Rollup merge of #81869 - mark-i-m:leading-vert, r=petrochenkov

Simplify pattern grammar, improve or-pattern diagnostics

This implements the change under FCP in https://github.com/rust-lang/rust/issues/81415. It allows nested or-patterns to contain a leading `|`, simplifying the [grammar for patterns](https://github.com/rust-lang/reference/pull/957/files?short_path=cc629f1#diff-cc629f15712821139bc706c63b3845ab59a008e2a998e08ffad42e3aebcbcbe2).

Along the way, we also improve the diagnostics around a few specially-handled cases, such as using `||` instead of `|`, using or-patterns in fn params, including the leading `|` in the pattern span, etc.

r? `@petrochenkov`

11 files changed, 73 insertions, 211 deletions

diff --git a/src/test/ui/or-patterns/feature-gate-or_patterns.stderr b/src/test/ui/or-patterns/feature-gate-or_patterns.stderr
index a9e43a4575d..c01d17c0b3d 100644
--- a/src/test/ui/or-patterns/feature-gate-or_patterns.stderr
+++ b/src/test/ui/or-patterns/feature-gate-or_patterns.stderr
@@ -8,10 +8,10 @@ LL |         Some(0 | 1 | 2) => {}
    = help: add `#![feature(or_patterns)]` to the crate attributes to enable
 
 error[E0658]: or-patterns syntax is experimental
-  --> $DIR/feature-gate-or_patterns.rs:28:11
+  --> $DIR/feature-gate-or_patterns.rs:28:9
    |
 LL |     let | A | B;
-   |           ^^^^^
+   |         ^^^^^^^
    |
    = note: see issue #54883 <https://github.com/rust-lang/rust/issues/54883> for more information
    = help: add `#![feature(or_patterns)]` to the crate attributes to enable
@@ -26,10 +26,10 @@ LL |     let A | B;
    = help: add `#![feature(or_patterns)]` to the crate attributes to enable
 
 error[E0658]: or-patterns syntax is experimental
-  --> $DIR/feature-gate-or_patterns.rs:30:11
+  --> $DIR/feature-gate-or_patterns.rs:30:9
    |
 LL |     for | A | B in 0 {}
-   |           ^^^^^
+   |         ^^^^^^^
    |
    = note: see issue #54883 <https://github.com/rust-lang/rust/issues/54883> for more information
    = help: add `#![feature(or_patterns)]` to the crate attributes to enable
diff --git a/src/test/ui/or-patterns/fn-param-wrap-parens.fixed b/src/test/ui/or-patterns/fn-param-wrap-parens.fixed
index 08730fe8b07..bbc75d2b411 100644
--- a/src/test/ui/or-patterns/fn-param-wrap-parens.fixed
+++ b/src/test/ui/or-patterns/fn-param-wrap-parens.fixed
@@ -11,4 +11,4 @@ enum E { A, B }
 use E::*;
 
 #[cfg(FALSE)]
-fn fun1((A | B): E) {} //~ ERROR an or-pattern parameter must be wrapped in parenthesis
+fn fun1((A | B): E) {} //~ ERROR an or-pattern parameter must be wrapped in parentheses
diff --git a/src/test/ui/or-patterns/fn-param-wrap-parens.rs b/src/test/ui/or-patterns/fn-param-wrap-parens.rs
index ed667e0e660..65b93dcbf74 100644
--- a/src/test/ui/or-patterns/fn-param-wrap-parens.rs
+++ b/src/test/ui/or-patterns/fn-param-wrap-parens.rs
@@ -11,4 +11,4 @@ enum E { A, B }
 use E::*;
 
