Add a note with a link to explain empty types

18 files changed, 171 insertions, 17 deletions

diff --git a/compiler/rustc_mir_build/messages.ftl b/compiler/rustc_mir_build/messages.ftl
index ae13485ce73..b6258045566 100644
--- a/compiler/rustc_mir_build/messages.ftl
+++ b/compiler/rustc_mir_build/messages.ftl
@@ -332,6 +332,7 @@ mir_build_unreachable_matches_same_values = matches some of the same values
 mir_build_unreachable_pattern = unreachable pattern
     .label = no value can reach this
     .unreachable_matches_no_values = matches no values because `{$ty}` is uninhabited
+    .unreachable_uninhabited_note = to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
     .unreachable_covered_by_catchall = matches any value
     .unreachable_covered_by_one = matches all the relevant values
     .unreachable_covered_by_many = multiple earlier patterns match some of the same values
diff --git a/compiler/rustc_mir_build/src/errors.rs b/compiler/rustc_mir_build/src/errors.rs
index 34577f102d1..a45a0311e32 100644
--- a/compiler/rustc_mir_build/src/errors.rs
+++ b/compiler/rustc_mir_build/src/errors.rs
@@ -588,6 +588,8 @@ pub(crate) struct UnreachablePattern<'tcx> {
     pub(crate) span: Option<Span>,
     #[subdiagnostic]
     pub(crate) matches_no_values: Option<UnreachableMatchesNoValues<'tcx>>,
+    #[note(mir_build_unreachable_uninhabited_note)]
+    pub(crate) uninhabited_note: Option<()>,
     #[label(mir_build_unreachable_covered_by_catchall)]
     pub(crate) covered_by_catchall: Option<Span>,
     #[label(mir_build_unreachable_covered_by_one)]
diff --git a/compiler/rustc_mir_build/src/thir/pattern/check_match.rs b/compiler/rustc_mir_build/src/thir/pattern/check_match.rs
index 85b9dacb129..a948e5d0c21 100644
--- a/compiler/rustc_mir_build/src/thir/pattern/check_match.rs
+++ b/compiler/rustc_mir_build/src/thir/pattern/check_match.rs
@@ -921,6 +921,7 @@ fn report_unreachable_pattern<'p, 'tcx>(
     let mut lint = UnreachablePattern {
         span: Some(pat_span),
         matches_no_values: None,
+        uninhabited_note: None,
         covered_by_catchall: None,
         covered_by_one: None,
         covered_by_many: None,
@@ -929,6 +930,7 @@ fn report_unreachable_pattern<'p, 'tcx>(
         [] => {
             // Empty pattern; we report the uninhabited type that caused the emptiness.
             lint.span = None; // Don't label the pattern itself
+            lint.uninhabited_note = Some(()); // Give a link about empty types
             pat.walk(&mut |subpat| {
                 let ty = **subpat.ty();
                 if cx.is_uninhabited(ty) {
diff --git a/tests/ui/pattern/usefulness/empty-match-check-notes.exhaustive_patterns.stderr b/tests/ui/pattern/usefulness/empty-match-check-notes.exhaustive_patterns.stderr
index 4cfa6182752..5ec14a7597a 100644
--- a/tests/ui/pattern/usefulness/empty-match-check-notes.exhaustive_patterns.stderr
+++ b/tests/ui/pattern/usefulness/empty-match-check-notes.exhaustive_patterns.stderr
@@ -5,6 +5,7 @@ LL |         _ => {}
    |         ^
    |
    = note: matches no values because `EmptyEnum` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 note: the lint level is defined here
   --> $DIR/empty-match-check-notes.rs:7:9
    |
@@ -12,31 +13,34 @@ LL | #![deny(unreachable_patterns)]
    |         ^^^^^^^^^^^^^^^^^^^^
 
 error: unreachable pattern
-  --> $DIR/empty-match-check-notes.rs:21:9
+  --> $DIR/empty-match-check-notes.rs:22:9
    |
 LL |         _ if false => {}
    |         ^
    |
    = note: matches no values because `EmptyEnum` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error: unreachable pattern
-  --> $DIR/empty-match-check-notes.rs:29:9
+  --> $DIR/empty-match-check-notes.rs:31:9
    |
 LL |         _ => {}
    |         ^
    |
    = note: matches no values because `EmptyForeignEnum` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error: unreachable pattern
-  --> $DIR/empty-match-check-notes.rs:33:9
+  --> $DIR/empty-match-check-notes.rs:36:9
    |
 LL |         _ if false => {}
    |         ^
    |
    = note: matches no values because `EmptyForeignEnum` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error[E0005]: refutable pattern in local binding
-  --> $DIR/empty-match-check-notes.rs:39:9
+  --> $DIR/empty-match-check-notes.rs:43:9
    |
 LL |     let None = *x;
    |         ^^^^ pattern `Some(_)` not covered
@@ -51,7 +55,7 @@ LL |     if let None = *x { todo!() };
    |     ++               +++++++++++
 
 error[E0004]: non-exhaustive patterns: `0_u8..=u8::MAX` not covered
-  --> $DIR/empty-match-check-notes.rs:49:11
+  --> $DIR/empty-match-check-notes.rs:53:11
    |
 LL |     match 0u8 {
    |           ^^^ pattern `0_u8..=u8::MAX` not covered
