[PATCH 1/1] configure.ac: Properly check for libintl

[PATCH 1/1] configure.ac: Properly check for libintl

[Vadim Kochan]

Some libc implementations like uclibc or musl provides
gettext stubs via libintl library but this case is not checked
by AC_CHECK_LIB(c, gettext ...) because gcc has gettext as builtin
which passess the check.

So check it with included libintl.h where gettext may unfold into
libintl_gettext which will cause check to fail if libintl_gettext are
needed to be linked with -lintl.

Signed-off-by: Vadim Kochan <vadim4j@gmail.com>
---
 configure.ac | 16 +++++++++++++---
 1 file changed, 13 insertions(+), 3 deletions(-)

diff --git a/configure.ac b/configure.ac
index e0d0da3c0c..be3b55f1cc 100644
--- a/configure.ac
+++ b/configure.ac
@@ -763,9 +763,19 @@ AC_CHECK_LIB([c], [basename],
 GIT_CONF_SUBST([NEEDS_LIBGEN])
 test -n "$NEEDS_LIBGEN" && LIBS="$LIBS -lgen"
 
-AC_CHECK_LIB([c], [gettext],
-[LIBC_CONTAINS_LIBINTL=YesPlease],
-[LIBC_CONTAINS_LIBINTL=])
+AC_DEFUN([LIBINTL_SRC], [
+AC_LANG_PROGRAM([[
+#include <libintl.h>
+]],[[
+char *msg = gettext("test");
+]])])
+
+AC_MSG_CHECKING([if libc contains libintl])
+AC_LINK_IFELSE([LIBINTL_SRC],
+	[AC_MSG_RESULT([yes])
+	LIBC_CONTAINS_LIBINTL=YesPlease],
+	[AC_MSG_RESULT([no])
+	LIBC_CONTAINS_LIBINTL=])
 GIT_CONF_SUBST([LIBC_CONTAINS_LIBINTL])
 
 #
-- 
2.14.1

Re: [PATCH 1/1] configure.ac: Properly check for libintl

[Junio C Hamano]

Vadim Kochan <vadim4j@gmail.com> writes:

> Some libc implementations like uclibc or musl provides
> gettext stubs via libintl library but this case is not checked
> by AC_CHECK_LIB(c, gettext ...) because gcc has gettext as builtin
> which passess the check.
>
> So check it with included libintl.h where gettext may unfold into
> libintl_gettext which will cause check to fail if libintl_gettext are
> needed to be linked with -lintl.

Let me make sure I can understand the above correctly (otherwise,
that is a sign that the proposed log message is lacking) by trying
to rephrase (iow, this is not me saying "your log message should be
rewritten like so"; it is "if I read what you wrote above correctly,
I think what I am going to write here is also correct"):

    Some libc implementations have function called gettext() that
    can be linked via -lc without -lintl, but these are mere stubs
    and do not do useful i18n.  On these systems, if a program that
    calls gettext() is built _with_ "#include <libintl.h>", the
    linker calls for the real version (e.g. libintl_gettext()) and
    that can be satisfied only by linking with -lintl.

    The current check to see if -lc provides with gettext() is
    sufficient for libc implementations like GNU libc that actually
    has full fledged gettext(); to detect libc with stub gettext()
    and libintl with real gettext(), aliased via <libintl.h>, the
    check to see if -lintl is necessary must be done with a sample
    source that #include's the header file.

Is that what is going on and why this patch is needed?

I think the only possibile kind of system this change could break
that currently is working is the one that has a usable gettext()
in -lc, but does not offer <libintl.h>, as the new test program
added by this patch will fail to compile, but I do not think that
is possible in practice---our own gettext.c #include's <libintl.h>
so there is no way such a hypothetical system that would be broken
by this change could possibly have built Git successfully.

Assuming that the way I read your log message is in line with what
you wanted to say, I think the patch looks good.

Thanks.


> Signed-off-by: Vadim Kochan <vadim4j@gmail.com>
> ---
>  configure.ac | 16 +++++++++++++---
>  1 file changed, 13 insertions(+), 3 deletions(-)
>
> diff --git a/configure.ac b/configure.ac
> index e0d0da3c0c..be3b55f1cc 100644
> --- a/configure.ac
> +++ b/configure.ac
> @@ -763,9 +763,19 @@ AC_CHECK_LIB([c], [basename],
>  GIT_CONF_SUBST([NEEDS_LIBGEN])
>  test -n "$NEEDS_LIBGEN" && LIBS="$LIBS -lgen"
>  
> -AC_CHECK_LIB([c], [gettext],
> -[LIBC_CONTAINS_LIBINTL=YesPlease],
> -[LIBC_CONTAINS_LIBINTL=])
> +AC_DEFUN([LIBINTL_SRC], [
> +AC_LANG_PROGRAM([[
> +#include <libintl.h>
> +]],[[
> +char *msg = gettext("test");
> +]])])
> +
> +AC_MSG_CHECKING([if libc contains libintl])
> +AC_LINK_IFELSE([LIBINTL_SRC],
> +	[AC_MSG_RESULT([yes])
> +	LIBC_CONTAINS_LIBINTL=YesPlease],
> +	[AC_MSG_RESULT([no])
> +	LIBC_CONTAINS_LIBINTL=])
>  GIT_CONF_SUBST([LIBC_CONTAINS_LIBINTL])
>  
>  #

