[Fontconfig] How necessary is 'scandir'?

Michael Felt aixtools at gmail.com
Sun Feb 15 08:05:44 PST 2015

>From gcc man page

-wInhibit all warning messages.
-WerrorMake all warnings into errors.

>From AIX compiler reference

Listings, messages, and compiler information
Chapter 4. Compiler options reference 299
Pragma equivalent
Suppresses informational, language-level and warning messages.
This option is equivalent to specifying -qflag=e : e.

Option I believe wanted is -qhalt


Error checking and debugging
Pragma equivalent
#pragma options halt
Stops compilation before producing any object, executable, or assembler
files if the maximum severity of compile-time messages equals or exceeds the
severity you specify.
-qhalt syntax — C

-qhalt = i


i Specifies that compilation is to stop for all types of errors: warning,
error and
informational. Informational diagnostics (I) are of the lowest severity.
w Specifies that compilation is to stop for warnings (W) and all types of
e Specifies that compilation is to stop for errors (E), severe errors (S),
unrecoverable errors (U).
s Specifies that compilation is to stop for severe errors (S) and
errors (U).

So, to make a warning a message that halts asif an error is needed

This patch:
diff -ur a/configure.ac b/configure.ac
--- a/configure.ac      2015-01-13 03:40:40 +0000
+++ b/configure.ac      2015-02-15 15:49:33 +0000
@@ -159,7 +159,11 @@
 if test "$os_win32" = "no"; then
        AC_MSG_CHECKING([for scandir])
+if test "x$GCC" = "xyes"; then
                #include <dirent.h>
                int main(void);

resolves the configure issue here

I do not wish to attempt a real fix here - as I disagree with the logic of
adding -Werror - in static text.
If a reaction like this is needed it should be a different variable - like
WARN_CFLAGS - that gets set per compiler.

Another general problem I see is that --prefix is not being applied by
configure (because libraries in /opt/lib, include files in /opt/include -
are not being found. Just the standard hard-coded (it seems) check of /usr
and /usr/local. Quite common that /usr/local is being checked, while
--prefix value is not.

ANYWAY - for the key question - is scandir needed - the problem is
configure.ac, not scandir() availability.

On Sun, Feb 15, 2015 at 2:01 PM, Raimund Steger <rs at mytum.de> wrote:

> On 02/12/15 03:59, Akira TAGOH wrote:
>> If the own scandir works on the platforms where don't have POSIX version
>> of scandir, we could drop that check. if anyone confirm, that would be
>> appreciated.
> The question is, for what cases would we need our own scandir. Because:
> (1) On Win32, FcDirChecksum isn't used (we use FcStat/GetFileAttributesEx
> only)
> (2) On all platforms we supported before 38ab7ab2fbd83c0c62e4b78302b5fe89da0cb79e
> (where the configure check was introduced), scandir *is* available. Either
> the POSIX one (in the sense of [1]) which uses dirent comparators or the
> one that uses void* [2].
> Because of that, we wouldn't need to specifically test for [1] and could
> just assume it's there, avoiding clashes with UNIX compilers that can't
> execute our test because of -Werror.
> Now what about platforms where there is indeed neither GetFileAttributesEx
> nor any version of scandir? I admit that these were probably supported
> before 0ac6c98294d666762960824d39329459b22b48b7 (
> https://bugs.freedesktop.org/show_bug.cgi?id=25535) and aren't now. If we
> wanted to support those, then yes, we would need to check for both scandir
> versions, although the check for the POSIX variant could be a simple
> fallback that doesn't need -Werror. And even then, we could probably simply
> ignore the result of FcIsFsMtimeBroken as the change addressed FAT file
> systems on UNIX/Linux only. I mean, the set of UNIX/Linux systems that
> don't have scandir and at the same time use a font directory on FAT is
> probably rather small...
> Raimund
> [1] http://pubs.opengroup.org/onlinepubs/9699919799/
> functions/alphasort.html
> [2] http://netbsd.gw.com/cgi-bin/man-cgi?scandir+3+NetBSD-current
>  On Thu, Feb 12, 2015 at 7:55 AM, Raimund Steger <rs at mytum.de
>> <mailto:rs at mytum.de>> wrote:
>>     On 02/11/15 19:40, Michael Felt wrote:
>>         Yes, xlC, and I was hoping it was just a stray gcc flag.
>>     If that's indeed the reason, you can:
>>     (0) To confirm whether it is, replace WERROR_CFLAGS="-Werror" with
>>     WERROR_CFLAGS="" in configure.ac <http://configure.ac>, run
>>     autoconf, configure etc.
>>     If that works:
>>     (1) find an equivalent flag for XL C and create a patch, just like
>>     the one for SunPRO [1]. If I understand the documentation right [2],
>>     this could be "-qmaxerr=1:w" (increase the number 1 if some
>>     'statement not reached' stuff gets in your way), but it's difficult
>>     to say without an actual installation to test.
>>     (2) create a patch similar to (1), but set WERROR_CFLAGS="" or
>>     disable the scandir check altogether when compiling with XL C. I
>>     believe before [3] there wasn't even a scandir check, and the change
>>     was only to silence warnings on NetBSD if I read the commit right. I
>>     doubt you will have any problem on AIX.
>>     Actually I'm still somewhat unhappy that configure wants to
>>     acknowledge the POSIX version of scandir specially when only
>>     recognizing the NetBSD version would probably have sufficed ...
>>     would have saved us a lot of if's, maybe even the one for $os_win32.
>>     But I'll shut my mouth again.
>>     -Raimund
>>     [1]
>>     http://cgit.freedesktop.org/__fontconfig/commit/?id=__
>> 694368667a15341ea30b37a36e9540__e6b1492680
>>     <http://cgit.freedesktop.org/fontconfig/commit/?id=
>> 694368667a15341ea30b37a36e9540e6b1492680>
>>     [2]
>>     http://www-01.ibm.com/support/__knowledgecenter/SSGH2K_13.1.
>> 0/__com.ibm.xlc131.aix.doc/__compiler_ref/opt_maxerr.html?__lang=en
>>     <http://www-01.ibm.com/support/knowledgecenter/
>> SSGH2K_13.1.0/com.ibm.xlc131.aix.doc/compiler_ref/opt_maxerr.html?lang=en
>> >
>>     [3]
>>     http://cgit.freedesktop.org/__fontconfig/commit/?id=__
>> 38ab7ab2fbd83c0c62e4b78302b5fe__89da0cb79e
>>     <http://cgit.freedesktop.org/fontconfig/commit/?id=
>> 38ab7ab2fbd83c0c62e4b78302b5fe89da0cb79e>
>> --
>> Akira TAGOH
> --
> Worringer Str 31 Duesseldorf 40211 DE  home: <rs at mytum.de>
> +49-179-2981632 icq 16845346           work: <rs at interface-ag.de>
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