On binding not present in all patterns, suggest potential typo

```
error[E0408]: variable `Ban` is not bound in all patterns
 --> f12.rs:9:9
  |
9 |         (Foo,Bar)|(Ban,Foo) => {}
  |         ^^^^^^^^^  --- variable not in all patterns
  |         |
  |         pattern doesn't bind `Ban`
  |
help: you might have meant to use the similarly named previously used binding `Bar`
  |
9 -         (Foo,Bar)|(Ban,Foo) => {}
9 +         (Foo,Bar)|(Bar,Foo) => {}
  |
```

7 files changed, 180 insertions, 19 deletions

diff --git a/tests/ui/or-patterns/mismatched-bindings-async-fn.stderr b/tests/ui/or-patterns/mismatched-bindings-async-fn.stderr
index 81602fffa8d..523cdf959e7 100644
--- a/tests/ui/or-patterns/mismatched-bindings-async-fn.stderr
+++ b/tests/ui/or-patterns/mismatched-bindings-async-fn.stderr
@@ -5,6 +5,12 @@ LL | async fn a((x | s): String) {}
    |             ^   - variable not in all patterns
    |             |
    |             pattern doesn't bind `s`
+   |
+help: you might have meant to use the similarly named previously used binding `x`
+   |
+LL - async fn a((x | s): String) {}
+LL + async fn a((x | x): String) {}
+   |
 
 error[E0408]: variable `x` is not bound in all patterns
   --> $DIR/mismatched-bindings-async-fn.rs:4:17
@@ -13,6 +19,12 @@ LL | async fn a((x | s): String) {}
    |             -   ^ pattern doesn't bind `x`
    |             |
    |             variable not in all patterns
+   |
+help: you might have meant to use the similarly named previously used binding `s`
+   |
+LL - async fn a((x | s): String) {}
+LL + async fn a((s | s): String) {}
+   |
 
 error[E0408]: variable `s` is not bound in all patterns
   --> $DIR/mismatched-bindings-async-fn.rs:9:10
@@ -21,6 +33,12 @@ LL |     let (x | s) = String::new();
    |          ^   - variable not in all patterns
    |          |
    |          pattern doesn't bind `s`
+   |
+help: you might have meant to use the similarly named previously used binding `x`
+   |
+LL -     let (x | s) = String::new();
+LL +     let (x | x) = String::new();
+   |
 
 error[E0408]: variable `x` is not bound in all patterns
   --> $DIR/mismatched-bindings-async-fn.rs:9:14
@@ -29,6 +47,12 @@ LL |     let (x | s) = String::new();
    |          -   ^ pattern doesn't bind `x`
    |          |
    |          variable not in all patterns
+   |
+help: you might have meant to use the similarly named previously used binding `s`
+   |
+LL -     let (x | s) = String::new();
+LL +     let (s | s) = String::new();
+   |
 
 error: aborting due to 4 previous errors
 
diff --git a/tests/ui/or-patterns/missing-bindings.stderr b/tests/ui/or-patterns/missing-bindings.stderr
index 6288cc58913..636f7016647 100644
--- a/tests/ui/or-patterns/missing-bindings.stderr
+++ b/tests/ui/or-patterns/missing-bindings.stderr
@@ -86,6 +86,12 @@ LL |     let (A(A(a, b) | B(c), d) | B(e)) = Y;
    |            ^^^^^^^     - variable not in all patterns
    |            |
    |            pattern doesn't bind `c`
+   |
+help: you might have meant to use the similarly named previously used binding `a`
+   |
+LL -     let (A(A(a, b) | B(c), d) | B(e)) = Y;
+LL +     let (A(A(a, b) | B(a), d) | B(e)) = Y;
+   |
 
 error[E0408]: variable `a` is not bound in all patterns
   --> $DIR/missing-bindings.rs:47:22
@@ -94,6 +100,12 @@ LL |     let (A(A(a, b) | B(c), d) | B(e)) = Y;
    |              -       ^^^^ pattern doesn't bind `a`
    |              |
    |              variable not in all patterns
+   |
+help: you might have meant to use the similarly named previously used binding `c`
+   |
+LL -     let (A(A(a, b) | B(c), d) | B(e)) = Y;
+LL +     let (A(A(c, b) | B(c), d) | B(e)) = Y;
+   |
 
