Suppress warnings if their instantiation location is in a system header, not

their spelling location.  This prevents warnings from being swallowed just
because the caret is on the first parenthesis in, say, NULL.

This is an experiment;  the risk is that there might be a substantial number
of system headers which #define symbols to expressions which inherently cause
warnings.  My theory is that that's rare enough that it can be worked
around case-by-case, and that producing useful warnings around NULL is worth 
it.  But I'm willing to accept that I might be empirically wrong.



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@95870 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Basic/Diagnostic.cpp

@@ -629,7 +629,7 @@ bool Diagnostic::ProcessDiag() {
   // it.
   if (SuppressSystemWarnings && !ShouldEmitInSystemHeader &&
       Info.getLocation().isValid() &&
-      Info.getLocation().getSpellingLoc().isInSystemHeader() &&
+      Info.getLocation().getInstantiationLoc().isInSystemHeader() &&
       (DiagLevel != Diagnostic::Note || LastDiagLevel == Diagnostic::Ignored)) {
     LastDiagLevel = Diagnostic::Ignored;
     return false;