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 <ja...@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 <pola...@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 <pola...@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;