https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101430
Bug ID: 101430
Summary: Passing a lambda as a template argument causes
internal compiler error
Product: gcc
Version: 11.1.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: jorg.brown at gmail dot com
Target Milestone: ---
This code causes gcc 11.1.0 to ICE:
////////////////////
extern "C" {
int printf(const char *, ...);
}
void g(int n) { printf("%d\n", n); }
template<auto Lambda = []{ g(1);} > void f(decltype(Lambda) x = {}) {
x();
}
int main() {
constexpr auto a = []{ g(3); };
// f<a>();
f<[]{g(2);}>();
f();
}
////////////////////
Output when compiled:
x86-64 gcc 11.1 (Editor #1, Compiler #1) C++
x86-64 gcc 11.1
-std=c++20
123
<Compilation failed>
# For more information see the output window
x86-64 gcc 11.1 - cached
Output of x86-64 gcc 11.1 (Compiler #1)
<source>: In substitution of 'template<auto Lambda> void f(decltype (Lambda))
[with auto Lambda = <missing>]':
<source>:17:6: required from here
<source>:7:33: internal compiler error: in convert_nontype_argument, at
cp/pt.c:7652
7 | template<auto Lambda = []{ g(1);} > void f(decltype(Lambda) x = {}) {
| ^
0x1780bf9 internal_error(char const*, ...)
???:0
0x677e40 fancy_abort(char const*, int, char const*)
???:0
0x7f3b4b fn_type_unification(tree_node*, tree_node*, tree_node*, tree_node*
const*, unsigned int, tree_node*, unification_kind_t, int, conversion**, bool,
bool)
???:0
0x68eda2 build_new_function_call(tree_node*, vec<tree_node*, va_gc,
vl_embed>**, int)
???:0
0x8070f0 finish_call_expr(tree_node*, vec<tree_node*, va_gc, vl_embed>**, bool,
bool, int)
???:0
0x7c0cab c_parse_file()
???:0
0x892aa2 c_common_parse_file()
???:0
////////////////////
Compiler Explorer link: https://godbolt.org/z/Evcd7oaz5
////////////////////
Interestingly, if I comment out the definition of `a`, it compiles and runs
properly.
And if I comment out either of the last two calls to f(), it compiles and runs
properly. Whether or not f<a>(); is commented out.
