[Parser] Perform CachedTokens update dependent on token consumption

In the context where we break one tok::greatergreater into two
tok::greater in order to correctly update the cached tokens; update the
CachedTokens with two tok::greater only if ParseGreaterThanInTemplateList
clients asks to consume the last token. Otherwise we only need to add
one because the second is already added later on, as a not yet cached token.

Differential Revision: http://reviews.llvm.org/D16906

rdar://problem/24488367

llvm-svn: 259910

clang/lib/Parse/ParseTemplate.cpp

@@ -855,8 +855,12 @@ bool Parser::ParseGreaterThanInTemplateList(SourceLocation &RAngleLoc,
       RemainingToken == tok::greater && PP.IsPreviousCachedToken(PrevTok)) {
     PrevTok.setKind(RemainingToken);
     PrevTok.setLength(1);
-    Token NewToks[] = {PrevTok, Tok};
-    PP.ReplacePreviousCachedToken(NewToks);
+    // Break tok::greatergreater into two tok::greater but only add the second
+    // one in case the client asks to consume the last token.
+    if (ConsumeLastToken)
+      PP.ReplacePreviousCachedToken({PrevTok, Tok});
+    else
+      PP.ReplacePreviousCachedToken({PrevTok});
   }
 
   if (!ConsumeLastToken) {

clang/test/Parser/objcxx14-protocol-in-template.mm

@@ -0,0 +1,15 @@
+// RUN: %clang_cc1 -fsyntax-only -verify -std=c++14 %s
+
+template<class T> class vector {};
+@protocol P @end
+
+// expected-no-diagnostics
+
+template <typename Functor> void F(Functor functor) {}
+
+// Test protocol in template within lambda capture initializer context.
+void z() {
+  id<P> x = 0;
+  (void)x;
+  F( [ x = vector<id<P>>{} ] {} );
+}