Missing information about Python dependencies in GettingStarted.md

[jpc-sf]

Description

I am following the Getting Started Guide for building the project, but got the following build error. I ran pip install sphinx to fix this.

The Guide should include a step to install Python dependencies.

[60/1812][  3%][1.865s] Building HTML documentation
FAILED: docs/CMakeFiles/docs_html /Volumes/src/swift-project/build/Ninja-RelWithDebInfoAssert/swift-macosx-arm64/docs/CMakeFiles/docs_html
cd /Volumes/src/swift-project/swift/docs && /Users/jpc/.pyenv/shims/sphinx-build -D latex_elements.papersize=letter -d /Volumes/src/swift-project/build/Ninja-RelWithDebInfoAssert/swift-macosx-arm64/doctrees -b html . /Volumes/src/swift-project/build/Ninja-RelWithDebInfoAssert/swift-macosx-arm64/docs/html
pyenv: sphinx-build: command not found

The `sphinx-build' command exists in these Python versions:
  3.9.6

Reproduction

pip uninstall sphinx
utils/build-script --skip-build-benchmarks \
  --swift-darwin-supported-archs "$(uname -m)" \
  --release-debuginfo --swift-disable-dead-stripping \
  --bootstrapping=hosttools

Expected behavior

I expected the Getting Started Guide to contain all the information I needed to get started.

Environment

n/a

Additional information

No response

[tbkka]

A Pull Request with suggested updates would be appreciated. I'm happy to review any such changes, just CC me on the PR.

[MaxDesiatov]

Do you have sphinx installed? I suspect this issue is not reproducible otherwise, and in that sense sphinx-build is an optional dependency. FWIW we don't publish sphinx documentation anywhere, it's a dead code path in the build script, and there's ongoing work to migrate documentation to DocC.

[MaxDesiatov]

Ah, I see you have it uninstalled first in your repro steps. Either way, it seems like there's something specific to your environment that triggers this sphinx-build codepath. I don't have sphinx installed, building on a relatively clean and fresh latest macOS and Xcode releases, I never ran pip install sphinx, and it builds fine with the steps from GettingStarted.md.