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From: "anlauf at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug fortran/95512] gcc/fortran/trans-decl.c:1066: array sanity
 check after use
Date: Sat, 06 Jun 2020 19:59:08 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D95512

--- Comment #3 from anlauf at gcc dot gnu.org ---
I didn't write the code, but for more context:

trans.h has:

#define GFC_TYPE_ARRAY_LBOUND(node, dim) \
  (TYPE_LANG_SPECIFIC(node)->lbound[dim])
#define GFC_TYPE_ARRAY_UBOUND(node, dim) \
  (TYPE_LANG_SPECIFIC(node)->ubound[dim])

The loop in trans-decl.c:

  for (dim =3D GFC_TYPE_ARRAY_RANK (type);
       dim < GFC_TYPE_ARRAY_RANK (type) + GFC_TYPE_ARRAY_CORANK (type); dim=
++)
    {
      if (GFC_TYPE_ARRAY_LBOUND (type, dim) =3D=3D NULL_TREE)
        {
          GFC_TYPE_ARRAY_LBOUND (type, dim) =3D create_index_var ("lbound",
nest);
          TREE_NO_WARNING (GFC_TYPE_ARRAY_LBOUND (type, dim)) =3D 1;
        }
      /* Don't try to use the unknown ubound for the last coarray dimension=
.=20
*/
      if (GFC_TYPE_ARRAY_UBOUND (type, dim) =3D=3D NULL_TREE
          && dim < GFC_TYPE_ARRAY_RANK (type) + GFC_TYPE_ARRAY_CORANK (type=
) -
1)
        {
          GFC_TYPE_ARRAY_UBOUND (type, dim) =3D create_index_var ("ubound",
nest);
          TREE_NO_WARNING (GFC_TYPE_ARRAY_UBOUND (type, dim)) =3D 1;
        }
    }

So the relevant check is in the loop header, and the current check is there
for the last index.

Maybe it is bad style, but I still consider it a false positive.
cppcheck's view is probably too narrow to understand the range of dim.=