Re: COMMENTS: building git on AIX

From: Jonathan Nieder <jrnieder@gmail.com>
Date: Oct 28, 2019, 21:43 UTC
Message-ID: <20191028214357.GB12487@google.com>
In-Reply-To: <1200106e-b75d-5b15-0608-427cd923578a@felt.demon.nl>

Hi,

Michael Felt wrote:

Show 13 quoted lines

> I have, a couple of time, successfully built git for AIX. However, my
> prior attempt (version 2.18) - I never got around to finishing and today
> with version 2.23.0 - I am unsure how to proceed without a lot of hacking.
>
> Just some comments - long long way from calling anything a bug - just
> not as portable as I would have hoped.
>
> The simple issues:
>
> 1. The "Makefile" is surprising. I expect to run ./configure (or better,
> out-of tree, e.g., ../src/git-2.23.0/configure). Just running OOT
> configure does not result in a "Makefile". So, copy source tree to dest
> and try again.

See INSTALL:

 [...]
 Alternatively you can use autoconf generated ./configure script to
 set up install paths (via config.mak.autogen), so you can write instead

so the output of the configure script is a config.mak.autogen file. Keep in mind that most of Git's developers don't use the configure script, mostly because it's slow.

I like the idea of teaching the configure script to set up a VPATH build. Would you be interested in working on that?

> 2. Makefile assumes gmake. Standard make does not support :: syntax
> (fix: install cmake)

I assume that by cmake you mean gmake here.

> 3. The default CFLAGS contains -Wall. Not all compilers support -Wall.
> "Fixed" by adding CFLAGS="-g -O2". I am also undecided on having -g as a
> default flag.

Interesting!  That doesn't feel like a recent change:

 $ git log -GWall -- Makefile
[...]
 commit b05701c5b4c7983ef04d8c286c65089596553bd6
 Author: Pavel Roskin <proski@gnu.org>
 Date:   Sat Aug 6 01:36:15 2005 -0400

     Make CFLAGS overridable from make command line.
[...]
 commit 19b2860cba5742ab31fd682b80fefefac19be141
 Author: Linus Torvalds <torvalds@linux-foundation.org>
 Date:   Fri Apr 8 09:59:28 2005 -0700

     Use "-Wall -O2" for the compiler to get more warnings.

It seems worth calling out in the INSTALL file (and autodetecting in the configure script).

> 4. Must have gettext installed, which needs GNU libiconv - sad to have
> these libraries as additional dependencies. e.g., bash 4.4 finally
> removed the gettext and iconv gnu dependencies. -- FYI!

See INSTALL:

 Set NO_GETTEXT to disable localization support and make Git only
 use English. Under autoconf the configure script will do this
 automatically if it can't find libintl on the system.

Did the part of the configure script that does this break?

> 5. Another "gcc"? dependency: "git-compat-util.h", line 361.1: 1506-277
> (S) Syntax error: possible missing ';'
> FIX: add 'CC=xlc_r' to get language extensions

That's

 static inline int noop_core_config(const char *var, const char *value, void *cb)

Does AIX cc have trouble with "static inline"?

> 6. Needs curl (libcurl and curl.h), but does not check until much later:
> FIX install curl; FIX2 add -I flag to find $prefix/include to CFLAGS
> (.e.g., CFLAGS="-g -O2 -I/opt/include") - FYI GNU autotools also fail to
> include $prefix/include

From INSTALL:

  "libcurl" library is used by git-http-fetch, git-fetch, and, if
  the curl version >= 7.34.0, for git-imap-send.  You might also
  want the "curl" executable for debugging purposes. If you do not
  use http:// or https:// repositories, and do not want to put
  patches into an IMAP mailbox, you do not have to have them
  (use NO_CURL).

Would you be interested in improving the configure script's detection of this?

> 7. More stuck here. libssh2 is built by curl, but as a static library. I
> could "hack" the libssh2.o file into the linkage, but unclear how well
> that will work. Also wonder if libssh2 is "required" or optional. For
> curl it has been optional (and I think it still is).

[...]

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> git-imap-send   imap-send.o http.o common-main.o \
>           -L/opt/lib -lcurl -lssh2 -lssh2 -lssl -lcrypto -lldap -llber
> -lssl -lcrypto -lz  -lssl  -lcrypto libgit.a xdiff/lib.a  -lz  -liconv
> -lintl -lpthread
> ld: 0706-006 Cannot find or open library file: -l ssh2

The "-lssh2" comes from "curl-config --libs" output. It sounds like your copy of $(which curl-config) should have CURLLIBDIR set but doesn't. Should we use "curl-config --static-libs" on AIX instead?

If you know what flags to use to link to curl, you can use CURL_LDFLAGS to set that instead.

> Not sure - if I can help - but do hope this already helps in a (small) way.

Thanks for working to keep Git portable.

Hope that helps, Jonathan