Unrevert r166268, reverted in r166272, with a fix for the issue which Nick

found: if an overloaded operator& is present before a template definition,
the expression &T::foo is represented as a CXXOperatorCallExpr, not as a
UnaryOperator, so we didn't notice that it's permitted to reference a non-static
data member of an unrelated class.

While investigating this, I discovered another problem in this area: we are
treating template default arguments as unevaluated contexts during substitution,
resulting in performing incorrect checks for uses of non-static data members in
C++11. That is not fixed by this patch (I'll look into this soon; it's related
to the failure to correctly instantiate constexpr function templates), but was
resulting in this bug not firing in C++11 mode (except with -Wc++98-compat).

Original message:

PR14124: When performing template instantiation of a qualified-id outside of a
class, diagnose if the qualified-id instantiates to a non-static class member.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@166385 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 12 insertions, 2 deletions

diff --git a/lib/Sema/SemaExpr.cpp b/lib/Sema/SemaExpr.cpp
index 6a6fe897c5..838d33150f 100644
--- a/lib/Sema/SemaExpr.cpp
+++ b/lib/Sema/SemaExpr.cpp
@@ -1895,7 +1895,8 @@ ExprResult Sema::ActOnIdExpression(Scope *S,
 /// this path.
 ExprResult
 Sema::BuildQualifiedDeclarationNameExpr(CXXScopeSpec &SS,
-                                        const DeclarationNameInfo &NameInfo) {
+                                        const DeclarationNameInfo &NameInfo,
+                                        bool IsAddressOfOperand) {
   DeclContext *DC;
   if (!(DC = computeDeclContext(SS, false)) || DC->isDependentContext())
     return BuildDependentDeclRefExpr(SS, /*TemplateKWLoc=*/SourceLocation(),
@@ -1916,7 +1917,16 @@ Sema::BuildQualifiedDeclarationNameExpr(CXXScopeSpec &SS,
     return ExprError();
   }
 
-  return BuildDeclarationNameExpr(SS, R, /*ADL*/ false);
+  // Defend against this resolving to an implicit member access. We usually
+  // won't get here if this might be a legitimate a class member (we end up in
+  // BuildMemberReferenceExpr instead), but this can be valid if we're forming
+  // a pointer-to-member or in an unevaluated context in C++11.
+  if (!R.empty() && (*R.begin())->isCXXClassMember() && !IsAddressOfOperand)
+    return BuildPossibleImplicitMemberExpr(SS,
+                                           /*TemplateKWLoc=*/SourceLocation(),
+                                           R, /*TemplateArgs=*/0);
+
+  return BuildDeclarationNameExpr(SS, R, /* ADL */ false);
 }
 
 /// LookupInObjCMethod - The parser has read a name in, and Sema has