diff --git a/tests/ui/pattern/usefulness/empty-match-check-notes.normal.stderr b/tests/ui/pattern/usefulness/empty-match-check-notes.normal.stderr
index 4cfa6182752..5ec14a7597a 100644
--- a/tests/ui/pattern/usefulness/empty-match-check-notes.normal.stderr
+++ b/tests/ui/pattern/usefulness/empty-match-check-notes.normal.stderr
@@ -5,6 +5,7 @@ LL |         _ => {}
    |         ^
    |
    = note: matches no values because `EmptyEnum` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 note: the lint level is defined here
   --> $DIR/empty-match-check-notes.rs:7:9
    |
@@ -12,31 +13,34 @@ LL | #![deny(unreachable_patterns)]
    |         ^^^^^^^^^^^^^^^^^^^^
 
 error: unreachable pattern
-  --> $DIR/empty-match-check-notes.rs:21:9
+  --> $DIR/empty-match-check-notes.rs:22:9
    |
 LL |         _ if false => {}
    |         ^
    |
    = note: matches no values because `EmptyEnum` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error: unreachable pattern
-  --> $DIR/empty-match-check-notes.rs:29:9
+  --> $DIR/empty-match-check-notes.rs:31:9
    |
 LL |         _ => {}
    |         ^
    |
    = note: matches no values because `EmptyForeignEnum` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error: unreachable pattern
-  --> $DIR/empty-match-check-notes.rs:33:9
+  --> $DIR/empty-match-check-notes.rs:36:9
    |
 LL |         _ if false => {}
    |         ^
    |
    = note: matches no values because `EmptyForeignEnum` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error[E0005]: refutable pattern in local binding
-  --> $DIR/empty-match-check-notes.rs:39:9
+  --> $DIR/empty-match-check-notes.rs:43:9
    |
 LL |     let None = *x;
    |         ^^^^ pattern `Some(_)` not covered
@@ -51,7 +55,7 @@ LL |     if let None = *x { todo!() };
    |     ++               +++++++++++
 
 error[E0004]: non-exhaustive patterns: `0_u8..=u8::MAX` not covered
-  --> $DIR/empty-match-check-notes.rs:49:11
+  --> $DIR/empty-match-check-notes.rs:53:11
    |
 LL |     match 0u8 {
    |           ^^^ pattern `0_u8..=u8::MAX` not covered
diff --git a/tests/ui/pattern/usefulness/empty-match-check-notes.rs b/tests/ui/pattern/usefulness/empty-match-check-notes.rs
index 61a75e6c801..48d20fd2d5c 100644
--- a/tests/ui/pattern/usefulness/empty-match-check-notes.rs
+++ b/tests/ui/pattern/usefulness/empty-match-check-notes.rs
@@ -16,10 +16,12 @@ fn empty_enum(x: EmptyEnum) {
     match x {
         _ => {} //~ ERROR unreachable pattern
                 //~^ NOTE matches no values
+                //~| NOTE to learn more about uninhabited types, see
     }
     match x {
         _ if false => {} //~ ERROR unreachable pattern
                          //~^ NOTE matches no values
+                         //~| NOTE to learn more about uninhabited types, see
     }
 }
 
@@ -28,10 +30,12 @@ fn empty_foreign_enum(x: empty::EmptyForeignEnum) {
     match x {
         _ => {} //~ ERROR unreachable pattern
                 //~^ NOTE matches no values
+                //~| NOTE to learn more about uninhabited types, see
     }
     match x {
         _ if false => {} //~ ERROR unreachable pattern
                          //~^ NOTE matches no values
+                         //~| NOTE to learn more about uninhabited types, see
     }
 }
 
diff --git a/tests/ui/pattern/usefulness/empty-types.exhaustive_patterns.stderr b/tests/ui/pattern/usefulness/empty-types.exhaustive_patterns.stderr
index 74cf75f3b40..4e5f1d0ea8c 100644
--- a/tests/ui/pattern/usefulness/empty-types.exhaustive_patterns.stderr
+++ b/tests/ui/pattern/usefulness/empty-types.exhaustive_patterns.stderr
@@ -5,6 +5,7 @@ LL |         _ => {}
    |         ^
    |
    = note: matches no values because `!` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 note: the lint level is defined here
   --> $DIR/empty-types.rs:15:9
    |
@@ -18,6 +19,7 @@ LL |         _x => {}
    |         ^^
    |
    = note: matches no values because `!` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error[E0004]: non-exhaustive patterns: type `&!` is non-empty
   --> $DIR/empty-types.rs:56:11
@@ -41,6 +43,7 @@ LL |         (_, _) => {}
    |         ^^^^^^
    |
    = note: matches no values because `(u32, !)` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error: unreachable pattern
   --> $DIR/empty-types.rs:76:9
@@ -49,6 +52,7 @@ LL |         _ => {}
    |         ^
    |
    = note: matches no values because `(!, !)` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error: unreachable pattern
   --> $DIR/empty-types.rs:79:9
@@ -57,6 +61,7 @@ LL |         (_, _) => {}
    |         ^^^^^^
    |
    = note: matches no values because `(!, !)` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error: unreachable pattern
