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Merge pull request #136 from birkenfeld/len_zero_expr

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len_zero: display full suggested expr in message
This commit is contained in:
Manish Goregaokar 2015-08-12 15:03:21 +05:30
commit 85499f31a7
2 changed files with 13 additions and 7 deletions
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14
src/len_zero.rs
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@ -9,7 +9,7 @@ use rustc::middle::ty::{self, TypeVariants, TypeAndMut, MethodTraitItemId, ImplO
use rustc::middle::def::{DefTy, DefStruct, DefTrait};
use syntax::codemap::{Span, Spanned};
use syntax::ast::*;
use utils::{span_lint, walk_ptrs_ty};
use utils::{span_lint, walk_ptrs_ty, snippet};
declare_lint!(pub LEN_ZERO, Warn,
"Warn when .is_empty() could be used instead of checking .len()");
@ -92,24 +92,24 @@ fn is_self_sig(sig: &MethodSig) -> bool {
false } else { sig.decl.inputs.len() == 1 }
}
fn check_cmp(cx: &Context, span: Span, left: &Expr, right: &Expr, empty: &str) {
fn check_cmp(cx: &Context, span: Span, left: &Expr, right: &Expr, op: &str) {
match (&left.node, &right.node) {
(&ExprLit(ref lit), &ExprMethodCall(ref method, _, ref args)) =>
check_len_zero(cx, span, method, args, lit, empty),
check_len_zero(cx, span, method, args, lit, op),
(&ExprMethodCall(ref method, _, ref args), &ExprLit(ref lit)) =>
check_len_zero(cx, span, method, args, lit, empty),
check_len_zero(cx, span, method, args, lit, op),
_ => ()
}
}
fn check_len_zero(cx: &Context, span: Span, method: &SpannedIdent,
args: &[P<Expr>], lit: &Lit, empty: &str) {
args: &[P<Expr>], lit: &Lit, op: &str) {
if let &Spanned{node: LitInt(0, _), ..} = lit {
if method.node.name == "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()`",
empty))
"consider replacing the len comparison with `{}{}.is_empty()`",
op, snippet(cx, args[0].span, "_")))
}
}
}

6
tests/compile-fail/len_zero.rs
View file

@ -87,6 +87,12 @@ fn main() {
if hie.len() == 0 { //~ERROR consider replacing the len comparison
println!("Or this!");
}
if hie.len() != 0 { //~ERROR consider replacing the len comparison
println!("Or this!");
}
if hie.len() > 0 { //~ERROR consider replacing the len comparison
println!("Or this!");
}
assert!(!hie.is_empty());
let wie : &WithIsEmpty = &Wither;