diff options
Diffstat (limited to 'compiler')
27 files changed, 90 insertions, 14 deletions
diff --git a/compiler/rustc_ast/src/ast.rs b/compiler/rustc_ast/src/ast.rs index 10776f31c07..f6f25247b9e 100644 --- a/compiler/rustc_ast/src/ast.rs +++ b/compiler/rustc_ast/src/ast.rs @@ -645,6 +645,7 @@ impl Pat { // These patterns do not contain subpatterns, skip. PatKind::Wild | PatKind::Rest + | PatKind::Never | PatKind::Lit(_) | PatKind::Range(..) | PatKind::Ident(..) @@ -795,6 +796,9 @@ pub enum PatKind { /// only one rest pattern may occur in the pattern sequences. Rest, + // A never pattern `!` + Never, + /// Parentheses in patterns used for grouping (i.e., `(PAT)`). Paren(P<Pat>), diff --git a/compiler/rustc_ast/src/mut_visit.rs b/compiler/rustc_ast/src/mut_visit.rs index 541b9872922..8ce86bf9ecf 100644 --- a/compiler/rustc_ast/src/mut_visit.rs +++ b/compiler/rustc_ast/src/mut_visit.rs @@ -1249,7 +1249,7 @@ pub fn noop_visit_pat<T: MutVisitor>(pat: &mut P<Pat>, vis: &mut T) { let Pat { id, kind, span, tokens } = pat.deref_mut(); vis.visit_id(id); match kind { - PatKind::Wild | PatKind::Rest => {} + PatKind::Wild | PatKind::Rest | PatKind::Never => {} PatKind::Ident(_binding_mode, ident, sub) => { vis.visit_ident(ident); visit_opt(sub, |sub| vis.visit_pat(sub)); diff --git a/compiler/rustc_ast/src/visit.rs b/compiler/rustc_ast/src/visit.rs index 1caa39e2dd9..9dbadcb49d3 100644 --- a/compiler/rustc_ast/src/visit.rs +++ b/compiler/rustc_ast/src/visit.rs @@ -559,7 +559,7 @@ pub fn walk_pat<'a, V: Visitor<'a>>(visitor: &mut V, pattern: &'a Pat) { walk_list!(visitor, visit_expr, lower_bound); walk_list!(visitor, visit_expr, upper_bound); } - PatKind::Wild | PatKind::Rest => {} + PatKind::Wild | PatKind::Rest | PatKind::Never => {} PatKind::Tuple(elems) | PatKind::Slice(elems) | PatKind::Or(elems) => { walk_list!(visitor, visit_pat, elems); } diff --git a/compiler/rustc_ast_lowering/src/pat.rs b/compiler/rustc_ast_lowering/src/pat.rs index a30f264bc7d..ce7fe5f371d 100644 --- a/compiler/rustc_ast_lowering/src/pat.rs +++ b/compiler/rustc_ast_lowering/src/pat.rs @@ -24,6 +24,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> { let node = loop { match &pattern.kind { PatKind::Wild => break hir::PatKind::Wild, + PatKind::Never => break hir::PatKind::Never, PatKind::Ident(binding_mode, ident, sub) => { let lower_sub = |this: &mut Self| sub.as_ref().map(|s| this.lower_pat(s)); break self.lower_pat_ident(pattern, *binding_mode, *ident, lower_sub); diff --git a/compiler/rustc_ast_passes/src/feature_gate.rs b/compiler/rustc_ast_passes/src/feature_gate.rs index 8fb7c7de50c..8851fbd28f0 100644 --- a/compiler/rustc_ast_passes/src/feature_gate.rs +++ b/compiler/rustc_ast_passes/src/feature_gate.rs @@ -555,6 +555,7 @@ pub fn check_crate(krate: &ast::Crate, sess: &Session, features: &Features) { gate_all!(explicit_tail_calls, "`become` expression is experimental"); gate_all!(generic_const_items, "generic const items are experimental"); gate_all!(unnamed_fields, "unnamed fields are not yet fully implemented"); + gate_all!(never_patterns, "`!