Reimplement the `map_clone` lint from scratch
This commit is contained in:
Oliver Schneider
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057243f16b
commit
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@ -688,8 +688,6 @@ All notable changes to this project will be documented in this file.
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[`float_arithmetic`]: https://rust-lang-nursery.github.io/rust-clippy/master/index.html#float_arithmetic
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[`float_cmp`]: https://rust-lang-nursery.github.io/rust-clippy/master/index.html#float_cmp
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[`float_cmp_const`]: https://rust-lang-nursery.github.io/rust-clippy/master/index.html#float_cmp_const
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[`fn_to_numeric_cast`]: https://rust-lang-nursery.github.io/rust-clippy/master/index.html#fn_to_numeric_cast
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[`fn_to_numeric_cast_with_truncation`]: https://rust-lang-nursery.github.io/rust-clippy/master/index.html#fn_to_numeric_cast_with_truncation
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[`for_kv_map`]: https://rust-lang-nursery.github.io/rust-clippy/master/index.html#for_kv_map
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[`for_loop_over_option`]: https://rust-lang-nursery.github.io/rust-clippy/master/index.html#for_loop_over_option
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[`for_loop_over_result`]: https://rust-lang-nursery.github.io/rust-clippy/master/index.html#for_loop_over_result
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@ -9,7 +9,7 @@ We are currently in the process of discussing Clippy 1.0 via the RFC process in
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A collection of lints to catch common mistakes and improve your [Rust](https://github.com/rust-lang/rust) code.
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[There are 279 lints included in this crate!](https://rust-lang-nursery.github.io/rust-clippy/master/index.html)
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[There are 277 lints included in this crate!](https://rust-lang-nursery.github.io/rust-clippy/master/index.html)
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We have a bunch of lint categories to allow you to choose how much Clippy is supposed to ~~annoy~~ help you:
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@ -129,6 +129,7 @@ pub mod let_if_seq;
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pub mod lifetimes;
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pub mod literal_representation;
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pub mod loops;
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pub mod map_clone;
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pub mod map_unit_fn;
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pub mod matches;
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pub mod mem_forget;
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@ -327,6 +328,7 @@ pub fn register_plugins(reg: &mut rustc_plugin::Registry<'_>, conf: &Conf) {
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reg.register_late_lint_pass(box strings::StringAdd);
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reg.register_early_lint_pass(box returns::ReturnPass);
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reg.register_late_lint_pass(box methods::Pass);
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reg.register_late_lint_pass(box map_clone::Pass);
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reg.register_late_lint_pass(box shadow::Pass);
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reg.register_late_lint_pass(box types::LetPass);
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reg.register_late_lint_pass(box types::UnitCmp);
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@ -583,6 +585,7 @@ pub fn register_plugins(reg: &mut rustc_plugin::Registry<'_>, conf: &Conf) {
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loops::WHILE_IMMUTABLE_CONDITION,
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loops::WHILE_LET_LOOP,
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loops::WHILE_LET_ON_ITERATOR,
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map_clone::MAP_CLONE,
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map_unit_fn::OPTION_MAP_UNIT_FN,
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map_unit_fn::RESULT_MAP_UNIT_FN,
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matches::MATCH_AS_REF,
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@ -742,6 +745,7 @@ pub fn register_plugins(reg: &mut rustc_plugin::Registry<'_>, conf: &Conf) {
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loops::FOR_KV_MAP,
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loops::NEEDLESS_RANGE_LOOP,
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loops::WHILE_LET_ON_ITERATOR,
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map_clone::MAP_CLONE,
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matches::MATCH_BOOL,
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matches::MATCH_OVERLAPPING_ARM,
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matches::MATCH_REF_PATS,
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@ -0,0 +1,100 @@
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use crate::rustc::hir;
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use crate::rustc::lint::{LateContext, LateLintPass, LintArray, LintPass};
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use crate::rustc::{declare_tool_lint, lint_array};
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use crate::syntax::source_map::Span;
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use crate::utils::paths;
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use crate::utils::{
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in_macro, match_trait_method, match_type,
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remove_blocks, snippet,
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span_lint_and_sugg,
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};
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use if_chain::if_chain;
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use crate::syntax::ast::Ident;
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#[derive(Clone)]
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pub struct Pass;
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/// **What it does:** Checks for usage of `iterator.map(|x| x.clone())` and suggests
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/// `iterator.cloned()` instead
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///
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/// **Why is this bad?** Readability, this can be written more concisely
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///
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/// **Known problems:** None.
