diff options
| -rw-r--r-- | compiler/rustc_mir_build/src/thir/pattern/check_match.rs | 299 |
1 files changed, 151 insertions, 148 deletions
diff --git a/compiler/rustc_mir_build/src/thir/pattern/check_match.rs b/compiler/rustc_mir_build/src/thir/pattern/check_match.rs index 933653e708e..136f4210fe4 100644 --- a/compiler/rustc_mir_build/src/thir/pattern/check_match.rs +++ b/compiler/rustc_mir_build/src/thir/pattern/check_match.rs @@ -572,6 +572,111 @@ impl<'p, 'tcx> MatchVisitor<'_, 'p, 'tcx> { } } +/// Check if a by-value binding is by-value. That is, check if the binding's type is not `Copy`. +/// Check that there are no borrow or move conflicts in `binding @ subpat` patterns. +/// +/// For example, this would reject: +/// - `ref x @ Some(ref mut y)`, +/// - `ref mut x @ Some(ref y)`, +/// - `ref mut x @ Some(ref mut y)`, +/// - `ref mut? x @ Some(y)`, and +/// - `x @ Some(ref mut? y)`. +/// +/// This analysis is *not* subsumed by NLL. +fn check_borrow_conflicts_in_at_patterns<'tcx>(cx: &MatchVisitor<'_, '_, 'tcx>, pat: &Pat<'tcx>) { + // Extract `sub` in `binding @ sub`. + let PatKind::Binding { name, mode, ty, subpattern: Some(box ref sub), .. } = pat.kind else { + return; + }; + + let is_binding_by_move = |ty: Ty<'tcx>| !ty.is_copy_modulo_regions(cx.tcx, cx.param_env); + + let sess = cx.tcx.sess; + + // Get the binding move, extract the mutability if by-ref. + let mut_outer = match mode { + BindingMode::ByValue if is_binding_by_move(ty) => { + // We have `x @ pat` where `x` is by-move. Reject all borrows in `pat`. + let mut conflicts_ref = Vec::new(); + sub.each_binding(|_, mode, _, span| match mode { + BindingMode::ByValue => {} + BindingMode::ByRef(_) => conflicts_ref.push(span), + }); + if !conflicts_ref.is_empty() { + sess.emit_err(BorrowOfMovedValue { + binding_span: pat.span, + conflicts_ref, + name, + ty, + suggest_borrowing: Some(pat.span.shrink_to_lo()), + }); + } + return; + } + BindingMode::ByValue => return, + BindingMode::ByRef(m) => m.mutability(), + }; + + // We now have `ref $mut_outer binding @ sub` (semantically). + // Recurse into each binding in `sub` and find mutability or move conflicts. + let mut conflicts_move = Vec::new(); + let mut conflicts_mut_mut = Vec::new(); + let mut conflicts_mut_ref = Vec::new(); + sub.each_binding(|name, mode, ty, span| { + match mode { + BindingMode::ByRef(mut_inner) => match (mut_outer, mut_inner.mutability()) { + // Both sides are `ref`. + (Mutability::Not, Mutability::Not) => {} + // 2x `ref mut`. + (Mutability::Mut, Mutability::Mut) => { + conflicts_mut_mut.push(Conflict::Mut { span, name }) + } + (Mutability::Not, Mutability::Mut) => { + conflicts_mut_ref.push(Conflict::Mut { span, name }) + } + (Mutability::Mut, Mutability::Not) => { + conflicts_mut_ref.push(Conflict::Ref { span, name }) + } + }, + BindingMode::ByValue if is_binding_by_move(ty) => { + conflicts_move.push(Conflict::Moved { span, name }) // `ref mut?` + by-move conflict. + } + BindingMode::ByValue => {} // `ref mut?