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Merge pull request #1433 from sinkuu/ref

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Don't lint needless_borrow when matching `&&mut` by `&ref`
This commit is contained in:
Oliver Schneider 2017-01-10 17:29:19 +01:00 committed by GitHub
commit 3cc5596466
2 changed files with 19 additions and 9 deletions
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19
clippy_lints/src/needless_borrow.rs
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@ -58,14 +58,15 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for NeedlessBorrow {
if in_macro(cx, pat.span) {
return;
}
if let PatKind::Binding(BindingMode::BindByRef(MutImmutable), _, _, _) = pat.node {
if let ty::TyRef(_, ref tam) = cx.tcx.tables().pat_ty(pat).sty {
if tam.mutbl == MutImmutable {
if let ty::TyRef(..) = tam.ty.sty {
span_lint(cx, NEEDLESS_BORROW, pat.span, "this pattern creates a reference to a reference")
}
}
}
}
if_let_chain! {[
let PatKind::Binding(BindingMode::BindByRef(MutImmutable), _, _, _) = pat.node,
let ty::TyRef(_, ref tam) = cx.tcx.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")
}}
}
}

9
tests/compile-fail/needless_borrow.rs
View File

@ -33,3 +33,12 @@ trait Trait {}
impl<'a> Trait for &'a str {}
fn h(_: &Trait) {}
#[allow(dead_code)]
fn issue_1432() {
let mut v = Vec::<String>::new();
let _ = v.iter_mut().filter(|&ref a| a.is_empty());
let _ = v.iter().filter(|&ref a| a.is_empty());
//~^WARNING this pattern creates a reference to a reference
let _ = v.iter().filter(|&a| a.is_empty());
}