add help on pattern guard #33260

mrmiywj · 2016-04-28T17:26:46Z

rust-highfive · 2016-04-28T17:27:02Z

Thanks for the pull request, and welcome! The Rust team is excited to review your changes, and you should hear from @nrc (or someone else) soon.

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mrmiywj · 2016-04-28T17:27:19Z

@GuillaumeGomez

GuillaumeGomez · 2016-04-28T18:46:58Z

Thanks for the PR!

However, I don't like the way you did. :-/
Let me explain: I think the best solution would be to rewrite the whole error explanation in order to show the two ways (by insisting on the first issue and demonstrating that in some cases we can fix it just by using reference). For now, it just comes out like "in this very specific example, you can also fix it this way".

mrmiywj · 2016-04-28T18:54:53Z

I thought providing solution is enough. Yep u r right. To emphasize the two ways, it's better to rewrite the whole explanation.
But I'm not sure what's the optimized solution to the second situation in which the value is consumed in the pattern guard. Using &self in the function? Or any other ideas?
Thank you for your attention!

GuillaumeGomez · 2016-04-28T20:11:14Z

You can't unfortunately. I see two solutions to avoid this issue:

Cloning the type.
Setting a boolean and then, depending on this value, consume the type.

If someone else has something in mind, I'd be glad to hear it! :)

mrmiywj · 2016-04-29T05:22:55Z

Thx for your reply!
I wrote two solutions to the two different situation in the issue. Is it Ok? Hmm, I'm not an experienced rust programmer, so I'm not sure these two solutions actually solve the two different errors.

#1
#2

GuillaumeGomez · 2016-04-29T08:47:27Z

You forgot the third case: when you can't clone. ;)

Otherwise that's it!

mrmiywj · 2016-04-29T13:11:25Z

Hmm, according to this rfc, I don't think there is any other solutions except use non-consume function when you can't clone? Like this

I'm sorry I don't understand "Setting a boolean and then, depending on this value, consume the type." I think if I call a consuming function, then the ownership is moved, so it will cause errors...

GuillaumeGomez · 2016-04-29T17:34:56Z

The goal is to move the consuming function call outside of the closure. But I think it's just too much precise to be used. Let's not consider it.

mrmiywj · 2016-04-29T17:39:38Z

Yep, it's a too-specific situation. Just the two examples are enough.

GuillaumeGomez · 2016-04-29T17:42:32Z

I let you handle it then! :)

mrmiywj · 2016-04-30T16:37:30Z

/cc @GuillaumeGomez Hope for your advice! It's my first PR to rust!

GuillaumeGomez · 2016-05-01T12:14:54Z

src/librustc_const_eval/diagnostics.rs


-```compile_fail
+The problem above can be solve by using `ref` keyword.


The problem above can be solve by using ref keyword.

"The problem above can be solved by using the ref keyword."

GuillaumeGomez · 2016-05-01T12:18:11Z

Except for the nits, it seems all good. Great job! Ping me once corrected and squashed.

mrmiywj · 2016-05-01T15:03:35Z

/cc @GuillaumeGomez
Thx! This my first PR to rust! I hope I can contribute to it from now on!

GuillaumeGomez · 2016-05-01T17:37:07Z

A line of your commit is longer than 80 columns. If you want to check issues like this, you can use make tidy. Once fixed, it's good to merge!

Thx! This my first PR to rust! I hope I can contribute to it from now on!

I hope so as well! :)

mrmiywj · 2016-05-01T17:55:13Z

/cc @GuillaumeGomez
I hope this a good start!

GuillaumeGomez · 2016-05-01T20:47:34Z

src/librustc_const_eval/diagnostics.rs

-reference when using guards or refactor the entire expression, perhaps by
-putting the condition inside the body of the arm.
+Though this example seems innocuous and easy to solve, the problem becomes clear
+when it encounters functions which consume the value.


Hum... Finally, this sounds better with ":". Can you change "consume the value." to "consume the value:" please?

GuillaumeGomez · 2016-05-01T20:48:03Z

Sorry, one last nit and ready to get merged!