` + by-copy is fine. + } + }); + + let report_mut_mut = !conflicts_mut_mut.is_empty(); + let report_mut_ref = !conflicts_mut_ref.is_empty(); + let report_move_conflict = !conflicts_move.is_empty(); + + let mut occurrences = match mut_outer { + Mutability::Mut => vec![Conflict::Mut { span: pat.span, name }], + Mutability::Not => vec![Conflict::Ref { span: pat.span, name }], + }; + occurrences.extend(conflicts_mut_mut); + occurrences.extend(conflicts_mut_ref); + occurrences.extend(conflicts_move); + + // Report errors if any. + if report_mut_mut { + // Report mutability conflicts for e.g. `ref mut x @ Some(ref mut y)`. + sess.emit_err(MultipleMutBorrows { span: pat.span, occurrences }); + } else if report_mut_ref { + // Report mutability conflicts for e.g. `ref x @ Some(ref mut y)` or the converse. + match mut_outer { + Mutability::Mut => { + sess.emit_err(AlreadyMutBorrowed { span: pat.span, occurrences }); + } + Mutability::Not => { + sess.emit_err(AlreadyBorrowed { span: pat.span, occurrences }); + } + }; + } else if report_move_conflict { + // Report by-ref and by-move conflicts, e.g. `ref x @ y`. + sess.emit_err(MovedWhileBorrowed { span: pat.span, occurrences }); + } +} + fn check_for_bindings_named_same_as_variants( cx: &MatchVisitor<'_, '_, '_>, pat: &Pat<'_>, @@ -616,25 +721,6 @@ fn check_for_bindings_named_same_as_variants( }); } -/// Checks for common cases of "catchall" patterns that may not be intended as such. -fn pat_is_catchall(pat: &DeconstructedPat<'_, '_>) -> bool { - use Constructor::*; - match pat.ctor() { - Wildcard => true, - Single => pat.iter_fields().all(|pat| pat_is_catchall(pat)), - _ => false, - } -} - -fn unreachable_pattern(tcx: TyCtxt<'_>, span: Span, id: HirId, catchall: Option<Span>) { - tcx.emit_spanned_lint( - UNREACHABLE_PATTERNS, - id, - span, - UnreachablePattern { span: if catchall.is_some() { Some(span) } else { None }, catchall }, - ); -} - fn irrefutable_let_patterns( tcx: TyCtxt<'_>, id: HirId, @@ -680,11 +766,23 @@ fn report_arm_reachability<'p, 'tcx>( cx: &MatchCheckCtxt<'p, 'tcx>, report: &UsefulnessReport<'p, 'tcx>, ) { + let report_unreachable_pattern = |span, hir_id, catchall: Option<Span>| { + cx.tcx.emit_spanned_lint( + UNREACHABLE_PATTERNS, + hir_id, + span, + UnreachablePattern { + span: if catchall.is_some() { Some(span) } else { None }, + catchall, + }, + ); + }; + use Reachability::*; let mut catchall = None; for (arm, is_useful) in report.arm_usefulness.iter() { match is_useful { - Unreachable => unreachable_pattern(cx.tcx, arm.pat.span(), arm.hir_id, catchall), + Unreachable => report_unreachable_pattern(arm.pat.span(), arm.hir_id, catchall), Reachable(unreachables) if unreachables.is_empty() => {} // The arm is reachable, but contains unreachable subpatterns (from or-patterns). Reachable(unreachables) => { @@ -692,7 +790,7 @@ fn report_arm_reachability<'p, 'tcx>( // Emit lints in the order in which they occur in the file. unreachables.sort_unstable(); for span in unreachables { - unreachable_pattern(cx.tcx, span, arm.hir_id, None); + report_unreachable_pattern(span, arm.hir_id, None); } } } @@ -702,22 +800,14 @@ fn report_arm_reachability<'p, 'tcx>( } } -fn collect_non_exhaustive_tys<'tcx>( - tcx: TyCtxt<'tcx>, - pat: &WitnessPat<'tcx>, - non_exhaustive_tys: &mut FxHashSet<Ty<'tcx>>, -) { - if matches!