[Clang] Improve infrastructure for libstdc++ workarounds (#141977)

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, 5 insertions, 2 deletions

diff --git a/clang/lib/Sema/SemaInit.cpp b/clang/lib/Sema/SemaInit.cpp
index 776cb02..5d870f07 100644
--- a/clang/lib/Sema/SemaInit.cpp
+++ b/clang/lib/Sema/SemaInit.cpp
@@ -21,6 +21,7 @@
 #include "clang/Basic/SourceManager.h"
 #include "clang/Basic/Specifiers.h"
 #include "clang/Basic/TargetInfo.h"
+#include "clang/Lex/Preprocessor.h"
 #include "clang/Sema/Designator.h"
 #include "clang/Sema/EnterExpressionEvaluationContext.h"
 #include "clang/Sema/Initialization.h"
@@ -641,8 +642,10 @@ ExprResult InitListChecker::PerformEmptyInit(SourceLocation Loc,
   // in that case. stlport does so too.
   // Look for std::__debug for libstdc++, and for std:: for stlport.
   // This is effectively a compiler-side implementation of LWG2193.
-  if (!InitSeq && EmptyInitList && InitSeq.getFailureKind() ==
-          InitializationSequence::FK_ExplicitConstructor) {
+  if (!InitSeq && EmptyInitList &&
+      InitSeq.getFailureKind() ==
+          InitializationSequence::FK_ExplicitConstructor &&
+      SemaRef.getPreprocessor().NeedsStdLibCxxWorkaroundBefore(2014'04'22)) {
     OverloadCandidateSet::iterator Best;
     OverloadingResult O =
         InitSeq.getFailedCandidateSet()