Lint for redundant imports #58805

fabric-and-ink · 2019-02-28T10:48:07Z

Add lint for redundant imports. The changes are suggested by @petrochenkov.

Closes #10178.

rust-highfive · 2019-02-28T10:48:11Z

r? @varkor

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petrochenkov · 2019-02-28T10:51:59Z

r? @petrochenkov

Mark::root() means that we are not in a macro, so the correct condition is

if directive.parent_scope.expansion != Mark::root() {
    return;
}

fabric-and-ink · 2019-02-28T11:06:38Z

With that change I get a different error:

error: redundant import                                                                                                     
  --> src/libstd/rt.rs:24:9
   |
24 |     use panic;
   |         ^^^^^
   |
note: the other one
  --> src/libstd/macros.rs:58:1
   |
58 | / macro_rules! panic {
59 | |     () => ({
60 | |         panic!("explicit panic")
61 | |     });
...  |
71 | |     });
72 | | }
   | |_^

error: aborting due to previous error

error: Could not compile `std`.

petrochenkov · 2019-02-28T11:13:44Z

@fabric-and-ink
That's because the error only needs to be reported if the import is redundant in all namespaces, rather than in any namespace like this PR is currently doing.

fabric-and-ink · 2019-02-28T13:33:18Z

I updated the check. Now it seems that my test file compiles fine, without a redundancy error reported.

petrochenkov · 2019-02-28T13:49:49Z

By "all namespaces" I mean all namespaces in which resolution exists, i.e. if source_bindings[ns] is None (or perhaps if its def() is Def::Err) then we shouldn't consider it.

(Right now the error is not reported if the import is unresolved in any of the namespaces.)

fabric-and-ink · 2019-02-28T16:35:38Z

I updated the check. Now I get the false positive again. 😄

error: redundant import                                                                                                     
  --> src/libstd/rt.rs:24:9
   |
24 |     use panic;
   |         ^^^^^
   |
note: the other one
  --> src/libstd/macros.rs:58:1
   |
58 | / macro_rules! panic {
59 | |     () => ({
60 | |         panic!("explicit panic")
61 | |     });
...  |
71 | |     });
72 | | }
   | |_^

error: aborting due to previous error

error: Could not compile `std`.

petrochenkov · 2019-02-28T20:42:22Z

I don't see an obvious error, try to use logging to see what happens in each individual namespace.

fabric-and-ink · 2019-03-03T17:28:38Z

Have some trouble getting helpful logs. I will try a few things and will get back to you if they don't seem to work out.

fabric-and-ink · 2019-03-10T11:52:29Z

~~Ok, I think this is more or less ready to go :)~~ Too early...

fabric-and-ink · 2019-03-10T17:39:53Z

Strange... why don't I see these locally?

fabric-and-ink · 2019-03-10T18:47:45Z

Ok, compilation should be fine now. But I see a few errors in the ui test suite. I could add #[allow(redundant_imports)] to the failing tests. What do you think?

src/librustc/lint/builtin.rs

src/librustc_resolve/macros.rs

src/librustc_resolve/resolve_imports.rs

src/test/ui/lint/use-redundant.rs

Centril · 2019-03-16T03:34:33Z

@Mark-Simulacrum Once this is implemented wdyt about integrating into tidy?

petrochenkov · 2019-03-16T12:55:38Z

@Centril
What do you mean? Enabling this warning in bootstrap?
It's already enabled by default currently.

Centril · 2019-03-16T13:00:15Z

@petrochenkov Oh, we reject all warnings? That should do it then, cool.

petrochenkov · 2019-03-16T13:05:28Z

@Centril
Yes

rust/src/bootstrap/bin/rustc.rs

Lines 298 to 302 in 0547ceb

    
           if env::var_os("RUSTC_DENY_WARNINGS").is_some() && env::var_os("RUSTC_EXTERNAL_TOOL").is_none() 
        
           { 
        
               cmd.arg("-Dwarnings"); 
        
               cmd.arg("-Dbare_trait_objects"); 
        
           }

bors · 2019-03-31T16:28:54Z

📌 Commit c1d5314 has been approved by petrochenkov

petrochenkov · 2019-03-31T16:30:18Z

@bors p=1

bors · 2019-03-31T17:18:56Z

⌛ Testing commit c1d5314 with merge cc77f27ad5253e79b795b0c48aafba0daf0b7d96...

@petrochenkov

…petrochenkov Lint for redundant imports Add lint for redundant imports. The changes are suggested by @petrochenkov. Closes rust-lang#10178.

Centril · 2019-03-31T17:21:09Z

@bors retry

Yielding to rollup that this PR is included in.