   --> $DIR/empty-types.rs:83:9
@@ -65,6 +70,7 @@ LL |         _ => {}
    |         ^
    |
    = note: matches no values because `!` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error[E0004]: non-exhaustive patterns: `Ok(_)` not covered
   --> $DIR/empty-types.rs:87:11
@@ -92,6 +98,7 @@ LL |         Err(_) => {}
    |         ^^^^^^
    |
    = note: matches no values because `!` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error: unreachable pattern
   --> $DIR/empty-types.rs:99:9
@@ -100,6 +107,7 @@ LL |         Err(_) => {}
    |         ^^^^^^
    |
    = note: matches no values because `!` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error[E0004]: non-exhaustive patterns: `Ok(1_u32..=u32::MAX)` not covered
   --> $DIR/empty-types.rs:96:11
@@ -140,6 +148,7 @@ LL |         _ => {}
    |         ^
    |
    = note: matches no values because `Result<!, !>` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error: unreachable pattern
   --> $DIR/empty-types.rs:115:9
@@ -148,6 +157,7 @@ LL |         Ok(_) => {}
    |         ^^^^^
    |
    = note: matches no values because `Result<!, !>` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error: unreachable pattern
   --> $DIR/empty-types.rs:118:9
@@ -156,6 +166,7 @@ LL |         Ok(_) => {}
    |         ^^^^^
    |
    = note: matches no values because `Result<!, !>` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error: unreachable pattern
   --> $DIR/empty-types.rs:119:9
@@ -164,6 +175,7 @@ LL |         _ => {}
    |         ^
    |
    = note: matches no values because `Result<!, !>` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error: unreachable pattern
   --> $DIR/empty-types.rs:122:9
@@ -172,6 +184,7 @@ LL |         Ok(_) => {}
    |         ^^^^^
    |
    = note: matches no values because `Result<!, !>` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error: unreachable pattern
   --> $DIR/empty-types.rs:123:9
@@ -180,6 +193,7 @@ LL |         Err(_) => {}
    |         ^^^^^^
    |
    = note: matches no values because `Result<!, !>` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error: unreachable pattern
   --> $DIR/empty-types.rs:132:13
@@ -188,6 +202,7 @@ LL |             _ => {}
    |             ^
    |
    = note: matches no values because `Void` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error: unreachable pattern
   --> $DIR/empty-types.rs:135:13
@@ -196,6 +211,7 @@ LL |             _ if false => {}
    |             ^
    |
    = note: matches no values because `Void` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error: unreachable pattern
   --> $DIR/empty-types.rs:143:13
@@ -204,6 +220,7 @@ LL |             Some(_) => {}
    |             ^^^^^^^
    |
    = note: matches no values because `Void` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error: unreachable pattern
   --> $DIR/empty-types.rs:147:13
@@ -220,6 +237,7 @@ LL |             _ => {}
    |             ^
    |
    = note: matches no values because `!` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error: unreachable pattern
   --> $DIR/empty-types.rs:204:13
@@ -228,6 +246,7 @@ LL |             _ => {}
    |             ^
    |
    = note: matches no values because `!` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error: unreachable pattern
   --> $DIR/empty-types.rs:209:13
@@ -236,6 +255,7 @@ LL |             _ => {}
    |             ^
    |
    = note: matches no values because `!` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error: unreachable pattern
   --> $DIR/empty-types.rs:214:13
@@ -244,6 +264,7 @@ LL |             _ => {}
    |             ^
    |
    = note: matches no values because `!` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error: unreachable pattern
   --> $DIR/empty-types.rs:220:13
@@ -252,6 +273,7 @@ LL |             _ => {}
    |             ^
    |
    = note: matches no values because `!` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error: unreachable pattern
   --> $DIR/empty-types.rs:281:9
@@ -260,6 +282,7 @@ LL |         _ => {}
    |         ^
    |
    = note: matches no values because `!` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error: unreachable pattern
   --> $DIR/empty-types.rs:284:9
@@ -268,6 +291,7 @@ LL |         (_, _) => {}
    |         ^^^^^^
    |
    = note: matches no values because `(!, !)` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error: unreachable pattern
   --> $DIR/empty-types.rs:287:9
@@ -276,6 +300,7 @@ LL |         Ok(_) => {}
    |         ^^^^^
    |
    = note: matches no values because `Result<!, !>` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error: unreachable pattern
   --> $DIR/empty-types.rs:288:9
