[clang] [Clang] Support libstdc++ workarounds when using `-E` (PR #210802)

[Corentin Jabot via cfe-commits]

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@@ -1018,9 +1018,16 @@ std::optional<uint64_t> Preprocessor::getStdLibCxxVersion() {
   return std::nullopt;
 }
 
+void Preprocessor::setStdLibCxxVersion(std::uint64_t Version) {
+  CXXStandardLibraryVersion = {
+      CXXStandardLibraryVersionInfo::LibStdCXX,
+      Version,
+  };
+}
+
 bool Preprocessor::NeedsStdLibCxxWorkaroundBefore(uint64_t FixedVersion) {
   assert(FixedVersion >= 2000'00'00 && FixedVersion <= 2100'00'00 &&
-         "invalid value for __GLIBCXX__");
+         "invalid libstdc++ version number");
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cor3ntin wrote:

Please revert that

https://github.com/llvm/llvm-project/pull/210802