https://gcc.gnu.org/bugzilla/show_bug.cgi?id=124203
Bug ID: 124203
Summary: ICE when using non-captured variable in lambda in
concept `requires` clause
Product: gcc
Version: 15.2.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: 4ernov at gmail dot com
Target Milestone: ---
Created attachment 63758
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=63758&action=edit
Auto-prepared report.
I've caught ICE when compiling these code (simplified example):
#include <tuple>
using namespace std;
namespace
{
template<typename T> void woo(const T v) {}
template<class T, class U> concept check = requires (T v, U u)
{
std::apply
(
[](auto... args) // adding `v` to capture fixes
{
woo(v);
},
u
);
};
}
int main(int, char**)
{
static_assert(check<int, std::tuple<double, float>>, "check failed");
return 0;
}
The output is:
./main.cpp: In instantiation of '{anonymous}::<lambda(auto:3 ...)> [with auto:3
= {double, float}]':
/usr/lib/gcc/x86_64-pc-linux-gnu/15/include/g++-v15/type_traits:3333:30:
required from 'struct std::is_nothrow_invocable<{anonymous}::<lambda(auto:3
...)>, double&, float&>'
3333 | : public __bool_constant<__is_nothrow_invocable(_Fn, _ArgTypes...)>
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/lib/gcc/x86_64-pc-linux-gnu/15/include/g++-v15/tuple:2904:31: required
from 'constexpr const bool std::__unpack_std_tuple<template<class _Fn, class
... _ArgTypes> struct std::is_nothrow_invocable, {anonymous}::<lambda(auto:3
...)>, std::tuple<double, float>&>'
2904 | = _Trait<_Tp, _Up&...>::value;
| ^~~~~
/usr/lib/gcc/x86_64-pc-linux-gnu/15/include/g++-v15/tuple:2931:14: required
from 'constexpr decltype(auto) std::apply(_Fn&&, _Tuple&&) [with _Fn =
{anonymous}::<lambda(auto:3 ...)>; _Tuple = tuple<double, float>&]'
2931 | noexcept(__unpack_std_tuple<is_nothrow_invocable, _Fn, _Tuple>)
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
./main.cpp:12:3: required from here
11 | std::apply
| ~~~~~~~~~~
12 | (
| ^
13 | [](auto... args)
| ~~~~~~~~~~~~~~~~
14 | {
| ~
15 | woo(v);
| ~~~~~~~
16 | },
| ~~
17 | u
| ~
18 | );
| ~
./main.cpp:15:37: internal compiler error: in tsubst_expr, at cp/pt.cc:22039
15 | woo(v);
| ^
0x55b223fa4ccc diagnostic_context::diagnostic_impl(rich_location*,
diagnostic_metadata const*, diagnostic_option_id, char const*, __va_list_tag
(*) [1], diagnostic_t)
???:0
0x55b223f71a08 internal_error(char const*, ...)
???:0
0x55b223f71aff fancy_abort(char const*, int, char const*)
???:0
0x55b22433b2b1 tsubst_expr(tree_node*, tree_node*, int, tree_node*)
???:0
0x55b22433b696 tsubst_expr(tree_node*, tree_node*, int, tree_node*)
???:0
0x55b22443f0a0 instantiate_decl(tree_node*, bool, bool)
???:0
0x55b22443debb maybe_instantiate_decl(tree_node*)
???:0
0x55b22418a2df mark_used(tree_node*, int)
???:0
0x55b2248007d5 build_op_call(tree_node*, vec<tree_node*, va_gc, vl_embed>**,
int)
???:0
0x55b2241b65aa finish_call_expr(tree_node*, vec<tree_node*, va_gc, vl_embed>**,
bool, bool, int)
???:0
0x55b22352f4ca build_invoke(tree_node*, tree_node const*, int)
???:0
0x55b2243e31f1 finish_trait_expr(unsigned long, cp_trait_kind, tree_node*,
tree_node*)
???:0
0x55b22433c37f tsubst_expr(tree_node*, tree_node*, int, tree_node*)
???:0
0x55b224373441 tsubst_template_args(tree_node*, tree_node*, int, tree_node*)
???:0
0x55b224296c6b tsubst(tree_node*, tree_node*, int, tree_node*)
???:0
0x55b2242971f3 tsubst(tree_node*, tree_node*, int, tree_node*)
???:0
0x55b2243c5e3b instantiate_class_template(tree_node*)
???:0
0x55b223feaabd complete_type(tree_node*)
???:0
0x55b2240fa82b lookup_member(tree_node*, tree_node*, int, bool, int,
access_failure_info*)
???:0
0x55b2240c73eb lookup_qualified_name(tree_node*, tree_node*, LOOK_want, bool)
???:0
Please submit a full bug report, with preprocessed source.
Please include the complete backtrace with any bug report.
See <https://bugs.gentoo.org/> for instructions.
After fixing the error in the code (adding `v` to lambda capture) it compiles
just fine.
Have tried my best to search for prior reports on this, sorry if it's still a
duplicate.
