https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94672
Tomáš Trnka <trnka at scm dot com> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |trnka at scm dot com
--- Comment #12 from Tomáš Trnka <trnka at scm dot com> ---
The fix for this broke assumed length optional character arguments. I have
noticed this on 10.2.1 20200723, which is currently used by Fedora 32.
Bisected using the following testcase:
subroutine foo (n, lVal, sVal)
integer, intent(in) :: n
logical, optional, intent(out) :: lVal(n)
character(*), optional, intent(out) :: sVal(n)
integer :: nFound
nFound = 0
if (present(lVal)) then
nFound = nFound + 1
end if
if (present(sVal)) then
nFound = nFound + 1
end if
write(*,*) nFound
end subroutine
Affected versions compile this to the following:
character(kind=1)[0:D.3919][1:_sval] * restrict sval.0;
…
if (sval.0 != 0B)
{
ubound.2 = (integer(kind=8)) *n;
size.3 = NON_LVALUE_EXPR <ubound.2>;
size.3 = MAX_EXPR <size.3, 0>;
D.3917 = (bitsizetype) (sizetype) NON_LVALUE_EXPR <_sval> * 8;
D.3918 = (sizetype) NON_LVALUE_EXPR <_sval>;
D.3919 = size.3 + -1;
D.3920 = ((bitsizetype) (sizetype) NON_LVALUE_EXPR <_sval> *
(bitsizetype) (sizetype) NON_LVALUE_EXPR <size.3>) * 8;
D.3921 = (sizetype) NON_LVALUE_EXPR <_sval> * (sizetype) NON_LVALUE_EXPR
<size.3>;
sval.0 = (character(kind=1)[0:D.3919][1:_sval] * restrict) sval;
}
…
if (sval.0 != 0B)
{
nfound = nfound + 1;
}
The first test thus relies on an unitialized value of sval.0. If that value
happens to be zero, the actual "sval" argument will be ignored even if it is
present.
