mark few deps as optional, which is used only from some features

[klensy]

No description provided.

[djc]

Makes sense, thanks! Have you looked at whether there is CI coverage of the various possible feature sets?

[klensy]

No, i didn't checked CI, only manually grepped sources for usage and tried to build with curl/reqwest backends.

[rami3l]

@djc cargo-all-features in our CI seems to be working.

Thanks a lot @klensy!

[djc]

Yeah, I was wondering about the --no-default-features case.

[rami3l]

Yeah, I was wondering about the --no-default-features case.

@djc It would surprise me if cargo-all-features considers default features at all.

Turns out that's indeed not the case:
https://github.com/frewsxcv/cargo-all-features/blob/fe252f463d6cf2969bf7ce5f911cc6222bc80c9d/src/test_runner.rs#L25

[djc]

I meant I was wondering if we have CI coverage of compiling with no default features.

[djc]

And the answer is no, because:

#[cfg(all(not(feature = "reqwest-backend"), not(feature = "curl-backend")))]
compile_error!("Must enable at least one backend");

[rami3l]

And the answer is no, because:

#[cfg(all(not(feature = "reqwest-backend"), not(feature = "curl-backend")))]
compile_error!("Must enable at least one backend");

@djc That case has been explicitly excluded to prevent CI failure:

rustup/Cargo.toml

Lines 193 to 195 in f26d16b

	[package.metadata.cargo-all-features]
	# Building with no web backend will error.
	always_include_features = ["reqwest-backend", "reqwest-rustls-tls"]

Apart from that, our cargo-all-features CI does test all possible feature combinations since it always adds --no-default-features to the call, as mentioned in #3774 (comment).

PS: You have probably misunderstood me: when I say cargo-all-features I mean the test plugin to ensure all feature combinations compile, rather than the cargo flag named --all-features.