https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91160
--- Comment #4 from Steve Kargl <sgk at troutmask dot apl.washington.edu> ---
On Mon, Jul 15, 2019 at 09:49:31AM +0000, dominiq at lps dot ens.fr wrote:
>
> --- Comment #3 from Dominique d'Humieres <dominiq at lps dot ens.fr> ---
> > Fortran allows the arguments of merge_bits() to be BOZ literal constants.
> > merge_bits is broken for said arguments.
>
> AFAIU the current implementation of BOZ literal constants, they are
> INTEGER(16)
That's going away soon. F2008 and newer state a BOZ is a string of
bits. The string is either truncated or padded as needed when conversion
is done. The immediate conversion of a BOZ to INTEGER(8) (or INTEGER(16)
depending on the target) was a convenient mistake to get F95 conformance
for a BOZ in a DATA statement (ie., the only place a BOZ is allowed in a
F95). This mistake has ugly consequences in that a BOZ can appear anywhere
an INTEGER can appear. For example,
% cat a.f90
program foo
print *, abs(z'1234')
end program foo
% gfortran8 -o z a.f90 && ./z
4660
% gfcx -c a.f90
a.f90:2:16:
2 | print *, abs(z'1234')
| 1
Error: 'a' argument of 'abs' intrinsic at (1) must have a numeric type
F2008 and F2018 state that a BOZ is typeless and does not have a kind
type parameter. Kind of unusual to have ABS(), a generic intrinsic
function, choose a specific function.
> (INTEGER(8) with -m32) and the error should be expected. The following changes
>
> ! { dg-do run }
> program foo
> integer(16) m, n, k
> m = merge_bits(b'010101', 1234_16, 42_16); if (m /= 1232) stop 1
> n = merge_bits(1234_16, z'3456', 42_16); if (n /= 13398) stop 2
> k = merge_bits(1234_16, 3456_16, o'12334'); if (k /= 3536) stop 3
> end program foo
>
> allow the code to compile and run (for -m64).
>
> Note that the errors "Error: 'j' argument ..." disappeared between revisions
> r267284 and r267553 (r267415?).
The correct fix would be to re-arrange gfc_check_merge_bits in
check.c to check for a BOZ before other checks, but as this
function is part of the BOZ rewrite I'm inclined to not fix
this on the branches.