 #[cfg(FALSE)]
-fn fun1(A | B: E) {} //~ ERROR an or-pattern parameter must be wrapped in parenthesis
+fn fun1(A | B: E) {} //~ ERROR an or-pattern parameter must be wrapped in parentheses
diff --git a/src/test/ui/or-patterns/fn-param-wrap-parens.stderr b/src/test/ui/or-patterns/fn-param-wrap-parens.stderr
index 2c6e4d9838d..0e6424a4300 100644
--- a/src/test/ui/or-patterns/fn-param-wrap-parens.stderr
+++ b/src/test/ui/or-patterns/fn-param-wrap-parens.stderr
@@ -1,8 +1,8 @@
-error: an or-pattern parameter must be wrapped in parenthesis
+error: an or-pattern parameter must be wrapped in parentheses
   --> $DIR/fn-param-wrap-parens.rs:14:9
    |
 LL | fn fun1(A | B: E) {}
-   |         ^^^^^ help: wrap the pattern in parenthesis: `(A | B)`
+   |         ^^^^^ help: wrap the pattern in parentheses: `(A | B)`
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/or-patterns/multiple-pattern-typo.rs b/src/test/ui/or-patterns/multiple-pattern-typo.rs
index 702c9573741..4d06101044f 100644
--- a/src/test/ui/or-patterns/multiple-pattern-typo.rs
+++ b/src/test/ui/or-patterns/multiple-pattern-typo.rs
@@ -4,41 +4,41 @@ fn main() {
     let x = 3;
 
     match x {
-        1 | 2 || 3 => (), //~ ERROR unexpected token `||` after pattern
+        1 | 2 || 3 => (), //~ ERROR unexpected token `||` in pattern
         _ => (),
     }
 
     match x {
-        (1 | 2 || 3) => (), //~ ERROR unexpected token `||` after pattern
+        (1 | 2 || 3) => (), //~ ERROR unexpected token `||` in pattern
         _ => (),
     }
 
     match (x,) {
-        (1 | 2 || 3,) => (), //~ ERROR unexpected token `||` after pattern
+        (1 | 2 || 3,) => (), //~ ERROR unexpected token `||` in pattern
         _ => (),
     }
 
     struct TS(u8);
 
     match TS(x) {
-        TS(1 | 2 || 3) => (), //~ ERROR unexpected token `||` after pattern
+        TS(1 | 2 || 3) => (), //~ ERROR unexpected token `||` in pattern
         _ => (),
     }
 
     struct NS { f: u8 }
 
     match (NS { f: x }) {
-        NS { f: 1 | 2 || 3 } => (), //~ ERROR unexpected token `||` after pattern
+        NS { f: 1 | 2 || 3 } => (), //~ ERROR unexpected token `||` in pattern
         _ => (),
     }
 
     match [x] {
-        [1 | 2 || 3] => (), //~ ERROR unexpected token `||` after pattern
+        [1 | 2 || 3] => (), //~ ERROR unexpected token `||` in pattern
         _ => (),
     }
 
     match x {
-        || 1 | 2 | 3 => (), //~ ERROR unexpected token `||` after pattern
+        || 1 | 2 | 3 => (), //~ ERROR unexpected token `||` in pattern
         _ => (),
     }
 }
diff --git a/src/test/ui/or-patterns/multiple-pattern-typo.stderr b/src/test/ui/or-patterns/multiple-pattern-typo.stderr
index cb32068ec0d..b0a82b3673b 100644
--- a/src/test/ui/or-patterns/multiple-pattern-typo.stderr
+++ b/src/test/ui/or-patterns/multiple-pattern-typo.stderr
@@ -1,4 +1,4 @@
-error: unexpected token `||` after pattern
+error: unexpected token `||` in pattern
   --> $DIR/multiple-pattern-typo.rs:7:15
    |
 LL |         1 | 2 || 3 => (),
@@ -6,7 +6,7 @@ LL |         1 | 2 || 3 => (),
    |         |
    |         while parsing this or-pattern starting here
 
-error: unexpected token `||` after pattern
+error: unexpected token `||` in pattern
   --> $DIR/multiple-pattern-typo.rs:12:16
    |
 LL |         (1 | 2 || 3) => (),
@@ -14,7 +14,7 @@ LL |         (1 | 2 || 3) => (),
    |          |
    |          while parsing this or-pattern starting here
 
-error: unexpected token `||` after pattern
+error: unexpected token `||` in pattern
   --> $DIR/multiple-pattern-typo.rs:17:16
    |
 LL |         (1 | 2 || 3,) => (),
@@ -22,7 +22,7 @@ LL |         (1 | 2 || 3,) => (),
    |          |
    |          while parsing this or-pattern starting here
 
