Re: Word For Today: “Uglification”

On 2024-03-15, Keith Thompson <Keith.S.Thompson+u@gmail.com> wrote:

scott@slp53.sl.home (Scott Lurndal) writes:

Keith Thompson <Keith.S.Thompson+u@gmail.com> writes:

Keith Thompson <Keith.S.Thompson+u@gmail.com> writes:
[...]

For context, here's the entire file from my system (Ubuntu 24.0.4,
package libc6-dev:amd64 2.35-0ubuntu3.6).  I get the impression that the
author(s) decided not to use memset to avoid the required #include,
which might increase compilation times for code that indirectly includes
this header.  (I offer no opinion on whether that's a good tradeoff.)

[...]
>
An older version did use memset().  It was changed to use a loop in
1997, with a commit message that included:
   "Don't use memset to prevent prototype trouble, use simple loop."
It may have been to avoid problems with pre-ANSI C compilers that didn't
support prototypes.  That's still speculation on my part.

>
Here's the full fc20 version:
$ rpm -q -f /usr/include/bits/select.h
glibc-headers-2.18-19.fc20.x86_64
>
>

[...]

#if defined __GNUC__ && __GNUC__ >= 2

Whoever wrote this didn't know that if __GNUC__ doesn't exist, it will
expand as 0, which is false, so this is equivalent to just

  #if __GNUC__ >= 2

[...]

#else   /* ! GNU CC */

[...]

#endif  /* GNU CC */

[...]
>
I don't see that in the GNU glibc git repo, even on branches with
"fedora" in their names.  Perhaps it's a change applied by Red Hat and
not propagated upstream.  (Though I'm not sure why Red Hat would need to
allow for glibc not being compiled by gcc.)

That it's checking for GNU C at least 2 suggests it is an old
patch.

If you look at the source directory for Fedora's package, you see
there are a bunch of patches that get applied:

https://src.fedoraproject.org/rpms/glibc/tree/rawhide

Now if we go to "f20", a heck of lot more patches were applied:

https://src.fedoraproject.org/rpms/glibc/tree/f20

Now, don't waste your time; it's not in any of those patches (I looked).

f20 references glibc-2.18.tar.gz, and that's where that code is found,
in this file:

  ./glibc-2.18/sysdeps/x86/bits/select.h

--
TXR Programming Language: http://nongnu.org/txr
Cygnal: Cygwin Native Application Library: http://kylheku.com/cygnal
Mastodon: @Kazinator@mstdn.ca