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Fix confusing message for STRING_TO_STRING

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This commit is contained in:
mcarton 2016-02-03 13:42:46 +01:00
parent 5eb884b7b0
commit fab10c07e8
3 changed files with 6 additions and 5 deletions
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2
README.md
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@ -98,7 +98,7 @@ name
[string_add](https://github.com/Manishearth/rust-clippy/wiki#string_add) | allow | using `x + ..` where x is a `String`; suggests using `push_str()` instead
[string_add_assign](https://github.com/Manishearth/rust-clippy/wiki#string_add_assign) | allow | using `x = x + ..` where x is a `String`; suggests using `push_str()` instead
[string_lit_as_bytes](https://github.com/Manishearth/rust-clippy/wiki#string_lit_as_bytes) | warn | calling `as_bytes` on a string literal; suggests using a byte string literal instead
[string_to_string](https://github.com/Manishearth/rust-clippy/wiki#string_to_string) | warn | calling `String.to_string()` which is a no-op
[string_to_string](https://github.com/Manishearth/rust-clippy/wiki#string_to_string) | warn | calling `String::to_string` which is inefficient
[temporary_assignment](https://github.com/Manishearth/rust-clippy/wiki#temporary_assignment) | warn | assignments to temporaries
[toplevel_ref_arg](https://github.com/Manishearth/rust-clippy/wiki#toplevel_ref_arg) | warn | An entire binding was declared as `ref`, in a function argument (`fn foo(ref x: Bar)`), or a `let` statement (`let ref x = foo()`). In such cases, it is preferred to take references with `&`.
[type_complexity](https://github.com/Manishearth/rust-clippy/wiki#type_complexity) | warn | usage of very complex types; recommends factoring out parts into `type` definitions

7
src/methods.rs
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@ -56,13 +56,14 @@ declare_lint!(pub STR_TO_STRING, Warn,
/// **What it does:** This lint checks for `.to_string()` method calls on values of type `String`. It is `Warn` by default.
///
/// **Why is this bad?** As our string is already owned, this whole operation is basically a no-op, but still creates a clone of the string (which, if really wanted, should be done with `.clone()`).
/// **Why is this bad?** This is an non-efficient way to clone a `String`, `.clone()` should be used
/// instead. `String` implements `ToString` mostly for generics.
///
/// **Known problems:** None
///
/// **Example:** `s.to_string()` where `s: String`
declare_lint!(pub STRING_TO_STRING, Warn,
"calling `String.to_string()` which is a no-op");
"calling `String::to_string` which is inefficient");
/// **What it does:** This lint checks for methods that should live in a trait implementation of a `std` trait (see [llogiq's blog post](http://llogiq.github.io/2015/07/30/traits.html) for further information) instead of an inherent implementation. It is `Warn` by default.
///
@ -560,7 +561,7 @@ fn lint_to_string(cx: &LateContext, expr: &Expr, to_string_args: &MethodArgs) {
span_lint(cx,
STRING_TO_STRING,
expr.span,
"`String.to_string()` is a no-op; use `clone()` to make a copy");
"`String::to_string` is an inefficient way to clone a `String`; use `clone()` instead");
}
}

2
tests/compile-fail/methods.rs
View file

@ -267,7 +267,7 @@ fn main() {
let v = &"str";
let string = v.to_string(); //~ERROR `(*v).to_owned()` is faster
let _again = string.to_string(); //~ERROR `String.to_string()` is a no-op
let _again = string.to_string(); //~ERROR `String::to_string` is an inefficient way to clone a `String`; use `clone()` instead
res.ok().expect("disaster!"); //~ERROR called `ok().expect()`
// the following should not warn, since `expect` isn't implemented unless