Unused import lint can be less noisy

[emberian]

Example:

/home/cmr/src/rust2/src/librustc/middle/trans/adt.rs:65:19: 65:22 warning: unused import, #[warn(unused_imports)] on by default
/home/cmr/src/rust2/src/librustc/middle/trans/adt.rs:65 use syntax::abi::{X86, X86_64, Arm, Mips, Mipsel};
                                                                          ^~~
/home/cmr/src/rust2/src/librustc/middle/trans/adt.rs:65:24: 65:30 warning: unused import, #[warn(unused_imports)] on by default
/home/cmr/src/rust2/src/librustc/middle/trans/adt.rs:65 use syntax::abi::{X86, X86_64, Arm, Mips, Mipsel};
                                                                               ^~~~~~
/home/cmr/src/rust2/src/librustc/middle/trans/adt.rs:65:32: 65:35 warning: unused import, #[warn(unused_imports)] on by default
/home/cmr/src/rust2/src/librustc/middle/trans/adt.rs:65 use syntax::abi::{X86, X86_64, Arm, Mips, Mipsel};
                                                                                       ^~~
/home/cmr/src/rust2/src/librustc/middle/trans/adt.rs:65:37: 65:41 warning: unused import, #[warn(unused_imports)] on by default
/home/cmr/src/rust2/src/librustc/middle/trans/adt.rs:65 use syntax::abi::{X86, X86_64, Arm, Mips, Mipsel};
                                                                                            ^~~~
/home/cmr/src/rust2/src/librustc/middle/trans/adt.rs:65:43: 65:49 warning: unused import, #[warn(unused_imports)] on by default
/home/cmr/src/rust2/src/librustc/middle/trans/adt.rs:65 use syntax::abi::{X86, X86_64, Arm, Mips, Mipsel};
                                                                                                  ^~~~~~

These are all on the same line. When visiting imports inside of an import list, it should underline each name individually, but in the same error message, with the other unused names in the import list, if any.

[emberian]

Example:

#![crate_type = "lib"]

use foo::{Foo, Bar, Baz, Qux};

mod foo {
    pub struct Foo;
    pub struct Bar;
    pub struct Baz;
    pub struct Qux;
}

Output:

foo.rs:3:11: 3:14 warning: unused import, #[warn(unused_imports)] on by default
foo.rs:3 use foo::{Foo, Bar, Baz, Qux};
                   ^~~
foo.rs:3:16: 3:19 warning: unused import, #[warn(unused_imports)] on by default
foo.rs:3 use foo::{Foo, Bar, Baz, Qux};
                        ^~~
foo.rs:3:21: 3:24 warning: unused import, #[warn(unused_imports)] on by default
foo.rs:3 use foo::{Foo, Bar, Baz, Qux};
                             ^~~
foo.rs:3:26: 3:29 warning: unused import, #[warn(unused_imports)] on by default
foo.rs:3 use foo::{Foo, Bar, Baz, Qux};
                                  ^~~

Desired output:

foo.rs:3:11: 3:14 warning: unused imports, #[warn(unused_imports)] on by default
foo.rs:3 use foo::{Foo, Bar, Baz, Qux};
                   ^~~  ^~~  ^~~  ^~~

[fhahn]

I had a look at this issue and was wondering whether multiple spans in one line are supported at the moment? I traced the code for the printing the spans to libsyntax/diagnostic.rs.

I guess a patch for this issue will require some digging there?

[emberian]

Multiple spans on one line are not supported, that would need to be added
(somehow) to fix this.

On Mon, Aug 4, 2014 at 3:26 PM, Florian Hahn notifications@github.com
wrote:

I had a look at this issue and was wondering whether multiple spans in one
line are supported at the moment? I traced the code for the printing the
spans to libsyntax/diagnostic.rs.

I guess a patch for this issue will require some digging there?

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#16132 (comment).

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[fhahn]

Now that there are MultiSpans (thanks to @mitaa), I'd like to look into this.

[mitaa]

@fhan note that compiletest doesnt yet know what to make of them
#31380

[cflewis]

Should this be closed?

[brson]

Looks like OPs example still creates the same spew. A lot has changed in rustc diagnostics so @fhahn's unmerged patch is probably unsalvageable.

@jonathandturner what's the correct approach for a newbie to tackle this?