https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91525
Bug ID: 91525
Summary: ICE (Segmentation Fault) on a bool conversion operator
with concepts
Product: gcc
Version: 8.3.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: gcc-bugs at marehr dot dialup.fu-berlin.de
Target Milestone: ---
The following code segfaults on gcc 7 and gcc 8.
It seems to be fixed in gcc 9, but a variant of the following code still
segfault on gcc 9 and 10.
```c++
#include <functional>
#include <iostream>
namespace ranges {
struct view_interface {
template < bool = true > operator bool();
#if 1
template < bool B = true> requires false operator bool(); // ICE on gcc <= 10
#elif 1
template < bool B = true> requires false explicit operator bool(); // ICE on
gcc <= 8. This code is working since gcc 9.
#else
template < bool B = true, std::enable_if_t<B>> explicit operator bool(); // a
possible workaround
#endif
};
template < typename View > struct impl {
template < typename... Ts, typename V = View >
static auto bind(Ts... ts) -> decltype(V::bind((ts)...));
};
template < typename > struct view;
template < typename Fun > view< Fun > make_view(Fun);
template < typename View > struct view {
template < typename Arg, typename Pipe >
friend auto operator|(Arg, Pipe)
-> decltype(Pipe::pipe(std::declval< Arg >, std::declval< Pipe >()));
View view_;
template < typename Rng, typename Vw > static auto pipe(Rng, Vw v) {
return v.view_(0);
}
template < typename... Ts, typename V = View >
auto operator()(Ts... ts)
-> decltype(make_view(impl< V >::bind(view_, (ts)...)));
};
struct f {
template < typename g > static auto bind(f h, g t) {
return std::bind(h, std::placeholders::_1, t);
}
template < typename a, typename ValRng >
auto operator()(a, ValRng) -> view_interface;
};
view< f > join;
} std::string e() {
std::vector< std::string > extensions;
std::string i;
auto o = extensions | ranges::join(i);
std::cout << o;
}
```
This will produce this error:
```terminal
> g++-9 -std=c++17 -fconcepts -c ice.cpp'
ice.cpp: In function ‘std::string e()’:
ice.cpp:53:16: internal compiler error: Segmentation fault
53 | std::cout << o;
| ^
Please submit a full bug report,
with preprocessed source if appropriate.
See <https://bugs.archlinux.org/> for instructions.
```
Tested compiler versions are:
```terminal
> g++-7 --version
g++-7 (GCC) 7.4.1 20181207
Copyright (C) 2017 Free Software Foundation, Inc.
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
> g++-8 --version
g++-8 (GCC) 8.3.0
Copyright (C) 2018 Free Software Foundation, Inc.
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
> g++-9 --version
g++ (GCC) 9.1.0
Copyright (C) 2019 Free Software Foundation, Inc.
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
> g++-git --version
g++-git (GCC) 10.0.0 20190709 (experimental)
Copyright (C) 2019 Free Software Foundation, Inc.
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
```
