diff --git a/README.md b/README.md index 29eb6750d16..0da037e7b16 100644 --- a/README.md +++ b/README.md @@ -6,7 +6,7 @@ A collection of lints to catch common mistakes and improve your Rust code. [Jump to usage instructions](#usage) ##Lints -There are 70 lints included in this crate: +There are 71 lints included in this crate: name | default | meaning -------------------------------------------------------------------------------------------------------|---------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ @@ -53,6 +53,7 @@ name [precedence](https://github.com/Manishearth/rust-clippy/wiki#precedence) | warn | catches operations where precedence may be unclear. See the wiki for a list of cases caught [ptr_arg](https://github.com/Manishearth/rust-clippy/wiki#ptr_arg) | warn | fn arguments of the type `&Vec<...>` or `&String`, suggesting to use `&[...]` or `&str` instead, respectively [range_step_by_zero](https://github.com/Manishearth/rust-clippy/wiki#range_step_by_zero) | warn | using Range::step_by(0), which produces an infinite iterator +[range_zip_with_len](https://github.com/Manishearth/rust-clippy/wiki#range_zip_with_len) | warn | zipping iterator with a range when enumerate() would do [redundant_closure](https://github.com/Manishearth/rust-clippy/wiki#redundant_closure) | warn | using redundant closures, i.e. `|a| foo(a)` (which can be written as just `foo`) [redundant_pattern](https://github.com/Manishearth/rust-clippy/wiki#redundant_pattern) | warn | using `name @ _` in a pattern [result_unwrap_used](https://github.com/Manishearth/rust-clippy/wiki#result_unwrap_used) | allow | using `Result.unwrap()`, which might be better handled diff --git a/src/lib.rs b/src/lib.rs index 60ab18566b8..525603dc2b8 100755 --- a/src/lib.rs +++ b/src/lib.rs @@ -166,6 +166,7 @@ pub fn plugin_registrar(reg: &mut Registry) { precedence::PRECEDENCE, ptr_arg::PTR_ARG, ranges::RANGE_STEP_BY_ZERO, + ranges::RANGE_ZIP_WITH_LEN, returns::LET_AND_RETURN, returns::NEEDLESS_RETURN, types::BOX_VEC, diff --git a/src/ranges.rs b/src/ranges.rs index 2ef272237d1..39ff7d3cd31 100644 --- a/src/ranges.rs +++ b/src/ranges.rs @@ -1,19 +1,23 @@ use rustc::lint::*; use rustc_front::hir::*; use syntax::codemap::Spanned; -use utils::{match_type, is_integer_literal}; +use utils::{is_integer_literal, match_type, snippet}; declare_lint! { pub RANGE_STEP_BY_ZERO, Warn, "using Range::step_by(0), which produces an infinite iterator" } +declare_lint! { + pub RANGE_ZIP_WITH_LEN, Warn, + "zipping iterator with a range when enumerate() would do" +} #[derive(Copy,Clone)] pub struct StepByZero; impl LintPass for StepByZero { fn get_lints(&self) -> LintArray { - lint_array!(RANGE_STEP_BY_ZERO) + lint_array!(RANGE_STEP_BY_ZERO, RANGE_ZIP_WITH_LEN) } } @@ -21,13 +25,40 @@ impl LateLintPass for StepByZero { fn check_expr(&mut self, cx: &LateContext, expr: &Expr) { if let ExprMethodCall(Spanned { node: ref name, .. }, _, ref args) = expr.node { - // Only warn on literal ranges. + // Range with step_by(0). if name.as_str() == "step_by" && args.len() == 2 && is_range(cx, &args[0]) && is_integer_literal(&args[1], 0) { cx.span_lint(RANGE_STEP_BY_ZERO, expr.span, "Range::step_by(0) produces an infinite iterator. \ Consider using `std::iter::repeat()` instead") } + + // x.iter().zip(0..x.len()) + else if name.as_str() == "zip" && args.len() == 2 { + let iter = &args[0].node; + let zip_arg = &args[1].node; + if_let_chain! { + [ + // .iter() call + let &ExprMethodCall( Spanned { node: ref iter_name, .. }, _, ref iter_args ) = iter, + iter_name.as_str() == "iter", + // range expression in .zip() call: 0..x.len() + let &ExprRange(Some(ref from), Some(ref to)) = zip_arg, + is_integer_literal(from, 0), + // .len() call + let ExprMethodCall(Spanned { node: ref len_name, .. }, _, ref len_args) = to.node, + len_name.as_str() == "len" && len_args.len() == 1, + // .iter() and .len() called on same Path + let ExprPath(_, Path { segments: ref iter_path, .. }) = iter_args[0].node, + let ExprPath(_, Path { segments: ref len_path, .. }) = len_args[0].node, + iter_path == len_path + ], { + cx.span_lint(RANGE_ZIP_WITH_LEN, expr.span, + &format!("It is more idiomatic to use {}.iter().enumerate()", + snippet(cx, iter_args[0].span, "_"))); + } + } + } } } } diff --git a/tests/compile-fail/range.rs b/tests/compile-fail/range.rs index 324f129fafa..2d731670cbe 100644 --- a/tests/compile-fail/range.rs +++ b/tests/compile-fail/range.rs @@ -7,7 +7,7 @@ impl NotARange { fn step_by(&self, _: u32) {} } -#[deny(range_step_by_zero)] +#[deny(range_step_by_zero, range_zip_with_len)] fn main() { (0..1).step_by(0); //~ERROR Range::step_by(0) produces an infinite iterator // No warning for non-zero step @@ -21,4 +21,9 @@ fn main() { // No error, not a range. let y = NotARange; y.step_by(0); + + let _v1 = vec![1,2,3]; + let _v2 = vec![4,5]; + let _x = _v1.iter().zip(0.._v1.len()); //~ERROR It is more idiomatic to use _v1.iter().enumerate() + let _y = _v1.iter().zip(0.._v2.len()); // No error }