[Bug c++/102740] [10/11/12 Regression] Data member not found in struct inside an unnamed union

[curdeius at gmail dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102740

--- Comment #3 from Curdeius Curdeius <curdeius at gmail dot com> ---
For other users with this problem, a workaround is to use a named struct. So
here, it would look like:
```
typedef struct {
    const void* content;
} put_t;

typedef struct {
    union {
        put_t put; // named struct
    };
} op_t;

op_t f(const char* alias) {
    return op_t{
        .put =
            put_t{ // named explicitly
                .content = alias,
            },
    };
}
```