[Bug fortran/47850] [4.6 Regression] ICE in gfc_conv_array_initializer

[burnus at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47850

--- Comment #5 from Tobias Burnus <burnus at gcc dot gnu.org> 2011-03-01 10:39:21 UTC ---
(In reply to comment #3)
> -std=f95 no longer generates the error that it should:
>    logical, parameter :: buf(3) = [(any(sc(i) ==nc), i = 1, 3)]
>                                     1
> Error: transformational intrinsic 'any' at (1) is not permitted in an
> initialization expression

Ignoring the issue of [ ] vs. (/ /) which kicks in first: gfortran 4.4
diagnoses this, 4.5/4.6 do not.

I think one reason that the error no longer is shown is the change with regards
to constant vs. initialization expression. Fortran 2003 merged the two concepts
to the name "initialization expressions" (which were renamed to "constant
expressions" in F2008) - but in Fortran 95 not every constant expression was an
initialization expression and some places mandated an initialization
expression. F95 had:

"7.1.6.1 Constant expression"
"A constant expression is an expression in which each operation is intrinsic
and each primary is [...] (5) A transformational intrinsic function reference
where each argument is a constant
expression,"

In the same section, "initialization expressions" are defined, which do not
allows the transformational function NULL - and no other one.

Thus, it might be that the missing diagnosis is a side effect of the
F2003/F2008 support. (I think one needs to revamp that area as there are
several bugs; unfortunately, it is a tedious task.)

 * * *

Regarding the simplification, I tried the following patch, but that fails due
to the above mentioned bug/mess with gfortran's implementation of init-expr vs.
const-expr.

In particular: The gfc_is_constant_expr(e) returns false as e->value.op.op1 is
EXPR_VARIABLE (of attr.flavor FL_PARAMETER) and that function simply returns
"0" if it encounters EXPR_VARIABLE.

I sincerely believe the we do not want to touch the const/init-expr mess when
the 4.6 release is imminent.

--- a/gcc/fortran/simplify.c
+++ b/gcc/fortran/simplify.c
@@ -231,9 +231,17 @@ is_constant_array_expr (gfc_expr *e)
   if (e == NULL)
     return true;

-  if (e->expr_type != EXPR_ARRAY || !gfc_is_constant_expr (e))
+  if (!gfc_is_constant_expr (e))
     return false;

+  if (e->expr_type != EXPR_ARRAY)
+    {
+      if (gfc_simplify_expr (e,1) != SUCCESS)
+       return false;
+      if (e->expr_type != EXPR_ARRAY)
+       return false;
+    }
+
   for (c = gfc_constructor_first (e->value.constructor);
        c; c = gfc_constructor_next (c))
     if (c->expr->expr_type != EXPR_CONSTANT