From ded9354dcf76aaa2cd2164a8b556f61c2f188d79 Mon Sep 17 00:00:00 2001 From: Samuel Tardieu Date: Sat, 11 Jan 2025 15:14:31 +0100 Subject: [PATCH] Suggest using `Vec::extend()` in `same_item_push` Using `Vec::extend(std::iter::repeat_n(item, N))` allows to use the more natural number of elements to add `N`, as is probably done in the original loop, instead of computing the difference between the existing number of elements and the wanted one. Before MSRV 1.82, the older suggestion to use `Vec::resize()` is still issued. --- book/src/lint_configuration.md | 1 + clippy_config/src/conf.rs | 1 + clippy_lints/src/loops/mod.rs | 2 +- clippy_lints/src/loops/same_item_push.rs | 34 ++++++++++++++-------- tests/ui/same_item_push.rs | 20 +++++++++---- tests/ui/same_item_push.stderr | 36 ++++++++++++++++-------- 6 files changed, 66 insertions(+), 28 deletions(-) diff --git a/book/src/lint_configuration.md b/book/src/lint_configuration.md index 181e794e6e46..a3e10088db26 100644 --- a/book/src/lint_configuration.md +++ b/book/src/lint_configuration.md @@ -767,6 +767,7 @@ The minimum rust version that the project supports. Defaults to the `rust-versio * [`ptr_as_ptr`](https://rust-lang.github.io/rust-clippy/master/index.html#ptr_as_ptr) * [`redundant_field_names`](https://rust-lang.github.io/rust-clippy/master/index.html#redundant_field_names) * [`redundant_static_lifetimes`](https://rust-lang.github.io/rust-clippy/master/index.html#redundant_static_lifetimes) +* [`same_item_push`](https://rust-lang.github.io/rust-clippy/master/index.html#same_item_push) * [`seek_from_current`](https://rust-lang.github.io/rust-clippy/master/index.html#seek_from_current) * [`seek_rewind`](https://rust-lang.github.io/rust-clippy/master/index.html#seek_rewind) * [`transmute_ptr_to_ref`](https://rust-lang.github.io/rust-clippy/master/index.html#transmute_ptr_to_ref) diff --git a/clippy_config/src/conf.rs b/clippy_config/src/conf.rs index c616589c56e0..9bf6c675f000 100644 --- a/clippy_config/src/conf.rs +++ b/clippy_config/src/conf.rs @@ -636,6 +636,7 @@ define_Conf! { ptr_as_ptr, redundant_field_names, redundant_static_lifetimes, + same_item_push, seek_from_current, seek_rewind, transmute_ptr_to_ref, diff --git a/clippy_lints/src/loops/mod.rs b/clippy_lints/src/loops/mod.rs index f3ca4a4a5715..c5e75af2303c 100644 --- a/clippy_lints/src/loops/mod.rs +++ b/clippy_lints/src/loops/mod.rs @@ -830,7 +830,7 @@ impl Loops { for_kv_map::check(cx, pat, arg, body); mut_range_bound::check(cx, arg, body); single_element_loop::check(cx, pat, arg, body, expr); - same_item_push::check(cx, pat, arg, body, expr); + same_item_push::check(cx, pat, arg, body, expr, &self.msrv); manual_flatten::check(cx, pat, arg, body, span); manual_find::check(cx, pat, arg, body, span, expr); unused_enumerate_index::check(cx, pat, arg, body); diff --git a/clippy_lints/src/loops/same_item_push.rs b/clippy_lints/src/loops/same_item_push.rs index 951ebc9caef0..c27e930c99a5 100644 --- a/clippy_lints/src/loops/same_item_push.rs +++ b/clippy_lints/src/loops/same_item_push.rs @@ -1,8 +1,9 @@ use super::SAME_ITEM_PUSH; -use clippy_utils::diagnostics::span_lint_and_help; -use clippy_utils::path_to_local; +use clippy_utils::diagnostics::span_lint_and_then; +use