https://gcc.gnu.org/bugzilla/show_bug.cgi?id=119408
Bug ID: 119408
Summary: LoongArch: Q Suffix for __float128 Literals Not
Supported
Product: gcc
Version: 14.2.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
Assignee: unassigned at gcc dot gnu.org
Reporter: wszqkzqk at qq dot com
Target Milestone: ---
The GCC manual explicitly states that __float128 literals require the Q suffix.
According to [GCC Manual: Floating
Types](https://gcc.gnu.org/onlinedocs/gcc/Floating-Types.html?spm=a2ty_o01.29997173.0.0.7c72c921e8gZ5X):
> Use a suffix ‘q’ or ‘Q’ for __float128.
> __float128 is available on [...] LoongArch [...] as an alias for _Float128.
This means platforms including LoongArch that support `__float128` should
support `Q` suffix in 128-bit float point literals. However, LoongArch's GCC
implementation contradicts this:
* The Q suffix (e.g., `1.0Q`) fails with `error: unsupported non-standard
suffix on floating constant`,
* While the GNU-extension f128 suffix (e.g., `1.0f128`) works for `_Float128`.
This inconsistency breaks code using `__float128` literals. (I found it by
build sleef on LoongArch64 platform).
Tested on Arch Linux for Loong64 with:
* gcc 14.2.1
* demo:
```c
#include <float.h>
int main() {
__float128 a = 1.11111111Q;
}
```
