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Subject: [Bug fortran/45777] Missing temporary ?
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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45777

--- Comment #5 from Tobias Burnus <burnus at gcc dot gnu.org> 2010-09-25 14:30:55 UTC ---
The issue seems to be how alias checking is implemented in trans-array.c:

gfc_could_be_alias (gfc_ss * lss, gfc_ss * rss)
[...]
  for (rref = rss->expr->ref; rref != rss->data.info.ref; rref = rref->next)
    {
      if (gfc_symbols_could_alias (rref->u.c.sym, lsym))
        return 1;
    }

While "rss->expr->symtree->n.sym" (= "rsym") has the pointer and target
attribute, the element "rref->u.c.sym" usually has not.

Thus, the gfc_symbols_could_alias check succeeds (first argument is neither a
pointer nor a target thus it cannot alias with the second argument, unless both
symbol are the same); cf. symbol.c's

gfc_symbols_could_alias (gfc_symbol *lsym, gfc_symbol *rsym)
[...]
  if (lsym->attr.pointer
      && (rsym->attr.pointer || rsym->attr.allocatable || rsym->attr.target))
    return 1;
  if (lsym->attr.target && rsym->attr.pointer)
    return 1;
  if (lsym->attr.allocatable && rsym->attr.pointer)
    return 1;
[...]
  return 0;

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