` patterns are experimental"); if !visitor.features.negative_bounds { for &span in spans.get(&sym::negative_bounds).iter().copied().flatten() { diff --git a/compiler/rustc_ast_pretty/src/pprust/state.rs b/compiler/rustc_ast_pretty/src/pprust/state.rs index a3bf47328ea..d7af97c4b60 100644 --- a/compiler/rustc_ast_pretty/src/pprust/state.rs +++ b/compiler/rustc_ast_pretty/src/pprust/state.rs @@ -1343,6 +1343,7 @@ impl<'a> State<'a> { is that it doesn't matter */ match &pat.kind { PatKind::Wild => self.word("_"), + PatKind::Never => self.word("!"), PatKind::Ident(BindingAnnotation(by_ref, mutbl), ident, sub) => { if *by_ref == ByRef::Yes { self.word_nbsp("ref"); diff --git a/compiler/rustc_feature/src/unstable.rs b/compiler/rustc_feature/src/unstable.rs index e34661d5fc6..bffc2848166 100644 --- a/compiler/rustc_feature/src/unstable.rs +++ b/compiler/rustc_feature/src/unstable.rs @@ -147,7 +147,7 @@ macro_rules! declare_features { // was set. // // Note that the features are grouped into internal/user-facing and then -// sorted by version inside those groups. This is enforced with tidy. +// sorted alphabetically inside those groups. This is enforced with tidy. // // N.B., `tools/tidy/src/features.rs` parses this information directly out of the // source, so take care when modifying it. @@ -512,6 +512,8 @@ declare_features! ( (unstable, native_link_modifiers_as_needed, "1.53.0", Some(81490), None), /// Allow negative trait implementations. (unstable, negative_impls, "1.44.0", Some(68318), None), + /// Allows the `!` pattern. + (incomplete, never_patterns, "CURRENT_RUSTC_VERSION", Some(118155), None), /// Allows the `!` type. Does not imply 'exhaustive_patterns' (below) any more. (unstable, never_type, "1.13.0", Some(35121), None), /// Allows diverging expressions to fall back to `!` rather than `()`. diff --git a/compiler/rustc_hir/src/hir.rs b/compiler/rustc_hir/src/hir.rs index d2b83d0eb00..9581f6cb040 100644 --- a/compiler/rustc_hir/src/hir.rs +++ b/compiler/rustc_hir/src/hir.rs @@ -1002,7 +1002,7 @@ impl<'hir> Pat<'hir> { use PatKind::*; match self.kind { - Wild | Lit(_) | Range(..) | Binding(.., None) | Path(_) => true, + Wild | Never | Lit(_) | Range(..) | Binding(.., None) | Path(_) => true, Box(s) | Ref(s, _) | Binding(.., Some(s)) => s.walk_short_(it), Struct(_, fields, _) => fields.iter().all(|field| field.pat.walk_short_(it)), TupleStruct(_, s, _) | Tuple(s, _) | Or(s) => s.iter().all(|p| p.walk_short_(it)), @@ -1029,7 +1029,7 @@ impl<'hir> Pat<'hir> { use PatKind::*; match self.kind { - Wild | Lit(_) | Range(..) | Binding(.., None) | Path(_) => {} + Wild | Never | Lit(_) | Range(..) | Binding(.., None) | Path(_) => {} Box(s) | Ref(s, _) | Binding(.., Some(s)) => s.walk_(it), Struct(_, fields, _) => fields.iter().for_each(|field| field.pat.walk_(it)), TupleStruct(_, s, _) | Tuple(s, _) | Or(s) => s.iter().for_each(|p| p.walk_(it)), @@ -1142,6 +1142,9 @@ pub enum PatKind<'hir> { /// Invariant: `pats.len() >= 2`. Or(&'hir [Pat<'hir>]), + /// A never pattern `!`. + Never, + /// A path pattern for a unit struct/variant or a (maybe-associated) constant. Path(QPath<'hir>), diff --git a/compiler/rustc_hir/src/intravisit.rs b/compiler/rustc_hir/src/intravisit.rs index 8a672855989..963b324ca13 100644 --- a/compiler/rustc_hir/src/intravisit.rs +++ b/compiler/rustc_hir/src/intravisit.rs @@ -660,7 +660,7 @@ pub fn walk_pat<'v, V: Visitor<'v>>(visitor: &mut V, pattern: &'v Pat<'v>) { walk_list!(visitor, visit_expr, lower_bound); walk_list!