rust/clippy_lints/src/repeat_once.rs
xFrednet d647696c1f
Added clippy::version attribute to all normal lints
So, some context for this, well, more a story. I'm not used to scripting, I've never really scripted anything, even if it's a valuable skill. I just never really needed it. Now, `@flip1995` correctly suggested using a script for this in `rust-clippy#7813`...

And I decided to write a script using nushell because why not? This was a mistake... I spend way more time on this than I would like to admit. It has definitely been more than 4 hours. It shouldn't take that long, but me being new to scripting and nushell just wasn't a good mixture... Anyway, here is the script that creates another script which adds the versions. Fun...

Just execute this on the `gh-pages` branch and the resulting `replacer.sh` in `clippy_lints` and it should all work.

```nu
mv v0.0.212 rust-1.00.0;
mv beta rust-1.57.0;
mv master rust-1.58.0;

let paths = (open ./rust-1.58.0/lints.json | select id id_span | flatten | select id path);
let versions = (
    ls | where name =~ "rust-" | select name | format {name}/lints.json |
    each { open $it | select id | insert version $it | str substring "5,11" version} |
    group-by id | rotate counter-clockwise id version |
    update version {get version | first 1} | flatten | select id version);
$paths | each { |row|
    let version = ($versions | where id == ($row.id) | format {version})
    let idu = ($row.id | str upcase)
    $"sed -i '0,/($idu),/{s/pub ($idu),/#[clippy::version = "($version)"]\n    pub ($idu),/}' ($row.path)"
} | str collect ";" | str find-replace --all '1.00.0' 'pre 1.29.0' | save "replacer.sh";
```

And this still has some problems, but at this point I just want to be done -.-
2021-11-10 19:48:31 +01:00

90 lines
3.5 KiB
Rust

use clippy_utils::consts::{constant_context, Constant};
use clippy_utils::diagnostics::span_lint_and_sugg;
use clippy_utils::source::snippet;
use clippy_utils::ty::is_type_diagnostic_item;
use if_chain::if_chain;
use rustc_errors::Applicability;
use rustc_hir::{Expr, ExprKind};
use rustc_lint::{LateContext, LateLintPass};
use rustc_session::{declare_lint_pass, declare_tool_lint};
use rustc_span::sym;
declare_clippy_lint! {
/// ### What it does
/// Checks for usage of `.repeat(1)` and suggest the following method for each types.
/// - `.to_string()` for `str`
/// - `.clone()` for `String`
/// - `.to_vec()` for `slice`
///
/// The lint will evaluate constant expressions and values as arguments of `.repeat(..)` and emit a message if
/// they are equivalent to `1`. (Related discussion in [rust-clippy#7306](https://github.com/rust-lang/rust-clippy/issues/7306))
///
/// ### Why is this bad?
/// For example, `String.repeat(1)` is equivalent to `.clone()`. If cloning
/// the string is the intention behind this, `clone()` should be used.
///
/// ### Example
/// ```rust
/// fn main() {
/// let x = String::from("hello world").repeat(1);
/// }
/// ```
/// Use instead:
/// ```rust
/// fn main() {
/// let x = String::from("hello world").clone();
/// }
/// ```
#[clippy::version = "1.47.0"]
pub REPEAT_ONCE,
complexity,
"using `.repeat(1)` instead of `String.clone()`, `str.to_string()` or `slice.to_vec()` "
}
declare_lint_pass!(RepeatOnce => [REPEAT_ONCE]);
impl<'tcx> LateLintPass<'tcx> for RepeatOnce {
fn check_expr(&mut self, cx: &LateContext<'_>, expr: &'tcx Expr<'_>) {
if_chain! {
if let ExprKind::MethodCall(path, _, [receiver, count], _) = &expr.kind;
if path.ident.name == sym!(repeat);
if constant_context(cx, cx.typeck_results()).expr(count) == Some(Constant::Int(1));
if !receiver.span.from_expansion();
then {
let ty = cx.typeck_results().expr_ty(receiver).peel_refs();
if ty.is_str() {
span_lint_and_sugg(
cx,
REPEAT_ONCE,
expr.span,
"calling `repeat(1)` on str",
"consider using `.to_string()` instead",
format!("{}.to_string()", snippet(cx, receiver.span, r#""...""#)),
Applicability::MachineApplicable,
);
} else if ty.builtin_index().is_some() {
span_lint_and_sugg(
cx,
REPEAT_ONCE,
expr.span,
"calling `repeat(1)` on slice",
"consider using `.to_vec()` instead",
format!("{}.to_vec()", snippet(cx, receiver.span, r#""...""#)),
Applicability::MachineApplicable,
);
} else if is_type_diagnostic_item(cx, ty, sym::String) {
span_lint_and_sugg(
cx,
REPEAT_ONCE,
expr.span,
"calling `repeat(1)` on a string literal",
"consider using `.clone()` instead",
format!("{}.clone()", snippet(cx, receiver.span, r#""...""#)),
Applicability::MachineApplicable,
);
}
}
}
}
}