[Clang] Fix handling of using declarations in for loop init statements.

[cor3ntin]

Summary

The type was never saved, and therefore never transformed
in dependent contexts.

[aaron.ballman]

LGTM!

clang/test/SemaCXX/cxx23-init-statement.cpp

2

This should suffice, yes?

[cor3ntin]

clang/test/SemaCXX/cxx23-init-statement.cpp

2

Yep!

clang/docs/ReleaseNotes.rst

- Allow omitting ``typename`` in the parameter declaration of a friend
   constructor declaration.
   (`#63119 <https://github.com/llvm/llvm-project/issues/63119>`_)
 - Fix access of a friend class declared in a local class. Clang previously
   emitted an error when a friend of a local class tried to access it's
   private data members.
 - Allow abstract parameter and return types in functions that are
   either deleted or not defined.
   (`#63012 <https://github.com/llvm/llvm-project/issues/63012>`_)
+- Fix handling of using-declarations in the init statements of for
+  loop declarations.
+  (`#63627 <https://github.com/llvm/llvm-project/issues/63627>`_)
 
 Bug Fixes to AST Handling
 ^^^^^^^^^^^^^^^^^^^^^^^^^
 
 - Preserve ``namespace`` definitions that follow malformed declarations.
 
 Miscellaneous Bug Fixes
 ^^^^^^^^^^^^^^^^^^^^^^^

clang/lib/Parse/ParseStmt.cpp

if (Tok.is(tok::semi)) {  // for (;
     ParenBraceBracketBalancer BalancerRAIIObj(*this);
 
     // Parse declaration, which eats the ';'.
     if (!C99orCXXorObjC) {   // Use of C99-style for loops in C90 mode?
       Diag(Tok, diag::ext_c99_variable_decl_in_for_loop);
       Diag(Tok, diag::warn_gcc_variable_decl_in_for_loop);
     }
     DeclGroupPtrTy DG;
+    SourceLocation DeclStart = Tok.getLocation(), DeclEnd;
     if (Tok.is(tok::kw_using)) {
       DG = ParseAliasDeclarationInInitStatement(DeclaratorContext::ForInit,
                                                 attrs);
+      FirstPart = Actions.ActOnDeclStmt(DG, DeclStart, Tok.getLocation());
     } else {
       // In C++0x, "for (T NS:a" might not be a typo for ::
       bool MightBeForRangeStmt = getLangOpts().CPlusPlus;
       ColonProtectionRAIIObject ColonProtection(*this, MightBeForRangeStmt);
-
-      SourceLocation DeclStart = Tok.getLocation(), DeclEnd;
       ParsedAttributes DeclSpecAttrs(AttrFactory);
       DG = ParseSimpleDeclaration(
           DeclaratorContext::ForInit, DeclEnd, attrs, DeclSpecAttrs, false,
           MightBeForRangeStmt ? &ForRangeInfo : nullptr);
       FirstPart = Actions.ActOnDeclStmt(DG, DeclStart, Tok.getLocation());
       if (ForRangeInfo.ParsedForRangeDecl()) {
         Diag(ForRangeInfo.ColonLoc, getLangOpts().CPlusPlus11
                                         ? diag::warn_cxx98_compat_for_range

clang/test/SemaCXX/cxx23-init-statement.cpp

+// RUN: %clang_cc1 -fsyntax-only -verify -std=c++23 %s
+
+namespace GH63627 {
+template<class T>
+void ok() {
+  if  (using U = decltype([]{ return 42;}); true) {
+      static_assert(U{}() == 42);
+  }
+  for (using U = decltype([]{ return 42;}); [[maybe_unused]] auto x : "abc") {
+      static_assert(U{}() == 42);
+  }
+  for (using U = decltype([]{ return 42;}); false; ) {
+      static_assert(U{}() == 42);
+  }
+}
+
+template<class T>
+void err() {
+  if  (using U = decltype([]{}.foo); true) {}  // expected-error {{no member named 'foo'}}
+
+  for (using U = decltype([]{}.foo);          // expected-error {{no member named 'foo'}}
+       [[maybe_unused]] auto x : "abc") { }
+
+  for (using U = decltype([]{}.foo);          // expected-error {{no member named 'foo'}}
+       false ; ) { }
+};
+
+void test() {
+  ok<int>();
+  err<int>(); // expected-note {{in instantiation of function template specialization 'GH63627::err<int>'}}
+}
+
+}