https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96990
Bug ID: 96990
Summary: Regression in aarch64 struct vector member
initialization
Product: gcc
Version: 10.2.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
Assignee: unassigned at gcc dot gnu.org
Reporter: yyc1992 at gmail dot com
Target Milestone: ---
The following code used to work on gcc 9.3 but stops working with 10.2 with an
error
```
a.c: In function ‘test_aa64_vec_2’:
a.c:19:24: error: incompatible types when initializing type ‘signed char’ using
type ‘int8x8_t’
19 | struct_aa64_3 x = {v1 + v1, v2 - v2};
| ^~
a.c:19:33: error: incompatible types when initializing type ‘signed char’ using
type ‘float32x2_t’
19 | struct_aa64_3 x = {v1 + v1, v2 - v2};
| ^~
```
Any one of the "working" version or compiling with c++ works.
>From the error message it seems that GCC correctly inferred the return type of
the `v1 + v1` or `v2 - v2` but instead got confused about the field type.
Reverssing the order of `v1` and `v2` in the struct causes the error to change
to `float` instead of `signed char` so it seems that gcc thinks the code is
trying to initialize the first vector member (with element type of `signed
char` or `float` instead). I thought such initialization should have an
additional `{}` instead... Given that explicit casting or compiling in c++ mode
helps I think this is a bug...
```
#include <arm_neon.h>
typedef struct {
int8x8_t v1;
float32x2_t v2;
} struct_aa64_3;
struct_aa64_3 test_aa64_vec_2(int8x8_t v1, float32x2_t v2)
{
// works
/* int8x8_t vi8 = v1 + v1; */
/* float32x2_t vf = v2 - v2; */
/* struct_aa64_3 x = {vi8, vf}; */
// works
/* struct_aa64_3 x = {(int8x8_t)(v1 + v1), (float32x2_t)(v2 - v2)}; */
// not
struct_aa64_3 x = {v1 + v1, v2 - v2};
return x;
}
```
