miri can't run single tests

[djugei]

I can't seem to find a way to make miri run just a subset of my tests.
cargo miri test always runs all of them and i don't see a way to cut that down.

[vakaras]

Have you tried: cargo miri test -- -- <test-name> ?

[RalfJung]

@djugei it would be helpful to know what exact commands you tried.

Also see the docs at https://github.com/rust-lang/miri#using-miri.

[djugei]

i tried cargo miri test -- test-name, but not the double-double-dashes, which work.

literally had to go /second on the docs to find it, there isn't an example of the double-double-dash-syntax. i also read the help text (no info) and the src/bin/miri.rs to have a look at comand line parsing, but thats hand-rolled, uses global state, and i did not look into the deeper function calls.

[RalfJung]

Clearly our docs need improvement, you are not the only one to be confused by this. FWIW, the right file to look at would have been src/bin/cargo-miri.rs, but even there this is not easy to see (Cc #546).

As a start, I'll add the example back to the README... we used to have one I think, but it somehow disappeared.

(Also, it's not global state, we are not that that crazy.^^)

[RalfJung]

Also, the help text (cargo miri --help) does indicate both double-dashes:

Usage:
    cargo miri [subcommand] [options] [--] [<miri opts>...] [--] [<program opts>...]

Looks like this is still not clear enough, maybe we should have examples here, too.

[djugei]

right, i looked at cargo-miri.rs, misremembered.

and you are right, the help text is there, must have overlooked it, guess i expected it to be right after the test-subcommand, also cargo miri --help and cargo miri test --help produce the same output (not more specific for subcommand)

i think the main confusion for me is that its different from how cargo without miri works

cargo run -- arguments
cargo miri run -- -- arguments

cargo test -- arguments
cargo miri test -- -- arguments

[djugei]

i think with those changes i would have found what i was looking for

[RalfJung]

i think the main confusion for me is that its different from how cargo without miri works

Yeah, that's a bit weird. But I don't really see another way as we also need a way to pass flags to Miri.

Maybe we could re-expose all these flags through cargo miri directly so they do not need a --. Or maybe that should be an env var, MIRIFLAGS or so. Though at this point we'd also have a backwards compatibility hazard if we changed this. :/
I opened an issue just for this: #1416

Also not sure if you saw that, I opened a PR to add more examples to the docs: #1415

[djugei]

yeah i closed the issue cause of the pr, thanks for the work!