https://gcc.gnu.org/bugzilla/show_bug.cgi?id=120041
Bug ID: 120041
Summary: ICE: unexpected expression of kind template_parm_index
Product: gcc
Version: 15.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: eczbek.void at gmail dot com
Target Milestone: ---
https://godbolt.org/z/jKTsW9bn8
```
template<int... i>
void f() {
(..., []() requires(!i) { i; });
}
int main() {
f<0>();
}
```
```
Using built-in specs.
COLLECT_GCC=/opt/compiler-explorer/gcc-snapshot/bin/g++
Target: x86_64-linux-gnu
Configured with: ../gcc-trunk-20250430/configure
--prefix=/opt/compiler-explorer/gcc-build/staging
--enable-libstdcxx-backtrace=yes --build=x86_64-linux-gnu
--host=x86_64-linux-gnu --target=x86_64-linux-gnu --disable-bootstrap
--enable-multiarch --with-abi=m64 --with-multilib-list=m32,m64,mx32
--enable-multilib --enable-clocale=gnu
--enable-languages=c,c++,fortran,ada,objc,obj-c++,go,d,rust,m2,cobol
--enable-ld=yes --enable-gold=yes --enable-libstdcxx-debug
--enable-libstdcxx-time=yes --enable-linker-build-id --enable-lto
--enable-plugins --enable-threads=posix
--with-pkgversion=Compiler-Explorer-Build-gcc-55b01e17c793688a2878fa43a76df1266153b438-binutils-2.42
Thread model: posix
Supported LTO compression algorithms: zlib
gcc version 16.0.0 20250430 (experimental)
(Compiler-Explorer-Build-gcc-55b01e17c793688a2878fa43a76df1266153b438-binutils-2.42)
COLLECT_GCC_OPTIONS='-fdiagnostics-color=always' '-g' '-o' '/app/output.s'
'-masm=intel' '-fno-verbose-asm' '-S' '-std=c++20' '-v' '-freport-bug'
'-isystem' '/opt/compiler-explorer/libs/xieite/main/include' '-shared-libgcc'
'-mtune=generic' '-march=x86-64' '-dumpdir' '/app/'
/opt/compiler-explorer/gcc-trunk-20250430/bin/../libexec/gcc/x86_64-linux-gnu/16.0.0/cc1plus
-quiet -v -imultiarch x86_64-linux-gnu -iprefix
/opt/compiler-explorer/gcc-trunk-20250430/bin/../lib/gcc/x86_64-linux-gnu/16.0.0/
-D_GNU_SOURCE -isystem /opt/compiler-explorer/libs/xieite/main/include <source>
-quiet -dumpdir /app/ -dumpbase output.cpp -dumpbase-ext .cpp -masm=intel
-mtune=generic -march=x86-64 -g -std=c++20 -version -fdiagnostics-color=always
-fno-verbose-asm -freport-bug -o /app/output.s
GNU C++20
(Compiler-Explorer-Build-gcc-55b01e17c793688a2878fa43a76df1266153b438-binutils-2.42)
version 16.0.0 20250430 (experimental) (x86_64-linux-gnu)
compiled by GNU C version 11.4.0, GMP version 6.2.1, MPFR version
4.1.0, MPC version 1.2.1, isl version isl-0.24-GMP
GGC heuristics: --param ggc-min-expand=30 --param ggc-min-heapsize=4096
ignoring nonexistent directory
"/opt/compiler-explorer/gcc-trunk-20250430/bin/../lib/gcc/x86_64-linux-gnu/16.0.0/../../../../x86_64-linux-gnu/include"
ignoring duplicate directory
"/opt/compiler-explorer/gcc-trunk-20250430/bin/../lib/gcc/../../lib/gcc/x86_64-linux-gnu/16.0.0/../../../../include/c++/16.0.0"
ignoring duplicate directory
"/opt/compiler-explorer/gcc-trunk-20250430/bin/../lib/gcc/../../lib/gcc/x86_64-linux-gnu/16.0.0/../../../../include/c++/16.0.0/x86_64-linux-gnu"
ignoring duplicate directory
"/opt/compiler-explorer/gcc-trunk-20250430/bin/../lib/gcc/../../lib/gcc/x86_64-linux-gnu/16.0.0/../../../../include/c++/16.0.0/backward"
