| Issue |
185070
|
| Summary |
[Clang] Confusing diagnostics on constexpr bit cast with casted pointer
|
| Labels |
clang
|
| Assignees |
|
| Reporter |
oToToT
|
From https://github.com/llvm/llvm-project/pull/184865, we see that
```cpp
#define fold(x) (__builtin_constant_p(x) ? (x) : (x))
constexpr long fn(void) {
return __builtin_bit_cast(long, fold((long)&fn));
}
static_assert(fn() == 1);
```
is showing this diagnostics
```
<source>:6:15: error: static assertion _expression_ is not an integral constant _expression_
6 | static_assert(fn() == 1);
| ^~~~~~~~~
<source>:4:10: note: constexpr bit cast involving type 'long' is not yet supported
4 | return __builtin_bit_cast(long, fold((long)&fn));
| ^
<source>:6:15: note: in call to 'fn()'
6 | static_assert(fn() == 1);
| ^~~~
1 error generated.
```
The message "constexpr bit cast involving type 'long' is not yet supported" is a bit confusing because `long` is actually supported and the real issue is that it's from a non-const value.
Compiler Explorer: https://godbolt.org/z/b85rxb5xe
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