added hie_bios_path_prefix attribute to haskell_repl

[ylecornec]

I added an attribute named hie_bios_path_prefix to the haskell_repl rule to address issue #1432.

This makes it possible for hie-bios to output paths relative to a different folder than the workspace root.

In order to use absolute paths, it is possible to use a placeholder in the prefix,
and then replace it with a call to pwd in the user defined .hie-bios script.

[aherrmann]

That looks good, thank you!

Could you add a test-case as well? We should test both cases: No prefix and some prefix.

Perhaps an sh_test that has a data dependency on a haskell_repl's hie-bios output would work.

[ylecornec]

I added a test case which contains two hs_repl rules, one with the hie_bios_path_prefix option and one without which generate hie-bios files.

Then a sh_test rule check that the prefix appears in the first file, and that if we remove this prefix using sed, then the two files are equals.

Some notes :

• Since the test uses a shell script, I added the dont_test_on_windows tag.
• I also added a newline at the end of the hie-bios files since sed on mac complained about it.
• I left some debug print which can be useful in case the test fails later, is this good practice ?

[aherrmann]

I left some debug print which can be useful in case the test fails later, is this good practice ?

I think it's better to not print this output in the success case and only print it in the failure case.

---

It looks like there's a conflict with master in haskell/repl.bzl. Could you rebase on master?

[aherrmann]

Suggested change

tags = ["dont_test_on_windows"],

This shouldn't be necessary. rules_haskell requires msys2 on Windows anyway, so a bash is availabl. And Bazel can generate executables from .sh scripts on Windows if a bash is a available.

[aherrmann]

Just saw the Windows CI failure:

grep: tests/hie-bios/hie-bios@hie-bios: No such file or directory

I think the issue has to do with runfiles. On Unix Bazel will create a tree of symlinks in the tests working directory pointing to data dependencies. However, on Windows symlinks are not generally available, so instead Bazel generates a runfiles manifest file and code needs to use a runfiles library to query the manifest file for the location of data dependencies. The bash runfiles library is documented here. Example uses can be found in the repository. In tests you can use the TEST_WORKSPACE env-var to find the workspace name, e.g.

file1="$(rlocation "$TEST_WORKSPACE/$1")"

[ylecornec]

Ah I see, thank you.

So I activated the windows test back on and it works with the bash runfiles library.
And now, debug information is only printed in case the test fails.

[aherrmann]

Thank you, looks good!