[Bug]: Hangs on windows?

[alexeagle]

What happened?

https://buildkite.com/bazel/bcr-presubmit/builds/839
is stuck at

(18:38:04) [5 / 7] Compiling //:compile [swc foo.ts]; 4216s local, remote-cache

Running the swc.exe command line manually on windows 10 seems to work fine. My windows machine isn't able to run Bazel 6 due to some dll problem.

Version

HEAD

[alexeagle]

Okay I got the windows machine working and can reproduce the hang.

[alexeagle]

Running swc.exe directly is fine:

c:\Users\Alex\Downloads\swc-win32-x64-msvc.exe 
compile --source-maps false --out-file bazel-out/x64_windows-fastbuild/bin/examples/simple/in.js examples/simple/in.ts

Under Bazel the same command hangs forever:

C:\Users\Alex\Documents\GitHub\rules_swc>bazel build -s examples/simple:all
Starting local Bazel server and connecting to it...
INFO: Analyzed 3 targets (57 packages loaded, 775 targets configured).
INFO: Found 3 targets...
SUBCOMMAND: # //examples/simple:compile [action 'Compiling //examples/simple:compile [swc examples/simple/in.ts]', configuration: 155c9a171140b1c2723aa9fb109eb10bad18c5ea8981c491a294cc417010afe3, execution platform: @local_config_platform//:host]
cd /d C:/users/alex/_bazel_alex/snzorioz/execroot/aspect_rules_swc
external\swc_win32-x64-msvc\swc-win32-x64-msvc.exe compile --source-maps false --out-file bazel-out/x64_windows-fastbuild/bin/examples/simple/in.js examples/simple/in.ts
# Configuration: 155c9a171140b1c2723aa9fb109eb10bad18c5ea8981c491a294cc417010afe3
# Execution platform: @local_config_platform//:host
[7 / 8] Compiling //examples/simple:compile [swc examples/simple/in.ts]; 14s local

I'm not much good at debugging on Windows. In the Task manager I was able to dump the swc.exe process to the attached .DMP file
swcdump.zip

[alexeagle]

@realtimetodie the most obvious explanation is that it's still waiting for input on stdin, perhaps there's a portability problem with your fix in swc-project/swc#6714 - do you have a way to test that change on Windows?

[realtimetodie]

I need some time to setup Bazel on Windows and compile the Rust binary to see what is going on. I found a note for std::io on Windows in non-tty environments. I'm looking into this.

https://doc.rust-lang.org/std/io/fn.stdin.html#note-windows-portability-considerations

[realtimetodie]

Is there a reason why the matrix test only runs on ubuntu-latest? Can this not be expanded? I think this limitation originated from the bazel-contrib template

https://github.com/bazel-contrib/rules-template/blob/0bcaef52fda3e7bcfd8d294fd1a82e5a23a9ad02/.github/workflows/ci.yaml#L39

[alexeagle]

Hm last time we thought about this, it seemed like our GH Actions setup would need us to self-host runners for Mac/Windows. Do you know if GitHub has one or both of those "out of the box"?

[realtimetodie]

I think the CI workflow can be expanded to macos-latest.

I used the ci.yaml from the bazel-contrib template recently for an example repository and expanded the workflow's matrix. It worked for the macos-latest default runner out of the box

https://github.com/realtimetodie/bazel-rust-grpc-aperture/blob/34fe3807fb44ae22d73c6f867e9fc168d83438a1/.github/workflows/ci.yaml#L44

[alexeagle]

Windows falls over pretty early:

[FATAL 20:30:03.203 src/main/cpp/util/path_windows.cc:86] MakeAbsolute(/.github/workflows/ci.bazelrc): AsAbsoluteWindowsPath failed: Unix-style paths are unsupported

https://github.com/aspect-build/rules_swc/actions/runs/3863790892/jobs/6586193651
I guess those runners would need some more work, not sure how much...

[realtimetodie]

the workflows for macos-latest passed at least.

I think for Windows, the path to the ci.bazelrc file needs to be updated in the ci.yaml and the MSYS2 package needs to be installed.

[realtimetodie]

I can reproduce this locally

[realtimetodie]

The problem is that the stdin handle waits for the read stream to finish. But in a non-tty environment on Windows, this never happens when the read stream is empty. I think this is a bug in the std::io module.