@@ -284,6 +309,7 @@ LL |         Err(_) => {}
    |         ^^^^^^
    |
    = note: matches no values because `Result<!, !>` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error[E0004]: non-exhaustive patterns: type `&[!]` is non-empty
   --> $DIR/empty-types.rs:327:11
@@ -347,6 +373,7 @@ LL |         _ => {}
    |         ^
    |
    = note: matches no values because `[!; 3]` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error: unreachable pattern
   --> $DIR/empty-types.rs:371:9
@@ -355,6 +382,7 @@ LL |         [_, _, _] => {}
    |         ^^^^^^^^^
    |
    = note: matches no values because `[!; 3]` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error: unreachable pattern
   --> $DIR/empty-types.rs:374:9
@@ -363,6 +391,7 @@ LL |         [_, ..] => {}
    |         ^^^^^^^
    |
    = note: matches no values because `[!; 3]` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error[E0004]: non-exhaustive patterns: type `[!; 0]` is non-empty
   --> $DIR/empty-types.rs:388:11
@@ -407,6 +436,7 @@ LL |         Some(_) => {}
    |         ^^^^^^^
    |
    = note: matches no values because `!` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error: unreachable pattern
   --> $DIR/empty-types.rs:421:9
@@ -415,6 +445,7 @@ LL |         Some(_a) => {}
    |         ^^^^^^^^
    |
    = note: matches no values because `!` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error: unreachable pattern
   --> $DIR/empty-types.rs:426:9
@@ -441,6 +472,7 @@ LL |         _ => {}
    |         ^
    |
    = note: matches no values because `!` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error: unreachable pattern
   --> $DIR/empty-types.rs:606:9
@@ -449,6 +481,7 @@ LL |         _x => {}
    |         ^^
    |
    = note: matches no values because `!` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error: unreachable pattern
   --> $DIR/empty-types.rs:609:9
@@ -457,6 +490,7 @@ LL |         _ if false => {}
    |         ^
    |
    = note: matches no values because `!` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error: unreachable pattern
   --> $DIR/empty-types.rs:612:9
@@ -465,6 +499,7 @@ LL |         _x if false => {}
    |         ^^
    |
    = note: matches no values because `!` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error: aborting due to 49 previous errors
 
diff --git a/tests/ui/pattern/usefulness/empty-types.never_pats.stderr b/tests/ui/pattern/usefulness/empty-types.never_pats.stderr
index e1a8458e5f8..3332eab8a77 100644
--- a/tests/ui/pattern/usefulness/empty-types.never_pats.stderr
+++ b/tests/ui/pattern/usefulness/empty-types.never_pats.stderr
@@ -14,6 +14,7 @@ LL |         _ => {}
    |         ^
    |
    = note: matches no values because `!` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 note: the lint level is defined here
   --> $DIR/empty-types.rs:15:9
    |
@@ -27,6 +28,7 @@ LL |         _x => {}
    |         ^^
    |
    = note: matches no values because `!` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error[E0004]: non-exhaustive patterns: type `&!` is non-empty
   --> $DIR/empty-types.rs:56:11
@@ -50,6 +52,7 @@ LL |         (_, _) => {}
    |         ^^^^^^
    |
    = note: matches no values because `(u32, !)` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error: unreachable pattern
   --> $DIR/empty-types.rs:76:9
@@ -58,6 +61,7 @@ LL |         _ => {}
    |         ^
    |
    = note: matches no values because `(!, !)` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error: unreachable pattern
   --> $DIR/empty-types.rs:79:9
@@ -66,6 +70,7 @@ LL |         (_, _) => {}
    |         ^^^^^^
    |
    = note: matches no values because `(!, !)` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error: unreachable pattern
   --> $DIR/empty-types.rs:83:9
@@ -74,6 +79,7 @@ LL |         _ => {}
    |         ^
    |
    = note: matches no values because `!` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error[E0004]: non-exhaustive patterns: `Ok(_)` not covered
   --> $DIR/empty-types.rs:87:11
@@ -101,6 +107,7 @@ LL |         Err(_) => {}
    |         ^^^^^^
    |
    = note: matches no values because `!` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error: unreachable pattern
   --> $DIR/empty-types.rs:99:9
@@ -109,6 +116,7 @@ LL |         Err(_) => {}
    |         ^^^^^^
    |
    = note: matches no values because `!` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error[E0004]: non-exhaustive patterns: `Ok(1_u32..=u32::MAX)` not covered
   --> $DIR/empty-types.rs:96:11
@@ -163,6 +171,7 @@ LL |         _ => {}
    |         ^
    |
    = note: matches no values because `Result<!, !>` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error: unreachable pattern
