Reword the "unreachable pattern" explanations

Author: Nadrieril

compiler/rustc_mir_build/messages.ftl

@@ -330,11 +330,11 @@ mir_build_unreachable_making_this_unreachable = collectively making this unreach
 mir_build_unreachable_matches_same_values = matches some of the same values
 
 mir_build_unreachable_pattern = unreachable pattern
-    .label = unreachable pattern
-    .unreachable_matches_no_values = this pattern matches no values because `{$ty}` is uninhabited
+    .label = no value can reach this
+    .unreachable_matches_no_values = matches no values because `{$ty}` is uninhabited
     .unreachable_covered_by_catchall = matches any value
-    .unreachable_covered_by_one = matches all the values already
-    .unreachable_covered_by_many = these patterns collectively make the last one unreachable
+    .unreachable_covered_by_one = matches all the relevant values
+    .unreachable_covered_by_many = multiple earlier patterns match some of the same values
 
 mir_build_unsafe_fn_safe_body = an unsafe function restricts its caller, but its body is safe by default
 mir_build_unsafe_not_inherited = items do not inherit unsafety from separate enclosing items

tests/ui/consts/packed_pattern.stderr

@@ -2,9 +2,9 @@ warning: unreachable pattern
   --> $DIR/packed_pattern.rs:16:9
    |
 LL |         Foo { field: (5, 6, 7, 8) } => {},
-   |         --------------------------- matches all the values already
+   |         --------------------------- matches all the relevant values
 LL |         FOO => unreachable!(),
-   |         ^^^ unreachable pattern
+   |         ^^^ no value can reach this
    |
    = note: `#[warn(unreachable_patterns)]` on by default
 

tests/ui/consts/packed_pattern2.stderr

@@ -2,9 +2,9 @@ warning: unreachable pattern
   --> $DIR/packed_pattern2.rs:24:9
    |
 LL |         Bar { a: Foo { field: (5, 6) } } => {},
-   |         -------------------------------- matches all the values already
+   |         -------------------------------- matches all the relevant values
 LL |         FOO => unreachable!(),
-   |         ^^^ unreachable pattern
+   |         ^^^ no value can reach this
    |
    = note: `#[warn(unreachable_patterns)]` on by default
 

tests/ui/error-codes/E0001.stderr

@@ -2,9 +2,9 @@ error: unreachable pattern
   --> $DIR/E0001.rs:8:9
    |
 LL |         _ => {/* ... */}
-   |         ^ unreachable pattern
+   |         ^ no value can reach this
    |
-note: these patterns collectively make the last one unreachable
+note: multiple earlier patterns match some of the same values
   --> $DIR/E0001.rs:8:9
    |
 LL |         Some(_) => {/* ... */}

tests/ui/lint/issue-30302.stderr

@@ -13,7 +13,7 @@ LL |         Nil => true,
    |         --- matches any value
 LL |
 LL |         _ => false
-   |         ^ unreachable pattern
+   |         ^ no value can reach this
    |
 note: the lint level is defined here
   --> $DIR/issue-30302.rs:4:9