On Fri, Jan 26, 2024 at 2:01 PM Franklin via Std-Proposals <
std-proposals_at_[hidden]> wrote:

> > This is not possible because stack allocation is done at runtime
> As is constant static and thread local initialization, done at program and
> threat start, respectively. constinit only specifies that the value they
> are initialized with is a compile time constant, which is also fine with
> automatic storage duration
>

My only concern with the idea is that it makes an "omitted `static`" typo
harder to catch.

int f(int i) {
  QUALIFIERS int a[] = {1,2,3,4,5,6,7,8,9,10};
  return a[i];
}

If -DQUALIFIERS= then both Clang and GCC generate inefficient code.
If -DQUALIFIERS=const then both Clang and GCC generate inefficient code.
If -DQUALIFIERS=constexpr then both Clang and GCC generate inefficient code.
If -DQUALIFIERS=constinit then both Clang and GCC reject with an error
diagnostic.
If -DQUALIFIERS=static then both Clang and GCC generate good code.
If -DQUALIFIERS=static const then both Clang and GCC generate good code.
If -DQUALIFIERS=static constexpr then both Clang and GCC generate good code.
If -DQUALIFIERS=static constinit then both Clang and GCC generate good code.

Now, it seems that the first three lines should all be considered
missed-optimization bugs in both Clang and GCC.
And the fourth line is *inconsistent* with the first three; that's
basically your argument, as I understand it, that inconsistency is bad (and
you're right).
But it's arguably convenient that line #4 is rejected, given that the
person writing line #3 certainly meant line #7 and the person writing #4
probably meant #8 (since if they didn't mean #8 then arguably they meant
#1). If you're not trying to avoid the Static Initialization Order Fiasco,
then you don't need `constinit`; so, any `constinit` variable that isn't
subject to static initialization probably indicates a bug.

I don't think my concern is terribly big; but it's the kind of thing that a
proposal should engage with and provide some reasonable argument that "the
ability to detect an omitted `static` here isn't something we ought to
value."

HTH,
Arthur