From: Marek Polacek <polacek@redhat.com>
To: Jason Merrill <jason@redhat.com>
Cc: Tim Song <t.canens.cpp@gmail.com>, GCC Patches <gcc-patches@gcc.gnu.org>
Subject: Re: C++ PATCH for c++/89024 - ICE with incomplete enum type
Date: Sat, 26 Jan 2019 01:25:00 -0000 [thread overview]
Message-ID: <20190125232227.GQ26714@redhat.com> (raw)
In-Reply-To: <8fb80442-9bbc-38fa-5b87-3aa940284fad@redhat.com>
On Fri, Jan 25, 2019 at 12:14:07PM -0500, Jason Merrill wrote:
> On 1/25/19 12:09 PM, Marek Polacek wrote:
> > On Fri, Jan 25, 2019 at 10:55:55AM -0600, Tim Song wrote:
> > > On Thu, Jan 24, 2019 at 4:14 PM Jason Merrill <jason@redhat.com> wrote:
> > > >
> > > > On 1/24/19 2:16 PM, Marek Polacek wrote:
> > > > > This test ICEs since r159006 which added
> > > > >
> > > > > type = ENUM_UNDERLYING_TYPE (type);
> > > > >
> > > > > to type_promotes_to. In this test ENUM_UNDERLYING_TYPE is null because we
> > > > > haven't yet parsed '}' of the enum and the underlying type isn't fixed, and
> > > > > so checking TYPE_UNSIGNED crashed.
> > > > >
> > > > > I've added some checks to the test to see if the types seem to be OK; clang++
> > > > > agrees.
> > > > >
> > > > > Bootstrapped/regtested on x86_64-linux, ok for trunk/8/7?
> > > > >
> > > > > 2019-01-24 Marek Polacek <polacek@redhat.com>
> > > > >
> > > > > PR c++/89024 - ICE with incomplete enum type.
> > > > > * cvt.c (type_promotes_to): Check if prom is non-null.
> > > >
> > > > 9.6/6: An enumeration whose underlying type is not fixed is an
> > > > incomplete type from its point of declaration to immediately after the
> > > > closing } of its enum-specifier, at which point it becomes a complete type.
> > > >
> > > > So the conversion is ill-formed.
> > > >
> > > > Jason
> > >
> > > But the conversion in the example (in
> > > decltype(__test_aux<_To1>(declval<_From1>())))
> > > is in a SFINAE context, so shouldn't it gracefully fall back to the
> > > `(...)` overload?
> >
> > I think so, and clang++ and icc also compile the testcase fine (and we used to
> > too, before r159006).
>
> Absolutely, the conversion being ill-formed means substitution fails, and we
> reject that candidate. I meant that we shouldn't get as far as
> type_promotes_to for an incomplete type.
Makes sense. So here's another attempt:
Bootstrapped/regtested on x86_64-linux, ok for trunk?
2019-01-25 Marek Polacek <polacek@redhat.com>
PR c++/89024 - ICE with incomplete enum type.
* call.c (standard_conversion): When converting an
ARITHMETIC_TYPE_P to an incomplete type, return NULL.
* g++.dg/cpp0x/enum37.C: New test.
diff --git gcc/cp/call.c gcc/cp/call.c
index 515a9420032..c74d1b4ebdf 100644
--- gcc/cp/call.c
+++ gcc/cp/call.c
@@ -1412,6 +1412,13 @@ standard_conversion (tree to, tree from, tree expr, bool c_cast_p,
|| (fcode == REAL_TYPE && !(flags & LOOKUP_NO_NON_INTEGRAL)))
|| SCOPED_ENUM_P (from))
return NULL;
+
+ /* If we're parsing an enum with no fixed underlying type, we're
+ dealing with an incomplete type, which renders the conversion
+ ill-formed. */
+ if (!COMPLETE_TYPE_P (from))
+ return NULL;
+
conv = build_conv (ck_std, to, conv);
/* Give this a better rank if it's a promotion. */
diff --git gcc/testsuite/g++.dg/cpp0x/enum37.C gcc/testsuite/g++.dg/cpp0x/enum37.C
new file mode 100644
index 00000000000..6aa3d4015d7
--- /dev/null
+++ gcc/testsuite/g++.dg/cpp0x/enum37.C
@@ -0,0 +1,24 @@
+// PR c++/89024
+// { dg-do compile { target c++11 } }
+
+template <class T, class U> struct same;
+template <class T> struct same<T,T> {};
+
+template<class T> T&& declval();
+
+template<typename _To1>
+void __test_aux(_To1);
+
+template<typename _From1, typename _To1,
+ typename = decltype(__test_aux<_To1>(declval<_From1>()))>
+char __test(int);
+
+template<typename, typename>
+int __test(...);
+
+enum E {
+ x = decltype(__test<E, int>(0))(0)
+};
+
+same<E,decltype(x)> s;
+same<unsigned int,__underlying_type(E)> s2;
next prev parent reply other threads:[~2019-01-25 23:22 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-01-24 19:19 Marek Polacek
2019-01-24 22:17 ` Jason Merrill
2019-01-25 17:00 ` Tim Song
2019-01-25 17:13 ` Marek Polacek
2019-01-25 17:16 ` Jason Merrill
2019-01-26 1:25 ` Marek Polacek [this message]
2019-01-27 4:22 ` Jason Merrill
2019-01-28 9:48 ` Christophe Lyon
2019-01-28 16:37 ` Marek Polacek
2019-01-28 17:01 ` Jason Merrill
2019-01-28 18:11 ` Marek Polacek
2019-01-28 21:52 ` Jason Merrill
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