Manishearth · 2016-05-02T22:16:29Z


failures:

---- Rust_Compiler_Error_Index_13 stdout ----
    <anon>:13:14: 13:15 error: cannot bind by-move into a pattern guard [E0008]
<anon>:13         Some(y) if y.clone().consume() > 0 => {}
                       ^
error: aborting due to previous error
thread 'Rust_Compiler_Error_Index_13' panicked at 'Box<Any>', /buildslave/rust-buildbot/slave/auto-linux-64-opt-rustbuild/build/src/libsyntax/errors/mod.rs:614
thread 'Rust_Compiler_Error_Index_13' panicked at 'couldn't compile the test', /buildslave/rust-buildbot/slave/auto-linux-64-opt-rustbuild/build/src/librustdoc/test.rs:276


failures:
    Rust_Compiler_Error_Index_13

test result: FAILED. 427 passed; 1 failed; 45 ignored; 0 measured

Rollup of 14 pull requests - Successful merges: #32756, #33129, #33225, #33260, #33309, #33320, #33323, #33324, #33325, #33330, #33332, #33334, #33335, #33346 - Failed merges:

fix too long column fix typo of help on pattern guard one nit fix compile fail

mrmiywj · 2016-05-03T02:03:01Z

/cc @GuillaumeGomez @steveklabnik
My bad. I'm too careless. Fix it now.

Rollup of 14 pull requests - Successful merges: #32756, #33129, #33225, #33260, #33309, #33320, #33323, #33324, #33325, #33330, #33332, #33334, #33335, #33346 - Failed merges:

GuillaumeGomez · 2016-05-03T09:11:47Z

@bors: rollup

steveklabnik · 2016-05-10T19:16:34Z

@bors: r=guillaumegomez rollup

bors · 2016-05-10T19:16:35Z

📌 Commit 201d9ed has been approved by guillaumegomez

steveklabnik · 2016-05-10T19:16:48Z

@mrmiywj sorry that this one slipped through the cracks!

…illaumegomez add help on pattern guard

Rollup of 9 pull requests - Successful merges: #33129, #33260, #33345, #33386, #33522, #33524, #33528, #33539, #33542 - Failed merges: #33342, #33475, #33517

rust-highfive assigned nrc Apr 28, 2016

GuillaumeGomez assigned steveklabnik and unassigned nrc Apr 28, 2016

mrmiywj force-pushed the help-on-pattern-guard branch from 3c17cbd to f6b06d3 Compare April 30, 2016 16:36

GuillaumeGomez reviewed May 1, 2016
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mrmiywj force-pushed the help-on-pattern-guard branch from f6b06d3 to 6f250d9 Compare May 1, 2016 15:02

mrmiywj force-pushed the help-on-pattern-guard branch from 6f250d9 to 1528150 Compare May 1, 2016 17:50

GuillaumeGomez reviewed May 1, 2016
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mrmiywj force-pushed the help-on-pattern-guard branch from 1528150 to 665be00 Compare May 2, 2016 05:47

Manishearth mentioned this pull request May 2, 2016

Rollup of 14 pull requests #33354

Merged

add help on pattern guard

201d9ed

fix too long column fix typo of help on pattern guard one nit fix compile fail

mrmiywj force-pushed the help-on-pattern-guard branch from 665be00 to 201d9ed Compare May 3, 2016 02:01

steveklabnik added a commit to steveklabnik/rust that referenced this pull request May 10, 2016

Rollup merge of rust-lang#33260 - mrmiywj:help-on-pattern-guard, r=gu…

1590fdd

…illaumegomez add help on pattern guard

steveklabnik mentioned this pull request May 10, 2016

Rollup of 9 pull requests #33548

Closed

steveklabnik added a commit to steveklabnik/rust that referenced this pull request May 10, 2016

Rollup merge of rust-lang#33260 - mrmiywj:help-on-pattern-guard, r=gu…

f9966df

…illaumegomez add help on pattern guard

steveklabnik mentioned this pull request May 10, 2016

Rollup of 8 pull requests #33551

Closed

steveklabnik added a commit to steveklabnik/rust that referenced this pull request May 11, 2016

Rollup merge of rust-lang#33260 - mrmiywj:help-on-pattern-guard, r=gu…

82c4f59

…illaumegomez add help on pattern guard

steveklabnik mentioned this pull request May 11, 2016

Rollup of 9 pull requests #33556

Merged

bors added a commit that referenced this pull request May 11, 2016

Auto merge of #33556 - steveklabnik:rollup, r=steveklabnik

e37f859

Rollup of 9 pull requests - Successful merges: #33129, #33260, #33345, #33386, #33522, #33524, #33528, #33539, #33542 - Failed merges: #33342, #33475, #33517

bors merged commit 201d9ed into rust-lang:master May 11, 2016

nikomatsakis mentioned this pull request Mar 24, 2017

Missing help on pattern guard #33247

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add help on pattern guard #33260

add help on pattern guard #33260

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		```compile_fail
		The problem above can be solve by using `ref` keyword.

add help on pattern guard #33260

add help on pattern guard #33260

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