[Objective-c] Fix a crash that occurs when ObjCTypeParamList::back() is

called on an empty list.

This commit makes Parser::parseObjCTypeParamListOrProtocolRefs return
nullptr if it sees an invalid type parameter (e.g., __kindof) in the
type parameter list.

rdar://problem/23068920

Differential Revision: http://reviews.llvm.org/D15463

llvm-svn: 255754

2 files changed, 17 insertions, 1 deletions

diff --git a/clang/lib/Parse/ParseObjc.cpp b/clang/lib/Parse/ParseObjc.cpp
index 63c01932c1a..8a028b50376 100644
--- a/clang/lib/Parse/ParseObjc.cpp
+++ b/clang/lib/Parse/ParseObjc.cpp
@@ -603,7 +603,7 @@ ObjCTypeParamList *Parser::parseObjCTypeParamListOrProtocolRefs(
   // whether there are any protocol references.
   lAngleLoc = SourceLocation();
   rAngleLoc = SourceLocation();
-  return list;
+  return invalid ? nullptr : list;
 }
 
 /// Parse an objc-type-parameter-list.
diff --git a/clang/test/SemaObjC/kindof.m b/clang/test/SemaObjC/kindof.m
index b19e4237207..f205e68ea12 100644
--- a/clang/test/SemaObjC/kindof.m
+++ b/clang/test/SemaObjC/kindof.m
@@ -302,3 +302,19 @@ void testNullability() {
   void processCopyable(__typeof(getSomeCopyable()) string);
   processCopyable(0); // expected-warning{{null passed to a callee that requires a non-null argument}}
 }
+
+// Check that clang doesn't crash when a type parameter is illegal.
+@interface Array1<T> : NSObject
+@end
+
+@interface I1 : NSObject
+@end
+
+@interface Array1<__kindof I1*>(extensions1) // expected-error{{expected type parameter name}}
+@end
+
+@interface Array2<T1, T2, T3> : NSObject
+@end
+
+@interface Array2<T, T, __kindof I1*>(extensions2) // expected-error{{expected type parameter name}} expected-error{{redeclaration of type parameter 'T'}}
+@end