diff options
Diffstat (limited to 'clippy_lints/src/len_zero.rs')
| -rw-r--r-- | clippy_lints/src/len_zero.rs | 125 |
1 files changed, 95 insertions, 30 deletions
diff --git a/clippy_lints/src/len_zero.rs b/clippy_lints/src/len_zero.rs index e13bc47973b..0805b4b1979 100644 --- a/clippy_lints/src/len_zero.rs +++ b/clippy_lints/src/len_zero.rs @@ -1,13 +1,14 @@ use clippy_utils::diagnostics::{span_lint, span_lint_and_sugg, span_lint_and_then}; -use clippy_utils::source::snippet_with_applicability; -use clippy_utils::{get_item_name, get_parent_as_impl, is_lint_allowed, peel_ref_operators}; +use clippy_utils::source::snippet_with_context; +use clippy_utils::{get_item_name, get_parent_as_impl, is_lint_allowed, peel_ref_operators, sugg::Sugg}; use if_chain::if_chain; use rustc_ast::ast::LitKind; use rustc_errors::Applicability; use rustc_hir::def_id::DefIdSet; use rustc_hir::{ - def_id::DefId, AssocItemKind, BinOpKind, Expr, ExprKind, FnRetTy, ImplItem, ImplItemKind, ImplicitSelfKind, Item, - ItemKind, Mutability, Node, TraitItemRef, TyKind, UnOp, + def::Res, def_id::DefId, lang_items::LangItem, AssocItemKind, BinOpKind, Expr, ExprKind, FnRetTy, GenericArg, + GenericBound, ImplItem, ImplItemKind, ImplicitSelfKind, Item, ItemKind, Mutability, Node, PathSegment, PrimTy, + QPath, TraitItemRef, TyKind, TypeBindingKind, }; use rustc_lint::{LateContext, LateLintPass}; use rustc_middle::ty::{self, AssocKind, FnSig, Ty}; @@ -16,7 +17,6 @@ use rustc_span::{ source_map::{Span, Spanned, Symbol}, symbol::sym, }; -use std::borrow::Cow; declare_clippy_lint! { /// ### What it does @@ -251,33 +251,98 @@ fn check_trait_items(cx: &LateContext<'_>, visited_trait: &Item<'_>, trait_items } #[derive(Debug, Clone, Copy)] -enum LenOutput<'tcx> { +enum LenOutput { Integral, Option(DefId), - Result(DefId, Ty<'tcx>), + Result(DefId), } -fn parse_len_output<'tcx>(cx: &LateContext<'_>, sig: FnSig<'tcx>) -> Option<LenOutput<'tcx>> { + +fn extract_future_output<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'tcx>) -> Option<&'tcx PathSegment<'tcx>> { + if let ty::Alias(_, alias_ty) = ty.kind() && + let Some(Node::Item(item)) = cx.tcx.hir().get_if_local(alias_ty.def_id) && + let Item { kind: ItemKind::OpaqueTy(opaque), .. } = item && + opaque.bounds.len() == 1 && + let GenericBound::LangItemTrait(LangItem::Future, _, _, generic_args) = &opaque.bounds[0] && + generic_args.bindings.len() == 1 && + let TypeBindingKind::Equality { + term: rustc_hir::Term::Ty(rustc_hir::Ty {kind: TyKind::Path(QPath::Resolved(_, path)), .. }), + } = &generic_args.bindings[0].kind && + path.segments.len() == 1 { + return Some(&path.segments[0]); + } + + None +} + +fn is_first_generic_integral<'tcx>(segment: &'tcx PathSegment<'tcx>) -> bool { + if let Some(generic_args) = segment.args { + if generic_args.args.is_empty() { + return false; + } + let arg = &generic_args.args[0]; + if let GenericArg::Type(rustc_hir::Ty { + kind: TyKind::Path(QPath::Resolved(_, path)), + .. + }) = arg + { + let segments = &path.segments; + let segment = &segments[0]; + let res = &segment.res; + if matches!(res, Res::PrimTy(PrimTy::Uint(_))) || matches!(res, Res::PrimTy(PrimTy::Int(_))) { + return true; + } + } + } + + false +} + +fn parse_len_output<'tcx>(cx: &LateContext<'tcx>, sig: FnSig<'tcx>) -> Option<LenOutput> { + if let Some(segment) = extract_future_output(cx, sig.output()) { + let res = segment.res; + + if matches!(res, Res::PrimTy(PrimTy::Uint(_))) || matches!