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Suggest renaming a trait import if the names clash #32354

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bluss opened this issue Mar 19, 2016 · 7 comments
Closed

Suggest renaming a trait import if the names clash #32354

bluss opened this issue Mar 19, 2016 · 7 comments
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A-diagnostics Area: Messages for errors, warnings, and lints C-enhancement Category: An issue proposing an enhancement or a PR with one. E-easy Call for participation: Easy difficulty. Experience needed to fix: Not much. Good first issue. E-mentor Call for participation: This issue has a mentor. Use #t-compiler/help on Zulip for discussion. WG-diagnostics Working group: Diagnostics

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@bluss
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bluss commented Mar 19, 2016

You can bring in multiple traits of the same name if you rename them.

Example use case (playground code)

use extension1::ConstructorExtension;
use extension2::ConstructorExtension;

current error:

<anon>:49:5: 49:37 error: a trait named `ConstructorExtension` has already been imported in this module [E0252]
<anon>:49 use extension2::ConstructorExtension;
              ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
<anon>:49:5: 49:37 help: see the detailed explanation for E0252
<anon>:48:5: 48:37 note: previous import of `ConstructorExtension` here
<anon>:48 use extension1::ConstructorExtension;
              ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Suggested note: "You can rename an imported name with as".
@GuillaumeGomez
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Seems like a nice idea. I'm taking this issue.

@petrochenkov
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Two thoughts: 1) This is not specific to traits, any import (or non-import) can be renamed in case of conflict 2) resolve already has too many overly specific errors and messages, which seemed like a nice idea and easy PR material, with no evidence of their actual helpfulness.

@Mark-Simulacrum
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@GuillaumeGomez Checking in; I think no progress has been made. Do you think you'll have a chance to work on this soon?

@Mark-Simulacrum Mark-Simulacrum added the A-diagnostics Area: Messages for errors, warnings, and lints label May 2, 2017
@GuillaumeGomez
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No I won't. Feel free to take it.

@Mark-Simulacrum Mark-Simulacrum added the C-enhancement Category: An issue proposing an enhancement or a PR with one. label Jul 24, 2017
@estebank
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Mentoring instructions:

The duplicated import struct is created in src/librustc_resolve/lib.rs. A new check should be added for at least one of the bindings being an import. If only one of them is an import, do the following on the binding that is an import, if both are, choose one (I'd say new_binding):

let cm = self.session.codemap();
if let Ok(snippet) = cm.span_to_snippet(import_binding.span) {
    err.span_suggestion(import_binding.span,
                        "You can use `as` to change the binding name of the import",
                        format!("use {} as Other{}", snippet, name));
} else {
    err.span_label(import_binding.span,
                   "You can use `as` to change the binding name of the import");
}

@estebank estebank added E-mentor Call for participation: This issue has a mentor. Use #t-compiler/help on Zulip for discussion. WG-diagnostics Working group: Diagnostics E-easy Call for participation: Easy difficulty. Experience needed to fix: Not much. Good first issue. labels Sep 29, 2017
@colinmarsh19
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I might take a look at this issue and see what I can do. Let me know if there are any conflicts --Colin

@estebank
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estebank commented Oct 9, 2017

@colinmarsh19 go ahead! Feel free to reach out for help here, gitter, or IRC.

@Cldfire Cldfire mentioned this issue Oct 31, 2017
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kennytm added a commit to kennytm/rust that referenced this issue Nov 1, 2017
@kennytm
Rollup merge of rust-lang#45660 - Cldfire:suggest-rename-import, r=es…
0ec40c1 
…tebank

Suggest renaming import if names clash

Closes rust-lang#32354.

The output for the example in the issue looks like this:

```
~/p/local-rust-dev-testing ❯❯❯ cargo +local-s1 build
   Compiling local-rust-dev-testing v0.1.0 (file:///home/cldfire/programming_projects/local-rust-dev-testing)
error[E0252]: the name `ConstructorExtension` is defined multiple times
  --> src/main.rs:49:5
   |
48 | use extension1::ConstructorExtension;
   |     -------------------------------- previous import of the trait `ConstructorExtension` here
49 | use extension2::ConstructorExtension;
   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `ConstructorExtension` reimported here
   |
   = note: `ConstructorExtension` must be defined only once in the type namespace of this module
help: You can use `as` to change the binding name of the import
   |
49 | use extension2::ConstructorExtension as OtherConstructorExtension;
   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

...
```

This is my first PR that touches the compiler in any way, so if there's something else I need to do here (e.g. add a test), please let me know :).
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A-diagnostics Area: Messages for errors, warnings, and lints C-enhancement Category: An issue proposing an enhancement or a PR with one. E-easy Call for participation: Easy difficulty. Experience needed to fix: Not much. Good first issue. E-mentor Call for participation: This issue has a mentor. Use #t-compiler/help on Zulip for discussion. WG-diagnostics Working group: Diagnostics
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@estebank @GuillaumeGomez @bluss @Mark-Simulacrum @petrochenkov @colinmarsh19