Fix the caching in CorrectTypo so that other non-keyword identifiers
are still added if the cached correction fails validation.

Also fix a copy-and-paste error in a comment from my previous commit.
Finally, add an example of the benefit the typo correction callback adds
to TryNamespaceTypoCorrection--which happens to also tickle the above
caching problem, as the only way a non-namespace Decl would be added to
the possible corrections is if it was cached as the correction for a
previous instance of the same typo where the typo was corrected to a
non-namespace via a different code path.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@147968 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Sema/SemaDeclCXX.cpp b/lib/Sema/SemaDeclCXX.cpp
index f21d766..9fcac22 100644
--- a/lib/Sema/SemaDeclCXX.cpp
+++ b/lib/Sema/SemaDeclCXX.cpp
@@ -1747,7 +1747,8 @@
 
 namespace {
 
-// Callback to only accept typo corrections that are namespaces.
+// Callback to only accept typo corrections that can be a valid C++ member
+// intializer: either a non-static field member or a base class.
 class MemInitializerValidatorCCC : public CorrectionCandidateCallback {
  public:
   explicit MemInitializerValidatorCCC(CXXRecordDecl *ClassDecl)
diff --git a/lib/Sema/SemaLookup.cpp b/lib/Sema/SemaLookup.cpp
index 5bf0ca5..c69022d 100644
--- a/lib/Sema/SemaLookup.cpp
+++ b/lib/Sema/SemaLookup.cpp
@@ -3650,7 +3650,8 @@
     IsUnqualifiedLookup = true;
     UnqualifiedTyposCorrectedMap::iterator Cached
       = UnqualifiedTyposCorrected.find(Typo);
-    if (Cached == UnqualifiedTyposCorrected.end()) {
+    if (Cached == UnqualifiedTyposCorrected.end() ||
+        (Cached->second && CCC && !CCC->ValidateCandidate(Cached->second))) {
       // Provide a stop gap for files that are just seriously broken.  Trying
       // to correct all typos can turn into a HUGE performance penalty, causing
       // some files to take minutes to get rejected by the parser.
diff --git a/test/SemaCXX/typo-correction.cpp b/test/SemaCXX/typo-correction.cpp
index 0fb33bc..c3e8480 100644
--- a/test/SemaCXX/typo-correction.cpp
+++ b/test/SemaCXX/typo-correction.cpp
@@ -40,3 +40,10 @@
   static int base_type;
   Derived() : basetype() {} // expected-error{{initializer 'basetype' does not name a non-static data member or base class; did you mean the base class 'BaseType'?}}
 };
+
+// In this example, somename should not be corrected to the cached correction
+// "some_name" since "some_name" is a class and a namespace name is needed.
+class some_name {}; // expected-note {{'some_name' declared here}}
+somename Foo; // expected-error {{unknown type name 'somename'; did you mean 'some_name'?}}
+namespace SomeName {} // expected-note {{namespace 'SomeName' defined here}}
+using namespace somename; // expected-error {{no namespace named 'somename'; did you mean 'SomeName'?}}