   --> $DIR/empty-types.rs:115:9
@@ -171,6 +180,7 @@ LL |         Ok(_) => {}
    |         ^^^^^
    |
    = note: matches no values because `Result<!, !>` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error: unreachable pattern
   --> $DIR/empty-types.rs:118:9
@@ -179,6 +189,7 @@ LL |         Ok(_) => {}
    |         ^^^^^
    |
    = note: matches no values because `Result<!, !>` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error: unreachable pattern
   --> $DIR/empty-types.rs:119:9
@@ -187,6 +198,7 @@ LL |         _ => {}
    |         ^
    |
    = note: matches no values because `Result<!, !>` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error: unreachable pattern
   --> $DIR/empty-types.rs:122:9
@@ -195,6 +207,7 @@ LL |         Ok(_) => {}
    |         ^^^^^
    |
    = note: matches no values because `Result<!, !>` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error: unreachable pattern
   --> $DIR/empty-types.rs:123:9
@@ -203,6 +216,7 @@ LL |         Err(_) => {}
    |         ^^^^^^
    |
    = note: matches no values because `Result<!, !>` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error: unreachable pattern
   --> $DIR/empty-types.rs:132:13
@@ -211,6 +225,7 @@ LL |             _ => {}
    |             ^
    |
    = note: matches no values because `Void` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error: unreachable pattern
   --> $DIR/empty-types.rs:135:13
@@ -219,6 +234,7 @@ LL |             _ if false => {}
    |             ^
    |
    = note: matches no values because `Void` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error: unreachable pattern
   --> $DIR/empty-types.rs:143:13
@@ -227,6 +243,7 @@ LL |             Some(_) => {}
    |             ^^^^^^^
    |
    = note: matches no values because `Void` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error: unreachable pattern
   --> $DIR/empty-types.rs:147:13
@@ -262,6 +279,7 @@ LL |             _ => {}
    |             ^
    |
    = note: matches no values because `!` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error: unreachable pattern
   --> $DIR/empty-types.rs:204:13
@@ -270,6 +288,7 @@ LL |             _ => {}
    |             ^
    |
    = note: matches no values because `!` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error: unreachable pattern
   --> $DIR/empty-types.rs:209:13
@@ -278,6 +297,7 @@ LL |             _ => {}
    |             ^
    |
    = note: matches no values because `!` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error: unreachable pattern
   --> $DIR/empty-types.rs:214:13
@@ -286,6 +306,7 @@ LL |             _ => {}
    |             ^
    |
    = note: matches no values because `!` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error: unreachable pattern
   --> $DIR/empty-types.rs:220:13
@@ -294,6 +315,7 @@ LL |             _ => {}
    |             ^
    |
    = note: matches no values because `!` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error: unreachable pattern
   --> $DIR/empty-types.rs:281:9
@@ -302,6 +324,7 @@ LL |         _ => {}
    |         ^
    |
    = note: matches no values because `!` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error: unreachable pattern
   --> $DIR/empty-types.rs:284:9
@@ -310,6 +333,7 @@ LL |         (_, _) => {}
    |         ^^^^^^
    |
    = note: matches no values because `(!, !)` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error: unreachable pattern
   --> $DIR/empty-types.rs:287:9
@@ -318,6 +342,7 @@ LL |         Ok(_) => {}
    |         ^^^^^
    |
    = note: matches no values because `Result<!, !>` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error: unreachable pattern
   --> $DIR/empty-types.rs:288:9
@@ -326,6 +351,7 @@ LL |         Err(_) => {}
    |         ^^^^^^
    |
    = note: matches no values because `Result<!, !>` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error[E0005]: refutable pattern in local binding
   --> $DIR/empty-types.rs:297:13
@@ -481,6 +507,7 @@ LL |         _ => {}
    |         ^
    |
    = note: matches no values because `[!; 3]` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error: unreachable pattern
   --> $DIR/empty-types.rs:371:9
@@ -489,6 +516,7 @@ LL |         [_, _, _] => {}
    |         ^^^^^^^^^
    |
    = note: matches no values because `[!; 3]` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error: unreachable pattern
   --> $DIR/empty-types.rs:374:9
@@ -497,6 +525,7 @@ LL |         [_, ..] => {}
    |         ^^^^^^^
    |
    = note: matches no values because `[!; 3]` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error[E0004]: non-exhaustive patterns: type `[!; 0]` is non-empty
