https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107151
Bug ID: 107151
Summary: Specializing a concepted template can emit bogus
assembly
Product: gcc
Version: 13.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: blubban at gmail dot com
Target Milestone: ---
#include <cstdio>
#include <concepts>
template <typename T>
void fun(T);
template <>
void fun(char c)
{
std::puts("foo<char>()");
}
template <std::integral I>
void fun(I i)
{
std::puts("foo<std::integral>()");
}
int main()
{
fun<char>(' ');
}
Compile with -std=c++20.
Result:
/tmp/cctfBAWi.s: Assembler messages:
/tmp/cctfBAWi.s:63: Error: symbol `_Z3funIcEvT_' is already defined
/tmp/cctfBAWi.s: Error: .size expression for _Z3funIcEvT_ does not evaluate to
a constant
Expected: Prints foo<char>(), or at least a less cryptic error. With -O2, GCC
only emits one _Z3funIcEvT_, but the resulting program prints
foo<std::integral>().
https://godbolt.org/z/axvdbK1Eh
Clang and MSVC have similar bugs:
https://github.com/llvm/llvm-project/issues/58142
https://developercommunity.visualstudio.com/t/Template-explicit-specializationconcept/10012835
