https://gcc.gnu.org/bugzilla/show_bug.cgi?id=118751
Bug ID: 118751
Summary: optional diagnostic not given on invalid bitfield
reference in uninstantiated template
Product: gcc
Version: 14.1.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: matoro_gcc_bugzilla at matoro dot tk
Target Milestone: ---
Sample comparison: https://godbolt.org/z/3zYfe35jM
gcc does not diagnose non-const bitfield references in uninstantiated
templates, while clang does.
#include <utility>
template <typename T>
struct s
{
int m : 5;
void swap()
{
std::swap(m, m);
}
};
clang:
<source>:9:19: error: non-const reference cannot bind to bit-field 'm'
9 | std::swap(m, m);
| ^
<source>:6:9: note: bit-field is declared here
6 | int m : 5;
| ^
/opt/compiler-explorer/gcc-14.2.0/lib/gcc/x86_64-linux-gnu/14.2.0/../../../../include/c++/14.2.0/bits/move.h:213:15:
note: passing argument to parameter '__a' here
213 | swap(_Tp& __a, _Tp& __b)
| ^
gcc does correctly diagnose if template is instantiated. This is technically
optional so it's not a correctness issue but gcc's lack of even a warning here
is giving the impression that clang is doing something wrong.