   --> $DIR/empty-types.rs:388:11
@@ -541,6 +570,7 @@ LL |         Some(_) => {}
    |         ^^^^^^^
    |
    = note: matches no values because `!` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error: unreachable pattern
   --> $DIR/empty-types.rs:421:9
@@ -549,6 +579,7 @@ LL |         Some(_a) => {}
    |         ^^^^^^^^
    |
    = note: matches no values because `!` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error: unreachable pattern
   --> $DIR/empty-types.rs:426:9
@@ -665,6 +696,7 @@ LL |         _ => {}
    |         ^
    |
    = note: matches no values because `!` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error: unreachable pattern
   --> $DIR/empty-types.rs:606:9
@@ -673,6 +705,7 @@ LL |         _x => {}
    |         ^^
    |
    = note: matches no values because `!` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error: unreachable pattern
   --> $DIR/empty-types.rs:609:9
@@ -681,6 +714,7 @@ LL |         _ if false => {}
    |         ^
    |
    = note: matches no values because `!` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error: unreachable pattern
   --> $DIR/empty-types.rs:612:9
@@ -689,6 +723,7 @@ LL |         _x if false => {}
    |         ^^
    |
    = note: matches no values because `!` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error[E0004]: non-exhaustive patterns: `&!` not covered
   --> $DIR/empty-types.rs:637:11
diff --git a/tests/ui/pattern/usefulness/empty-types.normal.stderr b/tests/ui/pattern/usefulness/empty-types.normal.stderr
index c9bd25d5f9d..89cf09f011e 100644
--- a/tests/ui/pattern/usefulness/empty-types.normal.stderr
+++ b/tests/ui/pattern/usefulness/empty-types.normal.stderr
@@ -5,6 +5,7 @@ LL |         _ => {}
    |         ^
    |
    = note: matches no values because `!` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 note: the lint level is defined here
   --> $DIR/empty-types.rs:15:9
    |
@@ -18,6 +19,7 @@ LL |         _x => {}
    |         ^^
    |
    = note: matches no values because `!` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error[E0004]: non-exhaustive patterns: type `&!` is non-empty
   --> $DIR/empty-types.rs:56:11
@@ -41,6 +43,7 @@ LL |         (_, _) => {}
    |         ^^^^^^
    |
    = note: matches no values because `(u32, !)` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error: unreachable pattern
   --> $DIR/empty-types.rs:76:9
@@ -49,6 +52,7 @@ LL |         _ => {}
    |         ^
    |
    = note: matches no values because `(!, !)` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error: unreachable pattern
   --> $DIR/empty-types.rs:79:9
@@ -57,6 +61,7 @@ LL |         (_, _) => {}
    |         ^^^^^^
    |
    = note: matches no values because `(!, !)` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error: unreachable pattern
   --> $DIR/empty-types.rs:83:9
@@ -65,6 +70,7 @@ LL |         _ => {}
    |         ^
    |
    = note: matches no values because `!` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error[E0004]: non-exhaustive patterns: `Ok(_)` not covered
   --> $DIR/empty-types.rs:87:11
@@ -92,6 +98,7 @@ LL |         Err(_) => {}
    |         ^^^^^^
    |
    = note: matches no values because `!` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error: unreachable pattern
   --> $DIR/empty-types.rs:99:9
@@ -100,6 +107,7 @@ LL |         Err(_) => {}
    |         ^^^^^^
    |
    = note: matches no values because `!` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error[E0004]: non-exhaustive patterns: `Ok(1_u32..=u32::MAX)` not covered
   --> $DIR/empty-types.rs:96:11
@@ -154,6 +162,7 @@ LL |         _ => {}
    |         ^
    |
    = note: matches no values because `Result<!, !>` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error: unreachable pattern
   --> $DIR/empty-types.rs:115:9
@@ -162,6 +171,7 @@ LL |         Ok(_) => {}
    |         ^^^^^
    |
    = note: matches no values because `Result<!, !>` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error: unreachable pattern
   --> $DIR/empty-types.rs:118:9
@@ -170,6 +180,7 @@ LL |         Ok(_) => {}
    |         ^^^^^
    |
    = note: matches no values because `Result<!, !>` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error: unreachable pattern
   --> $DIR/empty-types.rs:119:9
@@ -178,6 +189,7 @@ LL |         _ => {}
    |         ^
    |
    = note: matches no values because `Result<!, !>` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error: unreachable pattern
   --> $DIR/empty-types.rs:122:9
@@ -186,6 +198,7 @@ LL |         Ok(_) => {}
    |         ^^^^^
    |
    = note: matches no values because `Result<!, !>` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error: unreachable pattern
