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To: "fortran@gcc.gnu.org" <fortran@gcc.gnu.org>
From: Thomas Koenig <tkoenig@netcologne.de>
Subject: Strangeness for allocatable character arrays
Message-ID: <d78b9447-69ad-6e67-a253-f9d3e0987fc0@netcologne.de>
Date: Mon, 21 Dec 2020 09:38:40 +0100
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Hi,

here's a strangeness I noticed when chasing down one
bug in the shared memory code.

Consider

program main
   character (len=:), allocatable :: a(:)
   allocate (character(len=10) :: a(5))
end program main

This yields (in the tree dump)

   D.3941 = (bitsizetype) (sizetype) NON_LVALUE_EXPR <.a> * 8;
   D.3942 = (sizetype) NON_LVALUE_EXPR <.a>;
   a.data = 0B;
   {
     integer(kind=4) overflow.0;
     logical(kind=4) not_prev_allocated.1;

     .a = 10;

And later, if you use

size_in_bytes (gfc_get_element_type (TREE_TYPE(se->expr)))

you get an undefined variable.

I didn't pursue this any further, but it sure looks as
if this could be the cause of some bugs that we may or may
not have in bugzilla yet.

I've created https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98408
for this.