-error: unexpected token `||` after pattern
+error: unexpected token `||` in pattern
   --> $DIR/multiple-pattern-typo.rs:24:18
    |
 LL |         TS(1 | 2 || 3) => (),
@@ -30,7 +30,7 @@ LL |         TS(1 | 2 || 3) => (),
    |            |
    |            while parsing this or-pattern starting here
 
-error: unexpected token `||` after pattern
+error: unexpected token `||` in pattern
   --> $DIR/multiple-pattern-typo.rs:31:23
    |
 LL |         NS { f: 1 | 2 || 3 } => (),
@@ -38,7 +38,7 @@ LL |         NS { f: 1 | 2 || 3 } => (),
    |                 |
    |                 while parsing this or-pattern starting here
 
-error: unexpected token `||` after pattern
+error: unexpected token `||` in pattern
   --> $DIR/multiple-pattern-typo.rs:36:16
    |
 LL |         [1 | 2 || 3] => (),
@@ -46,7 +46,7 @@ LL |         [1 | 2 || 3] => (),
    |          |
    |          while parsing this or-pattern starting here
 
-error: unexpected token `||` after pattern
+error: unexpected token `||` in pattern
   --> $DIR/multiple-pattern-typo.rs:41:9
    |
 LL |         || 1 | 2 | 3 => (),
diff --git a/src/test/ui/or-patterns/or-patterns-syntactic-fail.rs b/src/test/ui/or-patterns/or-patterns-syntactic-fail.rs
index efe90b3e3c6..cbc24eb26fa 100644
--- a/src/test/ui/or-patterns/or-patterns-syntactic-fail.rs
+++ b/src/test/ui/or-patterns/or-patterns-syntactic-fail.rs
@@ -14,29 +14,8 @@ fn no_top_level_or_patterns() {
     //           -------- This looks like an or-pattern but is in fact `|A| (B: E | ())`.
 
     // ...and for now neither do we allow or-patterns at the top level of functions.
-    fn fun1(A | B: E) {} //~ ERROR an or-pattern parameter must be wrapped in parenthesis
+    fn fun1(A | B: E) {} //~ ERROR an or-pattern parameter must be wrapped in parentheses
 
     fn fun2(| A | B: E) {}
-    //~^ ERROR a leading `|` is not allowed in a parameter pattern
-    //~| ERROR an or-pattern parameter must be wrapped in parenthesis
-}
-
-// We also do not allow a leading `|` when not in a top level position:
-
-fn no_leading_inner() {
-    struct TS(E);
-    struct NS { f: E }
-
-    let ( | A | B) = E::A; //~ ERROR a leading `|` is only allowed in a top-level pattern
-    let ( | A | B,) = (E::B,); //~ ERROR a leading `|` is only allowed in a top-level pattern
-    let [ | A | B ] = [E::A]; //~ ERROR a leading `|` is only allowed in a top-level pattern
-    let TS( | A | B ); //~ ERROR a leading `|` is only allowed in a top-level pattern
-    let NS { f: | A | B }; //~ ERROR a leading `|` is only allowed in a top-level pattern
-
-    let ( || A | B) = E::A; //~ ERROR a leading `|` is only allowed in a top-level pattern
-    let [ || A | B ] = [E::A]; //~ ERROR a leading `|` is only allowed in a top-level pattern
-    let TS( || A | B ); //~ ERROR a leading `|` is only allowed in a top-level pattern
-    let NS { f: || A | B }; //~ ERROR a leading `|` is only allowed in a top-level pattern
-
-    let recovery_witness: String = 0; //~ ERROR mismatched types
+    //~^ ERROR an or-pattern parameter must be wrapped in parentheses
 }
diff --git a/src/test/ui/or-patterns/or-patterns-syntactic-fail.stderr b/src/test/ui/or-patterns/or-patterns-syntactic-fail.stderr
index 989aeb52006..db4d827757b 100644
--- a/src/test/ui/or-patterns/or-patterns-syntactic-fail.stderr
+++ b/src/test/ui/or-patterns/or-patterns-syntactic-fail.stderr
@@ -1,82 +1,14 @@
-error: an or-pattern parameter must be wrapped in parenthesis
+error: an or-pattern parameter must be wrapped in parentheses
   --> $DIR/or-patterns-syntactic-fail.rs:17:13
    |
 LL |     fn fun1(A | B: E) {}
-   |             ^^^^^ help: wrap the pattern in parenthesis: `(A | B)`
+   |             ^^^^^ help: wrap the pattern in parentheses: `(A | B)`
 
