diff options
10 files changed, 142 insertions, 53 deletions
diff --git a/compiler/rustc_mir_build/src/builder/scope.rs b/compiler/rustc_mir_build/src/builder/scope.rs index 5a5456aedc2..12a56d7c5ea 100644 --- a/compiler/rustc_mir_build/src/builder/scope.rs +++ b/compiler/rustc_mir_build/src/builder/scope.rs @@ -927,6 +927,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> { scrut_span: rustc_span::Span::default(), refutable: true, known_valid_scrutinee: true, + internal_state: Default::default(), }; let valtree = match self.eval_unevaluated_mir_constant_to_valtree(constant) { 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 b7b160c738d..a49bfc1b8f4 100644 --- a/compiler/rustc_mir_build/src/thir/pattern/check_match.rs +++ b/compiler/rustc_mir_build/src/thir/pattern/check_match.rs @@ -406,6 +406,7 @@ impl<'p, 'tcx> MatchVisitor<'p, 'tcx> { scrut_span, refutable, known_valid_scrutinee, + internal_state: Default::default(), } } diff --git a/compiler/rustc_pattern_analysis/src/checks.rs b/compiler/rustc_pattern_analysis/src/checks.rs new file mode 100644 index 00000000000..88ccaa1e0e5 --- /dev/null +++ b/compiler/rustc_pattern_analysis/src/checks.rs @@ -0,0 +1,50 @@ +//! Contains checks that must be run to validate matches before performing usefulness analysis. + +use crate::constructor::Constructor::*; +use crate::pat_column::PatternColumn; +use crate::{MatchArm, PatCx}; + +/// Validate that deref patterns and normal constructors aren't used to match on the same place. +pub(crate) fn detect_mixed_deref_pat_ctors<'p, Cx: PatCx>( + cx: &Cx, + arms: &[MatchArm<'p, Cx>], +) -> Result<(), Cx::Error> { + let pat_column = PatternColumn::new(arms); + detect_mixed_deref_pat_ctors_inner(cx, &pat_column) +} + +fn detect_mixed_deref_pat_ctors_inner<'p, Cx: PatCx>( + cx: &Cx, + column: &PatternColumn<'p, Cx>, +) -> Result<(), Cx::Error> { + let Some(ty) = column.head_ty() else { + return Ok(()); + }; + + // Check for a mix of deref patterns and normal constructors. + let mut deref_pat = None; + let mut normal_pat = None; + for pat in column.iter() { + match pat.ctor() { + // The analysis can handle mixing deref patterns with wildcards and opaque patterns. + Wildcard | Opaque(_) => {} + DerefPattern(_) => deref_pat = Some(pat), + // Nothing else can be compared to deref patterns in `Constructor::is_covered_by`. + _ => normal_pat = Some(pat), + } + } + if let Some(deref_pat) = deref_pat + && let Some(normal_pat) = normal_pat + { + return Err(cx.report_mixed_deref_pat_ctors(deref_pat, normal_pat)); + } + + // Specialize and recurse into the patterns' fields. + let set = column.analyze_ctors(cx, &ty)?; + for ctor in set.present { + for specialized_column in column.specialize(cx, &ty, &ctor).iter() { + detect_mixed_deref_pat_ctors_inner(cx, specialized_column)?; + } + } + Ok(()) +} diff --git a/compiler/rustc_pattern_analysis/src/lib.rs b/compiler/rustc_pattern_analysis/src/lib.rs index 2b85d7b26ce..66df35f9ee4 100644 --- a/compiler/rustc_pattern_analysis/src/lib.rs +++ b/compiler/rustc_pattern_analysis/src/lib.rs @@ -8,6 +8,7 @@ #![allow(unused_crate_dependencies)] // tidy-alphabetical-end +pub(crate) mod checks; pub mod constructor; #[cfg(feature = "rustc")] pub mod errors; @@ -107,6 +108,20 @@ pub trait PatCx: Sized + fmt::Debug { _gapped_with: &[&DeconstructedPat<Self>], ) { } + + /// Check if we may need to perform additional deref-pattern-specific validation. + fn match_may_contain_deref_pats(&self) -> bool { + true + } + + /// The current implementation of deref patterns requires that they can't match on the same + /// place as a normal constructor. Since this isn't caught by type-checking, we check it in the + /// `PatCx` before running the analysis. This reports an error if the check fails. + fn report_mixed_deref_pat_ctors( + &self, + deref_pat: &DeconstructedPat<Self>, + normal_pat: &DeconstructedPat<Self>, + ) -> Self::Error; } /// The arm of a match expression. diff --git a/compiler/rustc_pattern_analysis/src/rustc.rs b/compiler/rustc_pattern_analysis/src/rustc.rs index e53cebc59ba..ee72b676b38 100644 --- a/compiler/rustc_pattern_analysis/src/rustc.rs +++ b/compiler/rustc_pattern_analysis/src/rustc.rs @@ -1,3 +1,4 @@ +use std::cell::Cell; use std::fmt; use std::iter::once; @@ -99,6 +100,16 @@ pub struct RustcPatCtxt<'p, 'tcx: 'p> { /// Whether the data at the scrutinee is known to be valid. This is false if the scrutinee comes /// from a union field, a pointer deref, or a reference deref (pending opsem decisions). pub known_valid_scrutinee: bool, + pub internal_state: RustcPatCtxtState, +} + +/// Private fields of [`RustcPatCtxt`], separated out to permit record initialization syntax. +#[derive(Clone, Default)] +pub struct RustcPatCtxtState { + /// Has a deref pattern been lowered? This is initialized to `false` and is updated by + /// [`RustcPatCtxt::lower_pat`] in order to avoid performing deref-pattern-specific validation + /// for everything containing patterns. + has_lowered_deref_pat: Cell<bool>, } impl<'p, 'tcx: 'p> fmt::Debug for RustcPatCtxt<'p, 'tcx> { @@ -474,6 +485,7 @@ impl<'p, 'tcx: 'p> RustcPatCtxt<'p, 'tcx> { fields = vec![self.lower_pat(subpattern).at_index(0)]; arity = 1; ctor = DerefPattern(cx.reveal_opaque_ty(subpattern.ty)); + self.internal_state.has_lowered_deref_pat.set(true); } PatKind::Leaf { subpatterns } | PatKind::Variant { subpatterns, .. } => { match ty.kind() { @@ -1027,6 +1039,25 @@ impl<'p, 'tcx: 'p> PatCx for RustcPatCtxt<'p, 'tcx> { ); } } + + fn match_may_contain_deref_pats(&self) -> bool { + self.internal_state.has_lowered_deref_pat.get() + } + + fn report_mixed_deref_pat_ctors( + &self, + deref_pat: &crate::pat::DeconstructedPat<Self>, + normal_pat: &crate::pat::DeconstructedPat<Self>, + ) -> Self::Error { + let deref_pattern_label = deref_pat.data().span; + let normal_constructor_label = normal_pat.data().span; + self.tcx.dcx().emit_err(errors::MixedDerefPatternConstructors { + spans: vec![deref_pattern_label, normal_constructor_label], + smart_pointer_ty: deref_pat.ty().inner(), + deref_pattern_label, + normal_constructor_label, + }) + } } /// Recursively expand this pattern into its subpatterns. Only useful for or-patterns. @@ -1055,13 +1086,6 @@ pub fn analyze_match<'p, 'tcx>( ) -> Result<UsefulnessReport<'p, 'tcx>, ErrorGuaranteed> { let scrut_ty = tycx.reveal_opaque_ty(scrut_ty); - // The analysis doesn't support deref patterns mixed with normal constructors; error if present. - // FIXME(deref_patterns): This only needs to run when a deref pattern was found during lowering. - if tycx.tcx.features().deref_patterns() { - let pat_column = PatternColumn::new(arms); - detect_mixed_deref_pat_ctors(tycx, &pat_column)?; - } - let scrut_validity = PlaceValidity::from_bool(tycx.known_valid_scrutinee); let report = compute_match_usefulness( tycx, @@ -1080,48 +1104,3 @@ pub fn analyze_match<'p, 'tcx>( Ok(report) } - -// FIXME(deref_patterns): Currently it's the responsibility of the frontend (rustc or rust-analyzer) -// to ensure that deref patterns don't appear in the same column as normal constructors. Deref -// patterns aren't currently implemented in rust-analyzer, but should they be, the columnwise check -// here could be made generic and shared between frontends. -fn detect_mixed_deref_pat_ctors<'p, 'tcx>( - cx: &RustcPatCtxt<'p, 'tcx>, - column: &PatternColumn<'p, RustcPatCtxt<'p, 'tcx>>, -) -> Result<(), ErrorGuaranteed> { - let Some(&ty) = column.head_ty() else { - return Ok(()); - }; - - // Check for a mix of deref patterns and normal constructors. - let mut normal_ctor_span = None; - let mut deref_pat_span = None; - for pat in column.iter() { - match pat.ctor() { - // The analysis can handle mixing deref patterns with wildcards and opaque patterns. - Wildcard | Opaque(_) => {} - DerefPattern(_) => deref_pat_span = Some(pat.data().span), - // Nothing else can be compared to deref patterns in `Constructor::is_covered_by`. - _ => normal_ctor_span = Some(pat.data().span), - } - } - if let Some(normal_constructor_label) = normal_ctor_span - && let Some(deref_pattern_label) = deref_pat_span - { - return Err(cx.tcx.dcx().emit_err(errors::MixedDerefPatternConstructors { - spans: vec![deref_pattern_label, normal_constructor_label], - smart_pointer_ty: ty.inner(), - deref_pattern_label, - normal_constructor_label, - })); - } - - // Specialize and recurse into the patterns' fields. - let set = column.analyze_ctors(cx, &ty)?; - for ctor in set.present { - for specialized_column in