The "principal" parser is the one and only today; in the future we hope to
have multiple parsers to execute fish script in parallel.
Having a globally accessible "principle" parser is suspicious; now we can
get rid of it.
The "principal" environment stack was the one that was associated with the
"principal" parser and would dispatch changes like to TZ, etc.
This was always very suspicious, as a global; now we can remove it.
FISH_BUILD_DIR (nominally, ./build) is created by cmake. If you only check out
the project via git and then run `cargo build`, this directory won't exist and
many of the tests will fail.
See the changelog additions for user-visible changes.
Since we enable/disable terminal protocols whenever we pass terminal ownership,
tests can no longer run in parallel on the same terminal.
For the same reason, readline shortcuts in the gdb REPL will not work anymore.
As a remedy, use gdbserver, or lobby for CSI u support in libreadline.
Add sleep to some tests, otherwise they fall (both in CI and locally).
There are two weird failures on FreeBSD remaining, disable them for now
https://github.com/fish-shell/fish-shell/pull/10359/checks?check_run_id=23330096362
Design and implementation borrows heavily from Kakoune.
In future, we should try to implement more of the kitty progressive
enhancements.
Closes#10359
In particular, this allows restoring the terminal on crashes, which is
feasible now that we have the panic handler. Since std::process::exit() skips
destructors, we need to reshuffle some code. The "exit_without_destructors"
semantics (which std::process::exit() als has) was mostly necessary for C++
since Rust leaks global variables by default.
