2 files changed, 35 insertions, 5 deletions
diff --git a/clang/lib/Sema/SemaOverload.cpp b/clang/lib/Sema/SemaOverload.cpp
index 04bc6b10c0d..daf5b7f3600 100644
--- a/clang/lib/Sema/SemaOverload.cpp
+++ b/clang/lib/Sema/SemaOverload.cpp
@@ -4895,11 +4895,13 @@ Sema::CreateOverloadedBinOp(SourceLocation OpLoc,
   if (Opc == BinaryOperator::PtrMemD)
     return CreateBuiltinBinOp(OpLoc, Opc, Args[0], Args[1]);
 
-  // If this is one of the assignment operators, we only perform
-  // overload resolution if the left-hand side is a class or
-  // enumeration type (C++ [expr.ass]p3).
-  if (Opc >= BinaryOperator::Assign && Opc <= BinaryOperator::OrAssign &&
-      !Args[0]->getType()->isOverloadableType())
+  // If this is the assignment operator, we only perform overload resolution
+  // if the left-hand side is a class or enumeration type. This is actually
+  // a hack. The standard requires that we do overload resolution between the
+  // various built-in candidates, but as DR507 points out, this can lead to
+  // problems. So we do it this way, which pretty much follows what GCC does.
+  // Note that we go the traditional code path for compound assignment forms.
+  if (Opc==BinaryOperator::Assign && !Args[0]->getType()->isOverloadableType())
     return CreateBuiltinBinOp(OpLoc, Opc, Args[0], Args[1]);
 
   // Build an empty overload set.
diff --git a/clang/test/SemaCXX/overloaded-operator.cpp b/clang/test/SemaCXX/overloaded-operator.cpp
index 5fdbeebdfd1..16d37040f14 100644
--- a/clang/test/SemaCXX/overloaded-operator.cpp
+++ b/clang/test/SemaCXX/overloaded-operator.cpp
@@ -296,3 +296,31 @@ namespace pr5546
   const char* a() { return sMoveCommands[X][0][0]; }
   const char* b() { return (*(sMoveCommands+X))[0][0]; }
 }
+
+// PR5512 and its discussion
+namespace pr5512 {
+  struct Y {
+    operator short();
+    operator float();
+  };
+  void g_test(Y y) {
+    short s = 0;
+    // DR507, this should be ambiguous, but we special-case assignment
+    s = y;
+    // Note: DR507, this is ambiguous as specified
+    //s += y;
+  }
+
+  struct S {};
+  void operator +=(int&, S);
+  void f(S s) {
+    int i = 0;
+    i += s;
+  }
+
+  struct A {operator int();};
+  int a;
+  void b(A x) {
+    a += x;
+  }
+}