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methods: lint against String.to_string (fixes #100)

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This commit is contained in:
Georg Brandl 2015-08-12 17:02:49 +02:00
parent 6ff1e9a766
commit 4074c1f968
3 changed files with 14 additions and 1 deletions
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1
src/lib.rs
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@ -83,5 +83,6 @@ pub fn plugin_registrar(reg: &mut Registry) {
methods::OPTION_UNWRAP_USED,
methods::RESULT_UNWRAP_USED,
methods::STR_TO_STRING,
methods::STRING_TO_STRING,
]);
}

10
src/methods.rs
View file

@ -13,10 +13,12 @@ declare_lint!(pub RESULT_UNWRAP_USED, Allow,
"Warn on using unwrap() on a Result value");
declare_lint!(pub STR_TO_STRING, Warn,
"Warn when a String could use to_owned() instead of to_string()");
declare_lint!(pub STRING_TO_STRING, Warn,
"Warn when calling String.to_string()");
impl LintPass for MethodsPass {
fn get_lints(&self) -> LintArray {
lint_array!(OPTION_UNWRAP_USED, RESULT_UNWRAP_USED, STR_TO_STRING)
lint_array!(OPTION_UNWRAP_USED, RESULT_UNWRAP_USED, STR_TO_STRING, STRING_TO_STRING)
}
fn check_expr(&mut self, cx: &Context, expr: &Expr) {
@ -41,6 +43,12 @@ impl LintPass for MethodsPass {
if let ty::TyStr = *obj_ty {
span_lint(cx, STR_TO_STRING, expr.span, "`str.to_owned()` is faster");
}
else if let ty::TyStruct(did, _) = *obj_ty {
if match_def_path(cx, did.did, &["collections", "string", "String"]) {
span_lint(cx, STRING_TO_STRING, expr.span,
"`String.to_string()` is a no-op")
}
}
}
}
}

4
tests/compile-fail/methods.rs
View file

@ -2,10 +2,14 @@
#![plugin(clippy)]
#[deny(option_unwrap_used, result_unwrap_used)]
#[deny(str_to_string, string_to_string)]
fn main() {
let opt = Some(0);
let _ = opt.unwrap(); //~ERROR
let res: Result<i32, ()> = Ok(0);
let _ = res.unwrap(); //~ERROR
let string = "str".to_string(); //~ERROR
let _again = string.to_string(); //~ERROR
}