[Bug fortran/31610] ICE with transfer, merge in gfc_conv_expr_descriptor

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

------- Comment #7 from pault at gcc dot gnu dot org  2007-05-29 13:39 -------
(In reply to comment #4)
> I misunderstood something slightly in that last comment; MERGE is elemental, so
> the conforming I mentioned doesn't matter.  Also, my guess that fixing the
> transfer("A", "x", 20) problem would fix the whole thing proved to be
> incorrect.

See comment #6.

> So, even once the first bit is fixed, if we change the code to be legitimate,
> as follows, then it still has an error:
> character(len=20) :: string
> logical :: a(20)
> write(*,*) transfer (merge (transfer("A", "x", 20), "b", a), string )
> end

It also fails with a character(len = 1) array of size 20.

> Specifically, we ICE by failing the "gcc_assert (integer_zerop (loop ->
> from[n]))" at line 593 of trans-array.c, when doing gfc_conv... stuff to the
> arguments of the outer transfer function.
> I'm having a bear of a time tracking down why this is happening.  The problem
> is that we're generating a temporary, so loop->temp_dim is 1 (as set in
> gfc_trans_constant_array_constructor, line 1576).  However, the loop seems to
> be picking up dimensions from the result of the inner transfer function
> somehow.  Walking through the ss list for the loop gives a GFC_SS_CONSTRUCTOR,
> a GFC_SS_SCALAR, and a GFC_SS_SECTION, and the GFC_SS_SECTION causes the
> info->start[0] and info->end[0] values to be set (to 1 and 20, respectively) in
> gfc_conv_ss_startstride, which then propagate to the from[0] and to[0] values
> for the loop.
> I can't seem to duplicate this with any other set of functions.  It's only
> happening with characters, not integers, and if I break up the expression or
> substitute other things for transfer and merge, it doesn't replicate this
> behavior.
> Help?

I'll have a think about this tonight.  I NEVER find debugging the scalarizer
easy; not in small part because I have to re-understand it every time I go near
it.

Paul


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31610