-error: a leading `|` is not allowed in a parameter pattern
+error: an or-pattern parameter must be wrapped in parentheses
   --> $DIR/or-patterns-syntactic-fail.rs:19:13
    |
 LL |     fn fun2(| A | B: E) {}
-   |             ^ help: remove the `|`
-
-error: an or-pattern parameter must be wrapped in parenthesis
-  --> $DIR/or-patterns-syntactic-fail.rs:19:15
-   |
-LL |     fn fun2(| A | B: E) {}
-   |               ^^^^^ help: wrap the pattern in parenthesis: `(A | B)`
-
-error: a leading `|` is only allowed in a top-level pattern
-  --> $DIR/or-patterns-syntactic-fail.rs:30:11
-   |
-LL |     let ( | A | B) = E::A;
-   |           ^ help: remove the `|`
-
-error: a leading `|` is only allowed in a top-level pattern
-  --> $DIR/or-patterns-syntactic-fail.rs:31:11
-   |
-LL |     let ( | A | B,) = (E::B,);
-   |           ^ help: remove the `|`
-
-error: a leading `|` is only allowed in a top-level pattern
-  --> $DIR/or-patterns-syntactic-fail.rs:32:11
-   |
-LL |     let [ | A | B ] = [E::A];
-   |           ^ help: remove the `|`
-
-error: a leading `|` is only allowed in a top-level pattern
-  --> $DIR/or-patterns-syntactic-fail.rs:33:13
-   |
-LL |     let TS( | A | B );
-   |             ^ help: remove the `|`
-
-error: a leading `|` is only allowed in a top-level pattern
-  --> $DIR/or-patterns-syntactic-fail.rs:34:17
-   |
-LL |     let NS { f: | A | B };
-   |                 ^ help: remove the `|`
-
-error: a leading `|` is only allowed in a top-level pattern
-  --> $DIR/or-patterns-syntactic-fail.rs:36:11
-   |
-LL |     let ( || A | B) = E::A;
-   |           ^^ help: remove the `||`
-   |
-   = note: alternatives in or-patterns are separated with `|`, not `||`
-
-error: a leading `|` is only allowed in a top-level pattern
-  --> $DIR/or-patterns-syntactic-fail.rs:37:11
-   |
-LL |     let [ || A | B ] = [E::A];
-   |           ^^ help: remove the `||`
-   |
-   = note: alternatives in or-patterns are separated with `|`, not `||`
-
-error: a leading `|` is only allowed in a top-level pattern
-  --> $DIR/or-patterns-syntactic-fail.rs:38:13
-   |
-LL |     let TS( || A | B );
-   |             ^^ help: remove the `||`
-   |
-   = note: alternatives in or-patterns are separated with `|`, not `||`
-
-error: a leading `|` is only allowed in a top-level pattern
-  --> $DIR/or-patterns-syntactic-fail.rs:39:17
-   |
-LL |     let NS { f: || A | B };
-   |                 ^^ help: remove the `||`
-   |
-   = note: alternatives in or-patterns are separated with `|`, not `||`
+   |             ^^^^^^^ help: wrap the pattern in parentheses: `(A | B)`
 
 error[E0369]: no implementation for `E | ()`
   --> $DIR/or-patterns-syntactic-fail.rs:13:22
@@ -88,17 +20,6 @@ LL |     let _ = |A | B: E| ();
    |
    = note: an implementation of `std::ops::BitOr` might be missing for `E`
 
-error[E0308]: mismatched types
-  --> $DIR/or-patterns-syntactic-fail.rs:41:36
-   |
-LL |     let recovery_witness: String = 0;
-   |                           ------   ^
-   |                           |        |
-   |                           |        expected struct `String`, found integer
-   |                           |        help: try using a conversion method: `0.to_string()`
-   |                           expected due to this
-
-error: aborting due to 14 previous errors
+error: aborting due to 3 previous errors
 
