1 use clippy_utils::diagnostics::span_lint_and_sugg;
2 use clippy_utils::in_macro;
3 use clippy_utils::source::snippet;
4 use if_chain::if_chain;
5 use rustc_data_structures::fx::FxHashMap;
6 use rustc_errors::Applicability;
7 use rustc_hir::{self as hir, ExprKind};
8 use rustc_lint::{LateContext, LateLintPass};
9 use rustc_session::{declare_lint_pass, declare_tool_lint};
10 use rustc_span::symbol::Symbol;
12 declare_clippy_lint! {
14 /// Checks for struct constructors where all fields are shorthand and
15 /// the order of the field init shorthand in the constructor is inconsistent
16 /// with the order in the struct definition.
18 /// ### Why is this bad?
19 /// Since the order of fields in a constructor doesn't affect the
20 /// resulted instance as the below example indicates,
23 /// #[derive(Debug, PartialEq, Eq)]
31 /// // This assertion never fails:
32 /// assert_eq!(Foo { x, y }, Foo { y, x });
35 /// inconsistent order can be confusing and decreases readability and consistency.
59 pub INCONSISTENT_STRUCT_CONSTRUCTOR,
61 "the order of the field init shorthand is inconsistent with the order in the struct definition"
64 declare_lint_pass!(InconsistentStructConstructor => [INCONSISTENT_STRUCT_CONSTRUCTOR]);
66 impl LateLintPass<'_> for InconsistentStructConstructor {
67 fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx hir::Expr<'_>) {
69 if !in_macro(expr.span);
70 if let ExprKind::Struct(qpath, fields, base) = expr.kind;
71 let ty = cx.typeck_results().expr_ty(expr);
72 if let Some(adt_def) = ty.ty_adt_def();
73 if adt_def.is_struct();
74 if let Some(variant) = adt_def.variants.iter().next();
75 if fields.iter().all(|f| f.is_shorthand);
77 let mut def_order_map = FxHashMap::default();
78 for (idx, field) in variant.fields.iter().enumerate() {
79 def_order_map.insert(field.ident.name, idx);
82 if is_consistent_order(fields, &def_order_map) {
86 let mut ordered_fields: Vec<_> = fields.iter().map(|f| f.ident.name).collect();
87 ordered_fields.sort_unstable_by_key(|id| def_order_map[id]);
89 let mut fields_snippet = String::new();
90 let (last_ident, idents) = ordered_fields.split_last().unwrap();
92 fields_snippet.push_str(&format!("{}, ", ident));
94 fields_snippet.push_str(&last_ident.to_string());
96 let base_snippet = if let Some(base) = base {
97 format!(", ..{}", snippet(cx, base.span, ".."))
102 let sugg = format!("{} {{ {}{} }}",
103 snippet(cx, qpath.span(), ".."),
110 INCONSISTENT_STRUCT_CONSTRUCTOR,
112 "struct constructor field order is inconsistent with struct definition field order",
115 Applicability::MachineApplicable,
122 // Check whether the order of the fields in the constructor is consistent with the order in the
124 fn is_consistent_order<'tcx>(fields: &'tcx [hir::ExprField<'tcx>], def_order_map: &FxHashMap<Symbol, usize>) -> bool {
125 let mut cur_idx = usize::MIN;
127 let next_idx = def_order_map[&f.ident.name];
128 if cur_idx > next_idx {