(visitor, visit_expr, upper_bound); } - PatKind::Wild => (), + PatKind::Never | PatKind::Wild => (), PatKind::Slice(prepatterns, ref slice_pattern, postpatterns) => { walk_list!(visitor, visit_pat, prepatterns); walk_list!(visitor, visit_pat, slice_pattern); diff --git a/compiler/rustc_hir_analysis/src/check/region.rs b/compiler/rustc_hir_analysis/src/check/region.rs index 9557568b387..37b308f9f88 100644 --- a/compiler/rustc_hir_analysis/src/check/region.rs +++ b/compiler/rustc_hir_analysis/src/check/region.rs @@ -662,6 +662,7 @@ fn resolve_local<'tcx>( PatKind::Ref(_, _) | PatKind::Binding(hir::BindingAnnotation(hir::ByRef::No, _), ..) | PatKind::Wild + | PatKind::Never | PatKind::Path(_) | PatKind::Lit(_) | PatKind::Range(_, _, _) => false, diff --git a/compiler/rustc_hir_pretty/src/lib.rs b/compiler/rustc_hir_pretty/src/lib.rs index e9e8c7fd4fc..b7e7d258a90 100644 --- a/compiler/rustc_hir_pretty/src/lib.rs +++ b/compiler/rustc_hir_pretty/src/lib.rs @@ -1724,6 +1724,7 @@ impl<'a> State<'a> { // is that it doesn't matter match pat.kind { PatKind::Wild => self.word("_"), + PatKind::Never => self.word("!"), PatKind::Binding(BindingAnnotation(by_ref, mutbl), _, ident, sub) => { if by_ref == ByRef::Yes { self.word_nbsp("ref"); diff --git a/compiler/rustc_hir_typeck/src/expr_use_visitor.rs b/compiler/rustc_hir_typeck/src/expr_use_visitor.rs index d7cf6dba9aa..9991050d7b2 100644 --- a/compiler/rustc_hir_typeck/src/expr_use_visitor.rs +++ b/compiler/rustc_hir_typeck/src/expr_use_visitor.rs @@ -401,12 +401,17 @@ impl<'a, 'tcx> ExprUseVisitor<'a, 'tcx> { mc.cat_pattern(discr_place.clone(), pat, |place, pat| { match &pat.kind { PatKind::Binding(.., opt_sub_pat) => { - // If the opt_sub_pat is None, than the binding does not count as + // If the opt_sub_pat is None, then the binding does not count as // a wildcard for the purpose of borrowing discr. if opt_sub_pat.is_none() { needs_to_be_read = true; } } + PatKind::Never => { + // A never pattern reads the value. + // FIXME(never_patterns): does this do what I expect? + needs_to_be_read = true; + } PatKind::Path(qpath) => { // A `Path` pattern is just a name like `Foo`. This is either a // named constant or else it refers to an ADT variant diff --git a/compiler/rustc_hir_typeck/src/mem_categorization.rs b/compiler/rustc_hir_typeck/src/mem_categorization.rs index 94da4bfcdc4..0bcb7c7b5d7 100644 --- a/compiler/rustc_hir_typeck/src/mem_categorization.rs +++ b/compiler/rustc_hir_typeck/src/mem_categorization.rs @@ -766,6 +766,7 @@ impl<'a, 'tcx> MemCategorizationContext<'a, 'tcx> { | PatKind::Binding(.., None) | PatKind::Lit(..) | PatKind::Range(..) + | PatKind::Never | PatKind::Wild => { // always ok } diff --git a/compiler/rustc_hir_typeck/src/pat.rs b/compiler/rustc_hir_typeck/src/pat.rs index f11ffabf4d4..1ecf553d71d 100644 --- a/compiler/rustc_hir_typeck/src/pat.rs +++ b/compiler/rustc_hir_typeck/src/pat.rs @@ -178,6 +178,9 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { let ty = match pat.kind { PatKind::Wild => expected, + // FIXME(never_patterns): check the type is uninhabited. If that is not possible within + // typeck, do that in a later phase. + PatKind::Never => expected, PatKind::Lit(lt) => self.check_pat_lit(pat.span, lt, expected, ti), PatKind::Range(lhs, rhs, _) => self.check_pat_range(pat.span, lhs, rhs, expected, ti), PatKind::Binding(ba, var_id, _, sub) => { @@ -287,9 +290,11 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { | PatKind::Box(_) | PatKind::Range(..) | PatKind::Slice(..) => AdjustMode::Peel, + // A never pattern behaves somewhat like a literal or unit variant. + PatKind::Never => AdjustMode::Peel, // String and byte-string literals result in types `&str` and `&[u8]` respectively. // All other literals result in non-reference types. - // As a result, we allow `if let 0 = &&0 {}` but not `if let "foo" = &&"foo {}`. + // As a result, we allow `if let 0 = &&0 {}` but not `if let "foo" = &&"foo" {}`. // // Call `resolve_vars_if_possible` here for inline const blocks. PatKind::Lit(lt) => match self.resolve_vars_if_possible(self.check_expr(lt)).kind() { @@ -743,6 +748,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { | PatKind::Slice(..) => "binding", PatKind::Wild + | PatKind::Never | PatKind::Binding(..) | PatKind::Path(..) | PatKind::Box(..) diff --git a/compiler/rustc_lint/src/unused.rs b/compiler/rustc_lint/src/unused.rs index b4535c72d6c..b0ccffcecc4 100644 --- a/compiler/rustc_lint/src/unused.rs +++ b/compiler/rustc_lint/src/unused.rs @@ -1154,7 +1154,7 @@ impl EarlyLintPass for UnusedParens { // Do not lint on `(..)` as that will result in the other arms being useless. Paren(_) // The other cases do not contain sub-patterns. - | Wild | Rest | Lit(..) | MacCall(..) | Range(..) | Ident(.., None) | Path(..) => {}, + | Wild | Never | Rest | Lit(..) | MacCall(..) | Range(..) | Ident(.., None) | Path(..) => {}, // These are list-like patterns; parens can always be removed. TupleStruct(_, _, ps) | Tuple(ps) | Slice(ps) | Or(ps) => for p in ps { self.check_unused_parens_pat(cx, p, false, false, keep_space); diff --git a/compiler/rustc_middle/src/thir.rs b/compiler/rustc_middle/src/thir.rs index 00c33113692..c48428c713c 100644 --- a/compiler/rustc_middle/src/thir.rs +++ b/compiler/rustc_middle/src/thir.rs @@ -635,7 +635,12 @@ impl<'tcx> Pat<'tcx> { use PatKind::*; match &self.kind { - Wild | Range(..) | Binding { subpattern: None, .. } | Constant { .. } | Error(_) => {} + Wild + | Never + | Range(..) + | Binding { subpattern: None, .. } + | Constant { .. } + | Error(_) => {} AscribeUserType { subpattern, .. } | Binding { subpattern: Some(subpattern), .. } | Deref { subpattern } @@ -809,6 +814,9 @@ pub enum PatKind<'tcx> { pats: Box<[Box<Pat<'tcx>>]>, }, + /// A never pattern `!`. + Never, + /// An error has been encountered during lowering. We probably shouldn't report more lints /// related to this pattern. Error(ErrorGuaranteed), @@ -1069,6 +1077,7 @@ impl<'tcx> fmt::Display for Pat<'tcx> { match self.kind { PatKind::Wild => write!(f, "_"), + PatKind::Never => write!(f, "!"), PatKind::AscribeUserType { ref subpattern, .. } => write!