Propagate --color option to rustc

[matklad]

closes #2740

Will try to add a test for this soon (and fix failing tests if any, compiling/running tests locally is slow :( ).

I am not sure what is the right place to add --color option to the command line. I use build_base_args. process also looks like a good candidate, because it is more general, but if we look at the CommandType we see that only rustc command supports --color.

[rust-highfive]

r? @wycats

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[alexcrichton]

Ah yeah I think this location is fine, other places aren't necessarily invoking the compiler so it probably wants to avoid those directly. Thanks!

With a test r=me

[matklad]

Added the test.

And, OMG, someone has removed the test! macro, and I've just added support for context aware run configurations to IntelliJ Rust, so now I can run a single cargo test under cursor with just one shortcut!

[matklad]

Hm, ironically the tests pass in the IDE and not on the CI, because

        // Use `TermInfo::from_env()` and `TerminfoTerminal::supports_color()`
        // to determine if creation of a TerminfoTerminal is possible regardless
        // of the tty status. --color options are parsed after Shell creation so
        // always try to create a terminal that supports color output. Fall back
        // to a no-color terminal regardless of whether or not a tty is present
        // and if color output is not possible.

so no colors in the IDE with --color always without manually setting up the TERM env variable.

[alexcrichton]

Oh actually, this should implement fmt::Display conventionally instead of ToString directly.

[matklad]

Good to know, thanks!

[alexcrichton]

@bors: r+ 76a48a9

Thanks!

[bors]

⌛ Testing commit 76a48a9 with merge 13861b7...

[bors]

☀️ Test successful - cargo-cross-linux, cargo-linux-32, cargo-linux-64, cargo-mac-32, cargo-mac-64, cargo-win-gnu-32, cargo-win-gnu-64, cargo-win-msvc-32, cargo-win-msvc-64