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From: "mikael at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug fortran/64952] Missing temporary in assignment from elemental function
Date: Sun, 08 Feb 2015 13:00:00 -0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64952

--- Comment #4 from Mikael Morin <mikael at gcc dot gnu.org> ---
Hello Paul,

setting potentially_aliased should be done inside
gfc_walk_elemental_function_args, as the ss argument may be returned
unmodified.
In fact, I think it's better to do all the trans-array.c code inside
gfc_conv_resolve_dependencies without adding the gfc_ss_info flag.

There is also the case of typebound procedures and procedure pointer
components,
for which we should generate a temporary in any case.

I think this case is something that was overlooked by the standard commitee
when they introduced the PURE attribute.  Maybe they can provide some kind of
"REALLY_PURE" attribute (or PURE ELEMENTAL, different from regular ELEMENTAL)
that avoids generating temporaries everywhere?
Or maybe the function Fred should bee IMPURE ELEMENTAL?

Anyway, I think we should not rush to fix this before we are sure that the
standard committee really expects temporaries (almost) everywhere array
elemental functions are involved.