[Clang] Improve infrastructure for libstdc++ workarounds (Reland) (#142592)

Reland with debug traces to try to understand a bug that only happens on
one CI configuration

===

This introduces a way detect the libstdc++ version,
use that to enable workarounds.
The version is cached.

This should make it easier in the future to find and remove
these hacks.

I did not find the need for enabling a hack between or after
specific versions, so it's left as a future exercise.

We can extend this fature to other libraries as the need arise.

===

1 files changed, 3 insertions, 0 deletions

diff --git a/clang/lib/Sema/SemaExceptionSpec.cpp b/clang/lib/Sema/SemaExceptionSpec.cpp
index c83eab5..c692f82 100644
--- a/clang/lib/Sema/SemaExceptionSpec.cpp
+++ b/clang/lib/Sema/SemaExceptionSpec.cpp
@@ -18,6 +18,7 @@
 #include "clang/AST/TypeLoc.h"
 #include "clang/Basic/Diagnostic.h"
 #include "clang/Basic/SourceManager.h"
+#include "clang/Lex/Preprocessor.h"
 #include "clang/Sema/SemaInternal.h"
 #include "llvm/ADT/SmallPtrSet.h"
 #include <optional>
@@ -44,6 +45,8 @@ static const FunctionProtoType *GetUnderlyingFunction(QualType T)
 bool Sema::isLibstdcxxEagerExceptionSpecHack(const Declarator &D) {
   auto *RD = dyn_cast<CXXRecordDecl>(CurContext);
 
+  if (!getPreprocessor().NeedsStdLibCxxWorkaroundBefore(2016'04'27))
+    return false;
   // All the problem cases are member functions named "swap" within class
   // templates declared directly within namespace std or std::__debug or
   // std::__profile.