(res, Res::PrimTy(PrimTy::Int(_))) { + return Some(LenOutput::Integral); + } + + if let Res::Def(_, def_id) = res { + if cx.tcx.is_diagnostic_item(sym::Option, def_id) && is_first_generic_integral(segment) { + return Some(LenOutput::Option(def_id)); + } else if cx.tcx.is_diagnostic_item(sym::Result, def_id) && is_first_generic_integral(segment) { + return Some(LenOutput::Result(def_id)); + } + } + + return None; + } + match *sig.output().kind() { ty::Int(_) | ty::Uint(_) => Some(LenOutput::Integral), ty::Adt(adt, subs) if cx.tcx.is_diagnostic_item(sym::Option, adt.did()) => { subs.type_at(0).is_integral().then(|| LenOutput::Option(adt.did())) }, - ty::Adt(adt, subs) if cx.tcx.is_diagnostic_item(sym::Result, adt.did()) => subs - .type_at(0) - .is_integral() - .then(|| LenOutput::Result(adt.did(), subs.type_at(1))), + ty::Adt(adt, subs) if cx.tcx.is_diagnostic_item(sym::Result, adt.did()) => { + subs.type_at(0).is_integral().then(|| LenOutput::Result(adt.did())) + }, _ => None, } } -impl<'tcx> LenOutput<'tcx> { - fn matches_is_empty_output(self, ty: Ty<'tcx>) -> bool { +impl LenOutput { + fn matches_is_empty_output<'tcx>(self, cx: &LateContext<'tcx>, ty: Ty<'tcx>) -> bool { + if let Some(segment) = extract_future_output(cx, ty) { + return match (self, segment.res) { + (_, Res::PrimTy(PrimTy::Bool)) => true, + (Self::Option(_), Res::Def(_, def_id)) if cx.tcx.is_diagnostic_item(sym::Option, def_id) => true, + (Self::Result(_), Res::Def(_, def_id)) if cx.tcx.is_diagnostic_item(sym::Result, def_id) => true, + _ => false, + }; + } + match (self, ty.kind()) { (_, &ty::Bool) => true, (Self::Option(id), &ty::Adt(adt, subs)) if id == adt.did() => subs.type_at(0).is_bool(), - (Self::Result(id, err_ty), &ty::Adt(adt, subs)) if id == adt.did() => { - subs.type_at(0).is_bool() && subs.type_at(1) == err_ty - }, + (Self::Result(id), &ty::Adt(adt, subs)) if id == adt.did() => subs.type_at(0).is_bool(), _ => false, } } @@ -301,9 +366,14 @@ impl<'tcx> LenOutput<'tcx> { } /// Checks if the given signature matches the expectations for `is_empty` -fn check_is_empty_sig<'tcx>(sig: FnSig<'tcx>, self_kind: ImplicitSelfKind, len_output: LenOutput<'tcx>) -> bool { +fn check_is_empty_sig<'tcx>( + cx: &LateContext<'tcx>, + sig: FnSig<'tcx>, + self_kind: ImplicitSelfKind, + len_output: LenOutput, +) -> bool { match &**sig.inputs_and_output { - [arg, res] if len_output.matches_is_empty_output(*res) => { + [arg, res] if len_output.matches_is_empty_output(cx, *res) => { matches!( (arg.kind(), self_kind), (ty::Ref(_, _, Mutability::Not), ImplicitSelfKind::ImmRef) @@ -315,11 +385,11 @@ fn check_is_empty_sig<'tcx>(sig: FnSig<'tcx>, self_kind: ImplicitSelfKind, len_o } /// Checks if the given type has an `is_empty` method with the appropriate signature. -fn check_for_is_empty<'tcx>( - cx: &LateContext<'tcx>, +fn check_for_is_empty( + cx: &LateContext<'_>, span: Span, self_kind: ImplicitSelfKind, - output: LenOutput<'tcx>, + output: LenOutput, impl_ty: DefId, item_name: Symbol, item_kind: &str, @@ -352,6 +422,7 @@ fn check_for_is_empty<'tcx>( Some(is_empty) if !(is_empty.fn_has_self_parameter && check_is_empty_sig( + cx, cx.tcx.fn_sig(is_empty.def_id).subst_identity().skip_binder(), self_kind, output, @@ -431,7 +502,7 @@ fn check_len( &format!("using `{op}is_empty` is clearer and more explicit"), format!( "{op}{}.is_empty()", - snippet_with_applicability(cx, receiver.span, "_", &mut applicability) + snippet_with_context(cx, receiver.span, span.ctxt(), "_", &mut applicability).0, ), applicability, ); @@ -444,13 +515,7 @@ fn check_empty_expr(cx: &LateContext<'_>, span: Span, lit1: &Expr<'_>, lit2: &Ex let mut applicability = Applicability::MachineApplicable; let lit1 = peel_ref_operators(cx, lit1); - let mut lit_str = snippet_with_applicability(cx, lit1.span, "_", &mut applicability); - - // Wrap the expression in parentheses if it's a deref expression. Otherwise operator precedence will - // cause the code to dereference boolean(won't compile). - if let ExprKind::Unary(UnOp::Deref, _) = lit1.kind { - lit_str = Cow::from(format!("({lit_str})")); - } + let lit_str = Sugg::hir_with_context(cx, lit1, span.ctxt(), "_", &mut applicability).maybe_par(); span_lint_and_sugg( cx, |