-Some errors have detailed explanations: E0308, E0369.
-For more information about an error, try `rustc --explain E0308`.
+For more information about this error, try `rustc --explain E0369`.
diff --git a/src/test/ui/or-patterns/remove-leading-vert.fixed b/src/test/ui/or-patterns/remove-leading-vert.fixed
index 443ef398293..c8fac4faa2a 100644
--- a/src/test/ui/or-patterns/remove-leading-vert.fixed
+++ b/src/test/ui/or-patterns/remove-leading-vert.fixed
@@ -9,17 +9,17 @@ fn main() {}
 
 #[cfg(FALSE)]
 fn leading() {
-    fn fun1(  A: E) {} //~ ERROR a leading `|` is not allowed in a parameter pattern
-    fn fun2(  A: E) {} //~ ERROR a leading `|` is not allowed in a parameter pattern
-    let (  A): E; //~ ERROR a leading `|` is only allowed in a top-level pattern
-    let (  A): (E); //~ ERROR a leading `|` is only allowed in a top-level pattern
-    let (  A,): (E,); //~ ERROR a leading `|` is only allowed in a top-level pattern
-    let [  A ]: [E; 1]; //~ ERROR a leading `|` is only allowed in a top-level pattern
-    let [  A ]: [E; 1]; //~ ERROR a leading `|` is only allowed in a top-level pattern
-    let TS(  A ): TS; //~ ERROR a leading `|` is only allowed in a top-level pattern
-    let TS(  A ): TS; //~ ERROR a leading `|` is only allowed in a top-level pattern
-    let NS { f:  A }: NS; //~ ERROR a leading `|` is only allowed in a top-level pattern
-    let NS { f:  A }: NS; //~ ERROR a leading `|` is only allowed in a top-level pattern
+    fn fun1( A: E) {} //~ ERROR an or-pattern parameter must be wrapped in parentheses
+    fn fun2(  A: E) {} //~ ERROR unexpected `||` before function parameter
+    let ( | A): E;
+    let ( | A): (E); //~ ERROR unexpected token `||` in pattern
+    let ( | A,): (E,);
+    let [ | A ]: [E; 1];
+    let [ | A ]: [E; 1]; //~ ERROR unexpected token `||` in pattern
+    let TS( | A ): TS;
+    let TS( | A ): TS; //~ ERROR unexpected token `||` in pattern
+    let NS { f: | A }: NS;
+    let NS { f: | A }: NS; //~ ERROR unexpected token `||` in pattern
 }
 
 #[cfg(FALSE)]
@@ -29,12 +29,12 @@ fn trailing() {
     let ( A | B  ): E; //~ ERROR a trailing `|` is not allowed in an or-pattern
     let [ A | B  ]: [E; 1]; //~ ERROR a trailing `|` is not allowed in an or-pattern
     let S { f: B  }; //~ ERROR a trailing `|` is not allowed in an or-pattern
-    let ( A | B  ): E; //~ ERROR unexpected token `||` after pattern
+    let ( A | B  ): E; //~ ERROR unexpected token `||` in pattern
     //~^ ERROR a trailing `|` is not allowed in an or-pattern
     match A {
         A  => {} //~ ERROR a trailing `|` is not allowed in an or-pattern
         A  => {} //~ ERROR a trailing `|` is not allowed in an or-pattern
-        A | B  => {} //~ ERROR unexpected token `||` after pattern
+        A | B  => {} //~ ERROR unexpected token `||` in pattern
         //~^ ERROR a trailing `|` is not allowed in an or-pattern
         | A | B  => {}
         //~^ ERROR a trailing `|` is not allowed in an or-pattern
diff --git a/src/test/ui/or-patterns/remove-leading-vert.rs b/src/test/ui/or-patterns/remove-leading-vert.rs
index 3c427a6f7b2..2cf6b27ab1a 100644
--- a/src/test/ui/or-patterns/remove-leading-vert.rs
+++ b/src/test/ui/or-patterns/remove-leading-vert.rs
@@ -9,17 +9,17 @@ fn main() {}
 
