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

[luken-google]

Summary

Fixes issue #55216.

[luken-google]

Uploaded by mistake, kindly ignore.

clang/docs/ReleaseNotes.rst

- Support capturing structured bindings in lambdas
   `GH54301 <https://github.com/llvm/llvm-project/issues/54301>`_,
   and `GH49430 <https://github.com/llvm/llvm-project/issues/49430>`_.
 - Consider explicitly defaulted constexpr/consteval special member function
   template instantiation to be constexpr/consteval even though a call to such
   a function cannot appear in a constant expression.
   (C++14 [dcl.constexpr]p6 (CWG DR647/CWG DR1358))
 - Correctly defer dependent immediate function invocations until template instantiation.
   This fixes `GH55601 <https://github.com/llvm/llvm-project/issues/55601>`_.
-
-
+- Class member variables are now in scope when parsing requires clauses. Fixes
+  `GH55216 <https://github.com/llvm/llvm-project/issues/55216>`_.
 
 C++2b Feature Support
 ^^^^^^^^^^^^^^^^^^^^^
 
 CUDA/HIP Language Changes in Clang
 ----------------------------------
 
 Objective-C Language Changes in Clang

clang/lib/Parse/ParseTemplate.cpp

Decl *Parser::ParseSingleDeclarationAfterTemplate(
   llvm::TimeTraceScope TimeScope("ParseTemplate", [&]() {
     return std::string(DeclaratorInfo.getIdentifier() != nullptr
                            ? DeclaratorInfo.getIdentifier()->getName()
                            : "<unknown>");
   });
 
   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);
   }
 
   if (DeclaratorInfo.isFunctionDeclarator() &&
       isStartOfFunctionDefinition(DeclaratorInfo)) {
 
     // Function definitions are only allowed at file scope and in C++ classes.

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

 // RUN: %clang_cc1 -std=c++2a -x c++ %s -verify
 // RUN: %clang_cc1 -std=c++2b -x c++ %s -verify
 
 // Test parsing of the optional requires-clause in a template-declaration.
 
 template <typename T> requires true
 void foo() { }
 
 template <typename T> requires (!0)
 struct A {
   void foo();
   struct AA;
   enum E : int;
   static int x;
+  static constexpr int z = 16;
 
   template <typename> requires true
   void Mfoo();
 
   template <typename> requires true
   struct M;
 
   template <typename> requires true
   static int Mx;
 
   template <typename TT> requires true
   using MQ = M<TT>;
+
+  constexpr int bazz() requires (z == 16);
 };
 
 template <typename T> requires (!0)
 void A<T>::foo() { }
 
 template <typename T> requires (!0)
 struct A<T>::AA { };
 

 int A<T>::Mx = 0;
 
 template <typename T> requires true
 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();
 
   template <typename> requires true
   struct M;
 
   template <typename> requires true