This is not the most elegant, but will match the SOs in exporting
everything for now. Later we can refine what is public/private to clean
up the interface.
The Nix team has requested that this output format remain unchanged.
I've added a warning to the man page explaining that `nix-instantiate
--eval` output will not parse correctly in many situations.
Previously, there were two mostly-identical value printers -- one in
`libexpr/eval.cc` (which didn't force values) and one in
`libcmd/repl.cc` (which did force values and also printed ANSI color
codes).
This PR unifies both of these printers into `print.cc` and provides a
`PrintOptions` struct for controlling the output, which allows for
toggling whether values are forced, whether repeated values are tracked,
and whether ANSI color codes are displayed.
Additionally, `PrintOptions` allows tuning the maximum number of
attributes, list items, and bytes in a string that will be displayed;
this makes it ideal for contexts where printing too much output (e.g.
all of Nixpkgs) is distracting. (As requested by @roberth in
https://github.com/NixOS/nix/pull/9554#issuecomment-1845095735)
Please read the tests for example output.
Future work:
- It would be nice to provide this function as a builtin, perhaps
`builtins.toStringDebug` -- a printing function that never fails would
be useful when debugging Nix code.
- It would be nice to support customizing `PrintOptions` members on the
command line, e.g. `--option to-string-max-attrs 1000`.
We don't just want to pass `--enable-gc=no`; we also want to make sure
boehmgc is not a dependency. Creating a nix-level configuration option
to do both, and then using that for the CI job, is more robust.
Changes:
- CPP variable is now `USE_READLINE` not `READLINE`
- `configure.ac` supports with new CLI flag
- `package.nix` supports with new configuration option
- `flake.nix` CIs this (along with no markdown)
Remove old Ubuntu 16.04 stop-gap too, as that is now quite old.
Motivation:
- editline does not build for Windows, but readline *should*. (I am
still working on this in Nixpkgs at this time, however. So there will
be a follow-up Nix PR removing the windows-only skipping of the
readline library once I am done.)
- Per
https://salsa.debian.org/debian/nix/-/blob/master/debian/rules?ref_type=heads#L27
and #2551, Debian builds Nix with readline. Now we better support and
CI that build configuration.
This is picking up where #2551 left off, ensuring we test a few more
things not merely have CPP for them.
Co-authored-by: Weijia Wang <9713184+wegank@users.noreply.github.com>
Also move `SourcePath` into `libutil`.
These changes allow `error.hh` and `error.cc` to access source path and
position information, which we can use to produce better error messages
(for example, we could consider omitting filenames when two or more
consecutive stack frames originate from the same file).
* deduplicate installation instructions
- reorder sections to present pinned installation more prominently
- remove outdated notes on the macOS installer rework
- update instructions to handle the installer tarball
Co-authored-by: Travis A. Everett <travis.a.everett@gmail.com>
