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Improve iter_cloned_collect suggestions

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Fixes #3704
This commit is contained in:
Michael Wright 2019-02-18 07:30:50 +02:00
parent a71acac1da
commit 6e7a813ed2
3 changed files with 56 additions and 23 deletions
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41
clippy_lints/src/methods/mod.rs
View file

@ -1477,17 +1477,22 @@ fn lint_cstring_as_ptr(cx: &LateContext<'_, '_>, expr: &hir::Expr, new: &hir::Ex
}
}
fn lint_iter_cloned_collect(cx: &LateContext<'_, '_>, expr: &hir::Expr, iter_args: &[hir::Expr]) {
if match_type(cx, cx.tables.expr_ty(expr), &paths::VEC)
&& derefs_to_slice(cx, &iter_args[0], cx.tables.expr_ty(&iter_args[0])).is_some()
{
span_lint(
cx,
ITER_CLONED_COLLECT,
expr.span,
"called `cloned().collect()` on a slice to create a `Vec`. Calling `to_vec()` is both faster and \
more readable",
);
fn lint_iter_cloned_collect<'a, 'tcx>(cx: &LateContext<'a, 'tcx>, expr: &hir::Expr, iter_args: &'tcx [hir::Expr]) {
if match_type(cx, cx.tables.expr_ty(expr), &paths::VEC) {
if let Some(slice) = derefs_to_slice(cx, &iter_args[0], cx.tables.expr_ty(&iter_args[0])) {
if let Some(to_replace) = expr.span.trim_start(slice.span.source_callsite()) {
span_lint_and_sugg(
cx,
ITER_CLONED_COLLECT,
to_replace,
"called `iter().cloned().collect()` on a slice to create a `Vec`. Calling `to_vec()` is both faster and \
more readable",
"try",
".to_vec()".to_string(),
Applicability::MachineApplicable,
);
}
}
}
}
@ -1573,7 +1578,7 @@ fn lint_unnecessary_fold(cx: &LateContext<'_, '_>, expr: &hir::Expr, fold_args:
};
}
fn lint_iter_nth(cx: &LateContext<'_, '_>, expr: &hir::Expr, iter_args: &[hir::Expr], is_mut: bool) {
fn lint_iter_nth<'a, 'tcx>(cx: &LateContext<'a, 'tcx>, expr: &hir::Expr, iter_args: &'tcx [hir::Expr], is_mut: bool) {
let mut_str = if is_mut { "_mut" } else { "" };
let caller_type = if derefs_to_slice(cx, &iter_args[0], cx.tables.expr_ty(&iter_args[0])).is_some() {
"slice"
@ -1596,7 +1601,7 @@ fn lint_iter_nth(cx: &LateContext<'_, '_>, expr: &hir::Expr, iter_args: &[hir::E
);
}
fn lint_get_unwrap(cx: &LateContext<'_, '_>, expr: &hir::Expr, get_args: &[hir::Expr], is_mut: bool) {
fn lint_get_unwrap<'a, 'tcx>(cx: &LateContext<'a, 'tcx>, expr: &hir::Expr, get_args: &'tcx [hir::Expr], is_mut: bool) {
// Note: we don't want to lint `get_mut().unwrap` for HashMap or BTreeMap,
// because they do not implement `IndexMut`
let mut applicability = Applicability::MachineApplicable;
@ -1681,7 +1686,7 @@ fn lint_iter_skip_next(cx: &LateContext<'_, '_>, expr: &hir::Expr) {
}
}
fn derefs_to_slice(cx: &LateContext<'_, '_>, expr: &hir::Expr, ty: Ty<'_>) -> Option<sugg::Sugg<'static>> {
fn derefs_to_slice<'a, 'tcx>(cx: &LateContext<'a, 'tcx>, expr: &'tcx hir::Expr, ty: Ty<'tcx>) -> Option<&'tcx hir::Expr> {
fn may_slice(cx: &LateContext<'_, '_>, ty: Ty<'_>) -> bool {
match ty.sty {
ty::Slice(_) => true,
@ -1695,17 +1700,17 @@ fn derefs_to_slice(cx: &LateContext<'_, '_>, expr: &hir::Expr, ty: Ty<'_>) -> Op
if let hir::ExprKind::MethodCall(ref path, _, ref args) = expr.node {
if path.ident.name == "iter" && may_slice(cx, cx.tables.expr_ty(&args[0])) {
sugg::Sugg::hir_opt(cx, &args[0]).map(sugg::Sugg::addr)
Some(&args[0])
} else {
None
}
} else {
match ty.sty {
ty::Slice(_) => sugg::Sugg::hir_opt(cx, expr),
ty::Adt(def, _) if def.is_box() && may_slice(cx, ty.boxed_ty()) => sugg::Sugg::hir_opt(cx, expr),
ty::Slice(_) => Some(expr),
ty::Adt(def, _) if def.is_box() && may_slice(cx, ty.boxed_ty()) => Some(expr),
ty::Ref(_, inner, _) => {
if may_slice(cx, inner) {
sugg::Sugg::hir_opt(cx, expr)
Some(expr)
} else {
None
}

12
tests/ui/unnecessary_clone.rs
View file

@ -66,6 +66,18 @@ fn iter_clone_collect() {
let v2: Vec<isize> = v.iter().cloned().collect();
let v3: HashSet<isize> = v.iter().cloned().collect();
let v4: VecDeque<isize> = v.iter().cloned().collect();
// Handle macro expansion in suggestion
let _ : Vec<isize> = vec![1, 2, 3].iter().cloned().collect();
// Issue #3704
unsafe {
let _: Vec<u8> = std::ffi::CStr::from_ptr(std::ptr::null())
.to_bytes()
.iter()
.cloned()
.collect();
}
}
mod many_derefs {

26
tests/ui/unnecessary_clone.stderr
View file

@ -78,19 +78,35 @@ help: or try being explicit about what type to clone
LL | let z: &Vec<_> = &std::vec::Vec<i32>::clone(y);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
error: called `cloned().collect()` on a slice to create a `Vec`. Calling `to_vec()` is both faster and more readable
--> $DIR/unnecessary_clone.rs:66:26
error: called `iter().cloned().collect()` on a slice to create a `Vec`. Calling `to_vec()` is both faster and more readable
--> $DIR/unnecessary_clone.rs:66:27
|
LL | let v2: Vec<isize> = v.iter().cloned().collect();
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^
| ^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `.to_vec()`
|
= note: `-D clippy::iter-cloned-collect` implied by `-D warnings`
error: called `iter().cloned().collect()` on a slice to create a `Vec`. Calling `to_vec()` is both faster and more readable
--> $DIR/unnecessary_clone.rs:71:39
|
LL | let _ : Vec<isize> = vec![1, 2, 3].iter().cloned().collect();
| ^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `.to_vec()`
error: called `iter().cloned().collect()` on a slice to create a `Vec`. Calling `to_vec()` is both faster and more readable
--> $DIR/unnecessary_clone.rs:76:24
|
LL | .to_bytes()
| ________________________^
LL | | .iter()
LL | | .cloned()
LL | | .collect();
| |______________________^ help: try: `.to_vec()`
error: using `clone` on a `Copy` type
--> $DIR/unnecessary_clone.rs:102:20
--> $DIR/unnecessary_clone.rs:114:20
|
LL | let _: E = a.clone();
| ^^^^^^^^^ help: try dereferencing it: `*****a`
error: aborting due to 13 previous errors
error: aborting due to 15 previous errors