[tlbuild] with-system-lua52 ?

[Peter Breitenlohner]

On Thu, 19 Dec 2013, Norbert Preining wrote:

> I see that we have now lua52 in libs, and it is unchanged from
> the distribution.

Hi Norbert,

true, although libs/lua52/configure.ac contains
   KPSE_LARGEFILE([LUA52_DEFINES])
defining LUA52_DEFINES to whatever is required for LFS, e.g.,
'-D_LARGE_FILES', '-D_FILE_OFFSET_BITS=64', and/or '-D_LARGEFILE_SOURCE'
and libs/lua52/Makefile.am uses $(LUA52_DEFINES) for AM_CPPFLAGS.

> Is it on purpose to have no --with-system-lua52? Does luatex
> actually need the lua52 sources?

This is indeed intentional for several reasons.

(1) lua-5.x.y as distributed only builds a static library and installs just
a few headers.

(2) Some distros have added an Autotools based build system including a
shared library, and so did I to test things.  All distros I have seen
install only a few headers.  Moreover there is no agreement where to install
the headers and library, nor about the library name (liblua52.so,
liblua.so.5.2, liblua5.2.so, ...).  All this could be handles by pkg-config
or a suitable lua-config script, but there are no such things.

(3) I was able to build lua with the shared library but luac can only be
built with the static library because many of the required symbols are not
exported by the shared library.

(4) LuaTeX requires these same symbols (and more) as well as headers that
are not installed by the distros.  The only thing one could do is to use the
headers from the TL tree and build LuaTeX with the installed static library,
but what would be the gain?

Regards
Peter