From 966256afd49a4af0c002046a19bb0041a507909b Mon Sep 17 00:00:00 2001
From: Fariborz Jahanian <fjahanian@apple.com>
Date: Fri, 6 Nov 2009 00:23:08 +0000
Subject: [PATCH] This patch implements Sema for clause 13.3.3.1p4. It has to
 do with vararg constructors used as conversion functions. Code gen needs
 work. This is WIP.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@86207 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Sema/SemaDeclCXX.cpp  |  1 +
 lib/Sema/SemaExprCXX.cpp  | 21 ++++++++++++---------
 lib/Sema/SemaOverload.cpp | 11 +++++++++--
 lib/Sema/SemaOverload.h   |  8 ++++++++
 4 files changed, 30 insertions(+), 11 deletions(-)

diff --git a/lib/Sema/SemaDeclCXX.cpp b/lib/Sema/SemaDeclCXX.cpp
index b8977cfa14..f3561bfa0f 100644
--- a/lib/Sema/SemaDeclCXX.cpp
+++ b/lib/Sema/SemaDeclCXX.cpp
@@ -3827,6 +3827,7 @@ Sema::CheckReferenceInit(Expr *&Init, QualType DeclType,
         ICS->UserDefined.Before = Best->Conversions[0].Standard;
         ICS->UserDefined.After = Best->FinalConversion;
         ICS->UserDefined.ConversionFunction = Best->Function;
+        ICS->UserDefined.EllipsisConversion = false;
         assert(ICS->UserDefined.After.ReferenceBinding &&
                ICS->UserDefined.After.DirectBinding &&
                "Expected a direct reference binding!");
diff --git a/lib/Sema/SemaExprCXX.cpp b/lib/Sema/SemaExprCXX.cpp
index dc57681573..3408ff7087 100644
--- a/lib/Sema/SemaExprCXX.cpp
+++ b/lib/Sema/SemaExprCXX.cpp
@@ -1086,18 +1086,21 @@ Sema::PerformImplicitConversion(Expr *&From, QualType ToType,
       } else if (const CXXConstructorDecl *Ctor = 
                   dyn_cast<CXXConstructorDecl>(FD)) {
         CastKind = CastExpr::CK_ConstructorConversion;
-
-        // If the user-defined conversion is specified by a constructor, the 
-        // initial standard conversion sequence converts the source type to the
-        // type required by the argument of the constructor
-        BeforeToType = Ctor->getParamDecl(0)->getType();
+        // Do no conversion if dealing with ... for the first conversion.
+        if (!ICS.UserDefined.EllipsisConversion)
+          // If the user-defined conversion is specified by a constructor, the 
+          // initial standard conversion sequence converts the source type to the
+          // type required by the argument of the constructor
+          BeforeToType = Ctor->getParamDecl(0)->getType();
       }    
       else
         assert(0 && "Unknown conversion function kind!");
-
-      if (PerformImplicitConversion(From, BeforeToType, 
-                                    ICS.UserDefined.Before, "converting"))
-        return true;
+      // Whatch out for elipsis conversion.
+      if (!BeforeToType.isNull()) {
+        if (PerformImplicitConversion(From, BeforeToType, 
+                                      ICS.UserDefined.Before, "converting"))
+          return true;
+      }
     
       OwningExprResult CastArg 
         = BuildCXXCastArgument(From->getLocStart(),
diff --git a/lib/Sema/SemaOverload.cpp b/lib/Sema/SemaOverload.cpp
index 3e6778bc47..19f0885e8e 100644
--- a/lib/Sema/SemaOverload.cpp
+++ b/lib/Sema/SemaOverload.cpp
@@ -1481,9 +1481,14 @@ Sema::OverloadingResult Sema::IsUserDefinedConversion(
         //   sequence converts the source type to the type required by
         //   the argument of the constructor.
         //
-        // FIXME: What about ellipsis conversions?
         QualType ThisType = Constructor->getThisType(Context);
-        User.Before = Best->Conversions[0].Standard;
+        if (Best->Conversions[0].ConversionKind == 
+            ImplicitConversionSequence::EllipsisConversion)
+          User.EllipsisConversion = true;
+        else {
+          User.Before = Best->Conversions[0].Standard;
+          User.EllipsisConversion = false;
+        }
         User.ConversionFunction = Constructor;
         User.After.setAsIdentityConversion();
         User.After.FromTypePtr
@@ -1500,6 +1505,7 @@ Sema::OverloadingResult Sema::IsUserDefinedConversion(
         //   implicit object parameter of the conversion function.
         User.Before = Best->Conversions[0].Standard;
         User.ConversionFunction = Conversion;
+        User.EllipsisConversion = false;
 
         // C++ [over.ics.user]p2:
         //   The second standard conversion sequence converts the
@@ -2693,6 +2699,7 @@ void Sema::AddSurrogateCandidate(CXXConversionDecl *Conversion,
   Candidate.Conversions[0].ConversionKind
     = ImplicitConversionSequence::UserDefinedConversion;
   Candidate.Conversions[0].UserDefined.Before = ObjectInit.Standard;
+  Candidate.Conversions[0].UserDefined.EllipsisConversion = false;
   Candidate.Conversions[0].UserDefined.ConversionFunction = Conversion;
   Candidate.Conversions[0].UserDefined.After
     = Candidate.Conversions[0].UserDefined.Before;
diff --git a/lib/Sema/SemaOverload.h b/lib/Sema/SemaOverload.h
index 898393a9e4..0d1f37aa4b 100644
--- a/lib/Sema/SemaOverload.h
+++ b/lib/Sema/SemaOverload.h
@@ -156,6 +156,14 @@ namespace clang {
     ///   object parameter of the conversion function.
     StandardConversionSequence Before;
 
+    /// EllipsisConversion - When this is true, it means user-defined
+    /// conversion sequence starts with a ... (elipsis) conversion, instead of 
+    /// a standard conversion. In this case, 'Before' field must be ignored.
+    // FIXME. I much rather put this as the first field. But there seems to be
+    // a gcc code gen. bug which causes a crash in a test. Putting it here seems
+    // to work around the crash.
+    bool EllipsisConversion : 1;
+    
     /// After - Represents the standard conversion that occurs after
     /// the actual user-defined conversion.
     StandardConversionSequence After;
-- 
2.40.0