https://gcc.gnu.org/bugzilla/show_bug.cgi?id=121597
Bug ID: 121597
Summary: ICE: Segmentation fault, involving nested generic
lambda and argument deduction
Product: gcc
Version: 14.2.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: sneeddeens at mail dot ru
Target Milestone: ---
gcc version 14.2.0 (GCC)
Target: x86_64-pc-linux-gnu
Configured with: ../configure
Code compiled with: -Wall -Wextra -Wpedantic -std=c++20
But it seems any version of GCC can't compile example.
MSVC able to compile, Clang don't (see in Godbolt:
https://godbolt.org/z/qeeovMz3o)
Code:
template<int, class> struct Tmpl {};
template<typename T> struct Wrap {};
// needs to be a function template to trigger error
template<typename = void>
void foo()
{
// making operator() to be template gives that ICE,
// but non-template operator() also gives wrong
// behavior from the compiler: 'Type' becomes void
using Type = decltype([]<typename = void>{
return Tmpl<0, char>{};
}());
// operator() needs to be a function template to trigger error
[]<typename = void>{
using X = decltype([]<auto N, class T>(Tmpl<N, T>&&)
{}.template operator()<0>(Type{}));
// this 'Wrap' also needed to trigger error
return Wrap<X>{};
}();
};
template void foo<>();
Error output:
temp.cpp: In instantiation of ‘foo<>()::<lambda()> [with
<template-parameter-1-1> = void]’:
temp.cpp:1157:4: required from ‘void foo() [with <template-parameter-1-1> =
void]’
1152 | []<typename = void>{
| ~~~~~~~~~~~~~~~~~~~~
1153 | using X = decltype([]<auto N, class T>(Tmpl<N, T>&&)
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
1154 | {}.template operator()<0>(Type{}));
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
1155 | // this 'Wrap' also needed to trigger error
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
1156 | return Wrap<X>{};
| ~~~~~~~~~~~~~~~~~
1157 | }();
| ~^~
temp.cpp:1160:21: required from here
1160 | template void foo<>();
| ^
temp.cpp:1147:25: internal compiler error: Segmentation fault
1147 | using Type = decltype([]<typename = void>{
| ^~~~~~~~~~~~~~~~~~~~
1148 | return Tmpl<0, char>{};
| ~~~~~~~~~~~~~~~~~~~~~~~
1149 | }());
| ~
0xf1d99f crash_signal
../../gcc/toplev.cc:319
0x903554 template_parms_to_args(tree_node*)
../../gcc/cp/pt.cc:4950
0x92da66 tsubst_template_decl
../../gcc/cp/pt.cc:15037
0x92f724 tsubst_lambda_expr(tree_node*, tree_node*, int, tree_node*)
../../gcc/cp/pt.cc:19832
0x919e1d tsubst_expr(tree_node*, tree_node*, int, tree_node*)
../../gcc/cp/pt.cc:21806
0x9176fb tsubst_expr(tree_node*, tree_node*, int, tree_node*)
../../gcc/cp/pt.cc:20847
0x91f06a tsubst(tree_node*, tree_node*, int, tree_node*)
../../gcc/cp/pt.cc:16970
0x917bf5 tsubst_expr(tree_node*, tree_node*, int, tree_node*)
../../gcc/cp/pt.cc:21325
0x91e264 tsubst_call_args
../../gcc/cp/pt.cc:19994
0x917747 tsubst_expr(tree_node*, tree_node*, int, tree_node*)
../../gcc/cp/pt.cc:20855
0x91f06a tsubst(tree_node*, tree_node*, int, tree_node*)
../../gcc/cp/pt.cc:16970
0x920788 tsubst_template_args(tree_node*, tree_node*, int, tree_node*)
../../gcc/cp/pt.cc:13964
0x92bcc9 tsubst_aggr_type_1
../../gcc/cp/pt.cc:14239
0x92bcc9 tsubst_aggr_type_1
../../gcc/cp/pt.cc:14220
0x917bf5 tsubst_expr(tree_node*, tree_node*, int, tree_node*)
../../gcc/cp/pt.cc:21325
0x92651f tsubst_stmt
../../gcc/cp/pt.cc:19529
0x927a9f tsubst_stmt
../../gcc/cp/pt.cc:18457
0x927a9f tsubst_stmt
../../gcc/cp/pt.cc:18481
0x927ad8 tsubst_stmt
../../gcc/cp/pt.cc:18457
0x927ad8 tsubst_stmt
../../gcc/cp/pt.cc:18471
Please submit a full bug report, with preprocessed source (by using
-freport-bug).
Please include the complete backtrace with any bug report.
See <https://gcc.gnu.org/bugs/> for instructions.
Here's bug report for Clang with similar problem, but without ICE, if
interested:
https://github.com/llvm/llvm-project/issues/154065