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///
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/// **Example:**
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///
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/// ```rust
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/// let x = vec![42, 43];
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/// let y = x.iter();
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/// let z = y.map(|i| *i);
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/// ```
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///
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/// The correct use would be:
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///
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/// ```rust
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/// let x = vec![42, 43];
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/// let y = x.iter();
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/// let z = y.cloned();
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/// ```
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declare_clippy_lint! {
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pub MAP_CLONE,
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style,
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"using `iterator.map(|x| x.clone())`, or dereferencing closures for `Copy` types"
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}
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impl LintPass for Pass {
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fn get_lints(&self) -> LintArray {
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lint_array!(MAP_CLONE)
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}
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}
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impl<'a, 'tcx> LateLintPass<'a, 'tcx> for Pass {
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fn check_expr(&mut self, cx: &LateContext<'_, '_>, e: &hir::Expr) {
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if in_macro(e.span) {
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return;
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}
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if_chain! {
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if let hir::ExprKind::MethodCall(ref method, _, ref args) = e.node;
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if args.len() == 2;
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if method.ident.as_str() == "map";
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let ty = cx.tables.expr_ty(&args[0]);
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if match_type(cx, ty, &paths::OPTION) || match_trait_method(cx, e, &paths::ITERATOR);
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if let hir::ExprKind::Closure(_, _, body_id, _, _) = args[1].node;
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let closure_body = cx.tcx.hir.body(body_id);
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let closure_expr = remove_blocks(&closure_body.value);
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then {
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match closure_body.arguments[0].pat.node {
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hir::PatKind::Ref(ref inner, _) => if let hir::PatKind::Binding(hir::BindingAnnotation::Unannotated, _, name, None) = inner.node {
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lint(cx, e.span, args[0].span, name, closure_expr);
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},
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hir::PatKind::Binding(hir::BindingAnnotation::Unannotated, _, name, None) => match closure_expr.node {
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hir::ExprKind::Unary(hir::UnOp::UnDeref, ref inner) => lint(cx, e.span, args[0].span, name, inner),
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hir::ExprKind::MethodCall(ref method, _, ref obj) => if method.ident.as_str() == "clone" {
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if match_trait_method(cx, closure_expr, &paths::CLONE_TRAIT) {
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lint(cx, e.span, args[0].span, name, &obj[0]);
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}
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}
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_ => {},
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},
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_ => {},
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}
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}
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}
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}
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}
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fn lint(cx: &LateContext<'_, '_>, replace: Span, root: Span, name: Ident, path: &hir::Expr) {
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if let hir::ExprKind::Path(hir::QPath::Resolved(None, ref path)) = path.node {
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if path.segments.len() == 1 && path.segments[0].ident == name {
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span_lint_and_sugg(
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cx,
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MAP_CLONE,
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replace,
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"You are using an explicit closure for cloning elements",
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"Consider calling the dedicated `cloned` method",
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format!("{}.cloned()", snippet(cx, root, "..")),
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)
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}
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}
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}
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@ -0,0 +1,9 @@
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#![feature(tool_lints)]
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#![warn(clippy::all, clippy::pedantic)]
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#![allow(clippy::missing_docs_in_private_items)]
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fn main() {
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let _: Vec<i8> = vec![5_i8; 6].iter().map(|x| *x).collect();
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let _: Vec<String> = vec![String::new()].iter().map(|x| x.clone()).collect();
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let _: Vec<u32> = vec![42, 43].iter().map(|&x| x).collect();
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}
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@ -0,0 +1,22 @@
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error: You are using an explicit closure for cloning elements
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--> $DIR/map_clone.rs:6:22
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6 | let _: Vec<i8> = vec![5_i8; 6].iter().map(|x| *x).collect();
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| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: Consider calling the dedicated `cloned` method: `vec![5_i8; 6].iter().cloned()`
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= note: `-D clippy::map-clone` implied by `-D warnings`
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error: You are using an explicit closure for cloning elements
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--> $DIR/map_clone.rs:7:26
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7 | let _: Vec<String> = vec![String::new()].iter().map(|x| x.clone()).collect();
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| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: Consider calling the dedicated `cloned` method: `vec![String::new()].iter().cloned()`
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error: You are using an explicit closure for cloning elements
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--> $DIR/map_clone.rs:8:23
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8 | let _: Vec<u32> = vec![42, 43].iter().map(|&x| x).collect();
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| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: Consider calling the dedicated `cloned` method: `vec![42, 43].iter().cloned()`
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error: aborting due to 3 previous errors
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