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Const-eval array lengths in rustdoc. #46894

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merged 2 commits into from
Dec 24, 2017

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@detrumi detrumi commented Dec 20, 2017

Fixes #46727
r? @eddyb

Big thanks to @eddyb for helping me figure this out.

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@eddyb eddyb changed the title Const-eval TyArray trait implementors Const-eval array lengths in rustdoc. Dec 20, 2017
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eddyb commented Dec 20, 2017

@bors r+

cc @GuillaumeGomez

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bors commented Dec 20, 2017

📌 Commit d5b1119 has been approved by eddyb

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No tests? :'(

@kennytm kennytm added the S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. label Dec 21, 2017
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eddyb commented Dec 21, 2017

@bors r-

@GuillaumeGomez Can you help with the tests? I have no idea how rustdoc tests work.

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detrumi commented Dec 21, 2017

Creating a test at src/test/rustdoc/issue-46727.rs seems straightforward enough.

I have more problems with reproducing the problem in a test case.
When trying to use the array_impl_foo macro for some Foo trait, the docs show it as Implementations on Foreign Types instead of Implementors, and it won't reproduce the problem.

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eddyb commented Dec 21, 2017

@detrumi Try impl Foo for Bar<[T; 1 + 1 + 1]> {} where Foo and Bar are defined in the test.

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detrumi commented Dec 21, 2017

@eddyb You mean this?

pub trait Foo {}
pub struct Bar<T> { x: T }
impl<T> Foo for Bar<[T; 1 + 1 + 1]> {}

That just produces impl<T> Foo for Bar<[T; 3]>

Unless I'm mistaken, the problem only occurs because of the macro. However, this doesn't trigger it:

pub trait Foo {}
pub struct Bar<T> { x: T }
macro_rules! impl_foo {
    {$n:expr, $t:ident $($ts:ident)*} => {
        impl<T> Foo for Bar<[T; $n]> {}
        impl_foo!{($n - 1), $($ts)*}
    };
    {$n:expr,} => {
        impl<T> Foo for Bar<[T; $n]> {}
    };
}
impl_foo!{32, T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T}

(adapted from the macro here)

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eddyb commented Dec 21, 2017

The macro shouldn't affect it at all. I guess it's because of cross-crate inlining, so maybe just #[doc(inline)] a reexport with one of those impls from libcore and it might show up?

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QuietMisdreavus commented Dec 21, 2017

You can set up auxiliary builds in rustdoc tests to test for this. Set up the impls in src/test/rustdoc/auxiliary/issue-46727.rs, and then in src/test/rustdoc/issue-46727.rs, add a // aux-build:issue-46727.rs comment to the top so compiletest will link it in properly. You may need to add a #![crate_name="something"] to one or both crates to make sure their names don't clash. Then you can re-export whatever you need in src/test/rustdoc/issue-46727.rs and make tests off it in there.

EDIT: Here's an example of a really simple auxiliary build, for the doc(include) stuff.

@kennytm kennytm added S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. and removed S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. labels Dec 21, 2017
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detrumi commented Dec 23, 2017

Re-exporting did the trick, without needing #[doc(inline)].
I couldn't get #![crate_name="something"] working in this instance, but using compile-flags: -Cmetadata=aux, which was used in other auxiliary tests, made it work.

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eddyb commented Dec 23, 2017

@bors r+

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bors commented Dec 23, 2017

📌 Commit d10d389 has been approved by eddyb

@kennytm kennytm added S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. and removed S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Dec 23, 2017
kennytm added a commit to kennytm/rust that referenced this pull request Dec 23, 2017
Const-eval array lengths in rustdoc.

Fixes rust-lang#46727
r? @eddyb

Big thanks to @eddyb for helping me figure this out.
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bors commented Dec 24, 2017

⌛ Testing commit d10d389 with merge 304717b...

bors added a commit that referenced this pull request Dec 24, 2017
Const-eval array lengths in rustdoc.

Fixes #46727
r? @eddyb

Big thanks to @eddyb for helping me figure this out.
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bors commented Dec 24, 2017

☀️ Test successful - status-appveyor, status-travis
Approved by: eddyb
Pushing 304717b to master...

@bors bors merged commit d10d389 into rust-lang:master Dec 24, 2017
@detrumi detrumi deleted the fix-const-eval-trait branch January 31, 2021 13:08
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7 participants