Re: [PATCH 1/1] configure.ac: Properly check for libintl

[Vadym Kochan]

Hi Junio,

On Thu, Apr 18, 2019 at 02:45:56PM +0900, Junio C Hamano wrote:
> Vadim Kochan <vadim4j@gmail.com> writes:
> 
> > Some libc implementations like uclibc or musl provides
> > gettext stubs via libintl library but this case is not checked
> > by AC_CHECK_LIB(c, gettext ...) because gcc has gettext as builtin
> > which passess the check.
> >
> > So check it with included libintl.h where gettext may unfold into
> > libintl_gettext which will cause check to fail if libintl_gettext are
> > needed to be linked with -lintl.
> 
> Let me make sure I can understand the above correctly (otherwise,
> that is a sign that the proposed log message is lacking) by trying
> to rephrase (iow, this is not me saying "your log message should be
> rewritten like so"; it is "if I read what you wrote above correctly,
> I think what I am going to write here is also correct"):
> 
>     Some libc implementations have function called gettext() that
>     can be linked via -lc without -lintl, but these are mere stubs
>     and do not do useful i18n.  On these systems, if a program that
>     calls gettext() is built _with_ "#include <libintl.h>", the
>     linker calls for the real version (e.g. libintl_gettext()) and
>     that can be satisfied only by linking with -lintl.
> 
>     The current check to see if -lc provides with gettext() is
>     sufficient for libc implementations like GNU libc that actually
>     has full fledged gettext(); to detect libc with stub gettext()
>     and libintl with real gettext(), aliased via <libintl.h>, the
>     check to see if -lintl is necessary must be done with a sample
>     source that #include's the header file.
> 
> Is that what is going on and why this patch is needed?
> 
> I think the only possibile kind of system this change could break
> that currently is working is the one that has a usable gettext()
> in -lc, but does not offer <libintl.h>, as the new test program
> added by this patch will fail to compile, but I do not think that
> is possible in practice---our own gettext.c #include's <libintl.h>
> so there is no way such a hypothetical system that would be broken
> by this change could possibly have built Git successfully.
> 
> Assuming that the way I read your log message is in line with what
> you wanted to say, I think the patch looks good.
> 
> Thanks.

Yes you are correct. 'gettext' even might be defined as libintl_gettext.
When I got build error I checked config.log and I saw that gcc claims
that gettext builtin is used, so I think that was the reason why test
passed for non-glibc. So, if to use <libintl.h> then gettext might be
preprocessed to libintl_gettext in the test. The original error which I
was fixing is:

	http://autobuild.buildroot.net/results/8eeac7f7ddd97576eaeb87311bf0988d59d8b132/build-end.log

> 
> 
> > Signed-off-by: Vadim Kochan <vadim4j@gmail.com>
> > ---
> >  configure.ac | 16 +++++++++++++---
> >  1 file changed, 13 insertions(+), 3 deletions(-)
> >
> > diff --git a/configure.ac b/configure.ac
> > index e0d0da3c0c..be3b55f1cc 100644
> > --- a/configure.ac
> > +++ b/configure.ac
> > @@ -763,9 +763,19 @@ AC_CHECK_LIB([c], [basename],
> >  GIT_CONF_SUBST([NEEDS_LIBGEN])
> >  test -n "$NEEDS_LIBGEN" && LIBS="$LIBS -lgen"
> >  
> > -AC_CHECK_LIB([c], [gettext],
> > -[LIBC_CONTAINS_LIBINTL=YesPlease],
> > -[LIBC_CONTAINS_LIBINTL=])
> > +AC_DEFUN([LIBINTL_SRC], [
> > +AC_LANG_PROGRAM([[
> > +#include <libintl.h>
> > +]],[[
> > +char *msg = gettext("test");
> > +]])])
> > +
> > +AC_MSG_CHECKING([if libc contains libintl])
> > +AC_LINK_IFELSE([LIBINTL_SRC],
> > +	[AC_MSG_RESULT([yes])
> > +	LIBC_CONTAINS_LIBINTL=YesPlease],
> > +	[AC_MSG_RESULT([no])
> > +	LIBC_CONTAINS_LIBINTL=])
> >  GIT_CONF_SUBST([LIBC_CONTAINS_LIBINTL])
> >  
> >  #

