[Jump to usage instructions](#usage)
##Lints
-There are 93 lints included in this crate:
+There are 94 lints included in this crate:
name | default | meaning
---------------------------------------------------------------------------------------------------------------|---------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
[str_to_string](https://github.com/Manishearth/rust-clippy/wiki#str_to_string) | warn | using `to_string()` on a str, which should be `to_owned()`
[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
[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 `&`.
reg.register_late_lint_pass(box misc::UsedUnderscoreBinding);
reg.register_late_lint_pass(box array_indexing::ArrayIndexing);
reg.register_late_lint_pass(box panic::PanicPass);
+ reg.register_late_lint_pass(box strings::StringLitAsBytes);
reg.register_lint_group("clippy_pedantic", vec![
ranges::RANGE_ZIP_WITH_LEN,
returns::LET_AND_RETURN,
returns::NEEDLESS_RETURN,
+ strings::STRING_LIT_AS_BYTES,
temporary_assignment::TEMPORARY_ASSIGNMENT,
transmute::USELESS_TRANSMUTE,
types::BOX_VEC,
"using `x + ..` where x is a `String`; suggests using `push_str()` instead"
}
+/// **What it does:** This lint matches the `as_bytes` method called on string
+/// literals that contain only ascii characters. It is `Warn` by default.
+///
+/// **Why is this bad?** Byte string literals (e.g. `b"foo"`) can be used instead. They are shorter but less discoverable than `as_bytes()`.
+///
+/// **Example:**
+///
+/// ```
+/// let bs = "a byte string".as_bytes();
+/// ```
+declare_lint! {
+ pub STRING_LIT_AS_BYTES,
+ Warn,
+ "calling `as_bytes` on a string literal; suggests using a byte string literal instead"
+}
+
#[derive(Copy, Clone)]
pub struct StringAdd;
_ => false,
}
}
+
+#[derive(Copy, Clone)]
+pub struct StringLitAsBytes;
+
+impl LintPass for StringLitAsBytes {
+ fn get_lints(&self) -> LintArray {
+ lint_array!(STRING_LIT_AS_BYTES)
+ }
+}
+
+impl LateLintPass for StringLitAsBytes {
+ fn check_expr(&mut self, cx: &LateContext, e: &Expr) {
+ use std::ascii::AsciiExt;
+ use syntax::ast::Lit_::LitStr;
+ use utils::snippet;
+
+ if let ExprMethodCall(ref name, _, ref args) = e.node {
+ if name.node.as_str() == "as_bytes" {
+ if let ExprLit(ref lit) = args[0].node {
+ if let LitStr(ref lit_content, _) = lit.node {
+ if lit_content.chars().all(|c| c.is_ascii()) {
+ let msg = format!("calling `as_bytes()` on a string literal. \
+ Consider using a byte string literal instead: \
+ `b{}`",
+ snippet(cx, args[0].span, r#""foo""#));
+ span_lint(cx, STRING_LIT_AS_BYTES, e.span, &msg);
+ }
+ }
+ }
+ }
+ }
+ }
+}
assert_eq!(&x, &z);
}
+#[allow(dead_code, unused_variables)]
+#[deny(string_lit_as_bytes)]
+fn str_lit_as_bytes() {
+ let bs = "hello there".as_bytes(); //~ERROR calling `as_bytes()`
+ // no warning, because this cannot be written as a byte string literal:
+ let ubs = "☃".as_bytes();
+}
+
fn main() {
add_only();
add_assign_only();