extended information for slice pattern errors (E0527 through E0529)

[zackmdavis]

r? @GuillaumeGomez

[GuillaumeGomez]

This code throws E0308 on nightly as it seems.

[GuillaumeGomez]

Now it does.

[GuillaumeGomez]

Have you tested your code on nightly?

[zackmdavis]

That's strange! What specific nightly are you on? I composed these against 5c2a5d4 2016-06-11, and it looks like they still behave the same against bb4a79b 2016-06-15 (which multirust update nightly just gave me right now):

zmd@ExpectedReturn:~/Code/Misc$ rustc --version
rustc 1.11.0-nightly (bb4a79b08 2016-06-15)
zmd@ExpectedReturn:~/Code/Misc$ cat e0527.rs 
#![feature(slice_patterns)]

fn main() {
    let r = &[1, 2, 3, 4];
    match r {
        &[a, b] => { // error: pattern requires 2 elements but array
                     //        has 4
            println!("a={}, b={}", a, b);
        }
    }
}
zmd@ExpectedReturn:~/Code/Misc$ rustc e0527.rs 
e0527.rs:6:10: 6:16 error: pattern requires 2 elements but array has 4 [E0527]
e0527.rs:6         &[a, b] => { // error: pattern requires 2 elements but array
                    ^~~~~~
error: aborting due to previous error
zmd@ExpectedReturn:~/Code/Misc$ cat e0528.rs 
#![feature(slice_patterns)]

fn main() {
    let r = &[1, 2];
    match r {
        &[a, b, c, rest..] => { // error: pattern requires at least 3
                                //        elements but array has 2
            println!("a={}, b={}, c={} rest={:?}", a, b, c, rest);
        }
    }
}
zmd@ExpectedReturn:~/Code/Misc$ rustc e0528.rs 
e0528.rs:6:10: 6:27 error: pattern requires at least 3 elements but array has 2 [E0528]
e0528.rs:6         &[a, b, c, rest..] => { // error: pattern requires at least 3
                    ^~~~~~~~~~~~~~~~~
error: aborting due to previous error
zmd@ExpectedReturn:~/Code/Misc$ cat e0529.rs 
#![feature(slice_patterns)]

fn main() {
    let r: f32 = 1.0;
    match r {
        [a, b] => { // error: expected an array or slice, found `f32`
            println!("a={}, b={}", a, b);
        }
    }
}
zmd@ExpectedReturn:~/Code/Misc$ rustc e0529.rs 
e0529.rs:6:9: 6:15 error: expected an array or slice, found `f32` [E0529]
e0529.rs:6         [a, b] => { // error: expected an array or slice, found `f32`
                   ^~~~~~
error: aborting due to previous error

[zackmdavis]

Also, Travis points out that I made a syntax error (which I suppose is only just punishment for relying on CI instead of building it locally); I'll (force-)push a fix for that later.

[GuillaumeGomez]

I tried on play.rust-lang.org. So maybe the nightly version isn't up-to-date. Don't really know. I'll retry once you'll update it.

[zackmdavis]

@GuillaumeGomez Force-pushed to fix syntax. The playpen was very out of date, but has been fixed now (rust-lang/rust-playpen#215).

[zackmdavis]

Force-pushed again because the corrected code samples were failing tests due to the lack of the #![feature(slice_patterns)] attribute. I've marked them as ignore because I had deliberately left the attribute out because it's already in the erroneous code samples just above and I want to conserve vertical terminal space for people running --explain.

[GuillaumeGomez]

Please add "E0527 flag", like this:

```compile_fail,E0527

[GuillaumeGomez]

About the error code flags, take a look here for more information.

[zackmdavis]

(added error code flags)

[GuillaumeGomez]

Everything looks good. Can you make a commit for each error code explanation please? (So 3 commits in total.)

[zackmdavis]

@GuillaumeGomez Force-pushed with error code test directives squashed into the individual per-extended-error commits (and rebased on master). I regret the delay.

[GuillaumeGomez]

No need for main function.

[GuillaumeGomez]

No problem. A few nits to fix and it should be good to go!

[bors]

☔ The latest upstream changes (presumably #34365) made this pull request unmergeable. Please resolve the merge conflicts.

[bors]

💣 Buildbot returned an error: <span>exceptions.KeyError</span>: <span>'auto-linux-64-opt-mir'</span>

[bors]

⌛ Testing commit e960021 with merge 505842a...

[bors]

💔 Test failed - auto-win-msvc-64-opt-no-mir

[alexcrichton]

@bors: retry

• mk: Only pass -Zorbit=off in stage1/2 #35187

On Tue, Aug 2, 2016 at 12:05 PM, bors notifications@github.com wrote:

💔 Test failed - auto-win-msvc-64-opt-no-mir
https://buildbot.rust-lang.org/builders/auto-win-msvc-64-opt-no-mir/builds/0

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