(pat.ctor(), Constructor::NonExhaustive) { - non_exhaustive_tys.insert(pat.ty()); - } - if let Constructor::IntRange(range) = pat.ctor() { - if range.is_beyond_boundaries(pat.ty(), tcx) { - // The range denotes the values before `isize::MIN` or the values after `usize::MAX`/`isize::MAX`. - non_exhaustive_tys.insert(pat.ty()); - } +/// Checks for common cases of "catchall" patterns that may not be intended as such. +fn pat_is_catchall(pat: &DeconstructedPat<'_, '_>) -> bool { + use Constructor::*; + match pat.ctor() { + Wildcard => true, + Single => pat.iter_fields().all(|pat| pat_is_catchall(pat)), + _ => false, } - pat.iter_fields() - .for_each(|field_pat| collect_non_exhaustive_tys(tcx, field_pat, non_exhaustive_tys)) } /// Report that a match is not exhaustive. @@ -755,7 +845,14 @@ fn non_exhaustive_match<'p, 'tcx>( sp, format!("non-exhaustive patterns: {joined_patterns} not covered"), ); - err.span_label(sp, pattern_not_covered_label(&witnesses, &joined_patterns)); + err.span_label( + sp, + format!( + "pattern{} {} not covered", + rustc_errors::pluralize!(witnesses.len()), + joined_patterns + ), + ); patterns_len = witnesses.len(); pattern = if witnesses.len() < 4 { witnesses @@ -910,7 +1007,7 @@ fn non_exhaustive_match<'p, 'tcx>( err.emit() } -pub(crate) fn joined_uncovered_patterns<'p, 'tcx>( +fn joined_uncovered_patterns<'p, 'tcx>( cx: &MatchCheckCtxt<'p, 'tcx>, witnesses: &[WitnessPat<'tcx>], ) -> String { @@ -931,11 +1028,22 @@ pub(crate) fn joined_uncovered_patterns<'p, 'tcx>( } } -pub(crate) fn pattern_not_covered_label( - witnesses: &[WitnessPat<'_>], - joined_patterns: &str, -) -> String { - format!("pattern{} {} not covered", rustc_errors::pluralize!(witnesses.len()), joined_patterns) +fn collect_non_exhaustive_tys<'tcx>( + tcx: TyCtxt<'tcx>, + pat: &WitnessPat<'tcx>, + non_exhaustive_tys: &mut FxHashSet<Ty<'tcx>>, +) { + if matches!(pat.ctor(), Constructor::NonExhaustive) { + non_exhaustive_tys.insert(pat.ty()); + } + if let Constructor::IntRange(range) = pat.ctor() { + if range.is_beyond_boundaries(pat.ty(), tcx) { + // The range denotes the values before `isize::MIN` or the values after `usize::MAX`/`isize::MAX`. + non_exhaustive_tys.insert(pat.ty()); + } + } + pat.iter_fields() + .for_each(|field_pat| collect_non_exhaustive_tys(tcx, field_pat, non_exhaustive_tys)) } /// Point at the definition of non-covered `enum` variants. @@ -997,108 +1105,3 @@ fn maybe_point_at_variant<'a, 'p: 'a, 'tcx: 'a>( } covered } - -/// Check if a by-value binding is by-value. That is, check if the binding's type is not `Copy`. -/// Check that there are no borrow or move conflicts in `binding @ subpat` patterns. -/// -/// For example, this would reject: -/// - `ref x @ Some(ref mut y)`, -/// - `ref mut x @ Some(ref y)`, -/// - `ref mut x @ Some(ref mut y)`, -/// - `ref mut? x @ Some(y)`, and -/// - `x @ Some(ref mut? y)`. -/// -/// This analysis is *not* subsumed by NLL. -fn check_borrow_conflicts_in_at_patterns<'tcx>(cx: &MatchVisitor<'_, '_, 'tcx>, pat: &Pat<'tcx>) { - // Extract `sub` in `binding @ sub`. - let PatKind::Binding { name, mode, ty, subpattern: Some(box ref sub), .. } = pat.kind else { - return; - }; - - let is_binding_by_move = |ty: Ty<'tcx>| !ty.is_copy_modulo_regions(cx.tcx, cx.param_env); - - let sess = cx.tcx.sess; - - // Get the binding move, extract the mutability if by-ref. - let mut_outer = match mode { - BindingMode::ByValue if is_binding_by_move(ty) => { - // We have `x @ pat` where `x` is by-move. Reject all borrows in `pat`. - let mut conflicts_ref = Vec::new(); - sub.each_binding(|_, mode, _, span| match mode { - BindingMode::ByValue => {} - BindingMode::ByRef(_) => conflicts_ref.push(span), - }); - if !conflicts_ref.is_empty() { - sess.emit_err(BorrowOfMovedValue { - binding_span: pat.span, - conflicts_ref, - name, - ty, - suggest_borrowing: Some(pat.span.shrink_to_lo()), - }); - } - return; - } - BindingMode::ByValue => return, - BindingMode::ByRef(m) => m.mutability(), - }; - - // We now have `ref $mut_outer binding @ sub` (semantically). - // Recurse into each binding in `sub` and find mutability or move conflicts. - let mut conflicts_move = Vec::new(); - let mut conflicts_mut_mut = Vec::new(); - let mut conflicts_mut_ref = Vec::new(); - sub.each_binding(|name, mode, ty, span| { - match mode { - BindingMode::ByRef(mut_inner) => match (mut_outer, mut_inner.mutability()) { - // Both sides are `ref`. - (Mutability::Not, Mutability::Not) => {} - // 2x `ref mut`. - (Mutability::Mut, Mutability::Mut) => { - conflicts_mut_mut.push(Conflict::Mut { span, name }) - } - (Mutability::Not, Mutability::Mut) => { - conflicts_mut_ref.push(Conflict::Mut { span, name }) - } - (Mutability::Mut, Mutability::Not) => { - conflicts_mut_ref.push(Conflict::Ref { span, name }) - } - }, - BindingMode::ByValue if is_binding_by_move(ty) => { - conflicts_move.push(Conflict::Moved { span, name }) // `ref mut?` + by-move conflict. - } - BindingMode::ByValue => {} // `ref mut?` + by-copy is fine. - } - }); - - let report_mut_mut = !conflicts_mut_mut.is_empty(); - let report_mut_ref = !conflicts_mut_ref.is_empty(); - let report_move_conflict = !conflicts_move.is_empty(); - - let mut occurrences = match mut_outer { - Mutability::Mut => vec![Conflict::Mut { span: pat.span, name }], - Mutability::Not => vec![Conflict::Ref { span: pat.span, name }], - }; - occurrences.extend(conflicts_mut_mut); - occurrences.extend(conflicts_mut_ref); - occurrences.extend(conflicts_move); - - // Report errors if any. - if report_mut_mut { - // Report mutability conflicts for e.g. `ref mut x @ Some(ref mut y)`. - sess.emit_err(MultipleMutBorrows { span: pat.span, occurrences }); - } else if report_mut_ref { - // Report mutability conflicts for e.g. `ref x @ Some(ref mut y)` or the converse. - match mut_outer { - Mutability::Mut => { - sess.emit_err(AlreadyMutBorrowed { span: pat.span, occurrences }); - } - Mutability::Not => { - sess.emit_err(AlreadyBorrowed { span: pat.span, occurrences }); - } - }; - } else if report_move_conflict { - // Report by-ref and by-move conflicts, e.g. `ref x @ y`. - sess.emit_err(MovedWhileBorrowed { span: pat.span, occurrences }); - } -} |