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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,153 @@ | ||
| use clippy_utils::{ | ||
| diagnostics::span_lint_and_then, | ||
| get_trait_def_id, | ||
| higher::VecArgs, | ||
| macros::root_macro_call_first_node, | ||
| source::{snippet_opt, snippet_with_applicability}, | ||
| ty::implements_trait, | ||
| }; | ||
| use rustc_ast::{LitIntType, LitKind, UintTy}; | ||
| use rustc_errors::Applicability; | ||
| use rustc_hir::{Expr, ExprKind, LangItem, QPath}; | ||
| use rustc_lint::{LateContext, LateLintPass}; | ||
| use rustc_session::{declare_lint_pass, declare_tool_lint}; | ||
| use std::fmt::{self, Display, Formatter}; | ||
|
|
||
| declare_clippy_lint! { | ||
| /// ### What it does | ||
| /// Checks for `Vec` or array initializations that contain only one range. | ||
| /// | ||
| /// ### Why is this bad? | ||
| /// This is almost always incorrect, as it will result in a `Vec` that has only element. Almost | ||
| /// always, the programmer intended for it to include all elements in the range or for the end | ||
| /// of the range to be the length instead. | ||
| /// | ||
| /// ### Example | ||
| /// ```rust | ||
| /// let x = [0..200]; | ||
| /// ``` | ||
| /// Use instead: | ||
| /// ```rust | ||
| /// // If it was intended to include every element in the range... | ||
| /// let x = (0..200).collect::<Vec<i32>>(); | ||
| /// // ...Or if 200 was meant to be the len | ||
| /// let x = [0; 200]; | ||
| /// ``` | ||
| #[clippy::version = "1.72.0"] | ||
| pub SINGLE_RANGE_IN_VEC_INIT, | ||
| suspicious, | ||
| "checks for initialization of `Vec` or arrays which consist of a single range" | ||
| } | ||
| declare_lint_pass!(SingleRangeInVecInit => [SINGLE_RANGE_IN_VEC_INIT]); | ||
|
|
||
| enum SuggestedType { | ||
| Vec, | ||
| Array, | ||
| } | ||
|
|
||
| impl SuggestedType { | ||
| fn starts_with(&self) -> &'static str { | ||
| if matches!(self, SuggestedType::Vec) { | ||
| "vec!" | ||
| } else { | ||
| "[" | ||
| } | ||
| } | ||
|
|
||
| fn ends_with(&self) -> &'static str { | ||
| if matches!(self, SuggestedType::Vec) { "" } else { "]" } | ||
| } | ||
| } | ||
|
|
||
| impl Display for SuggestedType { | ||
| fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result { | ||
| if matches!(&self, SuggestedType::Vec) { | ||
| write!(f, "a `Vec`") | ||
| } else { | ||
| write!(f, "an array") | ||
| } | ||
| } | ||
| } | ||
|
|
||
| impl LateLintPass<'_> for SingleRangeInVecInit { | ||
| fn check_expr<'tcx>(&mut self, cx: &LateContext<'tcx>, expr: &Expr<'tcx>) { | ||
| // inner_expr: `vec![0..200]` or `[0..200]` | ||
| // ^^^^^^ ^^^^^^^ | ||
| // span: `vec![0..200]` or `[0..200]` | ||
| // ^^^^^^^^^^^^ ^^^^^^^^ | ||
| // kind: What to print, an array or a `Vec` | ||
| let (inner_expr, span, kind) = if let ExprKind::Array([inner_expr]) = expr.kind | ||
| && !expr.span.from_expansion() | ||
| { | ||
| (inner_expr, expr.span, SuggestedType::Array) | ||
| } else if let Some(macro_call) = root_macro_call_first_node(cx, expr) | ||
| && let Some(VecArgs::Vec([expr])) = VecArgs::hir(cx, expr) | ||
| { | ||
| (expr, macro_call.span, SuggestedType::Vec) | ||
| } else { | ||
| return; | ||
| }; | ||
|
|
||
| let ExprKind::Struct(QPath::LangItem(lang_item, ..), [start, end], None) = inner_expr.kind else { | ||
| return; | ||
| }; | ||
|
|
||
| if matches!(lang_item, LangItem::Range) | ||
