clippy_lints/src/redundant_field_names.rs

   1 use rustc::lint::*;
   2 use rustc::hir::*;
   3 use utils::{span_lint_and_sugg};
   4
   5 /// **What it does:** Checks for redundnat field names where shorthands
   6 /// can be used.
   7 ///
   8 /// **Why is this bad?** If the field and variable names are the same,
   9 /// the field name is redundant.
  10 ///
  11 /// **Known problems:** None.
  12 ///
  13 /// **Example:**
  14 /// ```rust
  15 /// let bar: u8 = 123;
  16 ///
  17 /// struct Foo {
  18 ///     bar: u8,
  19 /// }
  20 ///
  21 /// let foo = Foo{ bar: bar }
  22 /// ```
  23 declare_lint! {
  24     pub REDUNDANT_FIELD_NAMES,
  25     Warn,
  26     "using same name for field and variable ,where shorthand can be used"
  27 }
  28
  29 pub struct RedundantFieldNames;
  30
  31 impl LintPass for RedundantFieldNames {
  32     fn get_lints(&self) -> LintArray {
  33         lint_array!(REDUNDANT_FIELD_NAMES)
  34     }
  35 }
  36
  37 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for RedundantFieldNames {
  38     fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, expr: &'tcx Expr) {
  39         if let ExprStruct(_, ref fields, _) = expr.node {
  40             for field in fields {
  41                 let name = field.name.node;
  42                 if let ExprPath(ref qpath) = field.expr.node {
  43                     if let &QPath::Resolved(_, ref path) = qpath {
  44                         let segments = &path.segments;
  45
  46                         if segments.len() == 1 {
  47                             let expr_name = segments[0].name;
  48
  49                             if name == expr_name {
  50                                 span_lint_and_sugg(
  51                                     cx,
  52                                     REDUNDANT_FIELD_NAMES,
  53                                     path.span,
  54                                     "redundant field names in struct initialization",
  55                                     &format!(
  56                                         "replace '{0}: {0}' with '{0}'",
  57                                         name,
  58                                     ),
  59                                     "".to_string()
  60                                 );
  61                             }
  62                         }
  63                     }
  64                 }
  65             }
  66         }
  67     }
  68 }