Revert "Fixes and closes #53952. Setting the ASTHasCompilerErrors member variable correctly based on the PP diagnostics. (#68127)"

This reverts commit a50e63b38b931d945f97eac882278068221eca17.

With clang-14.0.6 as the host compiler, I'm getting:

ld.lld: error: undefined symbol: clang::ASTWriter::WriteAST(clang::Sema&, llvm::StringRef, clang::Module*, llvm::StringRef, bool, bool)
>>> referenced by ASTUnit.cpp
>>>               ASTUnit.cpp.o:(clang::ASTUnit::serialize(llvm::raw_ostream&)) in archive lib/libclangFrontend.a

1 files changed, 12 insertions, 5 deletions

diff --git a/clang/lib/Frontend/ASTUnit.cpp b/clang/lib/Frontend/ASTUnit.cpp
index 85157c3..016f88a 100644
--- a/clang/lib/Frontend/ASTUnit.cpp
+++ b/clang/lib/Frontend/ASTUnit.cpp
@@ -2341,9 +2341,12 @@ bool ASTUnit::Save(StringRef File) {
   return false;
 }
 
-static bool serializeUnit(ASTWriter &Writer, SmallVectorImpl<char> &Buffer,
-                          Sema &S, raw_ostream &OS) {
-  Writer.WriteAST(S, std::string(), nullptr, "");
+static bool serializeUnit(ASTWriter &Writer,
+                          SmallVectorImpl<char> &Buffer,
+                          Sema &S,
+                          bool hasErrors,
+                          raw_ostream &OS) {
+  Writer.WriteAST(S, std::string(), nullptr, "", hasErrors);
 
   // Write the generated bitstream to "Out".
   if (!Buffer.empty())
@@ -2353,14 +2356,18 @@ static bool serializeUnit(ASTWriter &Writer, SmallVectorImpl<char> &Buffer,
 }
 
 bool ASTUnit::serialize(raw_ostream &OS) {
+  // For serialization we are lenient if the errors were only warn-as-error kind.
+  bool hasErrors = getDiagnostics().hasUncompilableErrorOccurred();
+
   if (WriterData)
-    return serializeUnit(WriterData->Writer, WriterData->Buffer, getSema(), OS);
+    return serializeUnit(WriterData->Writer, WriterData->Buffer,
+                         getSema(), hasErrors, OS);
 
   SmallString<128> Buffer;
   llvm::BitstreamWriter Stream(Buffer);
   InMemoryModuleCache ModuleCache;
   ASTWriter Writer(Stream, Buffer, ModuleCache, {});
-  return serializeUnit(Writer, Buffer, getSema(), OS);
+  return serializeUnit(Writer, Buffer, getSema(), hasErrors, OS);
 }
 
 using SLocRemap = ContinuousRangeMap<unsigned, int, 2>;