 error[E0408]: variable `b` is not bound in all patterns
   --> $DIR/missing-bindings.rs:47:22
@@ -102,6 +114,12 @@ LL |     let (A(A(a, b) | B(c), d) | B(e)) = Y;
    |                 -    ^^^^ pattern doesn't bind `b`
    |                 |
    |                 variable not in all patterns
+   |
+help: you might have meant to use the similarly named previously used binding `c`
+   |
+LL -     let (A(A(a, b) | B(c), d) | B(e)) = Y;
+LL +     let (A(A(a, c) | B(c), d) | B(e)) = Y;
+   |
 
 error[E0408]: variable `e` is not bound in all patterns
   --> $DIR/missing-bindings.rs:47:10
@@ -110,6 +128,12 @@ LL |     let (A(A(a, b) | B(c), d) | B(e)) = Y;
    |          ^^^^^^^^^^^^^^^^^^^^     - variable not in all patterns
    |          |
    |          pattern doesn't bind `e`
+   |
+help: you might have meant to use the similarly named previously used binding `c`
+   |
+LL -     let (A(A(a, b) | B(c), d) | B(e)) = Y;
+LL +     let (A(A(a, b) | B(c), d) | B(c)) = Y;
+   |
 
 error[E0408]: variable `a` is not bound in all patterns
   --> $DIR/missing-bindings.rs:47:33
@@ -118,6 +142,12 @@ LL |     let (A(A(a, b) | B(c), d) | B(e)) = Y;
    |              -                  ^^^^ pattern doesn't bind `a`
    |              |
    |              variable not in all patterns
+   |
+help: you might have meant to use the similarly named previously used binding `e`
+   |
+LL -     let (A(A(a, b) | B(c), d) | B(e)) = Y;
+LL +     let (A(A(e, b) | B(c), d) | B(e)) = Y;
+   |
 
 error[E0408]: variable `b` is not bound in all patterns
   --> $DIR/missing-bindings.rs:47:33
@@ -126,6 +156,12 @@ LL |     let (A(A(a, b) | B(c), d) | B(e)) = Y;
    |                 -               ^^^^ pattern doesn't bind `b`
    |                 |
    |                 variable not in all patterns
+   |
+help: you might have meant to use the similarly named previously used binding `e`
+   |
+LL -     let (A(A(a, b) | B(c), d) | B(e)) = Y;
+LL +     let (A(A(a, e) | B(c), d) | B(e)) = Y;
+   |
 
 error[E0408]: variable `c` is not bound in all patterns
   --> $DIR/missing-bindings.rs:47:33
@@ -134,6 +170,12 @@ LL |     let (A(A(a, b) | B(c), d) | B(e)) = Y;
    |                        -        ^^^^ pattern doesn't bind `c`
    |                        |
    |                        variable not in all patterns
+   |
+help: you might have meant to use the similarly named previously used binding `e`
+   |
+LL -     let (A(A(a, b) | B(c), d) | B(e)) = Y;
+LL +     let (A(A(a, b) | B(e), d) | B(e)) = Y;
+   |
 
 error[E0408]: variable `d` is not bound in all patterns
   --> $DIR/missing-bindings.rs:47:33
@@ -142,6 +184,12 @@ LL |     let (A(A(a, b) | B(c), d) | B(e)) = Y;
    |                            -    ^^^^ pattern doesn't bind `d`
    |                            |
    |                            variable not in all patterns
+   |
+help: you might have meant to use the similarly named previously used binding `e`
+   |
+LL -     let (A(A(a, b) | B(c), d) | B(e)) = Y;
+LL +     let (A(A(a, b) | B(c), e) | B(e)) = Y;
+   |
 
 error[E0408]: variable `a` is not bound in all patterns
   --> $DIR/missing-bindings.rs:63:29
@@ -158,6 +206,12 @@ LL |                     A(_, a) |
    |                     ^^^^^^^ pattern doesn't bind `b`
 LL |                     B(b),
    |                       - variable not in all patterns
+   |
+help: you might have meant to use the similarly named previously used binding `a`
+   |
+LL -                     B(b),
+LL +                     B(a),
+   |
 
 error[E0408]: variable `a` is not bound in all patterns
   --> $DIR/missing-bindings.rs:71:21
@@ -166,6 +220,12 @@ LL |                     A(_, a) |
    |                          - variable not in all patterns
 LL |                     B(b),
    |                     ^^^^ pattern doesn't bind `a`
+   |
+help: you might have meant to use the similarly named previously used binding `b`
+   |
+LL -                     A(_, a) |
+LL +                     A(_, b) |
+   |
 