 #[cfg(FALSE)]
 fn leading() {
-    fn fun1( | A: E) {} //~ ERROR a leading `|` is not allowed in a parameter pattern
-    fn fun2( || A: E) {} //~ ERROR a leading `|` is not allowed in a parameter pattern
-    let ( | A): E; //~ ERROR a leading `|` is only allowed in a top-level pattern
-    let ( || A): (E); //~ ERROR a leading `|` is only allowed in a top-level pattern
-    let ( | A,): (E,); //~ ERROR a leading `|` is only allowed in a top-level pattern
-    let [ | A ]: [E; 1]; //~ ERROR a leading `|` is only allowed in a top-level pattern
-    let [ || A ]: [E; 1]; //~ ERROR a leading `|` is only allowed in a top-level pattern
-    let TS( | A ): TS; //~ ERROR a leading `|` is only allowed in a top-level pattern
-    let TS( || A ): TS; //~ ERROR a leading `|` is only allowed in a top-level pattern
-    let NS { f: | A }: NS; //~ ERROR a leading `|` is only allowed in a top-level pattern
-    let NS { f: || A }: NS; //~ ERROR a leading `|` is only allowed in a top-level pattern
+    fn fun1( | A: E) {} //~ ERROR an or-pattern parameter must be wrapped in parentheses
+    fn fun2( || A: E) {} //~ ERROR unexpected `||` before function parameter
+    let ( | A): E;
+    let ( || A): (E); //~ ERROR unexpected token `||` in pattern
+    let ( | A,): (E,);
+    let [ | A ]: [E; 1];
+    let [ || A ]: [E; 1]; //~ ERROR unexpected token `||` in pattern
+    let TS( | A ): TS;
+    let TS( || A ): TS; //~ ERROR unexpected token `||` in pattern
+    let NS { f: | A }: NS;
+    let NS { f: || A }: NS; //~ ERROR unexpected token `||` in pattern
 }
 
 #[cfg(FALSE)]
@@ -29,12 +29,12 @@ fn trailing() {
     let ( A | B | ): E; //~ ERROR a trailing `|` is not allowed in an or-pattern
     let [ A | B | ]: [E; 1]; //~ ERROR a trailing `|` is not allowed in an or-pattern
     let S { f: B | }; //~ ERROR a trailing `|` is not allowed in an or-pattern
-    let ( A || B | ): E; //~ ERROR unexpected token `||` after pattern
+    let ( A || B | ): E; //~ ERROR unexpected token `||` in pattern
     //~^ ERROR a trailing `|` is not allowed in an or-pattern
     match A {
         A | => {} //~ ERROR a trailing `|` is not allowed in an or-pattern
         A || => {} //~ ERROR a trailing `|` is not allowed in an or-pattern
-        A || B | => {} //~ ERROR unexpected token `||` after pattern
+        A || B | => {} //~ ERROR unexpected token `||` in pattern
         //~^ ERROR a trailing `|` is not allowed in an or-pattern
         | A | B | => {}
         //~^ ERROR a trailing `|` is not allowed in an or-pattern
diff --git a/src/test/ui/or-patterns/remove-leading-vert.stderr b/src/test/ui/or-patterns/remove-leading-vert.stderr
index 53025230a63..5c9efd44a18 100644
--- a/src/test/ui/or-patterns/remove-leading-vert.stderr
+++ b/src/test/ui/or-patterns/remove-leading-vert.stderr
@@ -1,10 +1,10 @@
-error: a leading `|` is not allowed in a parameter pattern
+error: an or-pattern parameter must be wrapped in parentheses
   --> $DIR/remove-leading-vert.rs:12:14
    |
 LL |     fn fun1( | A: E) {}
-   |              ^ help: remove the `|`
+   |              ^^^ help: remove the leading `|`: `A`
 
-error: a leading `|` is not allowed in a parameter pattern
+error: unexpected `||` before function parameter
   --> $DIR/remove-leading-vert.rs:13:14
    |
 LL |     fn fun2( || A: E) {}
@@ -12,67 +12,29 @@ LL |     fn fun2( || A: E) {}
    |
    = note: alternatives in or-patterns are separated with `|`, not `||`
 
