Rollup merge of #47947 - goodmanjonathan:stabilize_match_beginning_vert, r=petrochenkov

Stabilize feature(match_beginning_vert)

With this feature stabilized, match expressions can optionally have a `|` at the beginning of each arm.

Reference PR: rust-lang-nursery/reference#231

Closes #44101

9 files changed, 32 insertions, 103 deletions

diff --git a/src/doc/unstable-book/src/language-features/match-beginning-vert.md b/src/doc/unstable-book/src/language-features/match-beginning-vert.md
deleted file mode 100644
index f0a51af7fd1..00000000000
--- a/src/doc/unstable-book/src/language-features/match-beginning-vert.md
+++ /dev/null
@@ -1,23 +0,0 @@
-# `match_beginning_vert`
-
-The tracking issue for this feature is [#44101].
-
-With this feature enabled, you are allowed to add a '|' to the beginning of a
-match arm:
-
-```rust
-#![feature(match_beginning_vert)]
-
-enum Foo { A, B, C }
-
-fn main() {
-    let x = Foo::A;
-    match x {
-        | Foo::A 
-        | Foo::B => println!("AB"),
-        | Foo::C => println!("C"),
-    }
-}
-```
-
-[#44101]: https://github.com/rust-lang/rust/issues/44101
\ No newline at end of file
diff --git a/src/libsyntax/ast.rs b/src/libsyntax/ast.rs
index 73810b3fe81..c7ab6158256 100644
--- a/src/libsyntax/ast.rs
+++ b/src/libsyntax/ast.rs
@@ -883,7 +883,6 @@ pub struct Arm {
     pub pats: Vec<P<Pat>>,
     pub guard: Option<P<Expr>>,
     pub body: P<Expr>,
-    pub beginning_vert: Option<Span>, // For RFC 1925 feature gate
 }
 
 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
diff --git a/src/libsyntax/ext/build.rs b/src/libsyntax/ext/build.rs
index cf63592c2ec..2e6de96d65a 100644
--- a/src/libsyntax/ext/build.rs
+++ b/src/libsyntax/ext/build.rs
@@ -883,7 +883,6 @@ impl<'a> AstBuilder for ExtCtxt<'a> {
             pats,
             guard: None,
             body: expr,
-            beginning_vert: None,
         }
     }
 
diff --git a/src/libsyntax/feature_gate.rs b/src/libsyntax/feature_gate.rs
index 3e523fca92a..3e858c3b923 100644
--- a/src/libsyntax/feature_gate.rs
+++ b/src/libsyntax/feature_gate.rs
@@ -386,9 +386,6 @@ declare_features! (
     // allow `#[must_use]` on functions and comparison operators (RFC 1940)
     (active, fn_must_use, "1.21.0", Some(43302)),
 
-    // allow '|' at beginning of match arms (RFC 1925)
-    (active, match_beginning_vert, "1.21.0", Some(44101)),
-
     // Future-proofing enums/structs with #[non_exhaustive] attribute (RFC 2008)
     (active, non_exhaustive, "1.22.0", Some(44109)),
 
@@ -545,6 +542,8 @@ declare_features! (
     (accepted, abi_sysv64, "1.24.0", Some(36167)),
     // Allows `repr(align(16))` struct attribute (RFC 1358)
     (accepted, repr_align, "1.24.0", Some(33626)),
+    // allow '|' at beginning of match arms (RFC 1925)
+    (accepted, match_beginning_vert, "1.25.0", Some(44101)),
 );
 
 // If you change this, please modify src/doc/unstable-book as well. You must
@@ -1683,11 +1682,6 @@ impl<'a> Visitor<'a> for PostExpansionVisitor<'a> {
     }
 
     fn visit_arm(&mut self, arm: &'a ast::Arm) {
-        if let Some(span) = arm.beginning_vert {
-            gate_feature_post!(&self, match_beginning_vert,
-                               span,
-                               "Use of a '|' at the beginning of a match arm is experimental")
-        }
         visit::walk_arm(self, arm)
     }
 
diff --git a/src/libsyntax/fold.rs b/src/libsyntax/fold.rs
index 0f8fe57e380..921ed3565a4 100644
--- a/src/libsyntax/fold.rs
+++ b/src/libsyntax/fold.rs
@@ -340,14 +340,13 @@ pub fn fold_thin_attrs<T: Folder>(attrs: ThinVec<Attribute>, fld: &mut T) -> Thi
     fold_attrs(attrs.into(), fld).into()
 }
 
