For variables with dependent type, don't crash on `var->::new` or `var->__super`

ParsePostfixExpressionSuffix() for '->' (or '.') postfixes first calls
ActOnStartCXXMemberReference() to inform sema that a member reference is about
to start, and that function lets the parser know if sema thinks that the
base expression's type could allow a pseudo destructor from a semantic point of
view (for example, if the the base expression has a dependent type).

ParsePostfixExpressionSuffix() then calls ParseOptionalCXXScopeSpecifier() and
passes MayBePseudoDestructor on to that function, expecting the function to
set it to false if a pseudo destructor is impossible from a syntactic point of
view (due to a lack of '~' sigil).  However, ParseOptionalCXXScopeSpecifier()
had early-outs for ::new and __super, so MayBePseudoDestructor stayed true,
so we tried to parse a pseudo dtor, and then became confused since we couldn't
find a '~'.  Move the snippet in ParseOptionalCXXScopeSpecifier() that sets
MayBePseudoDestructor to false above the early exits.

Parts of this found by SLi's bot.

llvm-svn: 229449

1 files changed, 8 insertions, 6 deletions

diff --git a/clang/lib/Parse/ParseExprCXX.cpp b/clang/lib/Parse/ParseExprCXX.cpp
index e7ca66de487..d91744115cc 100644
--- a/clang/lib/Parse/ParseExprCXX.cpp
+++ b/clang/lib/Parse/ParseExprCXX.cpp
@@ -194,6 +194,7 @@ bool Parser::ParseOptionalCXXScopeSpecifier(CXXScopeSpec &SS,
 
   if (Tok.is(tok::annot_cxxscope)) {
     assert(!LastII && "want last identifier but have already annotated scope");
+    assert(!MayBePseudoDestructor && "unexpected annot_cxxscope");
     Actions.RestoreNestedNameSpecifierAnnotation(Tok.getAnnotationValue(),
                                                  Tok.getAnnotationRange(),
                                                  SS);
@@ -208,6 +209,13 @@ bool Parser::ParseOptionalCXXScopeSpecifier(CXXScopeSpec &SS,
     SS = TemplateId->SS;
   }
 
+  // Has to happen before any "return false"s in this function.
+  bool CheckForDestructor = false;
+  if (MayBePseudoDestructor && *MayBePseudoDestructor) {
+    CheckForDestructor = true;
+    *MayBePseudoDestructor = false;
+  }
+
   if (LastII)
     *LastII = nullptr;
 
@@ -244,12 +252,6 @@ bool Parser::ParseOptionalCXXScopeSpecifier(CXXScopeSpec &SS,
     return Actions.ActOnSuperScopeSpecifier(SuperLoc, ConsumeToken(), SS);
   }
 
-  bool CheckForDestructor = false;
-  if (MayBePseudoDestructor && *MayBePseudoDestructor) {
-    CheckForDestructor = true;
-    *MayBePseudoDestructor = false;
-  }
-
   if (!HasScopeSpecifier &&
       (Tok.is(tok::kw_decltype) || Tok.is(tok::annot_decltype))) {
     DeclSpec DS(AttrFactory);