| use crate::utils::{attr_by_name, in_macro, match_path_ast, span_lint_and_help}; |
| use rustc_ast::ast::{AssocItemKind, Extern, FnSig, Item, ItemKind, Ty, TyKind}; |
| use rustc_lint::{EarlyContext, EarlyLintPass}; |
| use rustc_session::{declare_tool_lint, impl_lint_pass}; |
| use rustc_span::Span; |
| |
| use std::convert::TryInto; |
| |
| declare_clippy_lint! { |
| /// **What it does:** Checks for excessive |
| /// use of bools in structs. |
| /// |
| /// **Why is this bad?** Excessive bools in a struct |
| /// is often a sign that it's used as a state machine, |
| /// which is much better implemented as an enum. |
| /// If it's not the case, excessive bools usually benefit |
| /// from refactoring into two-variant enums for better |
| /// readability and API. |
| /// |
| /// **Known problems:** None. |
| /// |
| /// **Example:** |
| /// Bad: |
| /// ```rust |
| /// struct S { |
| /// is_pending: bool, |
| /// is_processing: bool, |
| /// is_finished: bool, |
| /// } |
| /// ``` |
| /// |
| /// Good: |
| /// ```rust |
| /// enum S { |
| /// Pending, |
| /// Processing, |
| /// Finished, |
| /// } |
| /// ``` |
| pub STRUCT_EXCESSIVE_BOOLS, |
| pedantic, |
| "using too many bools in a struct" |
| } |
| |
| declare_clippy_lint! { |
| /// **What it does:** Checks for excessive use of |
| /// bools in function definitions. |
| /// |
| /// **Why is this bad?** Calls to such functions |
| /// are confusing and error prone, because it's |
| /// hard to remember argument order and you have |
| /// no type system support to back you up. Using |
| /// two-variant enums instead of bools often makes |
| /// API easier to use. |
| /// |
| /// **Known problems:** None. |
| /// |
| /// **Example:** |
| /// Bad: |
| /// ```rust,ignore |
| /// fn f(is_round: bool, is_hot: bool) { ... } |
| /// ``` |
| /// |
| /// Good: |
| /// ```rust,ignore |
| /// enum Shape { |
| /// Round, |
| /// Spiky, |
| /// } |
| /// |
| /// enum Temperature { |
| /// Hot, |
| /// IceCold, |
| /// } |
| /// |
| /// fn f(shape: Shape, temperature: Temperature) { ... } |
| /// ``` |
| pub FN_PARAMS_EXCESSIVE_BOOLS, |
| pedantic, |
| "using too many bools in function parameters" |
| } |
| |
| pub struct ExcessiveBools { |
| max_struct_bools: u64, |
| max_fn_params_bools: u64, |
| } |
| |
| impl ExcessiveBools { |
| #[must_use] |
| pub fn new(max_struct_bools: u64, max_fn_params_bools: u64) -> Self { |
| Self { |
| max_struct_bools, |
| max_fn_params_bools, |
| } |
| } |
| |
| fn check_fn_sig(&self, cx: &EarlyContext<'_>, fn_sig: &FnSig, span: Span) { |
| match fn_sig.header.ext { |
| Extern::Implicit | Extern::Explicit(_) => return, |
| Extern::None => (), |
| } |
| |
| let fn_sig_bools = fn_sig |
| .decl |
| .inputs |
| .iter() |
| .filter(|param| is_bool_ty(¶m.ty)) |
| .count() |
| .try_into() |
| .unwrap(); |
| if self.max_fn_params_bools < fn_sig_bools { |
| span_lint_and_help( |
| cx, |
| FN_PARAMS_EXCESSIVE_BOOLS, |
| span, |
| &format!("more than {} bools in function parameters", self.max_fn_params_bools), |
| None, |
| "consider refactoring bools into two-variant enums", |
| ); |
| } |
| } |
| } |
| |
| impl_lint_pass!(ExcessiveBools => [STRUCT_EXCESSIVE_BOOLS, FN_PARAMS_EXCESSIVE_BOOLS]); |
| |
| fn is_bool_ty(ty: &Ty) -> bool { |
| if let TyKind::Path(None, path) = &ty.kind { |
| return match_path_ast(path, &["bool"]); |
| } |
| false |
| } |
| |
| impl EarlyLintPass for ExcessiveBools { |
| fn check_item(&mut self, cx: &EarlyContext<'_>, item: &Item) { |
| if in_macro(item.span) { |
| return; |
| } |
| match &item.kind { |
| ItemKind::Struct(variant_data, _) => { |
| if attr_by_name(&item.attrs, "repr").is_some() { |
| return; |
| } |
| |
| let struct_bools = variant_data |
| .fields() |
| .iter() |
| .filter(|field| is_bool_ty(&field.ty)) |
| .count() |
| .try_into() |
| .unwrap(); |
| if self.max_struct_bools < struct_bools { |
| span_lint_and_help( |
| cx, |
| STRUCT_EXCESSIVE_BOOLS, |
| item.span, |
| &format!("more than {} bools in a struct", self.max_struct_bools), |
| None, |
| "consider using a state machine or refactoring bools into two-variant enums", |
| ); |
| } |
| }, |
| ItemKind::Impl { |
| of_trait: None, items, .. |
| } |
| | ItemKind::Trait(_, _, _, _, items) => { |
| for item in items { |
| if let AssocItemKind::Fn(_, fn_sig, _, _) = &item.kind { |
| self.check_fn_sig(cx, fn_sig, item.span); |
| } |
| } |
| }, |
| ItemKind::Fn(_, fn_sig, _, _) => self.check_fn_sig(cx, fn_sig, item.span), |
| _ => (), |
| } |
| } |
| } |