Serialization: Rename three AST diagnostics, NFC

[dexonsmith]

Summary

All three diagnostics have a select between "PCH", "module", and "AST"
in the text. The most generic of these is "AST", so rename them from
err_module_... to err_ast_....

[jansvoboda11]

LGTM

clang/include/clang/Basic/DiagnosticSerializationKinds.td

def err_pch_version_too_new : Error<
     "PCH file uses a newer PCH format that cannot be read">;
 def err_pch_different_branch : Error<
     "PCH file built from a different branch (%0) than the compiler (%1)">;
 def err_pch_with_compiler_errors : Error<
     "PCH file contains compiler errors">;
 
 def err_module_file_conflict : Error<
   "module '%0' is defined in both '%1' and '%2'">, DefaultFatal;
-def err_module_file_not_found : Error<
+def err_ast_file_not_found : Error<
   "%select{PCH|module|AST}0 file '%1' not found%select{|: %3}2">, DefaultFatal;
-def err_module_file_out_of_date : Error<
+def err_ast_file_out_of_date : Error<
   "%select{PCH|module|AST}0 file '%1' is out of date and "
   "needs to be rebuilt%select{|: %3}2">, DefaultFatal;
-def err_module_file_invalid : Error<
+def err_ast_file_invalid : Error<
   "file '%1' is not a valid precompiled %select{PCH|module|AST}0 file">, DefaultFatal;
 def note_module_file_imported_by : Note<
   "imported by %select{|module '%2' in }1'%0'">;
 def err_module_file_not_module : Error<
   "AST file '%0' was not built as a module">, DefaultFatal;
 def err_module_file_missing_top_level_submodule : Error<
   "module file '%0' is missing its top-level submodule">, DefaultFatal;
 

clang/lib/Serialization/ASTReader.cpp

ASTReader::ReadASTCore(StringRef FileName,
 
   case ModuleManager::Missing:
     // The module file was missing; if the client can handle that, return
     // it.
     if (ClientLoadCapabilities & ARR_Missing)
       return Missing;
 
     // Otherwise, return an error.
-    Diag(diag::err_module_file_not_found) << moduleKindForDiagnostic(Type)
-                                          << FileName << !ErrorStr.empty()
-                                          << ErrorStr;
+    Diag(diag::err_ast_file_not_found)
+        << moduleKindForDiagnostic(Type) << FileName << !ErrorStr.empty()
     return Failure;
 
   case ModuleManager::OutOfDate:
     // We couldn't load the module file because it is out-of-date. If the
     // client can handle out-of-date, return it.
     if (ClientLoadCapabilities & ARR_OutOfDate)
       return OutOfDate;
 
     // Otherwise, return an error.
-    Diag(diag::err_module_file_out_of_date) << moduleKindForDiagnostic(Type)
-                                            << FileName << !ErrorStr.empty()
-                                            << ErrorStr;
+    Diag(diag::err_ast_file_out_of_date)
+        << moduleKindForDiagnostic(Type) << FileName << !ErrorStr.empty()
     return Failure;
   }
 
   assert(M && "Missing module file");
 
   bool ShouldFinalizePCM = false;
   auto FinalizeOrDropPCM = llvm::make_scope_exit([&]() {
     auto &MC = getModuleManager().getModuleCache();
     if (ShouldFinalizePCM)
       MC.finalizePCM(FileName);
     else
       MC.tryToDropPCM(FileName);
   });
   ModuleFile &F = *M;
   BitstreamCursor &Stream = F.Stream;
   Stream = BitstreamCursor(PCHContainerRdr.ExtractPCH(*F.Buffer));
   F.SizeInBits = F.Buffer->getBufferSize() * 8;
 
   // Sniff for the signature.
   if (llvm::Error Err = doesntStartWithASTFileMagic(Stream)) {
-    Diag(diag::err_module_file_invalid)
+    Diag(diag::err_ast_file_invalid)
         << moduleKindForDiagnostic(Type) << FileName << std::move(Err);
     return Failure;
   }
 
   // This is used for compatibility with older PCH formats.
   bool HaveReadControlBlock = false;
   while (true) {
     Expected<llvm::BitstreamEntry> MaybeEntry = Stream.advance();