add example for multi-arch binary #160
Conversation
juliexxia
requested review from
gregestren
and removed request for
laurentlb,
brandjon and
c-parsons
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I guess checks won't pass until the logic is in bazel... |
| implementation = _rule_impl, | ||
| attrs = { | ||
| "tool": attr.label(cfg = fat_transition), | ||
| '_whitelist_function_transition': attr.label( |
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Let's comment why this is here, and in every other example that uses this attribute. I know users have been confused by it before.
Do we have a good canonical link to reference that explains this?
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Good idea. How does https://docs.bazel.build/versions/master/skylark/config.html#user-defined-transitions sound? it's where I've been linking to for other stuff.
| # The values of `x86_dep` and `armeabi-v7a_dep` here are regular | ||
| # dependencies with providers. | ||
| x86_dep = tools['x86-platform'] | ||
| armeabi_v7a_dep = tools['armeabi-v7a-platform'] |
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I have an idea that makes the example a bit more elaborate, but could really drive the point home by showing explicitly in the output what's going on.
What about having _impl below return a provider with a string based on its CPU, like SimpleProvider(my_info= "My CPU is X"). Then have print() statements in _rule_impl that say "tools['x86-platform'] provider says: <whatever that instance of the provider says".
If it's unclear what I'm saying, let me know and I'll share some more specific code snippets to demonstrate.
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That makes sense to me - do you mean by somehow pulling the cpu out of ctx? Is that possible? I know about ctx.fragments but I don't think cpu lives in any of those: https://docs.bazel.build/versions/master/skylark/lib/skylark-configuration-fragment.html
If we wanted to not use cpu/a native option and do a starlark option this would definitely be possible but I feel like it would be nice to keep this example simple AND i feel like cpu really hits home with people for this example.
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Oh, and if |
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Check out bazelbuild/bazel#11077. This might actually get released soon. |
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I temporarily disabled it with a TODO back to this issue to re-enable when the release happens |
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Added cpu printouts! |
Final step for bazelbuild/bazel#5575
Note - this logic isn't actually released in bazel yet but I think it's fine to document it prematurely.