`cargo build` for tests builds dependencies with `panic`

[ehuss]

Dependencies for tests should not have panic set from the profile. However, using cargo build (instead of cargo test) does not correctly clear the panic flag for dependencies.

Repro:

cargo new --lib a
cd a
cat >> Cargo.toml <<EOL
[profile.dev]
panic = "abort"
EOL
mkdir tests
echo "extern crate a;" > tests/t1.rs
cargo build --test t1 -v

I can fix this as part of working on profiles if you'd like.

[sfackler]

The test harness requires panic=unwind to work properly.

[alexcrichton]

Hm I'm not sure I entirely understand, but @ehuss I believe @sfackler is right in that if we actually respect the abort option for building tests we'll fail compilation?

[ehuss]

I would expect cargo build --test foo to build the target the same way cargo test --test foo does. Currently it is close. It picks the test profile, etc. However, dependencies don't pick up the test_deps profile in order to clear the panic setting. When you try the given example, rustc aborts with an error because of mixed panic settings.

My profile work "fixes" this, in that panic gets cleared for test dependencies regardless of which command is used.

[alexcrichton]

Aha that makes sense! In that case it'd be great to see this fixed, I definitely agree that cargo build --test foo should work the same way as cargo test --test foo