(f, "{subpattern}: _"), PatKind::Binding { mutability, name, mode, ref subpattern, .. } => { let is_mut = match mode { diff --git a/compiler/rustc_middle/src/thir/visit.rs b/compiler/rustc_middle/src/thir/visit.rs index 62c3ceeab8a..4943c11848b 100644 --- a/compiler/rustc_middle/src/thir/visit.rs +++ b/compiler/rustc_middle/src/thir/visit.rs @@ -227,7 +227,7 @@ pub fn walk_pat<'a, 'tcx: 'a, V: Visitor<'a, 'tcx>>(visitor: &mut V, pat: &Pat<' is_primary: _, name: _, } => visitor.visit_pat(subpattern), - Binding { .. } | Wild | Error(_) => {} + Binding { .. } | Wild | Never | Error(_) => {} Variant { subpatterns, adt_def: _, args: _, variant_index: _ } | Leaf { subpatterns } => { for subpattern in subpatterns { visitor.visit_pat(&subpattern.pattern); diff --git a/compiler/rustc_mir_build/src/build/matches/mod.rs b/compiler/rustc_mir_build/src/build/matches/mod.rs index 83686667a4a..90f950d59d5 100644 --- a/compiler/rustc_mir_build/src/build/matches/mod.rs +++ b/compiler/rustc_mir_build/src/build/matches/mod.rs @@ -827,6 +827,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> { PatKind::Constant { .. } | PatKind::Range { .. } | PatKind::Wild + | PatKind::Never | PatKind::Error(_) => {} PatKind::Deref { ref subpattern } => { diff --git a/compiler/rustc_mir_build/src/build/matches/simplify.rs b/compiler/rustc_mir_build/src/build/matches/simplify.rs index 8a6cb26242a..a7f6f4873e3 100644 --- a/compiler/rustc_mir_build/src/build/matches/simplify.rs +++ b/compiler/rustc_mir_build/src/build/matches/simplify.rs @@ -194,6 +194,12 @@ impl<'a, 'tcx> Builder<'a, 'tcx> { Ok(()) } + PatKind::Never => { + // A never pattern acts like a load from the place. + // FIXME(never_patterns): load from the place + Ok(()) + } + PatKind::Constant { .. } => { // FIXME normalize patterns when possible Err(match_pair) diff --git a/compiler/rustc_mir_build/src/build/matches/test.rs b/compiler/rustc_mir_build/src/build/matches/test.rs index 6bd60972c8b..2e7182f261e 100644 --- a/compiler/rustc_mir_build/src/build/matches/test.rs +++ b/compiler/rustc_mir_build/src/build/matches/test.rs @@ -75,6 +75,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> { | PatKind::Array { .. } | PatKind::Wild | PatKind::Binding { .. } + | PatKind::Never | PatKind::Leaf { .. } | PatKind::Deref { .. } | PatKind::Error(_) => self.error_simplifiable(match_pair), @@ -107,6 +108,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> { PatKind::Slice { .. } | PatKind::Array { .. } | PatKind::Wild + | PatKind::Never | PatKind::Or { .. } | PatKind::Binding { .. } | PatKind::AscribeUserType { .. } diff --git a/compiler/rustc_mir_build/src/check_unsafety.rs b/compiler/rustc_mir_build/src/check_unsafety.rs index bbaa02233e5..ca532e3d292 100644 --- a/compiler/rustc_mir_build/src/check_unsafety.rs +++ b/compiler/rustc_mir_build/src/check_unsafety.rs @@ -247,8 +247,9 @@ impl<'a, 'tcx> Visitor<'a, 'tcx> for UnsafetyVisitor<'a, 'tcx> { self.requires_unsafe(pat.span, AccessToUnionField); return; // we can return here since this already requires unsafe } - // wildcard doesn't take anything + // wildcard/never don't take anything PatKind::Wild | + PatKind::Never | // these just wrap other patterns PatKind::Or { .. } | PatKind::InlineConstant { .. } | diff --git a/compiler/rustc_mir_build/src/thir/pattern/deconstruct_pat.rs b/compiler/rustc_mir_build/src/thir/pattern/deconstruct_pat.rs index 8ddc6c924e2..31114190f07 100644 --- a/compiler/rustc_mir_build/src/thir/pattern/deconstruct_pat.rs +++ b/compiler/rustc_mir_build/src/thir/pattern/deconstruct_pat.rs @@ -1557,6 +1557,12 @@ impl<'p, 'tcx> DeconstructedPat<'p, 'tcx> { let pats = expand_or_pat(pat); fields = Fields::from_iter(cx, pats.into_iter().map(mkpat)); } + PatKind::Never => { + // FIXME(never_patterns): handle `!