diff options
| -rw-r--r-- | CHANGELOG.md | 1 | ||||
| -rw-r--r-- | clippy_lints/src/lib.rs | 5 | ||||
| -rw-r--r-- | clippy_lints/src/utils/paths.rs | 1 | ||||
| -rw-r--r-- | clippy_lints/src/vec_resize_to_zero.rs | 59 | ||||
| -rw-r--r-- | src/lintlist/mod.rs | 7 | ||||
| -rw-r--r-- | tests/ui/vec_resize_to_zero.rs | 15 | ||||
| -rw-r--r-- | tests/ui/vec_resize_to_zero.stderr | 13 |
7 files changed, 101 insertions, 0 deletions
diff --git a/CHANGELOG.md b/CHANGELOG.md index 2ac9057199f..f7dae3dcfff 100644 --- a/CHANGELOG.md +++ b/CHANGELOG.md @@ -1630,6 +1630,7 @@ Released 2018-09-13 [`useless_transmute`]: https://rust-lang.github.io/rust-clippy/master/index.html#useless_transmute [`useless_vec`]: https://rust-lang.github.io/rust-clippy/master/index.html#useless_vec [`vec_box`]: https://rust-lang.github.io/rust-clippy/master/index.html#vec_box +[`vec_resize_to_zero`]: https://rust-lang.github.io/rust-clippy/master/index.html#vec_resize_to_zero [`verbose_bit_mask`]: https://rust-lang.github.io/rust-clippy/master/index.html#verbose_bit_mask [`verbose_file_reads`]: https://rust-lang.github.io/rust-clippy/master/index.html#verbose_file_reads [`vtable_address_comparisons`]: https://rust-lang.github.io/rust-clippy/master/index.html#vtable_address_comparisons diff --git a/clippy_lints/src/lib.rs b/clippy_lints/src/lib.rs index 902f3d56c1e..4f0ecab393d 100644 --- a/clippy_lints/src/lib.rs +++ b/clippy_lints/src/lib.rs @@ -325,6 +325,7 @@ mod unwrap; mod use_self; mod useless_conversion; mod vec; +mod vec_resize_to_zero; mod verbose_file_reads; mod wildcard_dependencies; mod wildcard_imports; @@ -847,6 +848,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf: &utils::internal_lints::OUTER_EXPN_EXPN_DATA, &utils::internal_lints::PRODUCE_ICE, &vec::USELESS_VEC, + &vec_resize_to_zero::VEC_RESIZE_TO_ZERO, &verbose_file_reads::VERBOSE_FILE_READS, &wildcard_dependencies::WILDCARD_DEPENDENCIES, &wildcard_imports::ENUM_GLOB_USE, @@ -1062,6 +1064,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf: store.register_early_pass(|| box manual_non_exhaustive::ManualNonExhaustive); store.register_late_pass(|| box manual_async_fn::ManualAsyncFn); store.register_early_pass(|| box redundant_field_names::RedundantFieldNames); + store.register_late_pass(|| box vec_resize_to_zero::VecResizeToZero); let single_char_binding_names_threshold = conf.single_char_binding_names_threshold; store.register_early_pass(move || box non_expressive_names::NonExpressiveNames { single_char_binding_names_threshold, @@ -1430,6 +1433,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf: LintId::of(&unwrap::UNNECESSARY_UNWRAP), LintId::of(&useless_conversion::USELESS_CONVERSION), LintId::of(&vec::USELESS_VEC), + LintId::of(&vec_resize_to_zero::VEC_RESIZE_TO_ZERO), LintId::of(&write::PRINTLN_EMPTY_STRING), LintId::of(&write::PRINT_LITERAL), LintId::of(&write::PRINT_WITH_NEWLINE), @@ -1677,6 +1681,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf: LintId::of(&unnamed_address::VTABLE_ADDRESS_COMPARISONS), LintId::of(&unused_io_amount::UNUSED_IO_AMOUNT), LintId::of(&unwrap::PANICKING_UNWRAP), + LintId::of(&vec_resize_to_zero::VEC_RESIZE_TO_ZERO), ]); store.register_group(true, "clippy::perf", Some("clippy_perf"), vec![ diff --git a/clippy_lints/src/utils/paths.rs b/clippy_lints/src/utils/paths.rs index 779da7e6bf2..3b7e9739211 100644 --- a/clippy_lints/src/utils/paths.rs +++ b/clippy_lints/src/utils/paths.rs @@ -138,5 +138,6 @@ pub const VEC_AS_SLICE: [&str; 4] = ["alloc", "vec", "Vec", "as_slice"]; pub const VEC_DEQUE: [&str; 4] = ["alloc", "collections", "vec_deque", "VecDeque"]; pub const VEC_FROM_ELEM: [&str; 3] = ["alloc", "vec", "from_elem"]; pub const VEC_NEW: [&str; 4] = ["alloc", "vec", "Vec", "new"]; +pub const VEC_RESIZE: [&str; 4] = ["alloc", "vec", "Vec", "resize"]; pub const WEAK_ARC: [&str; 3] = ["alloc", "sync", "Weak"]; pub const