[lucida] [luatex] luatex hangs on lucida OT test file

[Reinhard Kotucha]

On 2017-03-11 at 11:58:16 +0100, Bruno Voisin wrote:

 > So I think there is really no one-command/one-click way to switch
 > between different sets of binaries for a given TeX Live tree. What
 > is needed is have two fully functional separate trees side-by side,
 > as Luigi suggested.

Format files are not system dependent in general.  Formerly they had
been due to the nasty endian-mess but Karl changed it because on a
live system all platforms have to share the same format files.  Here I
have 32 bit and 64 bit binaries for Linux installed and can switch
between them.  My system supports both.

The problem in your case is that the _content_ of the format files of
the different versions of LuaTeX is different.  Some macros were
added, changed, or removed.  This is what makes them incompatible but
they are still platform independent.

If you still have the setup I suggested, you can try this:

  * move the format files of the new version of LuaTeX to the
    directory containing the binaries.  Make sure to copy the correct
    ones.  If in doubt, generate them again.

  * put a texmf.cnf file into this directory containing the line:

        TEXFORMATS=$SELFAUTOLOC

    The new version of LuaTeX will then search in the directory
    containing the new binaries only.  The original TeX Live (from
    tug.org) will still search in its standard directories.

  * switch to the original TeX Live (from tug.org) and re-create
    all formats again.

  * when the directory containing the new version of LuaTeX is in
    PATH, *never* re-create any formats.  Maybe it's helpful to
    disable fmtutil[-sys] and/or tlmgr so that you can't destroy
    anything by accident.

    	chmod a-x fmtutil* tlmgr

    You can enable them temporarily if needed.

It's also possible to follow Luigi's suggestion.  However, this
requires much more disk space.  Though disk space isn't a problem
nowadays, you have to keep two systems up-to-date.  I don't doubt that
it works but I fear that maintenance is more time-consuming.

Kpathsea makes a TeX installation extremely flexible.  I never
encountered any situation where I had to configure something at
compile-time.  There is almost nothing you can't configure at
runtime.

What you have to know is that kpathsea looks for texmf.cnf files in
various directories and evaluates all of them.  A variable set in one
of them will not be overwritten if set in a file evaluated later.

If you create an extra bin/<platform>/ directory, as I suggested, it's
important to know that kpathsea looks for texmf.cnf files in
SELFAUTOLOC first (the directory containing the *tex executables).
TeX Live doesn't make use of this feature but it's very useful in
some situations, especially in our case.

BTW, kpathsea is well documented

  texdoc kpathsea

but in real life the comments in

  texmf-dist/web2c/texmf.cnf

are extremely helpful as well.

Bruno, please don't give up.  We'll find a reasonable solution,
one way or another.

Regards,
  Reinhard

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Reinhard Kotucha                            Phone: +49-511-3373112
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