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Merge pull request #2056 from topecongiro/issue-1851

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Add suggestion to needless_borrow
This commit is contained in:
llogiq 2017-09-16 09:13:13 +02:00 committed by GitHub
commit 013b1f5923
3 changed files with 26 additions and 11 deletions
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27
clippy_lints/src/needless_borrow.rs
View file

@ -6,7 +6,7 @@ use rustc::lint::*;
use rustc::hir::{BindingAnnotation, Expr, ExprAddrOf, MutImmutable, Pat, PatKind};
use rustc::ty;
use rustc::ty::adjustment::{Adjust, Adjustment};
use utils::{in_macro, span_lint};
use utils::{in_macro, snippet_opt, span_lint_and_then};
/// **What it does:** Checks for address of operations (`&`) that are going to
/// be dereferenced immediately by the compiler.
@ -54,12 +54,17 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for NeedlessBorrow {
..
}] = *adj3
{
span_lint(
span_lint_and_then(
cx,
NEEDLESS_BORROW,
e.span,
"this expression borrows a reference that is immediately dereferenced by the \
compiler",
"this expression borrows a reference that is immediately dereferenced \
by the compiler",
|db| {
if let Some(snippet) = snippet_opt(cx, inner.span) {
db.span_suggestion(e.span, "change this to", snippet);
}
}
);
}
}
@ -71,14 +76,24 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for NeedlessBorrow {
return;
}
if_let_chain! {[
let PatKind::Binding(BindingAnnotation::Ref, _, _, _) = pat.node,
let PatKind::Binding(BindingAnnotation::Ref, _, name, _) = pat.node,
let ty::TyRef(_, ref tam) = cx.tables.pat_ty(pat).sty,
tam.mutbl == MutImmutable,
let ty::TyRef(_, ref tam) = tam.ty.sty,
// only lint immutable refs, because borrowed `&mut T` cannot be moved out
tam.mutbl == MutImmutable,
], {
span_lint(cx, NEEDLESS_BORROW, pat.span, "this pattern creates a reference to a reference")
span_lint_and_then(
cx,
NEEDLESS_BORROW,
pat.span,
"this pattern creates a reference to a reference",
|db| {
if let Some(snippet) = snippet_opt(cx, name.span) {
db.span_suggestion(pat.span, "change this to", snippet);
}
}
)
}}
}
}

2
tests/ui/eta.stderr
View file

@ -22,7 +22,7 @@ error: this expression borrows a reference that is immediately dereferenced by t
--> $DIR/eta.rs:11:21
|
11 | all(&[1, 2, 3], &&2, |x, y| below(x, y)); //is adjusted
| ^^^
| ^^^ help: change this to: `&2`
|
= note: `-D needless-borrow` implied by `-D warnings`

8
tests/ui/needless_borrow.stderr
View file

@ -2,7 +2,7 @@ error: this expression borrows a reference that is immediately dereferenced by t
--> $DIR/needless_borrow.rs:13:15
|
13 | let c = x(&&a);
| ^^^
| ^^^ help: change this to: `&a`
|
= note: `-D needless-borrow` implied by `-D warnings`
@ -10,13 +10,13 @@ error: this pattern creates a reference to a reference
--> $DIR/needless_borrow.rs:20:17
|
20 | if let Some(ref cake) = Some(&5) {}
| ^^^^^^^^
| ^^^^^^^^ help: change this to: `cake`
error: this expression borrows a reference that is immediately dereferenced by the compiler
--> $DIR/needless_borrow.rs:27:15
|
27 | 46 => &&a,
| ^^^
| ^^^ help: change this to: `&a`
error: this pattern takes a reference on something that is being de-referenced
--> $DIR/needless_borrow.rs:49:34
@ -36,7 +36,7 @@ error: this pattern creates a reference to a reference
--> $DIR/needless_borrow.rs:50:31
|
50 | let _ = v.iter().filter(|&ref a| a.is_empty());
| ^^^^^
| ^^^^^ help: change this to: `a`
error: aborting due to 6 previous errors