Pull in r291403 from upstream clang trunk (by Richard Smith):

  PR30305: Implement proposed DR resolution to prevent slicing via
  inherited constructor.

  The rule we use is that a construction of a class type T from an
  argument of type U cannot use an inherited constructor if U is the
  same as T or is derived from T (or if the initialization would first
  convert it to such a type). This (approximately) matches the rule in
  use by GCC, and matches the current proposed DR resolution.

Pull in r291955 from upstream clang trunk (by Richard Smith):

  PR31606: Generalize our tentative DR resolution for inheriting
  copy/move constructors to better match the pre-P0136R1 behavior.

Together, these fix an issue with C++ using declarations sometimes
enabling illegal implicit casts.

Direct commit to stable/11, since head already has clang 4.0.0, which
includes this change.

Reported by:	kami
PR:		215969

2 files changed, 8 insertions, 1 deletions

diff --git a/contrib/llvm/tools/clang/include/clang/Basic/DiagnosticSemaKinds.td b/contrib/llvm/tools/clang/include/clang/Basic/DiagnosticSemaKinds.td
index 98b687b..c49adc3 100644
--- a/contrib/llvm/tools/clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/contrib/llvm/tools/clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -3180,6 +3180,9 @@ def note_ovl_candidate : Note<"candidate "
 
 def note_ovl_candidate_inherited_constructor : Note<
     "constructor from base class %0 inherited here">;
+def note_ovl_candidate_inherited_constructor_slice : Note<
+    "candidate %select{constructor|template}0 ignored: "
+    "inherited constructor cannot be used to %select{copy|move}1 object">;
 def note_ovl_candidate_illegal_constructor : Note<
     "candidate %select{constructor|template}0 ignored: "
     "instantiation %select{takes|would take}0 its own class type by value">;
diff --git a/contrib/llvm/tools/clang/include/clang/Sema/Overload.h b/contrib/llvm/tools/clang/include/clang/Sema/Overload.h
index d0f21cd..898b12e 100644
--- a/contrib/llvm/tools/clang/include/clang/Sema/Overload.h
+++ b/contrib/llvm/tools/clang/include/clang/Sema/Overload.h
@@ -586,7 +586,11 @@ namespace clang {
     ovl_fail_enable_if,
 
     /// This candidate was not viable because its address could not be taken.
-    ovl_fail_addr_not_available
+    ovl_fail_addr_not_available,
+
+    /// This inherited constructor is not viable because it would slice the
+    /// argument.
+    ovl_fail_inhctor_slice,
   };
 
   /// OverloadCandidate - A single candidate in an overload set (C++ 13.3).