Code changes for the new Clippy version and running test on Windows

[utpilla]

Changes

• There's a newer version of the rust toolchain which brings in newer clippy lints:

  • https://rust-lang.github.io/rust-clippy/master/index.html#/implied_bounds_in_impls
  • https://rust-lang.github.io/rust-clippy/master/index.html#/assigning_clones
  • https://rust-lang.github.io/rust-clippy/master/index.html#/unnecessary_clippy_cfg
  • https://rust-lang.github.io/rust-clippy/master/index.html#/let_unit_value

• Fix some tests to resolve the complaints from cargo test on Windows

After these changes, the commands specified in the test.sh file run successfully on Windows:

cargo test --workspace --all-features "$@" -- --test-threads=1

# See https://github.com/rust-lang/cargo/issues/5364
cargo test --manifest-path=opentelemetry/Cargo.toml --no-default-features

# Run global tracer provider test in single thread
cargo test --manifest-path=opentelemetry/Cargo.toml --all-features -- --ignored --test-threads=1

cargo test --manifest-path=opentelemetry/Cargo.toml --all-features
cargo test --manifest-path=opentelemetry-jaeger/Cargo.toml --all-features -- --test-threads=1
cargo test --manifest-path=opentelemetry-zipkin/Cargo.toml --all-features

[utpilla]

These tests use use std::os::unix::fs::PermissionsExt which cannot be used on Windows.

[TommyCpp]

why force_flush here?

[utpilla]

Just to trigger the callback code deterministically. This lets us assert things on the receiver end with certainty instead of waiting for interval * 2 milliseconds and hoping that the sender sends the data in that time.

[utpilla]

This is to suppress the clippy warning for the struct not being constructed. Check this for more details: https://github.com/open-telemetry/opentelemetry-rust/actions/runs/8943870592/job/24569519425?pr=1704

[lalitb]

I think the issue is that this module test_http_client is always defined, while used only when the feature rt-tokio is enabled. Should we define this module only when the rt-tokio is enabled?

#[cfg(test)]
#[cfg(feature = "rt-tokio")]
pub(crate) mod test_http_client {
    ..
}

[utpilla]

That's a good idea. Covered this in #1711

[lalitb]

LGTM apart from the nit comment. Thanks for fixing the rust toolchain upgrade issues also :)

[TommyCpp]

👍 Thanks for the fix