   --> $DIR/empty-types.rs:123:9
@@ -194,6 +207,7 @@ LL |         Err(_) => {}
    |         ^^^^^^
    |
    = note: matches no values because `Result<!, !>` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error: unreachable pattern
   --> $DIR/empty-types.rs:132:13
@@ -202,6 +216,7 @@ LL |             _ => {}
    |             ^
    |
    = note: matches no values because `Void` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error: unreachable pattern
   --> $DIR/empty-types.rs:135:13
@@ -210,6 +225,7 @@ LL |             _ if false => {}
    |             ^
    |
    = note: matches no values because `Void` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error: unreachable pattern
   --> $DIR/empty-types.rs:143:13
@@ -218,6 +234,7 @@ LL |             Some(_) => {}
    |             ^^^^^^^
    |
    = note: matches no values because `Void` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error: unreachable pattern
   --> $DIR/empty-types.rs:147:13
@@ -253,6 +270,7 @@ LL |             _ => {}
    |             ^
    |
    = note: matches no values because `!` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error: unreachable pattern
   --> $DIR/empty-types.rs:204:13
@@ -261,6 +279,7 @@ LL |             _ => {}
    |             ^
    |
    = note: matches no values because `!` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error: unreachable pattern
   --> $DIR/empty-types.rs:209:13
@@ -269,6 +288,7 @@ LL |             _ => {}
    |             ^
    |
    = note: matches no values because `!` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error: unreachable pattern
   --> $DIR/empty-types.rs:214:13
@@ -277,6 +297,7 @@ LL |             _ => {}
    |             ^
    |
    = note: matches no values because `!` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error: unreachable pattern
   --> $DIR/empty-types.rs:220:13
@@ -285,6 +306,7 @@ LL |             _ => {}
    |             ^
    |
    = note: matches no values because `!` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error: unreachable pattern
   --> $DIR/empty-types.rs:281:9
@@ -293,6 +315,7 @@ LL |         _ => {}
    |         ^
    |
    = note: matches no values because `!` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error: unreachable pattern
   --> $DIR/empty-types.rs:284:9
@@ -301,6 +324,7 @@ LL |         (_, _) => {}
    |         ^^^^^^
    |
    = note: matches no values because `(!, !)` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error: unreachable pattern
   --> $DIR/empty-types.rs:287:9
@@ -309,6 +333,7 @@ LL |         Ok(_) => {}
    |         ^^^^^
    |
    = note: matches no values because `Result<!, !>` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error: unreachable pattern
   --> $DIR/empty-types.rs:288:9
@@ -317,6 +342,7 @@ LL |         Err(_) => {}
    |         ^^^^^^
    |
    = note: matches no values because `Result<!, !>` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error[E0005]: refutable pattern in local binding
   --> $DIR/empty-types.rs:297:13
@@ -472,6 +498,7 @@ LL |         _ => {}
    |         ^
    |
    = note: matches no values because `[!; 3]` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error: unreachable pattern
   --> $DIR/empty-types.rs:371:9
@@ -480,6 +507,7 @@ LL |         [_, _, _] => {}
    |         ^^^^^^^^^
    |
    = note: matches no values because `[!; 3]` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error: unreachable pattern
   --> $DIR/empty-types.rs:374:9
@@ -488,6 +516,7 @@ LL |         [_, ..] => {}
    |         ^^^^^^^
    |
    = note: matches no values because `[!; 3]` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error[E0004]: non-exhaustive patterns: type `[!; 0]` is non-empty
   --> $DIR/empty-types.rs:388:11
@@ -532,6 +561,7 @@ LL |         Some(_) => {}
    |         ^^^^^^^
    |
    = note: matches no values because `!` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error: unreachable pattern
   --> $DIR/empty-types.rs:421:9
@@ -540,6 +570,7 @@ LL |         Some(_a) => {}
    |         ^^^^^^^^
    |
    = note: matches no values because `!` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error: unreachable pattern
   --> $DIR/empty-types.rs:426:9
@@ -656,6 +687,7 @@ LL |         _ => {}
    |         ^
    |
    = note: matches no values because `!` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error: unreachable pattern
   --> $DIR/empty-types.rs:606:9
@@ -664,6 +696,7 @@ LL |         _x => {}
    |         ^^
    |
    = note: matches no values because `!` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error: unreachable pattern
   --> $DIR/empty-types.rs:609:9