 error[E0408]: variable `a` is not bound in all patterns
   --> $DIR/missing-bindings.rs:74:17
@@ -202,6 +262,12 @@ LL |                       B(b),
 ...
 LL |               V3(c),
    |               ^^^^^ pattern doesn't bind `b`
+   |
+help: you might have meant to use the similarly named previously used binding `c`
+   |
+LL -                     B(b),
+LL +                     B(c),
+   |
 
 error[E0408]: variable `c` is not bound in all patterns
   --> $DIR/missing-bindings.rs:59:13
@@ -223,6 +289,12 @@ LL | |             ) |
    | |_____________^ pattern doesn't bind `c`
 LL |               V3(c),
    |                  - variable not in all patterns
+   |
+help: you might have meant to use the similarly named previously used binding `a`
+   |
+LL -             V3(c),
+LL +             V3(a),
+   |
 
 error[E0408]: variable `a` is not bound in all patterns
   --> $DIR/missing-bindings.rs:78:13
@@ -235,6 +307,15 @@ LL |                     A(_, a) |
 ...
 LL |             V3(c),
    |             ^^^^^ pattern doesn't bind `a`
+   |
+help: you might have meant to use the similarly named previously used binding `c`
+   |
+LL ~                 B(Ok(a) | Err(c))
+LL |             ) |
+LL |             V2(
+LL |                 A(
+LL ~                     A(_, c) |
+   |
 
 error[E0170]: pattern binding `beta` is named the same as one of the variants of the type `check_handling_of_paths::bar::foo`
   --> $DIR/missing-bindings.rs:19:18
diff --git a/tests/ui/or-patterns/nested-undelimited-precedence.stderr b/tests/ui/or-patterns/nested-undelimited-precedence.stderr
index 0835ca1929f..10dbc9d16c0 100644
--- a/tests/ui/or-patterns/nested-undelimited-precedence.stderr
+++ b/tests/ui/or-patterns/nested-undelimited-precedence.stderr
@@ -60,6 +60,12 @@ LL |     let b @ A | B: E = A;
    |         -       ^ pattern doesn't bind `b`
    |         |
    |         variable not in all patterns
+   |
+help: you might have meant to use the similarly named previously used binding `B`
+   |
+LL -     let b @ A | B: E = A;
+LL +     let B @ A | B: E = A;
+   |
 
 error[E0308]: mismatched types
   --> $DIR/nested-undelimited-precedence.rs:34:9
diff --git a/tests/ui/pattern/rfc-3637-guard-patterns/name-resolution.stderr b/tests/ui/pattern/rfc-3637-guard-patterns/name-resolution.stderr
index d76e60478a1..a5d9fd2b1a6 100644
--- a/tests/ui/pattern/rfc-3637-guard-patterns/name-resolution.stderr
+++ b/tests/ui/pattern/rfc-3637-guard-patterns/name-resolution.stderr
@@ -5,6 +5,12 @@ LL |         ((Ok(x) if y) | (Err(y) if x),) => x && y,
    |          ^^^^^^^^^^^^        - variable not in all patterns
    |          |
    |          pattern doesn't bind `y`
+   |
+help: you might have meant to use the similarly named previously used binding `x`
+   |
+LL -         ((Ok(x) if y) | (Err(y) if x),) => x && y,
+LL +         ((Ok(x) if y) | (Err(x) if x),) => x && y,
+   |
 
 error[E0408]: variable `x` is not bound in all patterns
   --> $DIR/name-resolution.rs:37:25
@@ -13,6 +19,12 @@ LL |         ((Ok(x) if y) | (Err(y) if x),) => x && y,
    |              -          ^^^^^^^^^^^^^ pattern doesn't bind `x`
    |              |
    |              variable not in all patterns
+   |
+help: you might have meant to use the similarly named previously used binding `y`
+   |
+LL -         ((Ok(x) if y) | (Err(y) if x),) => x && y,
+LL +         ((Ok(y) if y) | (Err(y) if x),) => x && y,
+   |
 
