diff options
| -rw-r--r-- | clippy_lints/src/matches.rs | 113 |
1 files changed, 50 insertions, 63 deletions
diff --git a/clippy_lints/src/matches.rs b/clippy_lints/src/matches.rs index e33001b16bc..efc8b139425 100644 --- a/clippy_lints/src/matches.rs +++ b/clippy_lints/src/matches.rs @@ -3,19 +3,19 @@ use crate::utils::sugg::Sugg; use crate::utils::visitors::LocalUsedVisitor; use crate::utils::{ expr_block, get_parent_expr, implements_trait, in_macro, indent_of, is_allowed, is_expn_of, is_refutable, - is_type_diagnostic_item, is_wild, match_qpath, match_type, meets_msrv, multispan_sugg, path_to_local_id, - peel_hir_pat_refs, peel_mid_ty_refs, peel_n_hir_expr_refs, remove_blocks, snippet, snippet_block, snippet_opt, - snippet_with_applicability, span_lint_and_help, span_lint_and_note, span_lint_and_sugg, span_lint_and_then, - strip_pat_refs, + is_type_diagnostic_item, is_wild, match_qpath, match_type, meets_msrv, multispan_sugg, path_to_local, + path_to_local_id, peel_hir_pat_refs, peel_mid_ty_refs, peel_n_hir_expr_refs, remove_blocks, snippet, snippet_block, + snippet_opt, snippet_with_applicability, span_lint_and_help, span_lint_and_note, span_lint_and_sugg, + span_lint_and_then, strip_pat_refs, }; use crate::utils::{paths, search_same, SpanlessEq, SpanlessHash}; use if_chain::if_chain; use rustc_ast::ast::LitKind; -use rustc_data_structures::fx::FxHashMap; +use rustc_data_structures::fx::{FxHashMap, FxHashSet}; use rustc_errors::Applicability; use rustc_hir::def::CtorKind; use rustc_hir::{ - Arm, BindingAnnotation, Block, BorrowKind, Expr, ExprKind, Guard, Local, MatchSource, Mutability, Node, Pat, + Arm, BindingAnnotation, Block, BorrowKind, Expr, ExprKind, Guard, HirId, Local, MatchSource, Mutability, Node, Pat, PatKind, QPath, RangeEnd, }; use rustc_lint::{LateContext, LateLintPass, LintContext}; @@ -24,7 +24,7 @@ use rustc_middle::ty::{self, Ty, TyS}; use rustc_semver::RustcVersion; use rustc_session::{declare_tool_lint, impl_lint_pass}; use rustc_span::source_map::{Span, Spanned}; -use rustc_span::{sym, Symbol}; +use rustc_span::sym; use std::cmp::Ordering; use std::collections::hash_map::Entry; use std::collections::Bound; @@ -1873,13 +1873,6 @@ fn test_overlapping() { /// Implementation of `MATCH_SAME_ARMS`. fn lint_match_arms<'tcx>(cx: &LateContext<'tcx>, expr: &Expr<'_>) { - fn same_bindings<'tcx>(lhs: &FxHashMap<Symbol, Ty<'tcx>>, rhs: &FxHashMap<Symbol, Ty<'tcx>>) -> bool { - lhs.len() == rhs.len() - && lhs - .iter() - .all(|(name, l_ty)| rhs.get(name).map_or(false, |r_ty| TyS::same_type(l_ty, r_ty))) - } - if let ExprKind::Match(_, ref arms, MatchSource::Normal) = expr.kind { let hash = |&(_, arm): &(usize, &Arm<'_>)| -> u64 { let mut h = SpanlessHash::new(cx); @@ -1891,12 +1884,38 @@ fn lint_match_arms<'tcx>(cx: &LateContext<'tcx>, expr: &Expr<'_>) { let min_index = usize::min(lindex, rindex); let max_index = usize::max(lindex, rindex); + let mut local_map: FxHashMap<HirId, HirId> = FxHashMap::default(); + let eq_fallback = |a: &Expr<'_>, b: &Expr<'_>| { + if_chain! { + if let Some(a_id) = path_to_local(a); + if let Some(b_id) = path_to_local(b); + let entry = match local_map.entry(a_id) { + Entry::Vacant(entry) => entry, + // check