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

This reverts commit a50e63b.

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

Author: kazutakahirata

clang/include/clang/Serialization/ASTWriter.h

@@ -613,6 +613,7 @@ class ASTWriter : public ASTDeserializationListener,
   /// the module but currently is merely a random 32-bit number.
   ASTFileSignature WriteAST(Sema &SemaRef, StringRef OutputFile,
                             Module *WritingModule, StringRef isysroot,
+                            bool hasErrors = false,
                             bool ShouldCacheASTInMemory = false);
 
   /// Emit a token.

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>;

clang/lib/Serialization/ASTWriter.cpp

@@ -4622,12 +4622,12 @@ time_t ASTWriter::getTimestampForOutput(const FileEntry *E) const {
 
 ASTFileSignature ASTWriter::WriteAST(Sema &SemaRef, StringRef OutputFile,
                                      Module *WritingModule, StringRef isysroot,
+                                     bool hasErrors,
                                      bool ShouldCacheASTInMemory) {
   llvm::TimeTraceScope scope("WriteAST", OutputFile);
   WritingAST = true;
 
-  ASTHasCompilerErrors =
-      SemaRef.PP.getDiagnostics().hasUncompilableErrorOccurred();
+  ASTHasCompilerErrors = hasErrors;
 
   // Emit the file header.
   Stream.Emit((unsigned)'C', 8);

clang/lib/Serialization/GeneratePCH.cpp

@@ -65,8 +65,12 @@ void PCHGenerator::HandleTranslationUnit(ASTContext &Ctx) {
 
   // Emit the PCH file to the Buffer.
   assert(SemaPtr && "No Sema?");
-  Buffer->Signature = Writer.WriteAST(*SemaPtr, OutputFile, Module, isysroot,
-                                      ShouldCacheASTInMemory);
+  Buffer->Signature =
+      Writer.WriteAST(*SemaPtr, OutputFile, Module, isysroot,
+                      // For serialization we are lenient if the errors were
+                      // only warn-as-error kind.
+                      PP.getDiagnostics().hasUncompilableErrorOccurred(),
+                      ShouldCacheASTInMemory);
 
   Buffer->IsComplete = true;
 }