 error[E0408]: variable `x` is not bound in all patterns
   --> $DIR/name-resolution.rs:63:28
diff --git a/tests/ui/resolve/resolve-inconsistent-names.rs b/tests/ui/resolve/resolve-inconsistent-names.rs
index 9a40b20346c..bf74a4ba0f3 100644
--- a/tests/ui/resolve/resolve-inconsistent-names.rs
+++ b/tests/ui/resolve/resolve-inconsistent-names.rs
@@ -10,8 +10,10 @@ pub mod m {
 fn main() {
     let y = 1;
     match y {
-       a | b => {} //~  ERROR variable `a` is not bound in all patterns
-                   //~| ERROR variable `b` is not bound in all patterns
+        a | b => {} //~  ERROR variable `a` is not bound in all patterns
+        //~| ERROR variable `b` is not bound in all patterns
+        //~| HELP you might have meant to use the similarly named previously used binding `a`
+        //~| HELP you might have meant to use the similarly named previously used binding `b`
     }
 
     let x = (E::A, E::B);
diff --git a/tests/ui/resolve/resolve-inconsistent-names.stderr b/tests/ui/resolve/resolve-inconsistent-names.stderr
index 5fac622eef2..152c16ad404 100644
--- a/tests/ui/resolve/resolve-inconsistent-names.stderr
+++ b/tests/ui/resolve/resolve-inconsistent-names.stderr
@@ -1,21 +1,33 @@
 error[E0408]: variable `b` is not bound in all patterns
-  --> $DIR/resolve-inconsistent-names.rs:13:8
+  --> $DIR/resolve-inconsistent-names.rs:13:9
+   |
+LL |         a | b => {}
+   |         ^   - variable not in all patterns
+   |         |
+   |         pattern doesn't bind `b`
+   |
+help: you might have meant to use the similarly named previously used binding `a`
+   |
+LL -         a | b => {}
+LL +         a | a => {}
    |
-LL |        a | b => {}
-   |        ^   - variable not in all patterns
-   |        |
-   |        pattern doesn't bind `b`
 
 error[E0408]: variable `a` is not bound in all patterns
-  --> $DIR/resolve-inconsistent-names.rs:13:12
+  --> $DIR/resolve-inconsistent-names.rs:13:13
+   |
+LL |         a | b => {}
+   |         -   ^ pattern doesn't bind `a`
+   |         |
+   |         variable not in all patterns
+   |
+help: you might have meant to use the similarly named previously used binding `b`
+   |
+LL -         a | b => {}
+LL +         b | b => {}
    |
-LL |        a | b => {}
-   |        -   ^ pattern doesn't bind `a`
-   |        |
-   |        variable not in all patterns
 
 error[E0408]: variable `c` is not bound in all patterns
-  --> $DIR/resolve-inconsistent-names.rs:19:9
+  --> $DIR/resolve-inconsistent-names.rs:21:9
    |
 LL |         (A, B) | (ref B, c) | (c, A) => ()
    |         ^^^^^^           -     - variable not in all patterns
@@ -24,7 +36,7 @@ LL |         (A, B) | (ref B, c) | (c, A) => ()
    |         pattern doesn't bind `c`
 
 error[E0408]: variable `A` is not bound in all patterns
-  --> $DIR/resolve-inconsistent-names.rs:19:18
+  --> $DIR/resolve-inconsistent-names.rs:21:18
    |
 LL |         (A, B) | (ref B, c) | (c, A) => ()
    |          -       ^^^^^^^^^^       - variable not in all patterns
@@ -38,7 +50,7 @@ LL |         (E::A, B) | (ref B, c) | (c, A) => ()
    |          +++
 
 error[E0408]: variable `B` is not bound in all patterns
-  --> $DIR/resolve-inconsistent-names.rs:19:31
+  --> $DIR/resolve-inconsistent-names.rs:21:31
    |
 LL |         (A, B) | (ref B, c) | (c, A) => ()
    |             -         -       ^^^^^^ pattern doesn't bind `B`
@@ -47,7 +59,7 @@ LL |         (A, B) | (ref B, c) | (c, A) => ()
    |             variable not in all patterns
 
 error[E0409]: variable `B` is bound inconsistently across alternatives separated by `|`
-  --> $DIR/resolve-inconsistent-names.rs:19:23
+  --> $DIR/resolve-inconsistent-names.rs:21:23
    |
 LL |         (A, B) | (ref B, c) | (c, A) => ()
    |             -         ^ bound in different ways
@@ -55,7 +67,7 @@ LL |         (A, B) | (ref B, c) | (c, A) => ()
    |             first binding
 
