Improve "Building compiler artifacts" output

[jyn514]

Right, now x build --dry-run outputs something like this:

Building stage0 library artifacts (x86_64-apple-darwin -> x86_64-apple-darwin)
Copying stage0 library from stage0 (x86_64-apple-darwin -> x86_64-apple-darwin / x86_64-apple-darwin)
Building stage0 compiler artifacts (x86_64-apple-darwin -> x86_64-apple-darwin)
Copying stage0 rustc from stage0 (x86_64-apple-darwin -> x86_64-apple-darwin / x86_64-apple-darwin)
Assembling stage1 compiler (x86_64-apple-darwin)
Building stage1 library artifacts (x86_64-apple-darwin -> x86_64-apple-darwin)
Copying stage1 library from stage1 (x86_64-apple-darwin -> x86_64-apple-darwin / x86_64-apple-darwin)
Building stage1 tool rust-analyzer-proc-macro-srv (x86_64-apple-darwin)
Building rustdoc for stage1 (x86_64-apple-darwin)

There are a few things here that are not ideal.

• x86_64-apple-darwin -> x86_64-apple-darwin doesn't give a lot of info and is very noisy. We should only print it when the host and target are different.
• "Building stage0 compiler artifacts" is very unclear that stage0 is the one doing the compiling.

I'd like to change this to something like Building compiler artifacts (stage0 -> stage1) when the target/host are the same and Building compiler artifacts (stage0: x86_64-apple-darwin -> stage1: x86_64-unknown-linux-gnu) when they're different.

[mattjperez]

@rustbot claim

[mattjperez]

@jyn514 How's?

# ./x.py build --dry-run
Building library artifacts (stage0 -> stage1)
Copying stage0-library artifacts to stage0 sysroot
Building compiler artifacts (stage0 -> stage1)
Copying stage0-rustc artifacts to stage0 sysroot
Assembling stage1 compiler (x86_64-unknown-linux-gnu)
Building library artifacts (stage1 -> stage2)
Copying stage1-library artifacts to stage1 sysroot
Building stage1 tool rust-analyzer-proc-macro-srv (x86_64-unknown-linux-gnu)
Building rustdoc for stage1 (x86_64-unknown-linux-gnu)

# ./x.py build --target x86_64-apple-darwin --dry-run
Building library artifacts (stage0 -> stage1)
Copying stage0-library artifacts to stage0 sysroot
Building compiler artifacts (stage0 -> stage1)
Copying stage0-rustc artifacts to stage0 sysroot
Assembling stage1 compiler (x86_64-unknown-linux-gnu)
Building library artifacts (stage1: x86_64-unknown-linux-gnu -> stage2: x86_64-apple-darwin)
Copying stage1-library artifacts to stage1 sysroot
Building library artifacts (stage1 -> stage2)
Copying stage1-library artifacts to stage1 sysroot
Building stage1 tool rust-analyzer-proc-macro-srv (x86_64-unknown-linux-gnu)
Building rustdoc for stage1 (x86_64-unknown-linux-gnu)

There isn't an associated target_compiler.stage when building library and compiler artifacts, so I'm just +1'ing for filler atm.

[jyn514]

This is a good start, thanks! I have a few comments:

• for the standard library, the build compiler and the target library will always be numbered the same (even if they might not be in the same sysroot), so you don't need an arrow, just "Building stage0 library artifacts".
• The Copying step should either be named after the folder in build/host/ or the description in the "Building" step; right now it's not consistent with either. I personally would be ok with just removing it altogether: right now, the only time when it's different from Building is for tools, and people regularly ask on Zulip why tools don't show up in the sysroot so clearly "Copying only doesn't show up when building tools" is too subtle for it to be helpful.
• I think we can remove the (x86_64-unknown-linux-gnu) output for Assemble and tools when it's the same as the host, like you've already done for the compiler and standard library.
• "Building stage1 tool proc-macro-server" and "Building rustdoc for stage1" would ideally use the same wording.
• All the tools are numbered differently than the host compiler so they should also show a stage arrow. For example rustdoc should show "Building rustdoc artifacts (stage0 -> stage1)"

[mattjperez]

Added your suggestions

# ./x.py build --dry-run
Building stage0 library artifacts
Building stage0 compiler artifacts
Assembling stage1 compiler
Building stage1 library artifacts
Building tool rust-analyzer-proc-macro-srv (stage0 -> stage1)
Building rustdoc (stage0 -> stage1)

# ./x.py build --target x86_64-apple-darwin --dry-run
Building stage0 library artifacts
Building stage0 compiler artifacts
Assembling stage1 compiler
Building stage1 library artifacts (x86_64-unknown-linux-gnu -> x86_64-apple-darwin)
Building stage1 library artifacts
Building tool rust-analyzer-proc-macro-srv (stage0 -> stage1)
Building rustdoc (stage0 -> stage1)

[jyn514]

That looks great! The last thing I would do is

• Add (stage0 -> stage1) for compiler artifacts, just like you have for rustdoc :)
• Show "host" (or maybe just x86_64-unknown-linux-gnu -> x86_64-unknown-linux-gnu?) for the standard library when the target and host are the same, but we're building for multiple targets (where you have Building stage1 library artifacts in the second output)

[mattjperez]

At least for the actual function in src/bootstrap/compiler.rs that generates the output, it doesn't appear to have context if there are multiple targets or only one. So it seems like for now printing the host is the most straightforward approach.

# ./x.py build --dry-run
Building stage0 library artifacts (x86_64-unknown-linux-gnu)
Building compiler artifacts (stage0 -> stage1)
Assembling stage1 compiler
Building stage1 library artifacts (x86_64-unknown-linux-gnu)
Building tool rust-analyzer-proc-macro-srv (stage0 -> stage1)
Building rustdoc (stage0 -> stage1)

# ./x.py build --target x86_64-apple-darwin --dry-run
Building stage0 library artifacts (x86_64-unknown-linux-gnu)
Building compiler artifacts (stage0 -> stage1)
Assembling stage1 compiler
Building stage1 library artifacts (x86_64-unknown-linux-gnu -> x86_64-apple-darwin)
Building stage1 library artifacts (x86_64-unknown-linux-gnu)
Building tool rust-analyzer-proc-macro-srv (stage0 -> stage1)
Building rustdoc (stage0 -> stage1)

[jyn514]

That looks amazing, thank you!

[mattjperez]

Latest output

➜ ./x.py build --target x86_64-apple-darwin --stage 2 compiler/rustc --dry-run
Building bootstrap
    Finished dev [unoptimized] target(s) in 0.03s
Building stage0 library artifacts (x86_64-unknown-linux-gnu)
Building compiler artifacts (stage0 -> stage1)
Assembling stage1 compiler
Building stage1 library artifacts (x86_64-unknown-linux-gnu)
Building compiler artifacts (stage1 -> stage2)
Assembling stage2 compiler
Uplifting library (stage1 -> stage2)
Uplifting rustc (stage1 -> stage3)