@ghost

Rollup of 7 pull requests Successful merges: - #58805 (Lint for redundant imports) - #59506 (Use platform dependent mcount function) - #59519 (rustc_target: factor out common fields of non-Single Variants.) - #59580 (Allow closure to unsafe fn coercion) - #59581 (Stabilize refcell_replace_swap feature) - #59583 (match match match match match) - #59587 (Remove #[doc(hidden)] from Error::type_id) Failed merges: r? @ghost

bors · 2019-03-31T20:27:23Z

⌛ Testing commit c1d5314 with merge 4fac5c9...

petrochenkov · 2019-03-31T20:35:51Z

@fabric-and-ink
Congrats.
This certainly wasn't an easy fix.

fabric-and-ink · 2019-03-31T20:44:54Z

@petrochenkov thanks for helping me! That was fun :) I will try to contribute more often.

Rustup to rust-lang/rust#58805

Fix unused import warning. 2019-04-01 nightly introduced a new warning (presumably rust-lang/rust#58805).

Changes: ```` Remove force-host and explain no-prefer-dynamic Escape a single quote in single_char_pattern hint cargo fmt Re-add tmp feature to compiletest Remove libtest from deps Re-allow clippy::identity_conversion in compiletest Use latest compiletest-rs Revert tests/compile-test.rs to 61aa5c9 Fix ICE in suspicious_else_formatting use a multispan for MANY_SINGLE_CHAR_NAMES Add missing `// run-pass` annotations to ICE tests Remove clippy_dev as dev-dependency NFC: fix typos rustup rust-lang#59657 Add TransmutingNull Lint * Late Lint pass, catches: * One liner: 0 -> null -> transmute * One liner: std:null() -> transmute * Const (which resolves to null) -> transmute * UI Test case for Lint * Updated test for issue 3849, because now the lint that code generated is in Clippy. * Expanded `const.rs` miri-based Constant Folding code, to cover raw pointers Run rustfmt Set level of identity_conversion FP to warn Rustup to rust-lang#58805 rustup 41316f0 Updated source to match with recent rustc `master` toolchain changes Fix dogfood error of question_mark lint fix Fix question_mark lint+test use `span_lint_and_sugg` in `explicit_counter_loop` Fix some test failures Hacky rustup run cargo fmt rustup rust-lang#59096 Change explicit_counter_loop's message to add parentheses if necessary Change explicit_counter_loop's message to reflect original variable name cargo fmt Add rustfix tests for mistyped_literal_suffix lint Move some `unreadable_literal` ui tests to correct file Add implementation for the EarlyLintPass trait into the Adding Lints documentation. Add rust-toolchain for clippy_dev ````

glium reexports glutin and I think this point needs to be stressed. So using glutin from the reexport instead of the possibly available extern crate is useful at least in the examples otherwise users might not realize that they don't have to add glutin to their Cargo.toml. Therefore, the lint is silenced instead of being followed. Link to the lint change that likely caused this: rust-lang/rust#58805

Changes: ```` Remove force-host and explain no-prefer-dynamic Escape a single quote in single_char_pattern hint cargo fmt Re-add tmp feature to compiletest Remove libtest from deps Re-allow clippy::identity_conversion in compiletest Use latest compiletest-rs Revert tests/compile-test.rs to 61aa5c9 Fix ICE in suspicious_else_formatting use a multispan for MANY_SINGLE_CHAR_NAMES Add missing `// run-pass` annotations to ICE tests Remove clippy_dev as dev-dependency NFC: fix typos rustup rust-lang/rust#59657 Add TransmutingNull Lint * Late Lint pass, catches: * One liner: 0 -> null -> transmute * One liner: std:null() -> transmute * Const (which resolves to null) -> transmute * UI Test case for Lint * Updated test for issue 3849, because now the lint that code generated is in Clippy. * Expanded `const.rs` miri-based Constant Folding code, to cover raw pointers Run rustfmt Set level of identity_conversion FP to warn Rustup to rust-lang/rust#58805 rustup 41316f0 Updated source to match with recent rustc `master` toolchain changes Fix dogfood error of question_mark lint fix Fix question_mark lint+test use `span_lint_and_sugg` in `explicit_counter_loop` Fix some test failures Hacky rustup run cargo fmt rustup rust-lang/rust#59096 Change explicit_counter_loop's message to add parentheses if necessary Change explicit_counter_loop's message to reflect original variable name cargo fmt Add rustfix tests for mistyped_literal_suffix lint Move some `unreadable_literal` ui tests to correct file Add implementation for the EarlyLintPass trait into the Adding Lints documentation. Add rust-toolchain for clippy_dev ````

rust-highfive assigned varkor Feb 28, 2019

rust-highfive added the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Feb 28, 2019

rust-highfive assigned petrochenkov and unassigned varkor Feb 28, 2019

petrochenkov 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-review Status: Awaiting review from the assignee but also interested parties. labels Feb 28, 2019

fabric-and-ink changed the title ~~WIP: Lint for redundant imports~~ Lint for redundant imports Mar 10, 2019