[Bug c++/97773] gcc crash after some noexcept magic
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97773 --- Comment #15 from Jonathan Wakely --- (In reply to Martin Liška from comment #12) > Started to ICE with -std=c++17 since r6-3372-g378b307d0d7e789c. That's the commit that added C++17 fold expressions, but the ICE doesn't depend on fold expressions. Comment 13 doesn't use them.
[Bug c++/97773] gcc crash after some noexcept magic
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97773 Jonathan Wakely changed: What|Removed |Added Resolution|--- |DUPLICATE Status|NEW |RESOLVED --- Comment #14 from Jonathan Wakely --- dup *** This bug has been marked as a duplicate of bug 82099 ***
[Bug c++/97773] gcc crash after some noexcept magic
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97773
--- Comment #13 from Jonathan Wakely ---
I think it's just a dup of PR 82099.
Reduced further to only use C++14
template
struct hash
{
int operator()(T) const noexcept { return 0; }
};
template
int hash_combine(T v) noexcept(noexcept(hash()(v)))
{
return 0;
}
template
auto
apply(F& f, T t)
{
return f(t);
}
auto x = apply(hash_combine, 0);
[Bug c++/97773] gcc crash after some noexcept magic
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97773 --- Comment #12 from Martin Liška --- Started to ICE with -std=c++17 since r6-3372-g378b307d0d7e789c. Before that it was rejected: pr97773-2.C:30:40: error: expected primary-expression before ‘...’ token ((hash>()(v)), ...))) ^ pr97773-2.C:30:40: error: expected ‘)’ before ‘...’ token pr97773-2.C:78:1: error: expected ‘)’ at end of input } ^ pr97773-2.C:78:1: error: expected ‘)’ at end of input pr97773-2.C:78:1: error: expected initializer at end of input posix.c (backtrace_open): Cast second argument of open() to int. 2015-09-17 Ian Lance Taylor * posix.c (backtrace_open): Cast second argument of open() to int. From-SVN: r227881
[Bug c++/97773] gcc crash after some noexcept magic
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97773 Jonathan Wakely changed: What|Removed |Added See Also||https://gcc.gnu.org/bugzill ||a/show_bug.cgi?id=82099 --- Comment #11 from Jonathan Wakely --- ICE happens at the same place as for PR 82099
[Bug c++/97773] gcc crash after some noexcept magic
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97773
--- Comment #10 from Jonathan Wakely ---
Reduced:
using size_t = decltype(sizeof(0));
template struct remove_reference { using type = T; };
template struct remove_reference { using type = T; };
template struct remove_reference { using type = T; };
template using remove_reference_t = typename
remove_reference::type;
struct seconds
{
long count() const;
};
template
struct hash
{
};
template <>
struct hash
{
auto operator()(seconds const cp) const noexcept
{
return (size_t)cp.count();
}
};
template
size_t hash_combine(T&& ...v) noexcept(noexcept(
((hash>()(v)), ...)))
{
auto seed{672807365};
(
(
seed ^= hash>()(v) +
0x9e3779b9 + (seed << 6) + (seed >> 2)
),
...
);
return seed;
}
template
struct tuple_node
{
T t;
};
template
struct tuple : tuple_node...
{
};
template
auto
apply(F& f, tuple t)
{
f(static_cast&>(t).t...);
}
template
struct hash>
{
auto operator()(tuple& t) const
{
return apply(hash_combine, t);
}
};
int main()
{
using T = tuple;
hash h;
T t;
h(t);
}
[Bug c++/97773] gcc crash after some noexcept magic
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97773 --- Comment #9 from Jonathan Wakely --- (In reply to Jonathan Wakely from comment #7) > N.B. your program has undefined behaviour. Specializing std::hash for > standard library types is forbidden. GCC shouldn't crash though. Oh, you didn't! I misread it, sorry.
[Bug c++/97773] gcc crash after some noexcept magic
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97773 --- Comment #7 from Jonathan Wakely --- N.B. your program has undefined behaviour. Specializing std::hash for standard library types is forbidden. GCC shouldn't crash though.
[Bug c++/97773] gcc crash after some noexcept magic
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97773 --- Comment #8 from Jonathan Wakely --- (In reply to Janez Zemva from comment #6) > try -std=c++20 ? Which is why the instructions at https://gcc.gnu.org/bugs clearly say you need to provide the options used.
[Bug c++/97773] gcc crash after some noexcept magic
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97773 --- Comment #6 from Janez Zemva --- try -std=c++20 ?
[Bug c++/97773] gcc crash after some noexcept magic
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97773
Martin Liška changed:
What|Removed |Added
CC||marxin at gcc dot gnu.org
--- Comment #5 from Martin Liška ---
I have reduced (but invalid test-case) that ICEs:
$ cat r.C
template void apply(_Fn, _Tuple);
template void hash_combine() noexcept(noexcept((T(), ...)));
int operator0_t {
apply(hash_combine<>, operator0_t);
}
I guess we can fix it in order to make clang++ accept it:
$ clang++ r.C
r.C:2:70: warning: pack fold expression is a C++17 extension
[-Wc++17-extensions]
template void hash_combine() noexcept(noexcept((T(), ...)));
^
r.C:4:37: error: unexpected ';' before '}'
apply(hash_combine<>, operator0_t);
^
r.C:4:3: error: cannot initialize a variable of type 'int' with an rvalue of
type 'void'
apply(hash_combine<>, operator0_t);
^~
r.C:5:2: error: expected ';' after top level declarator
}
^
;
1 warning and 3 errors generated.
?
[Bug c++/97773] gcc crash after some noexcept magic
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97773 Jonathan Wakely changed: What|Removed |Added Keywords||ice-on-valid-code Status|WAITING |NEW --- Comment #4 from Jonathan Wakely --- Thanks. Confirmed.
[Bug c++/97773] gcc crash after some noexcept magic
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97773 --- Comment #3 from Janez Zemva --- Created attachment 49535 --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=49535=edit bug
[Bug c++/97773] gcc crash after some noexcept magic
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97773
--- Comment #2 from Janez Zemva ---
#include
#include
#include
#include
#include
#include
template
struct hash : std::hash
{
};
template <>
struct hash
{
auto operator()(std::chrono::seconds const cp) const noexcept
{
return std::hash()(cp.count());
}
};
template <>
struct hash>
{
auto operator()(std::chrono::time_point const tp)
const noexcept
{
return
std::hash::rep>()(tp.time_since_epoch().count());
}
};
template
std::size_t hash_combine(T&& ...v) noexcept(noexcept(
((hash>()(std::declval())), ...)))
{
auto seed{672807365};
(
(
seed ^= hash>()(std::forward(v)) +
0x9e3779b9 + (seed << 6) + (seed >> 2)
),
...
);
return seed;
}
template
struct hash>
{
auto operator()(std::tuple const& t) const
{
return std::apply(hash_combine, t);
}
};
int main()
{
std::unordered_map<
std::tuple, std::string_view>,
int,
hash, std::string_view>>
> lol;
return lol.size();
}
[Bug c++/97773] gcc crash after some noexcept magic
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97773 Jonathan Wakely changed: What|Removed |Added Last reconfirmed||2020-11-10 Ever confirmed|0 |1 Status|UNCONFIRMED |WAITING --- Comment #1 from Jonathan Wakely --- Please provide a complete testcase, not just a snippet that doesn't compile. See https://gcc.gnu.org/bugs/ And please report the second bug separately.
