Compilation error with "alignas"

[8ss-boop]

#include <stdint.h>
#include <stdarg.h>


void compute_values(int count, ...) {
    static _Atomic(int) shared_value = 0;
    va_list args;
    va_start(args, count);

    int temp[16] = {0};

    for (int i = 0; i < count && i < 16; i++) {
        int val = va_arg(args, int);
        temp[i] = (val > 0)
            ? ((val & 1) ? (temp[i ? i - 1 : 0] + val) : (shared_value += val))
            : ((alignas(16) int){ val * -1 });
    }
}

Compilation error:

<source>:16:17: error: expected expression
   16 |             : ((alignas(16) int){ val * -1 });
      |                 ^
1 error generated.
Compiler returned: 1

https://godbolt.org/z/478dvGehr

Is this a bug?

[zwuis]

Is this a bug?

No. alignas can be used in declaration only.

[frederick-vs-ja]

See also N3038. Only storage class specifiers can be there.

[AaronBallman]

Closing the issue as this is behaving by design.