Add hooks for typo correction to ExternalSemaSource, courtesy of Luke Zarko.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@188196 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Sema/MultiplexExternalSemaSource.cpp b/lib/Sema/MultiplexExternalSemaSource.cpp
index de790e9..43bafd3 100644
--- a/lib/Sema/MultiplexExternalSemaSource.cpp
+++ b/lib/Sema/MultiplexExternalSemaSource.cpp
@@ -273,3 +273,19 @@
   for (size_t i = 0; i < Sources.size(); ++i)
     Sources[i]->ReadLateParsedTemplates(LPTMap);
 }
+
+TypoCorrection MultiplexExternalSemaSource::CorrectTypo(
+                                     const DeclarationNameInfo &Typo,
+                                     int LookupKind, Scope *S, CXXScopeSpec *SS,
+                                     CorrectionCandidateCallback &CCC,
+                                     DeclContext *MemberContext,
+                                     bool EnteringContext,
+                                     const ObjCObjectPointerType *OPT) {
+  for (size_t I = 0, E = Sources.size(); I < E; ++I) {
+    if (TypoCorrection C = Sources[I]->CorrectTypo(Typo, LookupKind, S, SS, CCC,
+                                                   MemberContext,
+                                                   EnteringContext, OPT))
+      return C;
+  }
+  return TypoCorrection();
+}
diff --git a/lib/Sema/SemaLookup.cpp b/lib/Sema/SemaLookup.cpp
index e95ffce..d0bb9f6 100644
--- a/lib/Sema/SemaLookup.cpp
+++ b/lib/Sema/SemaLookup.cpp
@@ -3872,6 +3872,14 @@
                                  DeclContext *MemberContext,
                                  bool EnteringContext,
                                  const ObjCObjectPointerType *OPT) {
+  // Always let the ExternalSource have the first chance at correction, even
+  // if we would otherwise have given up.
+  if (ExternalSource) {
+    if (TypoCorrection Correction = ExternalSource->CorrectTypo(
+        TypoName, LookupKind, S, SS, CCC, MemberContext, EnteringContext, OPT))
+      return Correction;
+  }
+
   if (Diags.hasFatalErrorOccurred() || !getLangOpts().SpellChecking)
     return TypoCorrection();