -289,8 +289,14 @@ Decl *Parser::ParseSingleDeclarationAfterTemplate(
 
   LateParsedAttrList LateParsedAttrs(true);
   if (DeclaratorInfo.isFunctionDeclarator()) {
-    if (Tok.is(tok::kw_requires))
+    if (Tok.is(tok::kw_requires)) {
+      CXXScopeSpec &ScopeSpec = DeclaratorInfo.getCXXScopeSpec();
+      DeclaratorScopeObj DeclScopeObj(*this, ScopeSpec);
+      if (ScopeSpec.isValid() &&
+          Actions.ShouldEnterDeclaratorScope(getCurScope(), ScopeSpec))
+        DeclScopeObj.EnterDeclaratorScope();
       ParseTrailingRequiresClause(DeclaratorInfo);
+    }
 
     MaybeParseGNUAttributes(DeclaratorInfo, &LateParsedAttrs);
   }

clang/test/Parser/cxx-concepts-requires-clause.cpp

@@ -12,6 +12,7 @@ struct A {
   struct AA;
   enum E : int;
   static int x;
+  static constexpr int z = 16;
 
   template <typename> requires true
   void Mfoo();
@@ -24,6 +25,8 @@ struct A {
 
   template <typename TT> requires true
   using MQ = M<TT>;
+
+  constexpr int bazz() requires (z == 16);
 };
 
 template <typename T> requires (!0)
@@ -56,6 +59,9 @@ int x = 0;
 template <typename T> requires true
 using Q = A<T>;
 
+template<typename T> requires (!0)
+constexpr int A<T>::bazz() requires (z == 16) { return z; }
+
 struct C {
   template <typename> requires true
   void Mfoo();