Re: [PATCH 1/1] configure.ac: Properly check for libintl

[Junio C Hamano]

Vadym Kochan <vadim4j@gmail.com> writes:

>>     Some libc implementations have function called gettext() that
>>     can be linked via -lc without -lintl, but these are mere stubs
>>     and do not do useful i18n.  On these systems, if a program that
>>     calls gettext() is built _with_ "#include <libintl.h>", the
>>     linker calls for the real version (e.g. libintl_gettext()) and
>>     that can be satisfied only by linking with -lintl.
>> 
>>     The current check to see if -lc provides with gettext() is
>>     sufficient for libc implementations like GNU libc that actually
>>     has full fledged gettext(); to detect libc with stub gettext()
>>     and libintl with real gettext(), aliased via <libintl.h>, the
>>     check to see if -lintl is necessary must be done with a sample
>>     source that #include's the header file.
>> 
>> Is that what is going on and why this patch is needed?
>> 
> Yes you are correct. 'gettext' even might be defined as libintl_gettext.

With this exchange, I was aiming for extracting a more useful title
for this patch out of you ;-), and I think I accomplished my goal.

"Properly" is fairly a useless adverb in the context of a patch
title, as it does not tell us why we thought the way in which the
updated code works is more "proper".  In addition, because no code
is perfect, future developers are bound to find something inproperly
done in checking for libintl after this patch gets applied.  It is
better to say the most important thing the change does concisely and
concretely.

I think

	autoconf: #include <libintl.h> when checking for gettext()

is probably a better title.  

Together with your originally proposed log message, which we now
know explains why this inclusion makes a difference sufficiently to
be understandable by an average Git developer, the resulting commit
will communicate to our future developers the reason why we thought
this was a good change clearly.

Thanks.

Re: [PATCH 1/1] configure.ac: Properly check for libintl

[Vadim Kochan]

Hi Junio,

On Fri, Apr 19, 2019 at 01:56:48PM +0900, Junio C Hamano wrote:
> Vadym Kochan <vadim4j@gmail.com> writes:
> 
> >>     Some libc implementations have function called gettext() that
> >>     can be linked via -lc without -lintl, but these are mere stubs
> >>     and do not do useful i18n.  On these systems, if a program that
> >>     calls gettext() is built _with_ "#include <libintl.h>", the
> >>     linker calls for the real version (e.g. libintl_gettext()) and
> >>     that can be satisfied only by linking with -lintl.
> >> 
> >>     The current check to see if -lc provides with gettext() is
> >>     sufficient for libc implementations like GNU libc that actually
> >>     has full fledged gettext(); to detect libc with stub gettext()
> >>     and libintl with real gettext(), aliased via <libintl.h>, the
> >>     check to see if -lintl is necessary must be done with a sample
> >>     source that #include's the header file.
> >> 
> >> Is that what is going on and why this patch is needed?
> >> 
> > Yes you are correct. 'gettext' even might be defined as libintl_gettext.
> 
> With this exchange, I was aiming for extracting a more useful title
> for this patch out of you ;-), and I think I accomplished my goal.
> 
> "Properly" is fairly a useless adverb in the context of a patch
> title, as it does not tell us why we thought the way in which the
> updated code works is more "proper".  In addition, because no code
> is perfect, future developers are bound to find something inproperly
> done in checking for libintl after this patch gets applied.  It is
> better to say the most important thing the change does concisely and
> concretely.
> 
> I think
> 
> 	autoconf: #include <libintl.h> when checking for gettext()
> 
> is probably a better title.  
> 
> Together with your originally proposed log message, which we now
> know explains why this inclusion makes a difference sufficiently to
> be understandable by an average Git developer, the resulting commit
> will communicate to our future developers the reason why we thought
> this was a good change clearly.
> 
> Thanks.

Thanks! Should I re-submit patch with title updated v2 ?

Regards,
Vadim Kochan

Re: [PATCH 1/1] configure.ac: Properly check for libintl

[Junio C Hamano]

Vadim Kochan <vadim4j@gmail.com> writes:

>> I think
>> 
>> 	autoconf: #include <libintl.h> when checking for gettext()
>> 
>> is probably a better title.  
>> 
>> Together with your originally proposed log message, which we now
>> know explains why this inclusion makes a difference sufficiently to
>> be understandable by an average Git developer, the resulting commit
>> will communicate to our future developers the reason why we thought
>> this was a good change clearly.
>> 
>> Thanks.
>
> Thanks! Should I re-submit patch with title updated v2 ?

You could if you feel like it, but in a case like this, responding
with "Yeah, I agree with your suggestion" and telling me to retitle
is sufficient, if you have nothing else to change in the v2.

I've already did the retitling while queuing it, so no need to
resend.

Thanks.