clippy_utils::msrvs::Msrv; use clippy_utils::source::snippet_with_context; use clippy_utils::ty::{implements_trait, is_type_diagnostic_item}; +use clippy_utils::{msrvs, path_to_local, std_or_core}; use rustc_data_structures::fx::FxHashSet; use rustc_errors::Applicability; use rustc_hir::def::{DefKind, Res}; @@ -19,19 +20,30 @@ pub(super) fn check<'tcx>( _: &'tcx Expr<'_>, body: &'tcx Expr<'_>, _: &'tcx Expr<'_>, + msrv: &Msrv, ) { - fn emit_lint(cx: &LateContext<'_>, vec: &Expr<'_>, pushed_item: &Expr<'_>, ctxt: SyntaxContext) { + fn emit_lint(cx: &LateContext<'_>, vec: &Expr<'_>, pushed_item: &Expr<'_>, ctxt: SyntaxContext, msrv: &Msrv) { let mut app = Applicability::Unspecified; let vec_str = snippet_with_context(cx, vec.span, ctxt, "", &mut app).0; let item_str = snippet_with_context(cx, pushed_item.span, ctxt, "", &mut app).0; - span_lint_and_help( + let secondary_help = if msrv.meets(msrvs::REPEAT_N) + && let Some(std_or_core) = std_or_core(cx) + { + format!("or `{vec_str}.extend({std_or_core}::iter::repeat_n({item_str}, SIZE))`") + } else { + format!("or `{vec_str}.resize(NEW_SIZE, {item_str})`") + }; + + span_lint_and_then( cx, SAME_ITEM_PUSH, vec.span, - "it looks like the same item is being pushed into this Vec", - None, - format!("consider using vec![{item_str};SIZE] or {vec_str}.resize(NEW_SIZE, {item_str})"), + "it looks like the same item is being pushed into this `Vec`", + |diag| { + diag.help(format!("consider using `vec![{item_str};SIZE]`")) + .help(secondary_help); + }, ); } @@ -67,11 +79,11 @@ pub(super) fn check<'tcx>( { match init.kind { // immutable bindings that are initialized with literal - ExprKind::Lit(..) => emit_lint(cx, vec, pushed_item, ctxt), + ExprKind::Lit(..) => emit_lint(cx, vec, pushed_item, ctxt, msrv), // immutable bindings that are initialized with constant ExprKind::Path(ref path) => { if let Res::Def(DefKind::Const, ..) = cx.qpath_res(path, init.hir_id) { - emit_lint(cx, vec, pushed_item, ctxt); + emit_lint(cx, vec, pushed_item, ctxt, msrv); } }, _ => {}, @@ -79,11 +91,11 @@ pub(super) fn check<'tcx>( } }, // constant - Res::Def(DefKind::Const, ..) => emit_lint(cx, vec, pushed_item, ctxt), + Res::Def(DefKind::Const, ..) => emit_lint(cx, vec, pushed_item, ctxt, msrv), _ => {}, } }, - ExprKind::Lit(..) => emit_lint(cx, vec, pushed_item, ctxt), + ExprKind::Lit(..) => emit_lint(cx, vec, pushed_item, ctxt, msrv), _ => {}, } } diff --git a/tests/ui/same_item_push.rs b/tests/ui/same_item_push.rs index df9c2817f508..87fd59ad3179 100644 --- a/tests/ui/same_item_push.rs +++ b/tests/ui/same_item_push.rs @@ -21,33 +21,43 @@ fn main() { let item = 2; for _ in 5..=20 { vec.push(item); - //~^ ERROR: it looks like the same item is being pushed into this Vec + //~^ ERROR: it looks like the same item is being pushed into this `Vec` } let mut vec: Vec = Vec::new(); for _ in 0..15 { let item = 2; vec.push(item); - //~^ ERROR: it looks like the same item is being pushed into this Vec + //~^ ERROR: it looks like the same item is being pushed into this `Vec` } let mut vec: Vec = Vec::new(); for _ in 0..15 { vec.push(13); - //~^ ERROR: it looks like the same item is being pushed into this Vec + //~^ ERROR: it looks like the same item is