 error[E0408]: variable `Const2` is not bound in all patterns
-  --> $DIR/resolve-inconsistent-names.rs:31:9
+  --> $DIR/resolve-inconsistent-names.rs:33:9
    |
 LL |         (CONST1, _) | (_, Const2) => ()
    |         ^^^^^^^^^^^       ------ variable not in all patterns
@@ -68,7 +80,7 @@ LL |         (CONST1, _) | (_, m::Const2) => ()
    |                           +++
 
 error[E0408]: variable `CONST1` is not bound in all patterns
-  --> $DIR/resolve-inconsistent-names.rs:31:23
+  --> $DIR/resolve-inconsistent-names.rs:33:23
    |
 LL |         (CONST1, _) | (_, Const2) => ()
    |          ------       ^^^^^^^^^^^ pattern doesn't bind `CONST1`
@@ -82,7 +94,7 @@ LL |     const CONST1: usize = 10;
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^ not accessible
 
 error[E0308]: mismatched types
-  --> $DIR/resolve-inconsistent-names.rs:19:19
+  --> $DIR/resolve-inconsistent-names.rs:21:19
    |
 LL |     match x {
    |           - this expression has type `(E, E)`
diff --git a/tests/ui/span/issue-39698.stderr b/tests/ui/span/issue-39698.stderr
index 73fcc5c8477..eb18969c3c0 100644
--- a/tests/ui/span/issue-39698.stderr
+++ b/tests/ui/span/issue-39698.stderr
@@ -7,6 +7,12 @@ LL |         T::T1(a, d) | T::T2(d, b) | T::T3(c) | T::T4(a) => { println!("{:?}
    |         |                      |    pattern doesn't bind `b`
    |         |                      variable not in all patterns
    |         pattern doesn't bind `b`
+   |
+help: you might have meant to use the similarly named previously used binding `c`
+   |
+LL -         T::T1(a, d) | T::T2(d, b) | T::T3(c) | T::T4(a) => { println!("{:?}", a); }
+LL +         T::T1(a, d) | T::T2(d, c) | T::T3(c) | T::T4(a) => { println!("{:?}", a); }
+   |
 
 error[E0408]: variable `c` is not bound in all patterns
   --> $DIR/issue-39698.rs:10:9
@@ -17,6 +23,12 @@ LL |         T::T1(a, d) | T::T2(d, b) | T::T3(c) | T::T4(a) => { println!("{:?}
    |         |             |                   variable not in all patterns
    |         |             pattern doesn't bind `c`
    |         pattern doesn't bind `c`
+   |
+help: you might have meant to use the similarly named previously used binding `d`
+   |
+LL -         T::T1(a, d) | T::T2(d, b) | T::T3(c) | T::T4(a) => { println!("{:?}", a); }
+LL +         T::T1(a, d) | T::T2(d, b) | T::T3(d) | T::T4(a) => { println!("{:?}", a); }
+   |
 
 error[E0408]: variable `a` is not bound in all patterns
   --> $DIR/issue-39698.rs:10:23
@@ -27,6 +39,12 @@ LL |         T::T1(a, d) | T::T2(d, b) | T::T3(c) | T::T4(a) => { println!("{:?}
    |               |       |             pattern doesn't bind `a`
    |               |       pattern doesn't bind `a`
    |               variable not in all patterns
+   |
+help: you might have meant to use the similarly named previously used binding `c`
+   |
+LL -         T::T1(a, d) | T::T2(d, b) | T::T3(c) | T::T4(a) => { println!("{:?}", a); }
+LL +         T::T1(c, d) | T::T2(d, b) | T::T3(c) | T::T4(c) => { println!("{:?}", a); }
+   |
 
 error[E0408]: variable `d` is not bound in all patterns
   --> $DIR/issue-39698.rs:10:37
@@ -37,6 +55,12 @@ LL |         T::T1(a, d) | T::T2(d, b) | T::T3(c) | T::T4(a) => { println!("{:?}
    |                  |          |       pattern doesn't bind `d`
    |                  |          variable not in all patterns
    |                  variable not in all patterns
+   |
+help: you might have meant to use the similarly named previously used binding `c`
+   |
+LL -         T::T1(a, d) | T::T2(d, b) | T::T3(c) | T::T4(a) => { println!("{:?}", a); }
+LL +         T::T1(a, c) | T::T2(c, b) | T::T3(c) | T::T4(a) => { println!("{:?}", a); }
+   |
 
 error[E0381]: used binding `a` is possibly-uninitialized
   --> $DIR/issue-39698.rs:10:79