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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,114 @@ | ||
| use clippy_utils::diagnostics::span_lint; | ||
| use clippy_utils::{in_macro, is_automatically_derived, is_default, match_def_path, paths}; | ||
| use rustc_hir::{Block, Expr, ExprField, ExprKind, Impl, ImplItemKind, Item, ItemKind, Node, QPath}; | ||
| use rustc_lint::{LateContext, LateLintPass}; | ||
| use rustc_session::{declare_lint_pass, declare_tool_lint}; | ||
|
|
||
| declare_clippy_lint! { | ||
| /// ### What it does | ||
| /// Checks for double comparisons that could be simplified to a single expression. | ||
| /// | ||
| /// | ||
| /// ### Why is this bad? | ||
| /// Readability. | ||
| /// | ||
| /// ### Example | ||
| /// ```rust | ||
| /// # let x = 1; | ||
| /// # let y = 2; | ||
| /// if x == y || x < y {} | ||
| /// ``` | ||
| /// | ||
| /// Could be written as: | ||
| /// | ||
| /// ```rust | ||
| /// # let x = 1; | ||
| /// # let y = 2; | ||
| /// if x <= y {} | ||
| /// ``` | ||
| pub DERIVABLE_IMPLS, | ||
| complexity, | ||
| "manual implementation of a trait which is equal to a derive" | ||
| } | ||
|
|
||
| declare_lint_pass!(DerivableImpls => [DERIVABLE_IMPLS]); | ||
|
|
||
| fn struct_fields<'hir>(e: &'hir Expr<'hir>) -> Option<&'hir [ExprField<'hir>]> { | ||
| match e.kind { | ||
| ExprKind::Struct(_, fields, _) => Some(fields), | ||
| ExprKind::Block(Block { expr, .. }, _) => expr.and_then(struct_fields), | ||
| _ => None, | ||
| } | ||
| } | ||
|
|
||
| fn is_path_self(e: &Expr<'_>) -> bool { | ||
| if let ExprKind::Path(QPath::Resolved(_, p)) = e.kind { | ||
| if p.segments.len() != 1 { | ||
| return false; | ||
| } | ||
| if p.segments[0].ident.name == rustc_span::symbol::kw::SelfUpper { | ||
| return true; | ||
| } | ||
| } | ||
| false | ||
| } | ||
|
|
||
| fn tuple_fields<'hir>(e: &'hir Expr<'hir>) -> Option<&'hir [Expr<'hir>]> { | ||
| match e.kind { | ||
| ExprKind::Tup(fields) => Some(fields), | ||
| ExprKind::Call(callee, args) => { | ||
| if is_path_self(callee) { | ||
| Some(args) | ||
| } else { | ||
| None | ||
| } | ||
| }, | ||
| ExprKind::Block(Block { expr, .. }, _) => expr.and_then(tuple_fields), | ||
| _ => None, | ||
| } | ||
| } | ||
|
|
||
| impl<'tcx> LateLintPass<'tcx> for DerivableImpls { | ||
| fn check_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx Item<'_>) { | ||
| if let ItemKind::Impl(Impl { | ||
| of_trait: Some(ref trait_ref), | ||
| items, | ||
| .. | ||
| }) = item.kind | ||
| { | ||
| let attrs = cx.tcx.hir().attrs(item.hir_id()); | ||
| if is_automatically_derived(attrs) { | ||
| return; | ||
| } | ||
| if in_macro(item.span) { | ||
| return; | ||
| } | ||
| if let Some(def_id) = trait_ref.trait_def_id() { | ||
| if !match_def_path(cx, def_id, &paths::DEFAULT_TRAIT) { | ||
| return; | ||
| } | ||
| } | ||
| let impl_item_hir = items[0].id.hir_id(); | ||
| let func_expr = match cx.tcx.hir().find(impl_item_hir) { | ||
| Some(Node::ImplItem(x)) => match &x.kind { | ||
| ImplItemKind::Fn(_, b) => match cx.tcx.hir().find(b.hir_id) { | ||
| Some(Node::Expr(e)) => e, | ||
| _ => return, | ||
| }, | ||
| _ => return, | ||
| }, | ||
| _ => return, | ||
| }; | ||
| let should_emit = if let Some(s) = struct_fields(func_expr) { | ||
| s.iter().all(|ef| is_default(cx, ef.expr)) | ||
| } else if let Some(s) = tuple_fields(func_expr) { | ||
| s.iter().all(|e| is_default(cx, e)) | ||
| } else { | ||
| return; | ||
| }; | ||
| if should_emit { | ||
| span_lint(cx, DERIVABLE_IMPLS, item.span, "derivable impl of trait Default:"); | ||
| } | ||
| } | ||
| } | ||
| } |
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