-pub fn noop_fold_arm<T: Folder>(Arm {attrs, pats, guard, body, beginning_vert}: Arm,
+pub fn noop_fold_arm<T: Folder>(Arm {attrs, pats, guard, body}: Arm,
     fld: &mut T) -> Arm {
     Arm {
         attrs: fold_attrs(attrs, fld),
         pats: pats.move_map(|x| fld.fold_pat(x)),
         guard: guard.map(|x| fld.fold_expr(x)),
         body: fld.fold_expr(body),
-        beginning_vert,
     }
 }
 
diff --git a/src/libsyntax/parse/parser.rs b/src/libsyntax/parse/parser.rs
index b3c485a85c0..764b3d0a848 100644
--- a/src/libsyntax/parse/parser.rs
+++ b/src/libsyntax/parse/parser.rs
@@ -3398,11 +3398,7 @@ impl<'a> Parser<'a> {
 
         let attrs = self.parse_outer_attributes()?;
         // Allow a '|' before the pats (RFC 1925)
-        let beginning_vert = if self.eat(&token::BinOp(token::Or)) {
-            Some(self.prev_span)
-        } else {
-            None
-        };
+        self.eat(&token::BinOp(token::Or));
         let pats = self.parse_pats()?;
         let guard = if self.eat_keyword(keywords::If) {
             Some(self.parse_expr()?)
@@ -3426,7 +3422,6 @@ impl<'a> Parser<'a> {
             pats,
             guard,
             body: expr,
-            beginning_vert,
         })
     }
 
diff --git a/src/test/run-pass/match-beginning-vert.rs b/src/test/run-pass/match-beginning-vert.rs
new file mode 100644
index 00000000000..cdacfb2f057
--- /dev/null
+++ b/src/test/run-pass/match-beginning-vert.rs
@@ -0,0 +1,28 @@
+// Copyright 2018 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+enum Foo {
+    A,
+    B,
+    C,
+    D,
+    E,
+}
+use Foo::*;
+
+fn main() {
+    for foo in &[A, B, C, D, E] {
+        match *foo {
+            | A => println!("A"),
+            | B | C if 1 < 2 => println!("BC!"),
+            | _ => {},
+        }
+    }
+}
diff --git a/src/test/ui/feature-gate-match_beginning_vert.rs b/src/test/ui/feature-gate-match_beginning_vert.rs
deleted file mode 100644
index 9085563c99d..00000000000
--- a/src/test/ui/feature-gate-match_beginning_vert.rs
+++ /dev/null
@@ -1,36 +0,0 @@
-// Copyright 2017 The Rust Project Developers. See the COPYRIGHT
-// file at the top-level directory of this distribution and at
-// http://rust-lang.org/COPYRIGHT.
-//
-// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
-// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
-// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
-// option. This file may not be copied, modified, or distributed
-// except according to those terms.
-
-#[allow(dead_code)]
-enum Foo {
-    A,
-    B,
-    C,
-    D,
-    E,
-}
-use Foo::*;
-
-fn main() {
-    let x = Foo::A;
-    match x {
-        | A => println!("A"),
-        //~^ ERROR: Use of a '|' at the beginning of a match arm is experimental (see issue #44101)
-        | B | C => println!("BC!"),
-        //~^ ERROR: Use of a '|' at the beginning of a match arm is experimental (see issue #44101)
-        | _ => {},
-        //~^ ERROR: Use of a '|' at the beginning of a match arm is experimental (see issue #44101)
-    };
-    match x {
-        A | B | C => println!("ABC!"),
-        _ => {},
-    };
-}
-
diff --git a/src/test/ui/feature-gate-match_beginning_vert.stderr b/src/test/ui/feature-gate-match_beginning_vert.stderr
deleted file mode 100644
index 1d45dedb497..00000000000
--- a/src/test/ui/feature-gate-match_beginning_vert.stderr
+++ /dev/null
@@ -1,26 +0,0 @@
-error[E0658]: Use of a '|' at the beginning of a match arm is experimental (see issue #44101)
-  --> $DIR/feature-gate-match_beginning_vert.rs:24:9
-   |
-24 |         | A => println!("A"),
-   |         ^
-   |
-   = help: add #![feature(match_beginning_vert)] to the crate attributes to enable
-
-error[E0658]: Use of a '|' at the beginning of a match arm is experimental (see issue #44101)
-  --> $DIR/feature-gate-match_beginning_vert.rs:26:9
-   |
-26 |         | B | C => println!("BC!"),
-   |         ^
-   |
-   = help: add #![feature(match_beginning_vert)] to the crate attributes to enable
-
-error[E0658]: Use of a '|' at the beginning of a match arm is experimental (see issue #44101)
-  --> $DIR/feature-gate-match_beginning_vert.rs:28:9
-   |
-28 |         | _ => {},
-   |         ^
-   |
-   = help: add #![feature(match_beginning_vert)] to the crate attributes to enable
-
-error: aborting due to 3 previous errors
-