rust-clippy/clippy_lints/src/redundant_field_names.rs

85 lines
2.5 KiB
Rust

use clippy_utils::diagnostics::span_lint_and_sugg;
use clippy_utils::{meets_msrv, msrvs};
use rustc_ast::ast::{Expr, ExprKind};
use rustc_errors::Applicability;
use rustc_lint::{EarlyContext, EarlyLintPass};
use rustc_middle::lint::in_external_macro;
use rustc_semver::RustcVersion;
use rustc_session::{declare_tool_lint, impl_lint_pass};
declare_clippy_lint! {
/// **What it does:** Checks for fields in struct literals where shorthands
/// could be used.
///
/// **Why is this bad?** If the field and variable names are the same,
/// the field name is redundant.
///
/// **Known problems:** None.
///
/// **Example:**
/// ```rust
/// let bar: u8 = 123;
///
/// struct Foo {
/// bar: u8,
/// }
///
/// let foo = Foo { bar: bar };
/// ```
/// the last line can be simplified to
/// ```ignore
/// let foo = Foo { bar };
/// ```
pub REDUNDANT_FIELD_NAMES,
style,
"checks for fields in struct literals where shorthands could be used"
}
pub struct RedundantFieldNames {
msrv: Option<RustcVersion>,
}
impl RedundantFieldNames {
#[must_use]
pub fn new(msrv: Option<RustcVersion>) -> Self {
Self { msrv }
}
}
impl_lint_pass!(RedundantFieldNames => [REDUNDANT_FIELD_NAMES]);
impl EarlyLintPass for RedundantFieldNames {
fn check_expr(&mut self, cx: &EarlyContext<'_>, expr: &Expr) {
if !meets_msrv(self.msrv.as_ref(), &msrvs::FIELD_INIT_SHORTHAND) {
return;
}
if in_external_macro(cx.sess, expr.span) {
return;
}
if let ExprKind::Struct(ref se) = expr.kind {
for field in &se.fields {
if field.is_shorthand {
continue;
}
if let ExprKind::Path(None, path) = &field.expr.kind {
if path.segments.len() == 1
&& path.segments[0].ident == field.ident
&& path.segments[0].args.is_none()
{
span_lint_and_sugg(
cx,
REDUNDANT_FIELD_NAMES,
field.span,
"redundant field names in struct initialization",
"replace it with",
field.ident.to_string(),
Applicability::MachineApplicable,
);
}
}
}
}
}
extract_msrv_attr!(EarlyContext);
}