Group "missing variable bind" spans in `or` matches and clarify wording
for the two possible cases: when a variable from the first pattern is
not in any of the subsequent patterns, and when a variable in any of the
other patterns is not in the first one.
Before:
```
error[E0408]: variable `a` from pattern #1 is not bound in pattern #2
--> file.rs:10:23
|
10 | T::T1(a, d) | T::T2(d, b) | T::T3(c) | T::T4(a) => { println!("{:?}", a); }
| ^^^^^^^^^^^ pattern doesn't bind `a`
error[E0408]: variable `b` from pattern #2 is not bound in pattern #1
--> file.rs:10:32
|
10 | T::T1(a, d) | T::T2(d, b) | T::T3(c) | T::T4(a) => { println!("{:?}", a); }
| ^ pattern doesn't bind `b`
error[E0408]: variable `a` from pattern #1 is not bound in pattern #3
--> file.rs:10:37
|
10 | T::T1(a, d) | T::T2(d, b) | T::T3(c) | T::T4(a) => { println!("{:?}", a); }
| ^^^^^^^^ pattern doesn't bind `a`
error[E0408]: variable `d` from pattern #1 is not bound in pattern #3
--> file.rs:10:37
|
10 | T::T1(a, d) | T::T2(d, b) | T::T3(c) | T::T4(a) => { println!("{:?}", a); }
| ^^^^^^^^ pattern doesn't bind `d`
error[E0408]: variable `c` from pattern #3 is not bound in pattern #1
--> file.rs:10:43
|
10 | T::T1(a, d) | T::T2(d, b) | T::T3(c) | T::T4(a) => { println!("{:?}", a); }
| ^ pattern doesn't bind `c`
error[E0408]: variable `d` from pattern #1 is not bound in pattern #4
--> file.rs:10:48
|
10 | T::T1(a, d) | T::T2(d, b) | T::T3(c) | T::T4(a) => { println!("{:?}", a); }
| ^^^^^^^^ pattern doesn't bind `d`
error: aborting due to 6 previous errors
```
After:
```
error[E0408]: variable `a` is not bound in all patterns
--> file.rs:20:37
|
20 | T::T1(a, d) | T::T2(d, b) | T::T3(c) | T::T4(a) => {
intln!("{:?}", a); }
| - ^^^^^^^^^^^ ^^^^^^^^ - variable
t in all patterns
| | | |
| | | pattern doesn't bind `a`
| | pattern doesn't bind `a`
| variable not in all patterns
error[E0408]: variable `d` is not bound in all patterns
--> file.rs:20:37
|
20 | T::T1(a, d) | T::T2(d, b) | T::T3(c) | T::T4(a) => {
intln!("{:?}", a); }
| - - ^^^^^^^^ ^^^^^^^^ pattern
esn't bind `d`
| | | |
| | | pattern doesn't bind `d`
| | variable not in all patterns
| variable not in all patterns
error[E0408]: variable `b` is not bound in all patterns
--> file.rs:20:37
|
20 | T::T1(a, d) | T::T2(d, b) | T::T3(c) | T::T4(a) => {
intln!("{:?}", a); }
| ^^^^^^^^^^^ - ^^^^^^^^ ^^^^^^^^ pattern
esn't bind `b`
| | | |
| | | pattern doesn't bind `b`
| | variable not in all patterns
| pattern doesn't bind `b`
error[E0408]: variable `c` is not bound in all patterns
--> file.rs:20:48
|
20 | T::T1(a, d) | T::T2(d, b) | T::T3(c) | T::T4(a) => {
intln!("{:?}", a); }
| ^^^^^^^^^^^ ^^^^^^^^^^^ - ^^^^^^^^ pattern
esn't bind `c`
| | | |
| | | variable not in all
tterns
| | pattern doesn't bind `c`
| pattern doesn't bind `c`
error: aborting due to 4 previous errors
```
* Have only one presentation for binding consistency errors
* Point to same binding in multiple patterns when possible
* Check inconsistent bindings in all arms
* Simplify wording of diagnostic message
* Sort emition and spans of binding errors for deterministic output
