Don't try to typo-correct 'super' in an objc method.

This created 2 issues:

1) Performance issue, since typo-correction with PCH/modules is rather expensive.
2) Correctness issue, since if it managed to "correct" 'super' then bogus compiler errors would
be emitted, like this:

3.m:8:3: error: unknown type name 'super'; did you mean 'super1'?
  super.x = 0;
  ^~~~~
  super1
t3.m:5:13: note: 'super1' declared here
typedef int super1;
            ^
t3.m:8:8: error: expected identifier or '('
  super.x = 0;
       ^

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@177126 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Sema/SemaLookup.cpp b/lib/Sema/SemaLookup.cpp
index eae6269..86ddad2 100644
--- a/lib/Sema/SemaLookup.cpp
+++ b/lib/Sema/SemaLookup.cpp
@@ -3734,6 +3734,16 @@
   if (!ActiveTemplateInstantiations.empty())
     return TypoCorrection();
 
+  // Don't try to correct 'super'.
+  if (S && S->isInObjcMethodScope() && Typo == getSuperIdentifier())
+    return TypoCorrection();
+
+  // This is for regression testing. It's disabled by default.
+  if (Diags.getDiagnosticLevel(diag::warn_spellcheck_initiated,
+                               TypoName.getLoc()) != DiagnosticsEngine::Ignored)
+    Diag(TypoName.getLoc(), diag::warn_spellcheck_initiated)
+      << TypoName.getName();
+
   NamespaceSpecifierSet Namespaces(Context, CurContext, SS);
 
   TypoCorrectionConsumer Consumer(*this, Typo);