Add variables errorline and halferrorline, perhaps

[muzimuzhi]

This would further normalize test files including error messages, in case users have error_line and half_error_line modified on their end.

• Currently l3build provides variable printmaxline which defaults to 79.
• By default error_line = 79 half_error_line = 50, see texmf.cfg in mirror repo texlive-source.
• For the developer of a package, the same effect can be achieved by adding a texmf.cfg local to the (root) package directory, see docs: Clarify where to put texmf.cfg #257. But for a forker of a package, executing export error_line=79; export half_error_line=50 before l3build save or l3build check is cumbersome.

[zauguin]

• Currently l3build provides variable printmaxline which defaults to 79.

• By default error_line = 79 half_error_line = 50, see texmf.cfg in mirror repo texlive-source.

Even though these are the defaults I don't think that they are good values if we decide to set them directly. In the context of l3build all three of these settings don't provide much value and can lead to system differences, so if we change something here they should IMO be set to their respective maximums.

• For the developer of a package, the same effect can be achieved by adding a texmf.cfg local to the (root) package directory, see docs: Clarify where to put texmf.cfg #257. But for a forker of a package, executing export error_line=79; export half_error_line=50 before l3build save or l3build check is cumbersome.

I don't see this point right now. Wouldn't a person forking a package also get the modified texmf.cnf and therefore pick up the settings automatically?

Otherwise there's the option of setting the environment variables directly in the build.lua.

[muzimuzhi]

• For the developer of a package, the same effect can be achieved by adding a texmf.cfg local to the (root) package directory, see docs: Clarify where to put texmf.cfg #257. But for a forker of a package, executing export error_line=79; export half_error_line=50 before l3build save or l3build check is cumbersome.

I don't see this point right now. Wouldn't a person forking a package also get the modified texmf.cnf and therefore pick up the settings automatically?

For example, if I modify error_line locally (for daily use) and tries to run l3build check on a cloned repo that has .tlg files generated with default error_line value, l3build check might fail.