[Bug fortran/50163] [4.3/4.4/4.5/4.6/4.7 Regression] ICE: initialization expression

["burnus at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50163

Tobias Burnus <burnus at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |ice-on-invalid-code
                 CC|                            |burnus at gcc dot gnu.org
      Known to work|                            |4.1.2
   Target Milestone|---                         |4.6.2
            Summary|Internal compiler error:    |[4.3/4.4/4.5/4.6/4.7
                   |initialization expression   |Regression] ICE:
                   |                            |initialization expression
      Known to fail|                            |4.3.4, 4.5.3, 4.6.1, 4.7.0

--- Comment #2 from Tobias Burnus <burnus at gcc dot gnu.org> 2011-08-23 10:37:38 UTC ---
That's actually a regression: With 4.1.2 I get:

  integer :: iloc=index(xx,'bb')
                       1
  Error: Parameter 'xx' at (1) has not been declared or is a variable,
  which does not reduce to a constant expression

While with GCC 4.3.4 and later, I get an ICE. I have not tested 4.2.

 * * *

The problem seems to be the delayed error output. In expr.c's check_init_expr,
one has:

        if ((m = check_conversion (e)) == MATCH_NO
            && (m = check_inquiry (e, 1)) == MATCH_NO
            && (m = check_null (e)) == MATCH_NO
            && (m = check_transformational (e)) == MATCH_NO
            && (m = check_elemental (e)) == MATCH_NO)
          {
            gfc_error ("Intrinsic function '%s' at %L is not permitted "
                       "in an initialization expression",
                       e->symtree->n.sym->name, &e->where);
            m = MATCH_ERROR;
          }

        /* Try to scalarize an elemental intrinsic function that has an
           array argument.  */
        isym = gfc_find_function (e->symtree->n.sym->name);
        if (isym && isym->elemental
            && (t = scalarize_intrinsic_call (e)) == SUCCESS)


What happens now is: "check_elemental" prints an error (which gets buffered)
and returns MATCH_ERROR. However, that value is not checked - thus the code
continues to the scalarize_intrinsic_call(e), which then gives an ICE.


Draft patch (only very lightly tested):

--- a/gcc/fortran/expr.c
+++ b/gcc/fortran/expr.c
@@ -2481,6 +2481,9 @@ check_init_expr (gfc_expr *e)
            m = MATCH_ERROR;
          }

+       if (m == MATCH_ERROR)
+         return FAILURE;
+
        /* Try to scalarize an elemental intrinsic function that has an
           array argument.  */
        isym = gfc_find_function (e->symtree->n.sym->name);