From 9bd4e5469e1ecb7d98602ba1d805872faa8bf2c9 Mon Sep 17 00:00:00 2001
From: Ryan Cumming <etaoins@gmail.com>
Date: Mon, 8 Oct 2018 06:20:32 +1100
Subject: [PATCH] Don't suggest cloned() for map Box deref
Boxes are a bit magic in that they need to use `*` to get an owned value
out of the box. They implement `Deref` but that only returns a
reference. This means an easy way to convert an `Option<Box<T>>` to an
`<Option<T>` is:
```
box_option.map(|b| *b)
```
However, since b36bb0a6 the `map_clone` lint is detecting this as an
attempt to copy the box. Fix by excluding boxes completely from the
deref part of this lint.
Fixes #3274
---
clippy_lints/src/map_clone.rs | 2 +-
tests/ui/map_clone.rs | 1 +
2 files changed, 2 insertions(+), 1 deletion(-)
diff --git a/clippy_lints/src/map_clone.rs b/clippy_lints/src/map_clone.rs
index c2bfcf18280..b2c08e6ae8c 100644
--- a/clippy_lints/src/map_clone.rs
+++ b/clippy_lints/src/map_clone.rs
@@ -79,7 +79,7 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for Pass {
lint(cx, e.span, args[0].span, name, closure_expr);
},
hir::PatKind::Binding(hir::BindingAnnotation::Unannotated, _, name, None) => match closure_expr.node {
- hir::ExprKind::Unary(hir::UnOp::UnDeref, ref inner) => lint(cx, e.span, args[0].span, name, inner),
+ hir::ExprKind::Unary(hir::UnOp::UnDeref, ref inner) if !cx.tables.expr_ty(inner).is_box() => lint(cx, e.span, args[0].span, name, inner),
hir::ExprKind::MethodCall(ref method, _, ref obj) => if method.ident.as_str() == "clone" && match_trait_method(cx, closure_expr, &paths::CLONE_TRAIT) {
lint(cx, e.span, args[0].span, name, &obj[0]);
}
diff --git a/tests/ui/map_clone.rs b/tests/ui/map_clone.rs
index 8a410737f83..90611023f75 100644
--- a/tests/ui/map_clone.rs
+++ b/tests/ui/map_clone.rs
@@ -16,4 +16,5 @@ fn main() {
let _: Vec<i8> = vec![5_i8; 6].iter().map(|x| *x).collect();
let _: Vec<String> = vec![String::new()].iter().map(|x| x.clone()).collect();
let _: Vec<u32> = vec![42, 43].iter().map(|&x| x).collect();
+ let _: Option<u64> = Some(Box::new(16)).map(|b| *b);
}