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| 1 | +use crate::utils::{attr_by_name, in_macro, match_path_ast, span_lint_and_help}; |
| 2 | +use rustc_lint::{EarlyContext, EarlyLintPass}; |
| 3 | +use rustc_session::{declare_tool_lint, impl_lint_pass}; |
| 4 | +use rustc_span::Span; |
| 5 | +use syntax::ast::{AssocItemKind, Extern, FnSig, Item, ItemKind, Ty, TyKind}; |
| 6 | + |
| 7 | +use std::convert::TryInto; |
| 8 | + |
| 9 | +declare_clippy_lint! { |
| 10 | + /// **What it does:** Checks for excessive |
| 11 | + /// use of bools in structs. |
| 12 | + /// |
| 13 | + /// **Why is this bad?** Excessive bools in a struct |
| 14 | + /// is often a sign that it's used as a state machine, |
| 15 | + /// which is much better implemented as an enum. |
| 16 | + /// If it's not the case, excessive bools usually benefit |
| 17 | + /// from refactoring into two-variant enums for better |
| 18 | + /// readability and API. |
| 19 | + /// |
| 20 | + /// **Known problems:** None. |
| 21 | + /// |
| 22 | + /// **Example:** |
| 23 | + /// Bad: |
| 24 | + /// ```rust |
| 25 | + /// struct S { |
| 26 | + /// is_pending: bool, |
| 27 | + /// is_processing: bool, |
| 28 | + /// is_finished: bool, |
| 29 | + /// } |
| 30 | + /// ``` |
| 31 | + /// |
| 32 | + /// Good: |
| 33 | + /// ```rust |
| 34 | + /// enum S { |
| 35 | + /// Pending, |
| 36 | + /// Processing, |
| 37 | + /// Finished, |
| 38 | + /// } |
| 39 | + /// ``` |
| 40 | + pub STRUCT_EXCESSIVE_BOOLS, |
| 41 | + pedantic, |
| 42 | + "using too many bools in a struct" |
| 43 | +} |
| 44 | + |
| 45 | +declare_clippy_lint! { |
| 46 | + /// **What it does:** Checks for excessive use of |
| 47 | + /// bools in function definitions. |
| 48 | + /// |
| 49 | + /// **Why is this bad?** Calls to such functions |
| 50 | + /// are confusing and error prone, because it's |
| 51 | + /// hard to remember argument order and you have |
| 52 | + /// no type system support to back you up. Using |
| 53 | + /// two-variant enums instead of bools often makes |
| 54 | + /// API easier to use. |
| 55 | + /// |
| 56 | + /// **Known problems:** None. |
| 57 | + /// |
| 58 | + /// **Example:** |
| 59 | + /// Bad: |
| 60 | + /// ```rust,ignore |
| 61 | + /// fn f(is_round: bool, is_hot: bool) { ... } |
| 62 | + /// ``` |
| 63 | + /// |
| 64 | + /// Good: |
| 65 | + /// ```rust,ignore |
| 66 | + /// enum Shape { |
| 67 | + /// Round, |
| 68 | + /// Spiky, |
| 69 | + /// } |
| 70 | + /// |
| 71 | + /// enum Temperature { |
| 72 | + /// Hot, |
| 73 | + /// IceCold, |
| 74 | + /// } |
| 75 | + /// |
| 76 | + /// fn f(shape: Shape, temperature: Temperature) { ... } |
| 77 | + /// ``` |
| 78 | + pub FN_PARAMS_EXCESSIVE_BOOLS, |
| 79 | + pedantic, |
| 80 | + "using too many bools in function parameters" |
| 81 | +} |
| 82 | + |
| 83 | +pub struct ExcessiveBools { |
| 84 | + max_struct_bools: u64, |
| 85 | + max_fn_params_bools: u64, |
| 86 | +} |
