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use rustc::lint::*;
use rustc::hir::*;
use utils::{in_macro, is_range_expression, match_var, span_lint_and_sugg};
/// **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 }
/// ```
declare_clippy_lint! {
pub REDUNDANT_FIELD_NAMES,
style,
"checks for fields in struct literals where shorthands could be used"
}
pub struct RedundantFieldNames;
impl LintPass for RedundantFieldNames {
fn get_lints(&self) -> LintArray {
lint_array!(REDUNDANT_FIELD_NAMES)
}
}
impl<'a, 'tcx> LateLintPass<'a, 'tcx> for RedundantFieldNames {
fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, expr: &'tcx Expr) {
// Ignore all macros including range expressions.
// They can have redundant field names when expanded.
// e.g. range expression `start..end` is desugared to `Range { start: start, end: end }`
if in_macro(expr.span) || is_range_expression(expr.span) {
return;
}
if let ExprStruct(_, ref fields, _) = expr.node {
for field in fields {
let name = field.name.node;
if match_var(&field.expr, name) && !field.is_shorthand {
span_lint_and_sugg (
cx,
REDUNDANT_FIELD_NAMES,
field.span,
"redundant field names in struct initialization",
"replace it with",
name.to_string()
);
}
}
}
}
}