Update to new resolution for DR1458. When taking the address of an object of

incomplete class type which has an overloaded operator&, it's now just
unspecified whether the overloaded operator or the builtin is used.

llvm-svn: 150234

3 files changed, 4 insertions, 18 deletions

diff --git a/clang/include/clang/Basic/DiagnosticASTKinds.td b/clang/include/clang/Basic/DiagnosticASTKinds.td
index 80d93291729..fb6e73090e2 100644
--- a/clang/include/clang/Basic/DiagnosticASTKinds.td
+++ b/clang/include/clang/Basic/DiagnosticASTKinds.td
@@ -55,9 +55,6 @@ def note_constexpr_pointer_comparison_differing_access : Note<
   "specifiers (%1 vs %3) has unspecified value">;
 def note_constexpr_compare_virtual_mem_ptr : Note<
   "comparison of pointer to virtual member function %0 has unspecified value">;
-def note_constexpr_addr_of_incomplete : Note<
-  "cannot take address of object of incomplete class type %0 "
-  "in a constant expression">;
 def note_constexpr_past_end : Note<
   "dereferenced pointer past the end of %select{|subobject of }0"
   "%select{temporary|%2}1 is not a constant expression">;
diff --git a/clang/lib/AST/ExprConstant.cpp b/clang/lib/AST/ExprConstant.cpp
index e43884e3766..998bb705f9d 100644
--- a/clang/lib/AST/ExprConstant.cpp
+++ b/clang/lib/AST/ExprConstant.cpp
@@ -2944,18 +2944,6 @@ bool PointerExprEvaluator::VisitBinaryOperator(const BinaryOperator *E) {
 }
 
 bool PointerExprEvaluator::VisitUnaryAddrOf(const UnaryOperator *E) {
-  QualType SrcTy = E->getSubExpr()->getType();
-  // In C++, taking the address of an object of incomplete class type has
-  // undefined behavior if the complete class type has an overloaded operator&.
-  // DR1458 makes such expressions non-constant.
-  if (Info.getLangOpts().CPlusPlus &&
-      SrcTy->isRecordType() && SrcTy->isIncompleteType()) {
-    const RecordType *RT = SrcTy->getAs<RecordType>();
-    Info.CCEDiag(E->getExprLoc(), diag::note_constexpr_addr_of_incomplete, 1)
-      << SrcTy;
-    Info.Note(RT->getDecl()->getLocation(), diag::note_forward_declaration)
-      << RT->getDecl();
-  }
   return EvaluateLValue(E->getSubExpr(), Result, Info);
 }
 
diff --git a/clang/test/CXX/expr/expr.const/p2-0x.cpp b/clang/test/CXX/expr/expr.const/p2-0x.cpp
index 43d683aeca4..2d4f4fb62e6 100644
--- a/clang/test/CXX/expr/expr.const/p2-0x.cpp
+++ b/clang/test/CXX/expr/expr.const/p2-0x.cpp
@@ -111,9 +111,10 @@ namespace RecursionLimits {
 
 // DR1458: taking the address of an object of incomplete class type
 namespace IncompleteClassTypeAddr {
-  struct S; // expected-note {{forward}}
+  struct S;
   extern S s;
-  constexpr S *p = &s; // expected-error {{constant expression}} expected-note {{cannot take address of object of incomplete class type 'IncompleteClassTypeAddr::S' in a constant expression}}
+  constexpr S *p = &s; // ok
+  static_assert(p, "");
 
   extern S sArr[];
   constexpr S (*p2)[] = &sArr; // ok
@@ -121,7 +122,7 @@ namespace IncompleteClassTypeAddr {
   struct S {
     constexpr S *operator&() { return nullptr; }
   };
-  constexpr S *q = &s;
+  constexpr S *q = &s; // ok
   static_assert(!q, "");
 }