| 87 | + |
| 88 | +impl ExcessiveBools { |
| 89 | + #[must_use] |
| 90 | + pub fn new(max_struct_bools: u64, max_fn_params_bools: u64) -> Self { |
| 91 | + Self { |
| 92 | + max_struct_bools, |
| 93 | + max_fn_params_bools, |
| 94 | + } |
| 95 | + } |
| 96 | + |
| 97 | + fn check_fn_sig(&self, cx: &EarlyContext<'_>, fn_sig: &FnSig, span: Span) { |
| 98 | + match fn_sig.header.ext { |
| 99 | + Extern::Implicit | Extern::Explicit(_) => return, |
| 100 | + Extern::None => (), |
| 101 | + } |
| 102 | + |
| 103 | + let fn_sig_bools = fn_sig |
| 104 | + .decl |
| 105 | + .inputs |
| 106 | + .iter() |
| 107 | + .filter(|param| is_bool_ty(¶m.ty)) |
| 108 | + .count() |
| 109 | + .try_into() |
| 110 | + .unwrap(); |
| 111 | + if self.max_fn_params_bools < fn_sig_bools { |
| 112 | + span_lint_and_help( |
| 113 | + cx, |
| 114 | + FN_PARAMS_EXCESSIVE_BOOLS, |
| 115 | + span, |
| 116 | + &format!("more than {} bools in function parameters", self.max_fn_params_bools), |
| 117 | + "consider refactoring bools into two-variant enums", |
| 118 | + ); |
| 119 | + } |
| 120 | + } |
| 121 | +} |
| 122 | + |
| 123 | +impl_lint_pass!(ExcessiveBools => [STRUCT_EXCESSIVE_BOOLS, FN_PARAMS_EXCESSIVE_BOOLS]); |
| 124 | + |
| 125 | +fn is_bool_ty(ty: &Ty) -> bool { |
| 126 | + if let TyKind::Path(None, path) = &ty.kind { |
| 127 | + return match_path_ast(path, &["bool"]); |
| 128 | + } |
| 129 | + false |
| 130 | +} |
| 131 | + |
| 132 | +impl EarlyLintPass for ExcessiveBools { |
| 133 | + fn check_item(&mut self, cx: &EarlyContext<'_>, item: &Item) { |
| 134 | + if in_macro(item.span) { |
| 135 | + return; |
| 136 | + } |
| 137 | + match &item.kind { |
| 138 | + ItemKind::Struct(variant_data, _) => { |
| 139 | + if attr_by_name(&item.attrs, "repr").is_some() { |
| 140 | + return; |
| 141 | + } |
| 142 | + |
| 143 | + let struct_bools = variant_data |
| 144 | + .fields() |
| 145 | + .iter() |
| 146 | + .filter(|field| is_bool_ty(&field.ty)) |
| 147 | + .count() |
| 148 | + .try_into() |
| 149 | + .unwrap(); |
| 150 | + if self.max_struct_bools < struct_bools { |
| 151 | + span_lint_and_help( |
| 152 | + cx, |
| 153 | + STRUCT_EXCESSIVE_BOOLS, |
| 154 | + item.span, |
| 155 | + &format!("more than {} bools in a struct", self.max_struct_bools), |
| 156 | + "consider using a state machine or refactoring bools into two-variant enums", |
| 157 | + ); |
| 158 | + } |
| 159 | + }, |
| 160 | + ItemKind::Impl { |
| 161 | + of_trait: None, items, .. |
| 162 | + } |
| 163 | + | ItemKind::Trait(_, _, _, _, items) => { |
| 164 | + for item in items { |
| 165 | + if let AssocItemKind::Fn(fn_sig, _) = &item.kind { |
| 166 | + self.check_fn_sig(cx, fn_sig, item.span); |
| 167 | + } |
| 168 | + } |
| 169 | + }, |
| 170 | + ItemKind::Fn(fn_sig, _, _) => self.check_fn_sig(cx, fn_sig, item.span), |
| 171 | + _ => (), |
| 172 | + } |
| 173 | + } |
| 174 | +} |
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