diff --git a/clippy_lints/src/loops.rs b/clippy_lints/src/loops.rs index 73926fed0f15..f3dd2d4b8e3c 100644 --- a/clippy_lints/src/loops.rs +++ b/clippy_lints/src/loops.rs @@ -588,28 +588,36 @@ fn check_for_loop_arg(cx: &LateContext, pat: &Pat, arg: &Expr, expr: &Expr) { if &*method_name.as_str() == "iter" || &*method_name.as_str() == "iter_mut" { if is_ref_iterable_type(cx, &args[0]) { let object = snippet(cx, args[0].span, "_"); - span_lint(cx, - EXPLICIT_ITER_LOOP, - expr.span, - &format!("it is more idiomatic to loop over `&{}{}` instead of `{}.{}()`", - if &*method_name.as_str() == "iter_mut" { - "mut " - } else { - "" - }, - object, - object, - method_name)); + let suggestion = format!("&{}{}", + if &*method_name.as_str() == "iter_mut" { + "mut " + } else { + "" + }, + object); + span_lint_and_then(cx, + EXPLICIT_ITER_LOOP, + arg.span, + &format!("it is more idiomatic to loop over `{}` instead of `{}.{}()`", + suggestion, + object, + method_name), + |db| { + db.span_suggestion(arg.span, "to write this more concisely, try looping over", suggestion); + }); } } else if &*method_name.as_str() == "into_iter" && match_trait_method(cx, arg, &paths::INTO_ITERATOR) { let object = snippet(cx, args[0].span, "_"); - span_lint(cx, - EXPLICIT_INTO_ITER_LOOP, - expr.span, - &format!("it is more idiomatic to loop over `{}` instead of `{}.{}()`", - object, - object, - method_name)); + span_lint_and_then(cx, + EXPLICIT_INTO_ITER_LOOP, + arg.span, + &format!("it is more idiomatic to loop over `{}` instead of `{}.{}()`", + object, + object, + method_name), + |db| { + db.span_suggestion(arg.span, "to write this more concisely, try looping over", object.to_string()); + }); } else if &*method_name.as_str() == "next" && match_trait_method(cx, arg, &paths::ITERATOR) { span_lint(cx, diff --git a/tests/compile-fail/for_loop.rs b/tests/compile-fail/for_loop.rs index 659935e6098e..09b0431c6566 100644 --- a/tests/compile-fail/for_loop.rs +++ b/tests/compile-fail/for_loop.rs @@ -286,39 +286,81 @@ fn main() { id_col[i] = 1f64; } - /* - for i in (10..0).map(|x| x * 2) { - println!("{}", i); - }*/ - - for _v in vec.iter() { } //~ERROR it is more idiomatic to loop over `&vec` - for _v in vec.iter_mut() { } //~ERROR it is more idiomatic to loop over `&mut vec` + for _v in vec.iter() { } + //~^ ERROR it is more idiomatic to loop over `&vec` + //~| HELP to write this more concisely, try looping over + //~| SUGGESTION for _v in &vec { + for _v in vec.iter_mut() { } + //~^ ERROR it is more idiomatic to loop over `&mut vec` + //~| HELP to write this more concisely, try looping over + //~| SUGGESTION for _v in &mut vec { let out_vec = vec![1,2,3]; - for _v in out_vec.into_iter() { } //~ERROR it is more idiomatic to loop over `out_vec` instead of `out_vec.into_iter()` + for _v in out_vec.into_iter() { } + //~^ ERROR it is more idiomatic to loop over `out_vec` instead of `out_vec.into_iter()` + //~| HELP to write this more concisely, try looping over + //~| SUGGESTION for _v in out_vec { for _v in &vec { } // these are fine for _v in &mut vec { } // these are fine - for _v in [1, 2, 3].iter() { } //~ERROR it is more idiomatic to loop over `&[ + for _v in [1, 2, 3].iter() { } + //~^ ERROR it is more idiomatic to loop over `&[ + //~| HELP to write this more concisely, try looping over + //~| SUGGESTION for _v in &[1, 2, 3] { + for _v in (&mut [1, 2, 3]).iter() { } // no error - for _v in [0; 32].iter() {} //~ERROR it is more idiomatic to loop over `&[ + + for _v in [0; 32].iter() {} + //~^ ERROR it is more idiomatic to loop over `&[ + //~| HELP to write this more concisely, try looping over + //~| SUGGESTION for _v in &[0; 32] { + for _v in [0; 33].iter() {} // no error + let ll: LinkedList<()> = LinkedList::new(); - for _v in ll.iter() { } //~ERROR it is more idiomatic to loop over `&ll` + for _v in ll.iter() { } + //~^ ERROR it is more idiomatic to loop over `&ll` + //~| HELP to write this more concisely, try looping over + //~| SUGGESTION for _v in &ll { + let vd: VecDeque<()> = VecDeque::new(); - for _v in vd.iter() { } //~ERROR it is more idiomatic to loop over `&vd` + for _v in vd.iter() { } + //~^ ERROR it is more idiomatic to loop over `&vd` + //~| HELP to write this more concisely, try looping over + //~| SUGGESTION for _v in &vd { + let bh: BinaryHeap<()> = BinaryHeap::new(); - for _v in bh.iter() { } //~ERROR it is more idiomatic to loop over `&bh` + for _v in bh.iter() { } + //~^ ERROR it is more idiomatic to loop over `&bh` + //~| HELP to write this more concisely, try looping over + //~| SUGGESTION for _v in &bh { + let hm: HashMap<(), ()> = HashMap::new(); - for _v in hm.iter() { } //~ERROR it is more idiomatic to loop over `&hm` + for _v in hm.iter() { } + //~^ ERROR it is more idiomatic to loop over `&hm` + //~| HELP to write this more concisely, try looping over + //~| SUGGESTION for _v in &hm { + let bt: BTreeMap<(), ()> = BTreeMap::new(); - for _v in bt.iter() { } //~ERROR it is more idiomatic to loop over `&bt` + for _v in bt.iter() { } + //~^ ERROR it is more idiomatic to loop over `&bt` + //~| HELP to write this more concisely, try looping over + //~| SUGGESTION for _v in &bt { + let hs: HashSet<()> = HashSet::new(); - for _v in hs.iter() { } //~ERROR it is more idiomatic to loop over `&hs` + for _v in hs.iter() { } + //~^ ERROR it is more idiomatic to loop over `&hs` + //~| HELP to write this more concisely, try looping over + //~| SUGGESTION for _v in &hs { + let bs: BTreeSet<()> = BTreeSet::new(); - for _v in bs.iter() { } //~ERROR it is more idiomatic to loop over `&bs` + for _v in bs.iter() { } + //~^ ERROR it is more idiomatic to loop over `&bs` + //~| HELP to write this more concisely, try looping over + //~| SUGGESTION for _v in &bs { + for _v in vec.iter().next() { } //~ERROR you are iterating over `Iterator::next()`