WEAK_RC: [&str; 3] = ["alloc", "rc", "Weak"]; diff --git a/clippy_lints/src/vec_resize_to_zero.rs b/clippy_lints/src/vec_resize_to_zero.rs new file mode 100644 index 00000000000..86cbfa8203d --- /dev/null +++ b/clippy_lints/src/vec_resize_to_zero.rs @@ -0,0 +1,59 @@ +use crate::utils::span_lint_and_then; +use if_chain::if_chain; +use rustc_errors::Applicability; +use rustc_hir::{Expr, ExprKind}; +use rustc_lint::{LateContext, LateLintPass}; +use rustc_session::{declare_lint_pass, declare_tool_lint}; +use rustc_span::source_map::Spanned; + +use crate::utils::{match_def_path, paths}; +use rustc_ast::ast::LitKind; +use rustc_hir as hir; + +declare_clippy_lint! { + /// **What it does:** Finds occurences of `Vec::resize(0, an_int)` + /// + /// **Why is this bad?** This is probably an argument inversion mistake. + /// + /// **Known problems:** None. + /// + /// **Example:** + /// ```rust + /// vec!(1, 2, 3, 4, 5).resize(0, 5) + /// ``` + pub VEC_RESIZE_TO_ZERO, + correctness, + "emptying a vector with `resize(0, an_int)` instead of `clear()` is probably an argument inversion mistake" +} + +declare_lint_pass!(VecResizeToZero => [VEC_RESIZE_TO_ZERO]); + +impl<'a, 'tcx> LateLintPass<'a, 'tcx> for VecResizeToZero { + fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, expr: &'tcx Expr<'_>) { + if_chain! { + if let hir::ExprKind::MethodCall(path_segment, _, ref args) = expr.kind; + if let Some(method_def_id) = cx.tables.type_dependent_def_id(expr.hir_id); + if match_def_path(cx, method_def_id, &paths::VEC_RESIZE) && args.len() == 3; + if let ExprKind::Lit(Spanned { node: LitKind::Int(0, _), .. }) = args[1].kind; + if let ExprKind::Lit(Spanned { node: LitKind::Int(..), .. }) = args[2].kind; + then { + let method_call_span = expr.span.with_lo(path_segment.ident.span.lo()); + span_lint_and_then( + cx, + VEC_RESIZE_TO_ZERO, + expr.span, + "emptying a vector with `resize`", + |db| { + db.help("the arguments may be inverted..."); + db.span_suggestion( + method_call_span, + "...or you can empty the vector with", + "clear()".to_string(), + Applicability::MaybeIncorrect, + ); + }, + ); + } + } + } +} diff --git a/src/lintlist/mod.rs b/src/lintlist/mod.rs index f63301c7db0..1e94ca00c14 100644 --- a/src/lintlist/mod.rs +++ b/src/lintlist/mod.rs @@ -2461,6 +2461,13 @@ pub static ref ALL_LINTS: Vec<Lint> = vec![ module: "types", }, Lint { + name: "vec_resize_to_zero", + group: "correctness", + desc: "emptying a vector with `resize(0, an_int)` instead of `clear()` is probably an argument inversion mistake", + deprecation: None, + module: "vec_resize_to_zero", + }, + Lint { name: "verbose_bit_mask", group: "style", desc: "expressions where a bit mask is less readable than the corresponding method call", diff --git a/tests/ui/vec_resize_to_zero.rs b/tests/ui/vec_resize_to_zero.rs new file mode 100644 index 00000000000..0263e2f5f20 --- /dev/null +++ b/tests/ui/vec_resize_to_zero.rs @@ -0,0 +1,15 @@ +#![warn(clippy::vec_resize_to_zero)] + +fn main() { + // applicable here + vec![1, 2, 3, 4, 5].resize(0, 5); + + // not applicable + vec![1, 2, 3, 4, 5].resize(2, 5); + + // applicable here, but only implemented for integer litterals for now + vec!["foo", "bar", "baz"].resize(0, "bar"); + + // not applicable + vec!["foo", "bar", "baz"].resize(2, "bar") +} diff --git a/tests/ui/vec_resize_to_zero.stderr b/tests/ui/vec_resize_to_zero.stderr new file mode 100644 index 00000000000..feb846298c6 --- /dev/null +++ b/tests/ui/vec_resize_to_zero.stderr @@ -0,0 +1,13 @@ +error: emptying a vector with `resize` + --> $DIR/vec_resize_to_zero.rs:5:5 + | +LL | vec![1, 2, 3, 4, 5].resize(0, 5); + | ^^^^^^^^^^^^^^^^^^^^------------ + | | + | help: ...or you can empty the vector with: `clear()` + | + = note: `-D clippy::vec-resize-to-zero` implied by `-D warnings` + = help: the arguments may be inverted... + +error: aborting due to previous error + |