Multiple conversions to the same type are ambiguous but for the
purpose of overload resolution is to be treated as a uner-defined
conversion.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@83004 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Sema/SemaOverload.cpp b/lib/Sema/SemaOverload.cpp
index 793041b..885f59c 100644
--- a/lib/Sema/SemaOverload.cpp
+++ b/lib/Sema/SemaOverload.cpp
@@ -1511,8 +1511,6 @@
return OR_Deleted;
case OR_Ambiguous:
- // FIXME: See C++ [over.best.ics]p10 for the handling of
- // ambiguous conversion sequences.
return OR_Ambiguous;
}
@@ -2236,8 +2234,20 @@
/*InOverloadResolution=*/true);
if (Candidate.Conversions[ArgIdx].ConversionKind
== ImplicitConversionSequence::BadConversion) {
- Candidate.Viable = false;
- break;
+ // 13.3.3.1-p10 If several different sequences of conversions exist that
+ // each convert the argument to the parameter type, the implicit conversion
+ // sequence associated with the parameter is defined to be the unique conversion
+ // sequence designated the ambiguous conversion sequence. For the purpose of
+ // ranking implicit conversion sequences as described in 13.3.3.2, the ambiguous
+ // conversion sequence is treated as a user-defined sequence that is
+ // indistinguishable from any other user-defined conversion sequence
+ if (Candidate.Conversions[ArgIdx].ConversionFunctionSet.size() > 0)
+ Candidate.Conversions[ArgIdx].ConversionKind =
+ ImplicitConversionSequence::UserDefinedConversion;
+ else {
+ Candidate.Viable = false;
+ break;
+ }
}
} else {
// (C++ 13.3.2p2): For the purposes of overload resolution, any
diff --git a/test/SemaCXX/ambig-user-defined-conversions.cpp b/test/SemaCXX/ambig-user-defined-conversions.cpp
index 1117253..94598f0 100644
--- a/test/SemaCXX/ambig-user-defined-conversions.cpp
+++ b/test/SemaCXX/ambig-user-defined-conversions.cpp
@@ -1,10 +1,11 @@
// RUN: clang-cc -fsyntax-only -verify %s
+// Test1
struct BASE {
- operator int &(); // expected-note 4 {{candidate function}}
+ operator int &(); // expected-note {{candidate function}}
};
struct BASE1 {
- operator int &(); // expected-note 4 {{candidate function}}
+ operator int &(); // expected-note {{candidate function}}
};
struct B : public BASE, BASE1 {
@@ -14,13 +15,38 @@
extern B f();
B b1;
-void func(const int ci, const char cc); // expected-note {{function not viable because of ambiguity in conversion of argument 1}}
-void func(const char ci, const B b); // expected-note {{function not viable because of ambiguity in conversion of argument 1}}
-void func(const B b, const int ci); // expected-note {{function not viable because of ambiguity in conversion of argument 2}}
+void func(const int ci, const char cc); // expected-note {{candidate function}}
+void func(const char ci, const B b); // expected-note {{candidate function}}
+void func(const B b, const int ci); // expected-note {{candidate function}}
-
-const int main() {
- func(b1, f()); // expected-error {{no matching function for call to 'func'}}
+const int Test1() {
+ func(b1, f()); // expected-error {{call to 'func' is ambiguous}}
return f(); // expected-error {{conversion from 'struct B' to 'int const' is ambiguous}}
}
+
+// Test2
+struct E;
+struct A {
+ A (E&);
+};
+
+struct E {
+ operator A ();
+};
+
+struct C {
+ C (E&);
+};
+
+void f1(A); // expected-note {{candidate function}}
+void f1(C); // expected-note {{candidate function}}
+
+void Test2()
+{
+ E b;
+ f1(b); // expected-error {{call to 'f1' is ambiguous}}
+ // ambiguous because b -> C via constructor and
+ // b → A via constructor or conversion function.
+}
+