PR c++/90998 - ICE with copy elision in init by ctor and -Wconversion.

	* call.c (joust): Don't attempt to warn if ->second_conv is null.

	* g++.dg/cpp0x/overload-conv-4.C: New test.

From-SVN: r277992

diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index c870d4a3817efa862e2e0fc87b38d4c77e46f9e6..f44fdee6aa1b6bde4ee68fc0440b259627f6bcba 100644 (file)
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -1,3 +1,11 @@
+2019-11-08  Marek Polacek  <polacek@redhat.com>
+
+       Backported from mainline
+       2019-10-29  Marek Polacek  <polacek@redhat.com>
+
+       PR c++/90998 - ICE with copy elision in init by ctor and -Wconversion.
+       * call.c (joust): Don't attempt to warn if ->second_conv is null.
+
 2019-11-08  Jakub Jelinek  <jakub@redhat.com>
 
        Backported from mainline

diff --git a/gcc/cp/call.c b/gcc/cp/call.c
index 14ddc98f3014d6272531cb1625c89f94510abae2..8f950d133214e6d2772534564d6a21ff3891457f 100644 (file)
--- a/gcc/cp/call.c
+++ b/gcc/cp/call.c
@@ -10739,7 +10739,9 @@ joust (struct z_candidate *cand1, struct z_candidate *cand2, bool warn,
      either between a constructor and a conversion op, or between two
      conversion ops.  */
   if ((complain & tf_warning)
-      && winner && warn_conversion && cand1->second_conv
+      /* In C++17, the constructor might have been elided, which means that
+        an originally null ->second_conv could become non-null.  */
+      && winner && warn_conversion && cand1->second_conv && cand2->second_conv
       && (!DECL_CONSTRUCTOR_P (cand1->fn) || !DECL_CONSTRUCTOR_P (cand2->fn))
       && winner != compare_ics (cand1->second_conv, cand2->second_conv))
     {

diff --git a/gcc/testsuite/g++.dg/cpp0x/overload-conv-4.C b/gcc/testsuite/g++.dg/cpp0x/overload-conv-4.C
new file mode 100644 (file)
index 0000000..6fcdbba
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/overload-conv-4.C
@@ -0,0 +1,23 @@
+// PR c++/90998 - ICE with copy elision in init by ctor and -Wconversion.
+// { dg-do compile { target c++11 } }
+// { dg-options "-Wconversion" }
+
+struct B;
+
+struct A {
+    operator B();
+};
+
+struct B {
+    B(A const &rs);
+    B(B const &rs);
+};
+
+B
+f (A x)
+{
+  // C++14: we call B::B(A const &)
+  // C++17: we call A::operator B()
+  return B(x); // { dg-warning "choosing .A::operator B\\(\\). over .B::B\\(const A&\\)" "" { target c++17 } }
+  // { dg-warning "for conversion from .A. to .B." "" { target c++17 } .-1 }
+}