bazelbuild/bazel

Documentation issue: General Rules: When to use genrule vs. rule ?

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#12,781 opened on Jan 6, 2021

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P3help wantedteam-Configurabilityteam-Documentationtype: documentation (cleanup)

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Description

Documentation URL: https://docs.bazel.build/versions/master/be/general.html#genrule

This documentation lacks guidance on whether, or in what situations, a rule() should be favored over a genrule() (or vice-versa).

IMHO, rules are preferable because:

  • They can return providers, thus allowing references to their targets to be typechecked.
  • The Make variable syntax of genrules is obscure and harder to look up.
  • They're more explicit in general and support various doc fields for documentation.
  • I seem to recall some quirks around inferring the relevant genrule from an output filename, but perhaps that's been fixed by now.

I guess maybe genrule's terseness could be justified if the target and its generator are one-offs?

But that's just my opinion. I'd prefer official guidance from Bazel Team, hence this issue.

Contributor guide

Research direction
Review the existing documentation on genrule and rule, and provide a comparison of use cases, advantages, and disadvantages.
Tech stack
java
Domain
documentation
Issue type
Documentation
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
2
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Half day
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Stale
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Clear
Prerequisites
Bazel
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
60