`-Wextra` demotes `-Winitializer-overrides` from error to warning even when `-pedantic-errors` is present

[HolyBlackCat]

struct A
{
    int a;
};

A a{
    .a = 10,
    .a = 20,
};

This correctly errors with -std=c++20 -pedantic-errors:

<source>:8:10: error: initializer overrides prior initialization of this subobject [-Werror,-Winitializer-overrides]
    8 |     .a = 20,
      |          ^~
<source>:7:10: note: previous initialization is here
    7 |     .a = 10,
      |          ^~

But if I use -std=c++20 -pedantic-errors -Wextra, this instead becomes a warning:

<source>:8:10: warning: initializer overrides prior initialization of this subobject [-Winitializer-overrides]
    8 |     .a = 20,
      |          ^~
<source>:7:10: note: previous initialization is here
    7 |     .a = 10,
      |          ^~

I get the same warning if I use just -std=c++20.

The correct behavior is for this to be an error if -pedantic-errors is present, regardless of -Wextra.

[AaronBallman]

It doesn't seem to be a last-flag-wins situation either, because -pedantic-errors -Wextra behaves the same way as -Wextra -pedantic-errors.

https://godbolt.org/z/nvrqfqMns