-error: a leading `|` is only allowed in a top-level pattern
-  --> $DIR/remove-leading-vert.rs:14:11
-   |
-LL |     let ( | A): E;
-   |           ^ help: remove the `|`
-
-error: a leading `|` is only allowed in a top-level pattern
+error: unexpected token `||` in pattern
   --> $DIR/remove-leading-vert.rs:15:11
    |
 LL |     let ( || A): (E);
-   |           ^^ help: remove the `||`
-   |
-   = note: alternatives in or-patterns are separated with `|`, not `||`
-
-error: a leading `|` is only allowed in a top-level pattern
-  --> $DIR/remove-leading-vert.rs:16:11
-   |
-LL |     let ( | A,): (E,);
-   |           ^ help: remove the `|`
+   |           ^^ help: use a single `|` to separate multiple alternative patterns: `|`
 
-error: a leading `|` is only allowed in a top-level pattern
-  --> $DIR/remove-leading-vert.rs:17:11
-   |
-LL |     let [ | A ]: [E; 1];
-   |           ^ help: remove the `|`
-
-error: a leading `|` is only allowed in a top-level pattern
+error: unexpected token `||` in pattern
   --> $DIR/remove-leading-vert.rs:18:11
    |
 LL |     let [ || A ]: [E; 1];
-   |           ^^ help: remove the `||`
-   |
-   = note: alternatives in or-patterns are separated with `|`, not `||`
-
-error: a leading `|` is only allowed in a top-level pattern
-  --> $DIR/remove-leading-vert.rs:19:13
-   |
-LL |     let TS( | A ): TS;
-   |             ^ help: remove the `|`
+   |           ^^ help: use a single `|` to separate multiple alternative patterns: `|`
 
-error: a leading `|` is only allowed in a top-level pattern
+error: unexpected token `||` in pattern
   --> $DIR/remove-leading-vert.rs:20:13
    |
 LL |     let TS( || A ): TS;
-   |             ^^ help: remove the `||`
-   |
-   = note: alternatives in or-patterns are separated with `|`, not `||`
-
-error: a leading `|` is only allowed in a top-level pattern
-  --> $DIR/remove-leading-vert.rs:21:17
-   |
-LL |     let NS { f: | A }: NS;
-   |                 ^ help: remove the `|`
+   |             ^^ help: use a single `|` to separate multiple alternative patterns: `|`
 
-error: a leading `|` is only allowed in a top-level pattern
+error: unexpected token `||` in pattern
   --> $DIR/remove-leading-vert.rs:22:17
    |
 LL |     let NS { f: || A }: NS;
-   |                 ^^ help: remove the `||`
-   |
-   = note: alternatives in or-patterns are separated with `|`, not `||`
+   |                 ^^ help: use a single `|` to separate multiple alternative patterns: `|`
 
 error: a trailing `|` is not allowed in an or-pattern
   --> $DIR/remove-leading-vert.rs:27:13
@@ -114,7 +76,7 @@ LL |     let S { f: B | };
    |                |
    |                while parsing this or-pattern starting here
 
-error: unexpected token `||` after pattern
+error: unexpected token `||` in pattern
   --> $DIR/remove-leading-vert.rs:32:13
    |
 LL |     let ( A || B | ): E;
@@ -148,7 +110,7 @@ LL |         A || => {}
    |
    = note: alternatives in or-patterns are separated with `|`, not `||`
 
-error: unexpected token `||` after pattern
+error: unexpected token `||` in pattern
   --> $DIR/remove-leading-vert.rs:37:11
    |
 LL |         A || B | => {}
@@ -168,9 +130,9 @@ error: a trailing `|` is not allowed in an or-pattern
   --> $DIR/remove-leading-vert.rs:39:17
    |
 LL |         | A | B | => {}
-   |           -     ^ help: remove the `|`
-   |           |
-   |           while parsing this or-pattern starting here
+   |         -       ^ help: remove the `|`
+   |         |
+   |         while parsing this or-pattern starting here
 
 error: a trailing `|` is not allowed in an or-pattern
   --> $DIR/remove-leading-vert.rs:43:11
@@ -196,5 +158,5 @@ LL |     let a | ;
    |         |
    |         while parsing this or-pattern starting here
 
-error: aborting due to 26 previous errors
+error: aborting due to 21 previous errors