Auto merge of rust-lang#85305 - MarcusDunn:master, r=pnkfelix

Stabilize bindings_after_at

attempting to stabilze bindings_after_at [rust-lang#65490](rust-lang#65490), im pretty new to the whole thing so any pointers are greatly appreciated.

Author: bors

compiler/rustc_ast_passes/src/lib.rs

@@ -4,7 +4,7 @@
 //!
 //! The crate also contains other misc AST visitors, e.g. `node_count` and `show_span`.
 
-#![feature(bindings_after_at)]
+#![cfg_attr(bootstrap, feature(bindings_after_at))]
 #![feature(iter_is_partitioned)]
 #![feature(box_patterns)]
 #![recursion_limit = "256"]

compiler/rustc_feature/src/accepted.rs

@@ -287,6 +287,9 @@ declare_features! (
     (accepted, const_fn_unsize, "1.54.0", Some(64992), None),
     /// Allows `impl Trait` with multiple unrelated lifetimes.
     (accepted, member_constraints, "1.54.0", Some(61997), None),
+    /// Allows bindings in the subpattern of a binding pattern.
+    /// For example, you can write `x @ Some(y)`.
+    (accepted, bindings_after_at, "1.54.0", Some(65490), None),
 
     // -------------------------------------------------------------------------
     // feature-group-end: accepted features

compiler/rustc_feature/src/active.rs

@@ -526,10 +526,6 @@ declare_features! (
     /// Allows using `&mut` in constant functions.
     (active, const_mut_refs, "1.41.0", Some(57349), None),
 
-    /// Allows bindings in the subpattern of a binding pattern.
-    /// For example, you can write `x @ Some(y)`.
-    (active, bindings_after_at, "1.41.0", Some(65490), None),
-
     /// Allows `impl const Trait for T` syntax.
     (active, const_trait_impl, "1.42.0", Some(67792), None),
 

compiler/rustc_mir/src/lib.rs

@@ -8,7 +8,7 @@ Rust MIR: a lowered representation of Rust.
 #![feature(in_band_lifetimes)]
 #![feature(array_windows)]
 #![feature(assert_matches)]
-#![feature(bindings_after_at)]
+#![cfg_attr(bootstrap, feature(bindings_after_at))]
 #![feature(bool_to_option)]
 #![feature(box_patterns)]
 #![feature(box_syntax)]

compiler/rustc_mir_build/src/thir/pattern/check_match.rs

@@ -16,9 +16,8 @@ use rustc_middle::thir::PatKind;
 use rustc_middle::ty::{self, Ty, TyCtxt};
 use rustc_session::lint::builtin::BINDINGS_WITH_VARIANT_NAME;
 use rustc_session::lint::builtin::{IRREFUTABLE_LET_PATTERNS, UNREACHABLE_PATTERNS};
-use rustc_session::parse::feature_err;
 use rustc_session::Session;
-use rustc_span::{sym, Span};
+use rustc_span::Span;
 use std::slice;
 
 crate fn check_match(tcx: TyCtxt<'_>, def_id: DefId) {
@@ -115,9 +114,6 @@ impl PatCtxt<'_, '_> {
 impl<'tcx> MatchVisitor<'_, 'tcx> {
     fn check_patterns(&mut self, pat: &Pat<'_>) {
         pat.walk_always(|pat| check_borrow_conflicts_in_at_patterns(self, pat));
-        if !self.tcx.features().bindings_after_at {
-            check_legality_of_bindings_in_at_patterns(self, pat);
-        }
         check_for_bindings_named_same_as_variants(self, pat);
     }
 
@@ -732,46 +728,3 @@ fn check_borrow_conflicts_in_at_patterns(cx: &MatchVisitor<'_, '_>, pat: &Pat<'_
         err.emit();
     }
 }
-
-/// Forbids bindings in `@` patterns. This used to be is necessary for memory safety,
-/// because of the way rvalues were handled in the borrow check. (See issue #14587.)
-fn check_legality_of_bindings_in_at_patterns(cx: &MatchVisitor<'_, '_>, pat: &Pat<'_>) {
-    AtBindingPatternVisitor { cx, bindings_allowed: true }.visit_pat(pat);
-
-    struct AtBindingPatternVisitor<'a, 'b, 'tcx> {
-        cx: &'a MatchVisitor<'b, 'tcx>,
-        bindings_allowed: bool,
-    }
-
-    impl<'v> Visitor<'v> for AtBindingPatternVisitor<'_, '_, '_> {
-        type Map = intravisit::ErasedMap<'v>;
-
-        fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
-            NestedVisitorMap::None
-        }
-
-        fn visit_pat(&mut self, pat: &Pat<'_>) {
-            match pat.kind {
-                hir::PatKind::Binding(.., ref subpat) => {
-                    if !self.bindings_allowed {
-                        feature_err(
-                            &self.cx.tcx.sess.parse_sess,
-                            sym::bindings_after_at,
-                            pat.span,
-                            "pattern bindings after an `@` are unstable",
-                        )
-                        .emit();
-                    }
-
-                    if subpat.is_some() {
-                        let bindings_were_allowed = self.bindings_allowed;
-                        self.bindings_allowed = false;
-                        intravisit::walk_pat(self, pat);
-                        self.bindings_allowed = bindings_were_allowed;
-                    }
-                }
-                _ => intravisit::walk_pat(self, pat),
-            }
-        }
-    }
-}

compiler/rustc_parse/src/lib.rs

@@ -2,7 +2,7 @@
 
 #![feature(array_windows)]
 #![feature(crate_visibility_modifier)]
-#![feature(bindings_after_at)]
+#![cfg_attr(bootstrap, feature(bindings_after_at))]
 #![feature(box_syntax)]
 #![feature(box_patterns)]
 #![recursion_limit = "256"]

compiler/rustc_typeck/src/lib.rs

@@ -56,7 +56,7 @@ This API is completely unstable and subject to change.
 */
 
 #![doc(html_root_url = "https://doc.rust-lang.org/nightly/nightly-rustc/")]
-#![feature(bindings_after_at)]
+#![cfg_attr(bootstrap, feature(bindings_after_at))]
 #![feature(bool_to_option)]
 #![feature(box_syntax)]
 #![feature(crate_visibility_modifier)]

library/alloc/src/lib.rs

@@ -85,6 +85,7 @@
 #![feature(allow_internal_unstable)]
 #![feature(arbitrary_self_types)]
 #![feature(async_stream)]
+#![cfg_attr(bootstrap, feature(bindings_after_at))]
 #![feature(box_patterns)]
 #![feature(box_syntax)]
 #![feature(cfg_sanitize)]
@@ -145,7 +146,6 @@
 #![feature(associated_type_bounds)]
 #![feature(slice_group_by)]
 #![feature(decl_macro)]
-#![feature(bindings_after_at)]
 // Allow testing this library
 
 #[cfg(test)]

src/etc/pre-commit.sh

@@ -1,5 +1,4 @@
 // Tests using a combination of pattern features has the expected borrow checking behavior
-#![feature(bindings_after_at)]
 #![feature(box_patterns)]
 
 enum Test {