Nixpkgs: When installing xetex (in TeXLive) the font cache is not initialized properly

[StefanSchroeder]

The TeXLive manual has a nice section on (Testing the installation). In step 8, the user is instructed to run

xetex opentype-info.tex

The file is part of the package xetexfontinfo

This command fails with the error:

“Invalid fontname ‘Latin Modern Roman/ICU’…”,

The same manual covers this error in section 3.4.4.

It says there:

```
To facilitate this, when the xetex package is installed (either at initial installation or later), the necessary configuration file is created in TEXMFSYSVAR/fonts/conf/texlive-fontconfig.conf.

To set up the TeX Live fonts for system-wide use (assuming you have suitable privileges), proceed as follows:

Copy the texlive-fontconfig.conf file to /etc/fonts/conf.d/09-texlive.conf.
Run fc-cache -fsv.

If you do not have sufficient privileges to carry out the steps above, or if you want to make the TeX Live fonts available to only one user, you can do the following:

Copy the texlive-fontconfig.conf file to ~/.fonts.conf, where ~ is your home directory.
Run fc-cache -fv.

```

But even after installing the Full-scheme of TeXLive I was unable to locate the file texlive-fontconfig.conf as described in the manual.

Running fc-cache as root or user does not help.

Perhaps this can be fixed for TL2020 #91994

@veprbl
@TredwellGit

Thanks

[Mathnerd314]

Here is the code that makes the fontconfig file: https://www.tug.org/texlive//Contents/live/tlpkg/tlpostcode/xetex.pl

It looks like you need to add the directories in $texdir/texmf-dist/fonts to the font path list, config.fonts.fonts in NixOS:

      for my $t (qw/opentype truetype type1/) {
        print FONTSCONF "  <dir>$texdir/texmf-dist/fonts/$t</dir>\n";
      }

[veprbl]

I think the solution by @Mathnerd314 is the correct one, you need to have the fonts installed to locate them by name instead of a path. So adding "${texlive.combined.scheme-full}/share/texmf/fonts" or lmodern to fonts.fonts should do the trick.

[StefanSchroeder]

Thanks for the quick response. I will give it a try and let you know here if it worked. When it works I'll try to assemble my first PR from it.

[newkozlukov]

Hi @Mathnerd314,
do you mean modification of the global environment, triggered by texlive installation? The fonts.fonts solution is NixOS-specific, how would one go about it on a non-NixOS system?

Thanks

_Aside: I tried skimming through fontconfig manuals in search for environment variables to modify search paths at runtime but had no luck_

[Mathnerd314]

From https://discourse.nixos.org/t/fonts-in-nix-installed-packages-on-a-non-nixos-system/5871/7 it seems the magic variable is FONTCONFIG_FILE.

@StefanSchroeder any luck trying it out?

[newkozlukov]

@Mathnerd314 this is most amusing and has saved my day!

For the context, I'm using nix to build a LaTeX project, so I had a default.nix file with mkDerivation which would just produce a pdf file. I found a makeFontsConf function in nixpkgs, so the final modification required was:

# ...
let
  myTexlive = with pkgs.texlive; (
    combine { /* ... */ }
  );
  fontsConf = pkgs.makeFontsConf {
    fontDirectories = [ 
      "${myTexlive}/share/texmf/"
    ];
  };
in
{
  myPdf = stdenv.mkDerivation {
    # ...
    buildInputs = [ myTexlive ];
    FONTCONFIG_FILE = fontsConf; # this sets an environment variable visible in buildPhase
    # ...
    };
}

[StefanSchroeder]

@Mathnerd314 I'm on vacation right now with no access to anything else than my cell phone. Will let you know as soon as I return. Thank you for keeping the ball rolling.

[StefanSchroeder]

@Mathnerd314 I confirm that the error is resolved by adding 'lmodern' to fonts.fonts in configuration.nix. I wonder if this could be implemented to be resolved automatically when installing the package xetexfontinfo which requires it. I haven't tried the suggestion by @newkozlukov, as the simple change did the job.