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Rollup merge of #121528 - Alexendoo:unused_qualifications, r=petrochenkov

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Consider middle segments of paths in `unused_qualifications`

Currently `unused_qualifications` looks at the last segment of a path to see if it can be trimmed, this PR extends the check to the middle segments also

```rust
// currently linted
use std::env::args();
std::env::args(); // Removes `std::env::`
```
```rust
// newly linted
use std::env;
std::env::args(); // Removes `std::`
```

Paths with generics in them are now linted as long as the part being trimmed is before any generic args, e.g. it will now suggest trimming `std::vec::` from `std::vec::Vec<usize>`

Paths with any segments that are from an expansion are no longer linted

Fixes #100979
Fixes #96698
This commit is contained in:
Matthias Krüger 2024-03-03 22:56:13 +01:00 • committed by GitHub
commit ed6d17523a
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4 changed files with 151 additions and 29 deletions
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46
compiler/rustc_resolve/src/late.rs
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@ -4150,34 +4150,36 @@ impl<'a: 'ast, 'b, 'ast, 'tcx> LateResolutionVisitor<'a, 'b, 'ast, 'tcx> {
PathResult::Indeterminate => bug!("indeterminate path result in resolve_qpath"),
};
if path.len() > 1
&& let Some(res) = result.full_res()
&& let Some((&last_segment, prev_segs)) = path.split_last()
&& prev_segs.iter().all(|seg| !seg.has_generic_args)
&& res != Res::Err
&& path[0].ident.name != kw::PathRoot
&& path[0].ident.name != kw::DollarCrate
{
let unqualified_result = {
match self.resolve_path(&[last_segment], Some(ns), None) {
PathResult::NonModule(path_res) => path_res.expect_full_res(),
PathResult::Module(ModuleOrUniformRoot::Module(module)) => {
module.res().unwrap()
}
_ => return Ok(Some(result)),
}
};
if res == unqualified_result {
let lint = lint::builtin::UNUSED_QUALIFICATIONS;
if path.iter().all(|seg| !seg.ident.span.from_expansion()) {
let end_pos =
path.iter().position(|seg| seg.has_generic_args).map_or(path.len(), |pos| pos + 1);
let unqualified =
path[..end_pos].iter().enumerate().skip(1).rev().find_map(|(i, seg)| {
// Preserve the current namespace for the final path segment, but use the type
// namespace for all preceding segments
//
// e.g. for `std::env::args` check the `ValueNS` for `args` but the `TypeNS` for
// `std` and `env`
//
// If the final path segment is beyond `end_pos` all the segments to check will
// use the type namespace
let ns = if i + 1 == path.len() { ns } else { TypeNS };
let res = self.r.partial_res_map.get(&seg.id?)?.full_res()?;
let binding = self.resolve_ident_in_lexical_scope(seg.ident, ns, None, None)?;
(res == binding.res()).then_some(seg)
});
if let Some(unqualified) = unqualified {
self.r.lint_buffer.buffer_lint_with_diagnostic(
lint,
lint::builtin::UNUSED_QUALIFICATIONS,
finalize.node_id,
finalize.path_span,
"unnecessary qualification",
lint::BuiltinLintDiagnostics::UnusedQualifications {
removal_span: finalize.path_span.until(last_segment.ident.span),
removal_span: finalize.path_span.until(unqualified.ident.span),
},
)
);
}
}