Merging r291955:

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r291955 | rsmith | 2017-01-13 12:46:54 -0800 (Fri, 13 Jan 2017) | 3 lines

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

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git-svn-id: https://llvm.org/svn/llvm-project/cfe/branches/release_40@292463 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 28 insertions, 26 deletions

diff --git a/lib/Sema/SemaOverload.cpp b/lib/Sema/SemaOverload.cpp
index afdae4ed6d..c66fe7678d 100644
--- a/lib/Sema/SemaOverload.cpp
+++ b/lib/Sema/SemaOverload.cpp
@@ -5944,6 +5944,28 @@ Sema::AddOverloadCandidate(FunctionDecl *Function,
       Candidate.FailureKind = ovl_fail_illegal_constructor;
       return;
     }
+
+    // C++ [over.match.funcs]p8: (proposed DR resolution)
+    //   A constructor inherited from class type C that has a first parameter
+    //   of type "reference to P" (including such a constructor instantiated
+    //   from a template) is excluded from the set of candidate functions when
+    //   constructing an object of type cv D if the argument list has exactly
+    //   one argument and D is reference-related to P and P is reference-related
+    //   to C.
+    auto *Shadow = dyn_cast<ConstructorUsingShadowDecl>(FoundDecl.getDecl());
+    if (Shadow && Args.size() == 1 && Constructor->getNumParams() >= 1 &&
+        Constructor->getParamDecl(0)->getType()->isReferenceType()) {
+      QualType P = Constructor->getParamDecl(0)->getType()->getPointeeType();
+      QualType C = Context.getRecordType(Constructor->getParent());
+      QualType D = Context.getRecordType(Shadow->getParent());
+      SourceLocation Loc = Args.front()->getExprLoc();
+      if ((Context.hasSameUnqualifiedType(P, C) || IsDerivedFrom(Loc, P, C)) &&
+          (Context.hasSameUnqualifiedType(D, P) || IsDerivedFrom(Loc, D, P))) {
+        Candidate.Viable = false;
+        Candidate.FailureKind = ovl_fail_inhctor_slice;
+        return;
+      }
+    }
   }
 
   unsigned NumParams = Proto->getNumParams();
@@ -6016,31 +6038,6 @@ Sema::AddOverloadCandidate(FunctionDecl *Function,
     }
   }
 
-  // C++ [over.best.ics]p4+: (proposed DR resolution)
-  //   If the target is the first parameter of an inherited constructor when
-  //   constructing an object of type C with an argument list that has exactly
-  //   one expression, an implicit conversion sequence cannot be formed if C is
-  //   reference-related to the type that the argument would have after the
-  //   application of the user-defined conversion (if any) and before the final
-  //   standard conversion sequence. 
-  auto *Shadow = dyn_cast<ConstructorUsingShadowDecl>(FoundDecl.getDecl());
-  if (Shadow && Args.size() == 1 && !isa<InitListExpr>(Args.front())) {
-    bool DerivedToBase, ObjCConversion, ObjCLifetimeConversion;
-    QualType ConvertedArgumentType = Args.front()->getType();
-    if (Candidate.Conversions[0].isUserDefined())
-      ConvertedArgumentType =
-          Candidate.Conversions[0].UserDefined.After.getFromType();
-    if (CompareReferenceRelationship(Args.front()->getLocStart(),
-                                     Context.getRecordType(Shadow->getParent()),
-                                     ConvertedArgumentType, DerivedToBase,
-                                     ObjCConversion,
-                                     ObjCLifetimeConversion) >= Ref_Related) {
-      Candidate.Viable = false;
-      Candidate.FailureKind = ovl_fail_inhctor_slice;
-      return;
-    }
-  }
-
   if (EnableIfAttr *FailedAttr = CheckEnableIf(Function, Args)) {
     Candidate.Viable = false;
     Candidate.FailureKind = ovl_fail_enable_if;
@@ -10222,8 +10219,13 @@ static void NoteFunctionCandidate(Sema &S, OverloadCandidate *Cand,
     return DiagnoseOpenCLExtensionDisabled(S, Cand);
 
   case ovl_fail_inhctor_slice:
+    // It's generally not interesting to note copy/move constructors here.
+    if (cast<CXXConstructorDecl>(Fn)->isCopyOrMoveConstructor())
+      return;
     S.Diag(Fn->getLocation(),
-           diag::note_ovl_candidate_inherited_constructor_slice);
+           diag::note_ovl_candidate_inherited_constructor_slice)
+      << (Fn->getPrimaryTemplate() ? 1 : 0)
+      << Fn->getParamDecl(0)->getType()->isRValueReferenceType();
     MaybeEmitInheritedConstructorNote(S, Cand->FoundDecl);
     return;