if using the same bindings as before + Entry::Occupied(entry) => return *entry.get() == b_id, + }; + // the names technically don't have to match; this makes the lint more conservative + if cx.tcx.hir().name(a_id) == cx.tcx.hir().name(b_id); + if TyS::same_type(cx.typeck_results().expr_ty(a), cx.typeck_results().expr_ty(b)); + if pat_contains_local(lhs.pat, a_id); + if pat_contains_local(rhs.pat, b_id); + then { + entry.insert(b_id); + true + } else { + false + } + } + }; // Arms with a guard are ignored, those can’t always be merged together // This is also the case for arms in-between each there is an arm with a guard - (min_index..=max_index).all(|index| arms[index].guard.is_none()) && - SpanlessEq::new(cx).eq_expr(&lhs.body, &rhs.body) && - // all patterns should have the same bindings - same_bindings(&bindings(cx, &lhs.pat), &bindings(cx, &rhs.pat)) + (min_index..=max_index).all(|index| arms[index].guard.is_none()) + && SpanlessEq::new(cx) + .expr_fallback(eq_fallback) + .eq_expr(&lhs.body, &rhs.body) + // these checks could be removed to allow unused bindings + && bindings_eq(lhs.pat, local_map.keys().copied().collect()) + && bindings_eq(rhs.pat, local_map.values().copied().collect()) }; let indexed_arms: Vec<(usize, &Arm<'_>)> = arms.iter().enumerate().collect(); @@ -1939,50 +1958,18 @@ fn lint_match_arms<'tcx>(cx: &LateContext<'tcx>, expr: &Expr<'_>) { } } -/// Returns the list of bindings in a pattern. -fn bindings<'tcx>(cx: &LateContext<'tcx>, pat: &Pat<'_>) -> FxHashMap<Symbol, Ty<'tcx>> { - fn bindings_impl<'tcx>(cx: &LateContext<'tcx>, pat: &Pat<'_>, map: &mut FxHashMap<Symbol, Ty<'tcx>>) { - match pat.kind { - PatKind::Box(ref pat) | PatKind::Ref(ref pat, _) => bindings_impl(cx, pat, map), - PatKind::TupleStruct(_, pats, _) => { - for pat in pats { - bindings_impl(cx, pat, map); - } - }, - PatKind::Binding(.., ident, ref as_pat) => { - if let Entry::Vacant(v) = map.entry(ident.name) { - v.insert(cx.typeck_results().pat_ty(pat)); - } - if let Some(ref as_pat) = *as_pat { - bindings_impl(cx, as_pat, map); - } - }, - PatKind::Or(fields) | PatKind::Tuple(fields, _) => { - for pat in fields { - bindings_impl(cx, pat, map); - } - }, - PatKind::Struct(_, fields, _) => { - for pat in fields { - bindings_impl(cx, &pat.pat, map); - } - }, - PatKind::Slice(lhs, ref mid, rhs) => { - for pat in lhs { - bindings_impl(cx, pat, map); - } - if let Some(ref mid) = *mid { - bindings_impl(cx, mid, map); - } - for pat in rhs { - bindings_impl(cx, pat, map); - } - }, - PatKind::Lit(..) | PatKind::Range(..) | PatKind::Wild | PatKind::Path(..) => (), - } - } - - let mut result = FxHashMap::default(); - bindings_impl(cx, pat, &mut result); +fn pat_contains_local(pat: &Pat<'_>, id: HirId) -> bool { + let mut result = false; + pat.walk_short(|p| { + result |= matches!(p.kind, PatKind::Binding(_, binding_id, ..) if binding_id == id); + !result + }); result } + +/// Returns true if all the bindings in the `Pat` are in `ids` and vice versa +fn bindings_eq(pat: &Pat<'_>, mut ids: FxHashSet<HirId>) -> bool { + let mut result = true; + pat.each_binding_or_first(&mut |_, id, _, _| result &= ids.remove(&id)); + result && ids.is_empty() +} |