| && let ty = cx.typeck_results().expr_ty(start.expr) | ||
| && let Some(snippet) = snippet_opt(cx, span) | ||
| // `is_from_proc_macro` will skip any `vec![]`. Let's not! | ||
| && snippet.starts_with(kind.starts_with()) | ||
| && snippet.ends_with(kind.ends_with()) | ||
| { | ||
| let mut app = Applicability::MaybeIncorrect; | ||
| let start_snippet = snippet_with_applicability(cx, start.span, "...", &mut app); | ||
| let end_snippet = snippet_with_applicability(cx, end.span, "...", &mut app); | ||
|
|
||
| let should_emit_every_value = if let Some(step_def_id) = get_trait_def_id(cx, &["core", "iter", "Step"]) | ||
| && implements_trait(cx, ty, step_def_id, &[]) | ||
| { | ||
| true | ||
| } else { | ||
| false | ||
| }; | ||
| let should_emit_of_len = if let Some(copy_def_id) = cx.tcx.lang_items().copy_trait() | ||
| && implements_trait(cx, ty, copy_def_id, &[]) | ||
| && let ExprKind::Lit(lit_kind) = end.expr.kind | ||
| && let LitKind::Int(.., suffix_type) = lit_kind.node | ||
| && let LitIntType::Unsigned(UintTy::Usize) | LitIntType::Unsuffixed = suffix_type | ||
| { | ||
| true | ||
| } else { | ||
| false | ||
| }; | ||
|
|
||
| if should_emit_every_value || should_emit_of_len { | ||
| span_lint_and_then( | ||
| cx, | ||
| SINGLE_RANGE_IN_VEC_INIT, | ||
| span, | ||
| &format!("{kind} of `Range` that is only one element"), | ||
| |diag| { | ||
| if should_emit_every_value { | ||
| diag.span_suggestion( | ||
| span, | ||
| "if you wanted a `Vec` that contains every value in the range, try", | ||
| format!("({start_snippet}..{end_snippet}).collect::<std::vec::Vec<{ty}>>()"), | ||
| app, | ||
| ); | ||
| } | ||
|
|
||
| if should_emit_of_len { | ||
| diag.span_suggestion( | ||
| inner_expr.span, | ||
| format!("if you wanted {kind} of len {end_snippet}, try"), | ||
| format!("{start_snippet}; {end_snippet}"), | ||
| app, | ||
| ); | ||
| } | ||
| }, | ||
| ); | ||
| } | ||
| } | ||
| } | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,58 @@ | ||
| //@aux-build:proc_macros.rs | ||
| #![allow(clippy::no_effect, clippy::useless_vec, unused)] | ||
| #![warn(clippy::single_range_in_vec_init)] | ||
| #![feature(generic_arg_infer)] | ||
|
|
||
| #[macro_use] | ||
| extern crate proc_macros; | ||
|
|
||
| macro_rules! a { | ||
| () => { | ||
| vec![0..200]; | ||
| }; | ||
| } | ||
|
|
||
| fn awa<T: PartialOrd>(start: T, end: T) { | ||
| [start..end]; | ||
| } | ||
|
|
||
| fn awa_vec<T: PartialOrd>(start: T, end: T) { | ||
| vec![start..end]; | ||
| } | ||
|
|
||
| fn main() { | ||
| // Lint | ||
| [0..200]; | ||
| vec![0..200]; | ||
| [0u8..200]; | ||
| [0usize..200]; | ||
| [0..200usize]; | ||
| vec![0u8..200]; | ||
| vec![0usize..200]; | ||
| vec![0..200usize]; | ||
| // Only suggest collect | ||
| [0..200isize]; | ||
| vec![0..200isize]; | ||
| // Do not lint | ||
| [0..200, 0..100]; | ||
| vec![0..200, 0..100]; | ||
| [0.0..200.0]; | ||
| vec![0.0..200.0]; | ||
| // `Copy` is not implemented for `Range`, so this doesn't matter | ||
| // [0..200; 2]; | ||
| // [vec!0..200; 2]; | ||
|
|
||
| // Unfortunately skips any macros | ||
| a!(); | ||
|
|
||
| // Skip external macros and procedural macros | ||
| external! { | ||
| [0..200]; | ||
| vec![0..200]; | ||
| } | ||
| with_span! { | ||
| span | ||
| [0..200]; | ||
| vec![0..200]; | ||
| } | ||
| } |
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