column.specialize(cx, &ty, &ctor).iter() { - detect_mixed_deref_pat_ctors(cx, specialized_column)?; - } - } - Ok(()) -} diff --git a/compiler/rustc_pattern_analysis/src/usefulness.rs b/compiler/rustc_pattern_analysis/src/usefulness.rs index c348cd508f9..b1c646e9884 100644 --- a/compiler/rustc_pattern_analysis/src/usefulness.rs +++ b/compiler/rustc_pattern_analysis/src/usefulness.rs @@ -720,7 +720,7 @@ use tracing::{debug, instrument}; use self::PlaceValidity::*; use crate::constructor::{Constructor, ConstructorSet, IntRange}; use crate::pat::{DeconstructedPat, PatId, PatOrWild, WitnessPat}; -use crate::{MatchArm, PatCx, PrivateUninhabitedField}; +use crate::{MatchArm, PatCx, PrivateUninhabitedField, checks}; #[cfg(not(feature = "rustc"))] pub fn ensure_sufficient_stack<R>(f: impl FnOnce() -> R) -> R { f() @@ -1836,6 +1836,11 @@ pub fn compute_match_usefulness<'p, Cx: PatCx>( scrut_validity: PlaceValidity, complexity_limit: usize, ) -> Result<UsefulnessReport<'p, Cx>, Cx::Error> { + // The analysis doesn't support deref patterns mixed with normal constructors; error if present. + if tycx.match_may_contain_deref_pats() { + checks::detect_mixed_deref_pat_ctors(tycx, arms)?; + } + let mut cx = UsefulnessCtxt { tycx, branch_usefulness: FxHashMap::default(), diff --git a/compiler/rustc_pattern_analysis/tests/common/mod.rs b/compiler/rustc_pattern_analysis/tests/common/mod.rs index 8980b644f59..0b939ef7816 100644 --- a/compiler/rustc_pattern_analysis/tests/common/mod.rs +++ b/compiler/rustc_pattern_analysis/tests/common/mod.rs @@ -1,6 +1,7 @@ use rustc_pattern_analysis::constructor::{ Constructor, ConstructorSet, IntRange, MaybeInfiniteInt, RangeEnd, VariantVisibility, }; +use rustc_pattern_analysis::pat::DeconstructedPat; use rustc_pattern_analysis::usefulness::{PlaceValidity, UsefulnessReport}; use rustc_pattern_analysis::{MatchArm, PatCx, PrivateUninhabitedField}; @@ -184,6 +185,14 @@ impl PatCx for Cx { fn complexity_exceeded(&self) -> Result<(), Self::Error> { Err(()) } + + fn report_mixed_deref_pat_ctors( + &self, + _deref_pat: &DeconstructedPat<Self>, + _normal_pat: &DeconstructedPat<Self>, + ) -> Self::Error { + panic!("`rustc_pattern_analysis::tests` currently doesn't test deref pattern errors") + } } /// Construct a single pattern; see `pats!()`. diff --git a/src/tools/rust-analyzer/crates/hir-ty/src/diagnostics/match_check/pat_analysis.rs b/src/tools/rust-analyzer/crates/hir-ty/src/diagnostics/match_check/pat_analysis.rs index 22b7f5ac9fd..56fd12e1f2b 100644 --- a/src/tools/rust-analyzer/crates/hir-ty/src/diagnostics/match_check/pat_analysis.rs +++ b/src/tools/rust-analyzer/crates/hir-ty/src/diagnostics/match_check/pat_analysis.rs @@ -489,6 +489,14 @@ impl PatCx for MatchCheckCtx<'_> { fn complexity_exceeded(&self) -> Result<(), Self::Error> { Err(()) } + + fn report_mixed_deref_pat_ctors( + &self, + _deref_pat: &DeconstructedPat<'_>, + _normal_pat: &DeconstructedPat<'_>, + ) { + // FIXME(deref_patterns): This could report an error comparable to the one in rustc. + } } impl fmt::Debug for MatchCheckCtx<'_> { diff --git a/tests/ui/pattern/box-pattern-constructor-mismatch.rs b/tests/ui/pattern/box-pattern-constructor-mismatch.rs new file mode 100644 index 00000000000..8f0a19d7407 --- /dev/null +++ b/tests/ui/pattern/box-pattern-constructor-mismatch.rs @@ -0,0 +1,11 @@ +//! Test that `box _` patterns and `Box { .. }` patterns can't be used to match on the same place. +//! This is required for the current implementation of exhaustiveness analysis for deref patterns. + +#![feature(box_patterns)] + +fn main() { + match Box::new(0) { + box _ => {} //~ ERROR mix of deref patterns and normal constructors + Box { .. } => {} + } +} diff --git a/tests/ui/pattern/box-pattern-constructor-mismatch.stderr b/tests/ui/pattern/box-pattern-constructor-mismatch.stderr new file mode 100644 index 00000000000..489eefe0d21 --- /dev/null +++ b/tests/ui/pattern/box-pattern-constructor-mismatch.stderr @@ -0,0 +1,10 @@ +error: mix of deref patterns and normal constructors + --> $DIR/box-pattern-constructor-mismatch.rs:8:9 + | +LL | box _ => {} + | ^^^^^ matches on the result of dereferencing `Box<i32>` +LL | Box { .. } => {} + | ^^^^^^^^^^ matches directly on `Box<i32>` + +error: aborting due to 1 previous error + |