From patchwork Tue Dec 18 19:45:49 2012
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Subject: [Fortran,
 (RFC)] PR49110/51055 Assignment to alloc. deferred-length character
 vars
From: Tobias Burnus <burnus@net-b.de>
X-Patchwork-Id: 207189
Message-Id: <50D0C7ED.7020809@net-b.de>
To: Jakub Jelinek <jakub@redhat.com>
Cc: Janus Weil <janus@gcc.gnu.org>, David Edelsohn <dje.gcc@gmail.com>,
 Fortran List <fortran@gcc.gnu.org>,
 Paul Richard Thomas <paul.richard.thomas@gmail.com>,
 GCC Patches <gcc-patches@gcc.gnu.org>
Date: Tue, 18 Dec 2012 20:45:49 +0100

Jakub Jelinek wrote:
> On Tue, Dec 18, 2012 at 04:40:10PM +0100, Tobias Burnus wrote:
>> Looks mostly okay, however, I fear that for
>>
>> subroutine foo()
>> character(len=:), allocatable :: str
>> allocate(str, stat=istat)
>> end subroutine foo
>>
>> compiled with "-fno-automatic", gfortran will still generate the
>> non-GFC_PREFIX-mangled string.
> That doesn't compile:
> Error: Allocate-object at (1) with a deferred type parameter requires either a type-spec or SOURCE tag or a MOLD tag

Sorry for the bad example. I added the allocate just to mark the 
variable as used (otherwise no decl is generated); but my cut-down 
example was wrong. Try:

subroutine foo()
   character(len=:), allocatable :: str
   print *, allocated(str)
end subroutine foo


Or one of the examples from PR55733. The example above gives currently 
(w/o your patch):

   static character(kind=1)[1:.str] * str = 0B;
   integer(kind=4) .str;


> Where would be TREE_STATIC set on the length variable with -fno-automatic,
> and on which testcase?

As written, TREE_STATIC is currently not set (which is a bug, cf. 
PR55733); I think one needs a patch like:



Tobias


--- a/gcc/fortran/trans-decl.c
+++ b/gcc/fortran/trans-decl.c
@@ -1107,3 +1107,4 @@ gfc_create_string_length (gfc_symbol * sym)

-      if (sym->attr.save || sym->ns->proc_name->attr.flavor == FL_MODULE)
+      if (sym->attr.save || sym->ns->proc_name->attr.flavor == FL_MODULE
+         || gfc_option.flag_max_stack_var_size == 0)
         TREE_STATIC (length) = 1;