[Bug fortran/107721] Lost typespec with constant expressions using array constructors and parentheses

["jvdelisle at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107721

--- Comment #4 from Jerry DeLisle <jvdelisle at gcc dot gnu.org> ---
Well folks, I like to document my thought process.

From the 2022 draft standard we have:

  R781 ac-value is expr or ac-implied-do

  R782 ac-implied-do is ( ac-value-list , ac-implied-do-control )

In our code within array.cc we are clearly matching for R782.

However, we are not really trying to match expr of R781.

Our basic problem here is we have the following:

  print *, [integer :: ([1.0])] **  2

The ([1.0]) portion is clearly not an ac-implied-do, so what is it?

So is it an expr?

  R1023 expr is [ expr defined-binary-op ] level-5-expr

Looks to me that it is an expr.

  print *, ([1.0]) works quite well.

We have, therefore an expr.

In array.cc we have gfc_match_array_constructor.  As far as I can tell we are
matching the ac-implied-do, however we are not even trying to match expr.

Let's see what we can do about it.