Index: cfe/trunk/include/clang/Basic/DiagnosticParseKinds.td
===================================================================
--- cfe/trunk/include/clang/Basic/DiagnosticParseKinds.td
+++ cfe/trunk/include/clang/Basic/DiagnosticParseKinds.td
@@ -347,8 +347,6 @@
 def warn_cxx98_compat_static_assert : Warning<
   "static_assert declarations are incompatible with C++98">,
   InGroup<CXX98Compat>, DefaultIgnore;
-def err_paren_after_colon_colon : Error<
-  "unexpected parenthesis after '::'">;
 def err_function_definition_not_allowed : Error<
   "function definition is not allowed here">;
 def err_expected_end_of_enumerator : Error<
Index: cfe/trunk/include/clang/Parse/Parser.h
===================================================================
--- cfe/trunk/include/clang/Parse/Parser.h
+++ cfe/trunk/include/clang/Parse/Parser.h
@@ -1530,8 +1530,6 @@
                                       bool IsTypename = false,
                                       IdentifierInfo **LastII = nullptr);
 
-  void CheckForLParenAfterColonColon();
-
   //===--------------------------------------------------------------------===//
   // C++0x 5.1.2: Lambda expressions
 
Index: cfe/trunk/lib/Parse/ParseExprCXX.cpp
===================================================================
--- cfe/trunk/lib/Parse/ParseExprCXX.cpp
+++ cfe/trunk/lib/Parse/ParseExprCXX.cpp
@@ -100,48 +100,6 @@
              /*AtDigraph*/false);
 }
 
-/// \brief Emits an error for a left parentheses after a double colon.
-///
-/// When a '(' is found after a '::', emit an error.  Attempt to fix the token
-/// stream by removing the '(', and the matching ')' if found.
-void Parser::CheckForLParenAfterColonColon() {
-  if (!Tok.is(tok::l_paren))
-    return;
-
-  Token LParen = Tok;
-  Token NextTok = GetLookAheadToken(1);
-  Token StarTok = NextTok;
-  // Check for (identifier or (*identifier
-  Token IdentifierTok = StarTok.is(tok::star) ? GetLookAheadToken(2) : StarTok;
-  if (IdentifierTok.isNot(tok::identifier))
-    return;
-  // Eat the '('.
-  ConsumeParen();
-  Token RParen;
-  RParen.setLocation(SourceLocation());
-  // Do we have a ')' ?
-  NextTok = StarTok.is(tok::star) ? GetLookAheadToken(2) : GetLookAheadToken(1);
-  if (NextTok.is(tok::r_paren)) {
-    RParen = NextTok;
-    // Eat the '*' if it is present.
-    if (StarTok.is(tok::star))
-      ConsumeToken();
-    // Eat the identifier.
-    ConsumeToken();
-    // Add the identifier token back.
-    PP.EnterToken(IdentifierTok);
-    // Add the '*' back if it was present.
-    if (StarTok.is(tok::star))
-      PP.EnterToken(StarTok);
-    // Eat the ')'.
-    ConsumeParen();
-  }
-
-  Diag(LParen.getLocation(), diag::err_paren_after_colon_colon)
-      << FixItHint::CreateRemoval(LParen.getLocation())
-      << FixItHint::CreateRemoval(RParen.getLocation());
-}
-
 /// \brief Parse global scope or nested-name-specifier if present.
 ///
 /// Parses a C++ global scope specifier ('::') or nested-name-specifier (which
@@ -237,8 +195,6 @@
       if (Actions.ActOnCXXGlobalScopeSpecifier(ConsumeToken(), SS))
         return true;
 
-      CheckForLParenAfterColonColon();
-
       HasScopeSpecifier = true;
     }
   }
@@ -491,8 +447,6 @@
       Token ColonColon = Tok;
       SourceLocation CCLoc = ConsumeToken();
 
-      CheckForLParenAfterColonColon();
-
       bool IsCorrectedToColon = false;
       bool *CorrectionFlagPtr = ColonIsSacred ? &IsCorrectedToColon : nullptr;
       if (Actions.ActOnCXXNestedNameSpecifier(getCurScope(), IdInfo,
Index: cfe/trunk/test/Parser/colon-colon-parentheses.cpp
===================================================================
--- cfe/trunk/test/Parser/colon-colon-parentheses.cpp
+++ cfe/trunk/test/Parser/colon-colon-parentheses.cpp
@@ -1,30 +1,36 @@
-// RUN: %clang_cc1 %s -fsyntax-only -verify -DPR21815
-// RUN: cp %s %t
-// RUN: not %clang_cc1 -x c++ -fixit %t
-// RUN: %clang_cc1 -x c++ %t
+// RUN: %clang_cc1 %s -verify -fno-spell-checking
 
 struct S { static int a,b,c;};
-int S::(a);  // expected-error{{unexpected parenthesis after '::'}}
-int S::(b;  // expected-error{{unexpected parenthesis after '::'}}
+int S::(a);  // expected-error{{expected unqualified-id}}
+int S::(b;  // expected-error{{expected unqualified-id}}
+        );
 int S::c;
-int S::(*d);  // expected-error{{unexpected parenthesis after '::'}}
-int S::(*e;  // expected-error{{unexpected parenthesis after '::'}}
+int S::(*d);  // expected-error{{expected unqualified-id}}
+int S::(*e;  // expected-error{{expected unqualified-id}}
+        );
 int S::*f;
-int g = S::(a);  // expected-error{{unexpected parenthesis after '::'}}
-int h = S::(b;  // expected-error{{unexpected parenthesis after '::'}}
+int g = S::(a);  // expected-error {{expected unqualified-id}} expected-error {{use of undeclared identifier 'a'}}
+int h = S::(b;  // expected-error {{expected unqualified-id}} expected-error {{use of undeclared identifier 'b'}}
+            );
 int i = S::c;
 
 void foo() {
   int a;
-  a = ::(g);  // expected-error{{unexpected parenthesis after '::'}}
-  a = ::(h;  // expected-error{{unexpected parenthesis after '::'}}
+  a = ::(g);  // expected-error{{expected unqualified-id}}
+  a = ::(h;  // expected-error{{expected unqualified-id}}
   a = ::i;
 }
 
-#ifdef PR21815
+// The following tests used to be crash bugs.
+
+// PR21815
 // expected-error@+2{{C++ requires a type specifier for all declarations}}
 // expected-error@+1{{expected unqualified-id}}
 a (::( ));
 
 ::((c )); // expected-error{{expected unqualified-id}}
-#endif
+
+// PR26623
+int f1(::(B) p); // expected-error {{expected unqualified-id}} expected-error {{use of undeclared identifier 'B'}}
+
+int f2(::S::(C) p); // expected-error {{expected unqualified-id}} expected-error {{use of undeclared identifier 'C'}}