[Bug fortran/65585] Implicit allocation of unallocated array with an implicit summation

[dominiq at lps dot ens.fr]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65585

Dominique d'Humieres <dominiq at lps dot ens.fr> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |RESOLVED
         Resolution|---                         |INVALID

--- Comment #1 from Dominique d'Humieres <dominiq at lps dot ens.fr> ---
gfortran is behaving as expected: iamwild is allocated on assignment as stated
in the manual

-frealloc-lhs
An allocatable left-hand side of an intrinsic assignment is automatically
(re)allocated if it is either unallocated or has a different shape. The option
is enabled by default except when -std=f95 is given. See also -Wrealloc-lhs. 

Note this apply to full arrays only, hence the segfault if you use iamwild(:)
and iamwild unallocated.

> PS: took me the day to understand why my code was not working with another
> compiler... :-/

If the "other compiler" is ifort, this behavior is not the default and has to
be set by some option.