Hi,
I have an idea for another AS_EXECUTABLE_P improvement. The following
explanation is somewhat complicated, but I couldn't help.
On systems supporting `test -x', AS_EXECUTABLE_P is
{ test -f $1 && test -x $1; }dnl
Let me remind, that test -x alone wouldn't be enough, because
it would succeed on a directory.
But this may cause problems on MS-DOS derivations.
Lets suppose that we have a file named foo.exe, but not foo.
Both DJGPP and Cygwin have extensions which cause `test -x foo' to succeed.
But `test -f' fails, so the whole AS_EXECUTABLE_P(foo) fails too.
One could think that
{ test -x $1 && test ! -d $1; }dnl
is better, because works equally well on Unices, but improves the above
situation. AS_EXECUTABLE_P(foo) would succeed in the above situation. [1]
(There is no problem for autoconf itself, as it has
$ac_executable_extensions, but the improvement could be helpful for other
m4sh scripts.[2])
So, back to the above proposal:
1) Is `test -d' portable enough? The manual doesn't say the contrary.
2) The autoconf manual says you cannot use `test ! -d' with `if'.
Which platforms have this problem? Does it help if the test command is
embedded somehow?
In other words, would really both the following three examples fail
on that platform?
if { test -x foo && test ! -d foo; }; then
echo Yes.
fi
if ( test -x foo && test ! -d foo ); then
echo Yes.
fi
And if yes, wouldn't the following work?
if { if test -d foo; then false; else test -x foo; fi; }; then
echo Yes.
fi
This would mean that AS_EXECUTABLE_P implementation would change to
{ if test -d $1; then false; else test -x $1; fi; }dnl
Looking forward to any comments,
Stepan
[1] It would still fail if _both_ the file `foo.exe' and `foo' existed,
but it is less probable.
[2] Because of the situation described in [1], autoconf has to keep
$ac_executable_extensions, even if we improve the AS_EXECUTABLE_P macro.
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