being pushed into this `Vec` } let mut vec = Vec::new(); for _ in 0..20 { vec.push(VALUE); - //~^ ERROR: it looks like the same item is being pushed into this Vec + //~^ ERROR: it looks like the same item is being pushed into this `Vec` } let mut vec = Vec::new(); let item = VALUE; for _ in 0..20 { vec.push(item); - //~^ ERROR: it looks like the same item is being pushed into this Vec + //~^ ERROR: it looks like the same item is being pushed into this `Vec` + } + + #[clippy::msrv = "1.81"] + fn older_msrv() { + let mut vec = Vec::new(); + let item = VALUE; + for _ in 0..20 { + vec.push(item); + //~^ ERROR: it looks like the same item is being pushed into this `Vec` + } } // ** non-linted cases ** diff --git a/tests/ui/same_item_push.stderr b/tests/ui/same_item_push.stderr index eb296ed4ce4a..e3fa4f9cbcec 100644 --- a/tests/ui/same_item_push.stderr +++ b/tests/ui/same_item_push.stderr @@ -1,44 +1,58 @@ -error: it looks like the same item is being pushed into this Vec +error: it looks like the same item is being pushed into this `Vec` --> tests/ui/same_item_push.rs:23:9 | LL | vec.push(item); | ^^^ | - = help: consider using vec![item;SIZE] or vec.resize(NEW_SIZE, item) + = help: consider using `vec![item;SIZE]` + = help: or `vec.extend(std::iter::repeat_n(item, SIZE))` = note: `-D clippy::same-item-push` implied by `-D warnings` = help: to override `-D warnings` add `#[allow(clippy::same_item_push)]` -error: it looks like the same item is being pushed into this Vec +error: it looks like the same item is being pushed into this `Vec` --> tests/ui/same_item_push.rs:30:9 | LL | vec.push(item); | ^^^ | - = help: consider using vec![item;SIZE] or vec.resize(NEW_SIZE, item) + = help: consider using `vec![item;SIZE]` + = help: or `vec.extend(std::iter::repeat_n(item, SIZE))` -error: it looks like the same item is being pushed into this Vec +error: it looks like the same item is being pushed into this `Vec` --> tests/ui/same_item_push.rs:36:9 | LL | vec.push(13); | ^^^ | - = help: consider using vec![13;SIZE] or vec.resize(NEW_SIZE, 13) + = help: consider using `vec![13;SIZE]` + = help: or `vec.extend(std::iter::repeat_n(13, SIZE))` -error: it looks like the same item is being pushed into this Vec +error: it looks like the same item is being pushed into this `Vec` --> tests/ui/same_item_push.rs:42:9 | LL | vec.push(VALUE); | ^^^ | - = help: consider using vec![VALUE;SIZE] or vec.resize(NEW_SIZE, VALUE) + = help: consider using `vec![VALUE;SIZE]` + = help: or `vec.extend(std::iter::repeat_n(VALUE, SIZE))` -error: it looks like the same item is being pushed into this Vec +error: it looks like the same item is being pushed into this `Vec` --> tests/ui/same_item_push.rs:49:9 | LL | vec.push(item); | ^^^ | - = help: consider using vec![item;SIZE] or vec.resize(NEW_SIZE, item) + = help: consider using `vec![item;SIZE]` + = help: or `vec.extend(std::iter::repeat_n(item, SIZE))` -error: aborting due to 5 previous errors +error: it looks like the same item is being pushed into this `Vec` + --> tests/ui/same_item_push.rs:58:13 + | +LL | vec.push(item); + | ^^^ + | + = help: consider using `vec![item;SIZE]` + = help: or `vec.resize(NEW_SIZE, item)` + +error: aborting due to 6 previous errors