rust-clippy/clippy_lints/src/manual_main_separator_str.rs
Samuel "Sam" Tardieu 728ee6f8cd Really dogfood clippy
The dogfood success condition was inverted in `tests/dogfood.rs`:

```rust
  assert!(!failed_packages.is_empty(), …);
```

while instead the `failed_packages` collection must be empty:

```rust
  assert!(failed_packages.is_empty(), …);
```

And indeed, several clippy lint source files were not clean and had to be
fixed in the process.
2023-03-21 22:00:58 +01:00

74 lines
2.6 KiB
Rust

use clippy_utils::diagnostics::span_lint_and_sugg;
use clippy_utils::msrvs::{self, Msrv};
use clippy_utils::{is_trait_method, match_def_path, paths, peel_hir_expr_refs};
use rustc_errors::Applicability;
use rustc_hir::def::{DefKind, Res};
use rustc_hir::{Expr, ExprKind, Mutability, QPath};
use rustc_lint::{LateContext, LateLintPass};
use rustc_middle::ty;
use rustc_session::{declare_tool_lint, impl_lint_pass};
use rustc_span::sym;
declare_clippy_lint! {
/// ### What it does
/// Checks for references on `std::path::MAIN_SEPARATOR.to_string()` used
/// to build a `&str`.
///
/// ### Why is this bad?
/// There exists a `std::path::MAIN_SEPARATOR_STR` which does not require
/// an extra memory allocation.
///
/// ### Example
/// ```rust
/// let s: &str = &std::path::MAIN_SEPARATOR.to_string();
/// ```
/// Use instead:
/// ```rust
/// let s: &str = std::path::MAIN_SEPARATOR_STR;
/// ```
#[clippy::version = "1.70.0"]
pub MANUAL_MAIN_SEPARATOR_STR,
complexity,
"`&std::path::MAIN_SEPARATOR.to_string()` can be replaced by `std::path::MAIN_SEPARATOR_STR`"
}
pub struct ManualMainSeparatorStr {
msrv: Msrv,
}
impl ManualMainSeparatorStr {
#[must_use]
pub fn new(msrv: Msrv) -> Self {
Self { msrv }
}
}
impl_lint_pass!(ManualMainSeparatorStr => [MANUAL_MAIN_SEPARATOR_STR]);
impl LateLintPass<'_> for ManualMainSeparatorStr {
fn check_expr(&mut self, cx: &LateContext<'_>, expr: &Expr<'_>) {
if self.msrv.meets(msrvs::PATH_MAIN_SEPARATOR_STR) &&
let (target, _) = peel_hir_expr_refs(expr) &&
is_trait_method(cx, target, sym::ToString) &&
let ExprKind::MethodCall(path, receiver, &[], _) = target.kind &&
path.ident.name == sym::to_string &&
let ExprKind::Path(QPath::Resolved(None, path)) = receiver.kind &&
let Res::Def(DefKind::Const, receiver_def_id) = path.res &&
match_def_path(cx, receiver_def_id, &paths::PATH_MAIN_SEPARATOR) &&
let ty::Ref(_, ty, Mutability::Not) = cx.typeck_results().expr_ty_adjusted(expr).kind() &&
ty.is_str()
{
span_lint_and_sugg(
cx,
MANUAL_MAIN_SEPARATOR_STR,
expr.span,
"taking a reference on `std::path::MAIN_SEPARATOR` conversion to `String`",
"replace with",
"std::path::MAIN_SEPARATOR_STR".to_owned(),
Applicability::MachineApplicable,
);
}
}
extract_msrv_attr!(LateContext);
}