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Use span_suggestion in len_zero

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This commit is contained in:
mcarton 2016-02-24 20:52:47 +01:00
parent d299b5d4d9
commit c1b2fe31b7
2 changed files with 32 additions and 13 deletions
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20
src/len_zero.rs
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@ -8,7 +8,7 @@ use rustc::middle::ty::{self, MethodTraitItemId, ImplOrTraitItemId};
use syntax::ast::{Lit, LitKind};
use utils::{get_item_name, snippet, span_lint, walk_ptrs_ty};
use utils::{get_item_name, snippet, span_lint, span_lint_and_then, walk_ptrs_ty};
/// **What it does:** This lint checks for getting the length of something via `.len()` just to compare to zero, and suggests using `.is_empty()` where applicable.
///
@ -80,7 +80,6 @@ fn check_trait_items(cx: &LateContext, item: &Item, trait_items: &[TraitItem]) {
}
if !trait_items.iter().any(|i| is_named_self(i, "is_empty")) {
// span_lint(cx, LEN_WITHOUT_IS_EMPTY, item.span, &format!("trait {}", item.ident));
for i in trait_items {
if is_named_self(i, "len") {
span_lint(cx,
@ -151,12 +150,17 @@ fn check_cmp(cx: &LateContext, span: Span, left: &Expr, right: &Expr, op: &str)
fn check_len_zero(cx: &LateContext, span: Span, name: &Name, args: &[P<Expr>], lit: &Lit, op: &str) {
if let Spanned{node: LitKind::Int(0, _), ..} = *lit {
if name.as_str() == "len" && args.len() == 1 && has_is_empty(cx, &args[0]) {
span_lint(cx,
LEN_ZERO,
span,
&format!("consider replacing the len comparison with `{}{}.is_empty()`",
op,
snippet(cx, args[0].span, "_")));
span_lint_and_then(cx,
LEN_ZERO,
span,
"length comparison to zero",
|db| {
db.span_suggestion(span,
"consider using `is_empty`",
format!("{}{}.is_empty()",
op,
snippet(cx, args[0].span, "_")));
});
}
}
}

25
tests/compile-fail/len_zero.rs
View file

@ -69,7 +69,10 @@ impl HasWrongIsEmpty {
#[deny(len_zero)]
fn main() {
let x = [1, 2];
if x.len() == 0 { //~ERROR consider replacing the len comparison
if x.len() == 0 {
//~^ERROR length comparison to zero
//~|HELP consider using `is_empty`
//~|SUGGESTION x.is_empty()
println!("This should not happen!");
}
@ -84,19 +87,31 @@ fn main() {
}
let hie = HasIsEmpty;
if hie.len() == 0 { //~ERROR consider replacing the len comparison
if hie.len() == 0 {
//~^ERROR length comparison to zero
//~|HELP consider using `is_empty`
//~|SUGGESTION hie.is_empty()
println!("Or this!");
}
if hie.len() != 0 { //~ERROR consider replacing the len comparison
if hie.len() != 0 {
//~^ERROR length comparison to zero
//~|HELP consider using `is_empty`
//~|SUGGESTION !hie.is_empty()
println!("Or this!");
}
if hie.len() > 0 { //~ERROR consider replacing the len comparison
if hie.len() > 0 {
//~^ERROR length comparison to zero
//~|HELP consider using `is_empty`
//~|SUGGESTION !hie.is_empty()
println!("Or this!");
}
assert!(!hie.is_empty());
let wie : &WithIsEmpty = &Wither;
if wie.len() == 0 { //~ERROR consider replacing the len comparison
if wie.len() == 0 {
//~^ERROR length comparison to zero
//~|HELP consider using `is_empty`
//~|SUGGESTION wie.is_empty()
println!("Or this!");
}
assert!(!wie.is_empty());