ignoring duplicate directory
"/opt/compiler-explorer/gcc-trunk-20250430/bin/../lib/gcc/../../lib/gcc/x86_64-linux-gnu/16.0.0/include"
ignoring nonexistent directory "/usr/local/include/x86_64-linux-gnu"
ignoring duplicate directory
"/opt/compiler-explorer/gcc-trunk-20250430/bin/../lib/gcc/../../lib/gcc/x86_64-linux-gnu/16.0.0/include-fixed/x86_64-linux-gnu"
ignoring duplicate directory
"/opt/compiler-explorer/gcc-trunk-20250430/bin/../lib/gcc/../../lib/gcc/x86_64-linux-gnu/16.0.0/include-fixed"
ignoring nonexistent directory
"/opt/compiler-explorer/gcc-trunk-20250430/bin/../lib/gcc/../../lib/gcc/x86_64-linux-gnu/16.0.0/../../../../x86_64-linux-gnu/include"
#include "..." search starts here:
#include <...> search starts here:
/opt/compiler-explorer/libs/xieite/main/include
/opt/compiler-explorer/gcc-trunk-20250430/bin/../lib/gcc/x86_64-linux-gnu/16.0.0/../../../../include/c++/16.0.0
/opt/compiler-explorer/gcc-trunk-20250430/bin/../lib/gcc/x86_64-linux-gnu/16.0.0/../../../../include/c++/16.0.0/x86_64-linux-gnu
/opt/compiler-explorer/gcc-trunk-20250430/bin/../lib/gcc/x86_64-linux-gnu/16.0.0/../../../../include/c++/16.0.0/backward
/opt/compiler-explorer/gcc-trunk-20250430/bin/../lib/gcc/x86_64-linux-gnu/16.0.0/include
/opt/compiler-explorer/gcc-trunk-20250430/bin/../lib/gcc/x86_64-linux-gnu/16.0.0/include-fixed/x86_64-linux-gnu
/opt/compiler-explorer/gcc-trunk-20250430/bin/../lib/gcc/x86_64-linux-gnu/16.0.0/include-fixed
/usr/local/include
/opt/compiler-explorer/gcc-trunk-20250430/bin/../lib/gcc/../../include
/usr/include/x86_64-linux-gnu
/usr/include
End of search list.
Compiler executable checksum: 05da47424619e92bd68fc5a89e040a26
<source>: In instantiation of 'f<0>()::<lambda()>':
<source>:3:8: required from 'void f() [with int ...i = {0}]'
3 | (..., []() requires(!i) { i; });
| ^~~~~~~~~~~~~~~~~~~~~~~~
<source>:7:6: required from here
7 | f<0>();
| ~~~~^~
<source>:3:29: internal compiler error: unexpected expression 'i' of kind
template_parm_index
3 | (..., []() requires(!i) { i; });
| ~^~~
0x293a135 diagnostic_context::diagnostic_impl(rich_location*,
diagnostic_metadata const*, diagnostic_option_id, char const*, __va_list_tag
(*) [1], diagnostic_t)
???:0
0x29511e6 internal_error(char const*, ...)
???:0
0xb536f0 maybe_constant_value(tree_node*, tree_node*, mce_value)
???:0
0xb60d28 constraints_satisfied_p(tree_node*, tree_node*)
???:0
0xc119e9 maybe_add_lambda_conv_op(tree_node*)
???:0
0xd4da6c tsubst_lambda_expr(tree_node*, tree_node*, int, tree_node*)
???:0
0xd43e45 tsubst_pack_expansion(tree_node*, tree_node*, int, tree_node*)
???:0
0xd254ad instantiate_decl(tree_node*, bool, bool)
???:0
0xd5fa22 instantiate_pending_templates(int)
???:0
0xbe48f9 c_parse_final_cleanups()
???:0
0xe5d458 c_common_parse_file()
???:0
Please submit a full bug report, with preprocessed source.
Please include the complete backtrace with any bug report.
See <https://gcc.gnu.org/bugs/> for instructions.
Preprocessed source stored into /tmp/ccf7KUS3.out file, please attach this to
your bugreport.
Compiler returned: 1
```
