Implement -fno-validate-pch at the -cc1 level, which suppresses most

of the usual consistency checks used to determine when a precompiled
header is incompatible with the translation unit it's being loaded
into.

Enable this option when loading a precompiled preamble, because the
preamble loader will be performing all of this checking itself. Enable
the preamble-based test now that it's working.

This option is also useful for debugging Clang's PCH
(<rdar://problem/7532213>).

llvm-svn: 109475

clang/lib/Frontend/CompilerInvocation.cpp

@@ -1353,7 +1353,8 @@ static void ParsePreprocessorArgs(PreprocessorOptions &Opts, ArgList &Args,
     Opts.TokenCache = Opts.ImplicitPTHInclude;
   Opts.UsePredefines = !Args.hasArg(OPT_undef);
   Opts.DetailedRecord = Args.hasArg(OPT_detailed_preprocessing_record);
-  
+  Opts.DisablePCHValidation = Args.hasArg(OPT_fno_validate_pch);
+
   if (const Arg *A = Args.getLastArg(OPT_preamble_bytes_EQ)) {
     llvm::StringRef Value(A->getValue(Args));
     size_t Comma = Value.find(',');