https://gcc.gnu.org/bugzilla/show_bug.cgi?id=120151
Bug ID: 120151
Summary: ICE in GCC when compiling a templated decltype with
incomplete lambda body with -std=c++20
Product: gcc
Version: 16.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: mario.rodriguezb1 at um dot es
Target Milestone: ---
It is interesting the fact that this ICE arises from the same program as
#120149 but removing a line, resulting in a totally different stack dump
```
#include <iostream>
#include <vector>
#include <numeric>
using namespace std;
template<class A, class B>
auto f(A a, B b)
-> decltype(accumulate(begin(a), end(a), B{},
[](B t, A i) -> B
{
}))
{
}
int main()
{
vector<int> v;
int i;
f(v, i);
}
```
Stack dump
```
internal compiler error: error reporting routines re-entered.
0x228730d diagnostic_context::report_diagnostic(diagnostic_info*)
???:0
0x2287465 diagnostic_context::diagnostic_impl(rich_location*,
diagnostic_metadata const*, diagnostic_option_id, char const*, __va_list_tag
(*) [1], diagnostic_t)
???:0
0x229746e warning_at(rich_location*, diagnostic_option_id, char const*, ...)
???:0
0x884c40 finish_function(bool)
???:0
0x8bb3dc finish_lambda_function(tree_node*)
???:0
0x9b883b tsubst_lambda_expr(tree_node*, tree_node*, int, tree_node*)
???:0
0x9ab9bc tsubst(tree_node*, tree_node*, int, tree_node*)
???:0
0x22a4c53 pretty_printer::format(text_info&)
???:0
0x22a6ed3 pp_verbatim(pretty_printer*, char const*, ...)
???:0
0x2296158 diagnostic_text_output_format::on_report_diagnostic(diagnostic_info
const&, diagnostic_t)
???:0
0x2287092 diagnostic_context::report_diagnostic(diagnostic_info*)
???:0
0x2287465 diagnostic_context::diagnostic_impl(rich_location*,
diagnostic_metadata const*, diagnostic_option_id, char const*, __va_list_tag
(*) [1], diagnostic_t)
???:0
0x229746e warning_at(rich_location*, diagnostic_option_id, char const*, ...)
???:0
0x884c40 finish_function(bool)
???:0
0x99f62f instantiate_decl(tree_node*, bool, bool)
???:0
0x9c5b03 instantiate_pending_templates(int)
???:0
0x898b1a c_parse_final_cleanups()
???:0
0xa8b768 c_common_parse_file()
???:0
```
To quickly reproduce
https://gcc.godbolt.org/z/v5v37qhdo
