Allow passing env files to build script runtime env

[dzbarsky]

Fixes #3625, see that issue for explanation

[UebelAndre]

Thanks! Can you add a regression test for this?

[dzbarsky]

Thanks! Can you add a regression test for this?

Yeah, I wasn't sure the best way to test this. Ideally we would have some e2e cargo_universe tests but I didn't see them (maybe I missed them)? I can add a unit test for this attribute though, it would be better than nothing

[UebelAndre]

Thanks! Can you add a regression test for this?

Yeah, I wasn't sure the best way to test this. Ideally we would have some e2e cargo_universe tests but I didn't see them (maybe I missed them)? I can add a unit test for this attribute though, it would be better than nothing

Well the straight forward one is the change to cargo_build_script where you can generate an env file and make sure that's set where you expect it. For crate_universe that's a bit more complicated...

[dzbarsky]

Thanks! Can you add a regression test for this?

Yeah, I wasn't sure the best way to test this. Ideally we would have some e2e cargo_universe tests but I didn't see them (maybe I missed them)? I can add a unit test for this attribute though, it would be better than nothing

Well the straight forward one is the change to cargo_build_script where you can generate an env file and make sure that's set where you expect it. For crate_universe that's a bit more complicated...

Yep that's what I ended up implementing, PTAL :)

[UebelAndre]

Thanks!