./x.py build --help gives misleading help

[jsgf]

$ ./x.py build --help
[...]
    For a quick build of a usable compiler, you can pass:

        ./x.py build --stage 1 src/libtest

But in practice:

$ ./x.py build --stage 1 src/libtest
Updating only changed submodules
Submodules updated in 0.13 seconds
    Finished dev [unoptimized] target(s) in 0.15s
thread 'main' panicked at 'Error: no rules matched src/libtest.', src/bootstrap/builder.rs:231:21
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace.
failed to run: /data/users/jsgf/third-party2/rust/build/bootstrap/debug/bootstrap build --stage 1 src/libtest
Build completed unsuccessfully in 0:00:01

Should this still work, or is the help message wrong?

[mati865]

I think it stopped working after #63637 and the message should be updated.

[JohnTitor]

Should be ./x.py build --stage 1 src/libstd?

[Mark-Simulacrum]

We should probably change all_krates("std") to all_krates("test")` in a few places -- notably here

rust/src/bootstrap/compile.rs

Line 42 in 7e0afda

run.all_krates("std")

and in a similar place in check.rs