From: Jonathan Wakely <jwakely.gcc@gmail.com>
To: Iain Sandoe <iain@sandoe.co.uk>
Cc: "libstdc++" <libstdc++@gcc.gnu.org>,
GCC Patches <gcc-patches@gcc.gnu.org>
Subject: Re: [PATCH] libstdc++, configure: Fix GLIBCXX_ZONEINFO_DIR configuration macro.
Date: Sat, 24 Dec 2022 10:01:34 +0000 [thread overview]
Message-ID: <CAH6eHdRvDn3uT8+Sdw+wabefE223gUQ0AsSiD3sa6Q2WTmcRTA@mail.gmail.com> (raw)
In-Reply-To: <DF91A3D6-015F-4315-988D-960E341F950E@sandoe.co.uk>
[-- Attachment #1: Type: text/plain, Size: 4649 bytes --]
On Sat, 24 Dec 2022, 09:56 Iain Sandoe, <iain@sandoe.co.uk> wrote:
> Hi,
>
> > On 23 Dec 2022, at 23:17, Jonathan Wakely <jwakely.gcc@gmail.com> wrote:
> >
> > On Fri, 23 Dec 2022, 17:06 Iain Sandoe via Libstdc++, <
> libstdc++@gcc.gnu.org> wrote:
> > This is a patch for comment on the approach - tested on x86_64-darwi21
> > thoughts?
> > Iain
> >
> > --- 8< ---
> >
> > Testing on Darwin revealed that the GLIBCXX_ZONEINFO_DIR was not doing
> quite
> > the right thing (we ended up with ${withval} in the config.h file).
> >
> > This patch proposes revising the behaviour of the configure flag thus:
> >
> > --with-libstdcxx-zoneinfo-dir=
> > unspecified : Set _GLIBCXX_ZONEINFO_DIR to a default suitable for $host
> > yes : Set _GLIBCXX_ZONEINFO_DIR to a default suitable for $host
> > no : Do not set _GLIBCXX_ZONEINFO_DIR
> >
> > What's the use case for "no"? Enforcing a UTC-only tzdb that doesn't
> even try to load the tzdata? If that's desirable, we could #ifdef huge
> parts of src/c++20/tzdb.cc to make the library smaller. That might make
> sense for a toolchain for embedded targets where it's known there's no need
> for time zone conversions.
>
> Actually, I had not explored all those possibilities.
>
> My thinking was that ’no’ is a valid answer and either we need to produce
> a configure diagnostic saying that it is not a valid choice - or we should
> apply it in some useful way. Silent acceptance but doing something
> different from what the user was expecting seems a bad idea.
>
> Your use cases seem quite reasonable - and, yes, I guess that means the
> code could be stubbed or given a trivial impl. for that case.
>
I'll look into doing that in the new year.
> cheers, and season’s greetings,
> Iain
>
>
> >
> >
> >
> > /some/path : set _GLIBCXX_ZONEINFO_DIR = "/some/path"
> >
> > Signed-off-by: Iain Sandoe <iain@sandoe.co.uk>
> >
> > libstdc++-v3/ChangeLog:
> >
> > * acinclude.m4 (GLIBCXX_ZONEINFO_DIR): Revise configure flag
> > handling.
> > * configure: Regenerate.
> > * src/c++20/tzdb.cc: Add a comment that an unset
> _GLIBCXX_ZONEINFO_DIR
> > implies that the configuration specified that no directory
> should be
> > used.
> > ---
> > libstdc++-v3/acinclude.m4 | 21 ++++++++++++++-------
> > libstdc++-v3/configure | 28 +++++++++++++++++++---------
> > libstdc++-v3/src/c++20/tzdb.cc | 1 +
> > 3 files changed, 34 insertions(+), 16 deletions(-)
> >
> > diff --git a/libstdc++-v3/acinclude.m4 b/libstdc++-v3/acinclude.m4
> > index f73946a4918..3653822aed4 100644
> > --- a/libstdc++-v3/acinclude.m4
> > +++ b/libstdc++-v3/acinclude.m4
> > @@ -5153,18 +5153,25 @@ AC_DEFUN([GLIBCXX_ZONEINFO_DIR], [
> > AC_ARG_WITH([libstdcxx-zoneinfo-dir],
> > AC_HELP_STRING([--with-libstdcxx-zoneinfo-dir],
> > [the directory to search for tzdata files]),
> > - [zoneinfo_dir="${withval}"
> > - AC_DEFINE(_GLIBCXX_ZONEINFO_DIR, "${withval}",
> > - [Define if a non-default location should be used for tzdata
> files.])
> > - ],
> > - [
> > + [],[with_libstdcxx_zoneinfo_dir=yes])
> > +
> > + # Pick a default when no specific path is set.
> > + if test x${with_libstdcxx_zoneinfo_dir} = xyes; then
> > case "$host" in
> > # *-*-aix*) zoneinfo_dir="/usr/share/lib/zoneinfo" ;;
> > + *-*-darwin2*) zoneinfo_dir="/usr/share/lib/zoneinfo.default" ;;
> > *) zoneinfo_dir="/usr/share/zoneinfo" ;;
> > esac
> > - ])
> > -
> > + elif test x${with_libstdcxx_zoneinfo_dir} = xno; then
> > + zoneinfo_dir=none
> > + else
> > + zoneinfo_dir=${with_libstdcxx_zoneinfo_dir}
> > + fi
> > AC_MSG_NOTICE([zoneinfo data directory: ${zoneinfo_dir}])
> > + if test x${zoneinfo_dir} != xnone; then
> > + AC_DEFINE_UNQUOTED(_GLIBCXX_ZONEINFO_DIR, "${zoneinfo_dir}",
> > + [Define if a non-default location should be used for tzdata
> files.])
> > + fi
> > ])
> >
> > # Macros from the top-level gcc directory.
> >
> > diff --git a/libstdc++-v3/src/c++20/tzdb.cc
> b/libstdc++-v3/src/c++20/tzdb.cc
> > index 5f5c4199f65..c4311d0902a 100644
> > --- a/libstdc++-v3/src/c++20/tzdb.cc
> > +++ b/libstdc++-v3/src/c++20/tzdb.cc
> > @@ -52,6 +52,7 @@
> > # endif
> > #endif
> >
> > +// This is a bit odd; the configure-time setting was 'no zoneinfo
> directory'
> > #ifndef _GLIBCXX_ZONEINFO_DIR
> > # define _GLIBCXX_ZONEINFO_DIR "/usr/share/zoneinfo"
> > #endif
> > --
> > 2.37.1 (Apple Git-137.1)
>
>
next prev parent reply other threads:[~2022-12-24 10:01 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-12-23 17:06 Iain Sandoe
2022-12-23 23:17 ` Jonathan Wakely
2022-12-24 9:56 ` Iain Sandoe
2022-12-24 10:01 ` Jonathan Wakely [this message]
2023-01-14 18:24 ` Jonathan Wakely
2023-01-14 18:26 ` Jonathan Wakely
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