Auto merge of rust-lang#79278 - mark-i-m:stabilize-or-pattern, r=nikomatsakis

Stabilize or_patterns (RFC 2535, 2530, 2175)

closes rust-lang#54883

This PR stabilizes the or_patterns feature in Rust 1.53.

This is blocked on the following (in order):
- [x] The crater run in rust-lang#78935 (comment)
- [x] The resolution of the unresolved questions and a second crater run (rust-lang#78935 (comment))
    - It looks like we will need to pursue some sort of edition-based transition for `:pat`.
- [x] Nomination and discussion by T-lang
- [x] Implement new behavior for `:pat` based on consensus (rust-lang#80100).
- [ ] An FCP on stabilization

EDIT: Stabilization report is in rust-lang#79278 (comment)

Author: bors

compiler/rustc_apfloat/src/lib.rs

@@ -34,7 +34,7 @@
 #![no_std]
 #![forbid(unsafe_code)]
 #![feature(nll)]
-#![feature(or_patterns)]
+#![cfg_attr(bootstrap, feature(or_patterns))]
 
 #[macro_use]
 extern crate alloc;

compiler/rustc_ast/src/lib.rs

@@ -16,7 +16,7 @@
 #![feature(crate_visibility_modifier)]
 #![feature(label_break_value)]
 #![feature(nll)]
-#![feature(or_patterns)]
+#![cfg_attr(bootstrap, feature(or_patterns))]
 #![recursion_limit = "256"]
 
 #[macro_use]

compiler/rustc_ast_lowering/src/lib.rs

@@ -31,7 +31,7 @@
 //! in the HIR, especially for multiple identifiers.
 
 #![feature(crate_visibility_modifier)]
-#![feature(or_patterns)]
+#![cfg_attr(bootstrap, feature(or_patterns))]
 #![feature(box_patterns)]
 #![recursion_limit = "256"]
 

compiler/rustc_ast_passes/src/feature_gate.rs

@@ -686,7 +686,6 @@ pub fn check_crate(krate: &ast::Crate, sess: &Session) {
         "to use an async block, remove the `||`: `async {`"
     );
     gate_all!(generators, "yield syntax is experimental");
-    gate_all!(or_patterns, "or-patterns syntax is experimental");
     gate_all!(raw_ref_op, "raw address of syntax is experimental");
     gate_all!(const_trait_bound_opt_out, "`?const` on trait bounds is experimental");
     gate_all!(const_trait_impl, "const trait impls are experimental");

compiler/rustc_ast_pretty/src/lib.rs

@@ -1,6 +1,6 @@
 #![feature(bool_to_option)]
 #![feature(crate_visibility_modifier)]
-#![feature(or_patterns)]
+#![cfg_attr(bootstrap, feature(or_patterns))]
 #![feature(box_patterns)]
 #![recursion_limit = "256"]
 

compiler/rustc_attr/src/lib.rs

@@ -4,7 +4,7 @@
 //! The goal is to move the definition of `MetaItem` and things that don't need to be in `syntax`
 //! to this crate.
 
-#![feature(or_patterns)]
+#![cfg_attr(bootstrap, feature(or_patterns))]
 
 #[macro_use]
 extern crate rustc_macros;

compiler/rustc_builtin_macros/src/lib.rs

@@ -8,7 +8,7 @@
 #![feature(crate_visibility_modifier)]
 #![feature(decl_macro)]
 #![feature(nll)]
-#![feature(or_patterns)]
+#![cfg_attr(bootstrap, feature(or_patterns))]
 #![feature(proc_macro_internals)]
 #![feature(proc_macro_quote)]
 #![recursion_limit = "256"]

compiler/rustc_codegen_llvm/src/lib.rs

@@ -12,7 +12,7 @@
 #![feature(extern_types)]
 #![feature(in_band_lifetimes)]
 #![feature(nll)]
-#![feature(or_patterns)]
+#![cfg_attr(bootstrap, feature(or_patterns))]
 #![recursion_limit = "256"]
 
 use back::write::{create_informational_target_machine, create_target_machine};

compiler/rustc_codegen_ssa/src/lib.rs

@@ -6,7 +6,7 @@
 #![feature(try_blocks)]
 #![feature(in_band_lifetimes)]
 #![feature(nll)]
-#![feature(or_patterns)]
+#![cfg_attr(bootstrap, feature(or_patterns))]
 #![feature(associated_type_bounds)]
 #![recursion_limit = "256"]
 #![feature(box_syntax)]

compiler/rustc_expand/src/expand.rs

@@ -22,7 +22,7 @@ use rustc_data_structures::stack::ensure_sufficient_stack;
 use rustc_data_structures::sync::Lrc;
 use rustc_errors::{Applicability, PResult};
 use rustc_feature::Features;
-use rustc_parse::parser::{AttemptLocalParseRecovery, ForceCollect, GateOr, Parser, RecoverComma};
+use rustc_parse::parser::{AttemptLocalParseRecovery, ForceCollect, Parser, RecoverComma};
 use rustc_parse::validate_attr;
 use rustc_session::lint::builtin::UNUSED_DOC_COMMENTS;
 use rustc_session::lint::BuiltinLintDiagnostics;
@@ -917,7 +917,7 @@ pub fn parse_ast_fragment<'a>(
         }
         AstFragmentKind::Ty => AstFragment::Ty(this.parse_ty()?),
         AstFragmentKind::Pat => {
-            AstFragment::Pat(this.parse_pat_allow_top_alt(None, GateOr::Yes, RecoverComma::No)?)
+            AstFragment::Pat(this.parse_pat_allow_top_alt(None, RecoverComma::No)?)
         }
         AstFragmentKind::Arms
         | AstFragmentKind::Fields