[Sema] PR25181 Fix crash when method declaration with throw spec fails to parse correctly

[hintonda]

Summary

Fixes crash referenced in PR25181 where dyn_cast is called on a null instance of LM.Method.

[majnemer]

This needs a testcase added to the tests directory.

[hintonda]

• Reformatted change with clang-format

[hintonda]

• Added test for PR25181

[hintonda]

I don't have commit access, so if this patch is accepted, could someone please commit it for me?

[hintonda]

• Only call HandleMemberFunctionDeclDelays() for valid NamedDecl pointers.
  
  HandleMemberFunctionDeclDelays() adds LateParsedMethodDeclaration elements to LateParsedDeclarations if the method has default args or exception-specifications. If null Methods are added, they will assert when cast in ParseLexedMethodDeclaration().

[rnk]

Looks good, thanks. I like the new approach of avoiding the creation of a LateParsedMethodDeclaration if we couldn't get a NamedDecl back. I'll land it soon.

cfe/trunk/lib/Parse/ParseCXXInlineMethods.cpp

FnD = Actions.ActOnCXXMemberDeclarator(getCurScope(), AS, D,
                                            VS, ICIS_NoInit);
     if (FnD) {
       Actions.ProcessDeclAttributeList(getCurScope(), FnD, AccessAttrs);
       if (PureSpecLoc.isValid())
         Actions.ActOnPureSpecifier(FnD, PureSpecLoc);
     }
   }
 
+  if (FnD)
     HandleMemberFunctionDeclDelays(D, FnD);
 
   D.complete(FnD);
 
   if (TryConsumeToken(tok::equal)) {
     if (!FnD) {
       SkipUntil(tok::semi);
       return nullptr;
     }

cfe/trunk/test/SemaCXX/pr25181-crash-on-invalid.cpp

+// RUN: %clang_cc1 -fsyntax-only -verify -std=c++11 %s
+// Don't crash (PR25181).
+
+template <typename T> class Foo { // expected-note {{template parameter is declared here}}
+  template <typename T> // expected-error {{declaration of 'T' shadows template parameter}}
+  void Foo<T>::method(T *) const throw() {} // expected-error {{nested name specifier 'Foo<T>::' for declaration does not refer into a class, class template or class template partial specialization}}
+};