When removing the SAVE attribute ...


module mytypes
   implicit none
 contains
   pure integer function get_i ()
     get_i = 13
   end function
end module

program test
  use mytypes
  implicit none
  integer, dimension(get_i()) :: x
  print *, size (x)
end


... it compiles fine with all tested versions. However, this variant is a regression of the patch for PR 55207, see:

https://gcc.gnu.org/ml/fortran/2014-03/msg00108.html

However, as comment 0 shows, it is not a problem introduced with that patch, but it is rather a long-standing problem that is only uncovered by the patch (according to F08, variables in the main PROGRAM implicitly get the SAVE attribute).

(In reply to janus from comment #0)
> On trunk, the error looks like this:
> 
> internal compiler error: in gfc_trans_auto_array_allocation, at
> fortran/trans-array.c:5979

This line is an assert, and simply removing it makes the code in comment 0 compile and run without errors:


Index: gcc/fortran/trans-array.c
===================================================================
--- gcc/fortran/trans-array.c	(Revision 242535)
+++ gcc/fortran/trans-array.c	(Arbeitskopie)
@@ -5976,7 +5976,6 @@ gfc_trans_auto_array_allocation (tree decl, gfc_sy
   type = TREE_TYPE (type);
 
   gcc_assert (!sym->attr.use_assoc);
-  gcc_assert (!TREE_STATIC (decl));
   gcc_assert (!sym->module);
 
   if (sym->ts.type == BT_CHARACTER


It also regtests cleanly on current trunk. With this patch, the only difference in the dump of comment 0 and comment 1 is:


--- c0.f90.003t.original	2016-11-17 13:15:57.487735846 +0100
+++ c1.f90.003t.original	2016-11-17 13:13:07.096377920 +0100
@@ -12,7 +12,7 @@ test ()
   void * restrict D.3458;
   integer(kind=8) ubound.0;
   integer(kind=8) size.1;
-  static integer(kind=4)[0:D.3455] * restrict x;
+  integer(kind=4)[0:D.3455] * restrict x;
   integer(kind=8) D.3455;
   bitsizetype D.3456;
   sizetype D.3457;


As an alternative to removing the assert, one could possibly prevent SAVEd variables in the main PROGRAM from being declared as "static" (which might also cure the performance regressions that Dominique reported for my patch for PR 55207)?

(In reply to janus from comment #2)
> As an alternative to removing the assert, one could possibly prevent SAVEd
> variables in the main PROGRAM from being declared as "static" (which might
> also cure the performance regressions that Dominique reported for my patch
> for PR 55207)?

This could possibly be accomplished like this:

Index: gcc/fortran/trans-decl.c
===================================================================
--- gcc/fortran/trans-decl.c	(Revision 242584)
+++ gcc/fortran/trans-decl.c	(Arbeitskopie)
@@ -635,7 +635,8 @@ gfc_finish_var_decl (tree decl, gfc_symbol * sym)
      initialized variables are SAVE_IMPLICIT and explicitly saved are
      SAVE_EXPLICIT.  */
   if (!sym->attr.use_assoc
-	&& (sym->attr.save != SAVE_NONE || sym->attr.data
+	&& ((sym->attr.save != SAVE_NONE && !sym->ns->proc_name->attr.is_main_program)
+	    || sym->attr.data
 	    || (sym->value && sym->ns->proc_name->attr.is_main_program)
 	    || (flag_coarray == GFC_FCOARRAY_LIB
 		&& sym->attr.codimension && !sym->attr.allocatable)))

That indeed removes the ICE on comment 0, however it causes loads of testsuite regressions, so it's certainly not a very good idea.

Confirmed from 4.8 up to trunk (7.0).

> As an alternative to removing the assert, one could possibly prevent SAVEd
> variables in the main PROGRAM from being declared as "static" (which might
> also cure the performance regressions that Dominique reported for my patch
> for PR 55207)?

Related to pr42122?

(In reply to Dominique d'Humieres from comment #5)
> Related to pr42122?

Don't think so.

Likely a duplicate of pr42359.

(In reply to Dominique d'Humieres from comment #7)
> Likely a duplicate of pr42359.

Agreed.

*** Bug 42359 has been marked as a duplicate of this bug. ***

Working patch at https://gcc.gnu.org/ml/fortran/2016-11/msg00188.html.

As noted by Dominique, the problem here has originally been introduced by r126826.

Author: janus
Date: Mon Dec 12 18:54:54 2016
New Revision: 243580

URL: https://gcc.gnu.org/viewcvs?rev=243580&root=gcc&view=rev
Log:
2016-12-12  Janus Weil  <janus@gcc.gnu.org>

	PR fortran/78392
	* expr.c (gfc_is_constant_expr): Specification functions are not
	compile-time constants. Update documentation (add reference to F08
	standard), add a FIXME.
	(external_spec_function): Add reference to F08 standard.
	* resolve.c (resolve_fl_variable): Ditto.

2016-12-12  Janus Weil  <janus@gcc.gnu.org>

	PR fortran/78392
	* gfortran.dg/constant_shape.f90: New test case.

Added:
    trunk/gcc/testsuite/gfortran.dg/constant_shape.f90
Modified:
    trunk/gcc/fortran/ChangeLog
    trunk/gcc/fortran/expr.c
    trunk/gcc/fortran/resolve.c
    trunk/gcc/testsuite/ChangeLog

Fixed on 7-trunk with r243580. Closing.