` in exhaustiveness. This is a sane default + // in the meantime. + ctor = Wildcard; + fields = Fields::empty(); + } PatKind::Error(_) => { ctor = Opaque(OpaqueId::new()); fields = Fields::empty(); diff --git a/compiler/rustc_mir_build/src/thir/pattern/mod.rs b/compiler/rustc_mir_build/src/thir/pattern/mod.rs index 8b2a96cff41..5edb2054fd4 100644 --- a/compiler/rustc_mir_build/src/thir/pattern/mod.rs +++ b/compiler/rustc_mir_build/src/thir/pattern/mod.rs @@ -251,6 +251,8 @@ impl<'a, 'tcx> PatCtxt<'a, 'tcx> { let kind = match pat.kind { hir::PatKind::Wild => PatKind::Wild, + hir::PatKind::Never => PatKind::Never, + hir::PatKind::Lit(value) => self.lower_lit(value), hir::PatKind::Range(ref lo_expr, ref hi_expr, end) => { diff --git a/compiler/rustc_mir_build/src/thir/print.rs b/compiler/rustc_mir_build/src/thir/print.rs index c3b2309b7cd..d65ebb39805 100644 --- a/compiler/rustc_mir_build/src/thir/print.rs +++ b/compiler/rustc_mir_build/src/thir/print.rs @@ -636,6 +636,9 @@ impl<'a, 'tcx> ThirPrinter<'a, 'tcx> { PatKind::Wild => { print_indented!(self, "Wild", depth_lvl + 1); } + PatKind::Never => { + print_indented!(self, "Never", depth_lvl + 1); + } PatKind::AscribeUserType { ascription, subpattern } => { print_indented!(self, "AscribeUserType: {", depth_lvl + 1); print_indented!(self, format!("ascription: {:?}", ascription), depth_lvl + 2); diff --git a/compiler/rustc_parse/src/parser/pat.rs b/compiler/rustc_parse/src/parser/pat.rs index 15491cac56a..7e2cba044f2 100644 --- a/compiler/rustc_parse/src/parser/pat.rs +++ b/compiler/rustc_parse/src/parser/pat.rs @@ -368,8 +368,12 @@ impl<'a> Parser<'a> { self.recover_dotdotdot_rest_pat(lo) } else if let Some(form) = self.parse_range_end() { self.parse_pat_range_to(form)? // `..=X`, `...X`, or `..X`. + } else if self.eat(&token::Not) { + // Parse `!` + self.sess.gated_spans.gate(sym::never_patterns, self.prev_token.span); + PatKind::Never } else if self.eat_keyword(kw::Underscore) { - // Parse _ + // Parse `_` PatKind::Wild } else if self.eat_keyword(kw::Mut) { self.parse_pat_ident_mut(syntax_loc)? diff --git a/compiler/rustc_passes/src/hir_stats.rs b/compiler/rustc_passes/src/hir_stats.rs index f915c1057d6..28354ab0986 100644 --- a/compiler/rustc_passes/src/hir_stats.rs +++ b/compiler/rustc_passes/src/hir_stats.rs @@ -286,7 +286,21 @@ impl<'v> hir_visit::Visitor<'v> for StatCollector<'v> { fn visit_pat(&mut self, p: &'v hir::Pat<'v>) { record_variants!( (self, p, p.kind, Id::Node(p.hir_id), hir, Pat, PatKind), - [Wild, Binding, Struct, TupleStruct, Or, Path, Tuple, Box, Ref, Lit, Range, Slice] + [ + Wild, + Binding, + Struct, + TupleStruct, + Or, + Never, + Path, + Tuple, + Box, + Ref, + Lit, + Range, + Slice + ] ); hir_visit::walk_pat(self, p) } @@ -554,6 +568,7 @@ impl<'v> ast_visit::Visitor<'v> for StatCollector<'v> { Range, Slice, Rest, + Never, Paren, MacCall ] diff --git a/compiler/rustc_span/src/symbol.rs b/compiler/rustc_span/src/symbol.rs index 40b03874242..9a2fe01229d 100644 --- a/compiler/rustc_span/src/symbol.rs +++ b/compiler/rustc_span/src/symbol.rs @@ -1097,6 +1097,7 @@ symbols! { negative_impls, neon, never, + never_patterns, never_type, never_type_fallback, new, |