@@ -672,6 +705,7 @@ LL |         _ if false => {}
    |         ^
    |
    = note: matches no values because `!` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error: unreachable pattern
   --> $DIR/empty-types.rs:612:9
@@ -680,6 +714,7 @@ LL |         _x if false => {}
    |         ^^
    |
    = note: matches no values because `!` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error[E0004]: non-exhaustive patterns: `&_` not covered
   --> $DIR/empty-types.rs:637:11
diff --git a/tests/ui/pattern/usefulness/explain-unreachable-pats.rs b/tests/ui/pattern/usefulness/explain-unreachable-pats.rs
index bc4abd343ad..746343246c6 100644
--- a/tests/ui/pattern/usefulness/explain-unreachable-pats.rs
+++ b/tests/ui/pattern/usefulness/explain-unreachable-pats.rs
@@ -32,6 +32,7 @@ fn main() {
         Err(_) => {}
         //~^ ERROR unreachable pattern
         //~| NOTE matches no values because `!` is uninhabited
+        //~| NOTE to learn more about uninhabited types, see
     }
 
     #[derive(Copy, Clone)]
@@ -45,12 +46,14 @@ fn main() {
         (Err(_), Err(_)) => {}
         //~^ ERROR unreachable pattern
         //~| NOTE matches no values because `Void2` is uninhabited
+        //~| NOTE to learn more about uninhabited types, see
         _ => {}
     }
     match (res1, &res2) {
         (Err(_), Err(_)) => {}
         //~^ ERROR unreachable pattern
         //~| NOTE matches no values because `Void1` is uninhabited
+        //~| NOTE to learn more about uninhabited types, see
         _ => {}
     }
 
diff --git a/tests/ui/pattern/usefulness/explain-unreachable-pats.stderr b/tests/ui/pattern/usefulness/explain-unreachable-pats.stderr
index da9bf30aa58..0dfd0980050 100644
--- a/tests/ui/pattern/usefulness/explain-unreachable-pats.stderr
+++ b/tests/ui/pattern/usefulness/explain-unreachable-pats.stderr
@@ -38,25 +38,28 @@ LL |         Err(_) => {}
    |         ^^^^^^
    |
    = note: matches no values because `!` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error: unreachable pattern
-  --> $DIR/explain-unreachable-pats.rs:45:9
+  --> $DIR/explain-unreachable-pats.rs:46:9
    |
 LL |         (Err(_), Err(_)) => {}
    |         ^^^^^^^^^^^^^^^^
    |
    = note: matches no values because `Void2` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error: unreachable pattern
-  --> $DIR/explain-unreachable-pats.rs:51:9
+  --> $DIR/explain-unreachable-pats.rs:53:9
    |
 LL |         (Err(_), Err(_)) => {}
    |         ^^^^^^^^^^^^^^^^
    |
    = note: matches no values because `Void1` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error: unreachable pattern
-  --> $DIR/explain-unreachable-pats.rs:60:11
+  --> $DIR/explain-unreachable-pats.rs:63:11
    |
 LL |     if let (0
    |             - matches all the relevant values
@@ -65,13 +68,13 @@ LL |         | 0, _) = (0, 0) {}
    |           ^ no value can reach this
 
 error: unreachable pattern
-  --> $DIR/explain-unreachable-pats.rs:70:9
+  --> $DIR/explain-unreachable-pats.rs:73:9
    |
 LL |         (_, true) => {}
    |         ^^^^^^^^^ no value can reach this
    |
 note: multiple earlier patterns match some of the same values
-  --> $DIR/explain-unreachable-pats.rs:70:9
+  --> $DIR/explain-unreachable-pats.rs:73:9
    |
 LL |         (true, _) => {}
    |         --------- matches some of the same values
@@ -83,7 +86,7 @@ LL |         (_, true) => {}
    |         ^^^^^^^^^ collectively making this unreachable
 
 error: unreachable pattern
-  --> $DIR/explain-unreachable-pats.rs:83:9
+  --> $DIR/explain-unreachable-pats.rs:86:9
    |
 LL |         (true, _) => {}
    |         --------- matches all the relevant values
@@ -92,7 +95,7 @@ LL |         (true, true) => {}
    |         ^^^^^^^^^^^^ no value can reach this
 
 error: unreachable pattern
-  --> $DIR/explain-unreachable-pats.rs:95:9
+  --> $DIR/explain-unreachable-pats.rs:98:9
    |
 LL |         (_, true, 0..10) => {}
    |         ---------------- matches all the relevant values
diff --git a/tests/ui/pattern/usefulness/impl-trait.stderr b/tests/ui/pattern/usefulness/impl-trait.stderr
index 04d6671bb9a..0abfeb5b529 100644
--- a/tests/ui/pattern/usefulness/impl-trait.stderr
+++ b/tests/ui/pattern/usefulness/impl-trait.stderr
@@ -5,6 +5,7 @@ LL |             _ => {}
    |             ^
    |
    = note: matches no values because `Void` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 note: the lint level is defined here
   --> $DIR/impl-trait.rs:4:9
    |
@@ -18,6 +19,7 @@ LL |             _ => {}
    |             ^
    |
    = note: matches no values because `Void` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error: unreachable pattern
   --> $DIR/impl-trait.rs:44:13
@@ -26,6 +28,7 @@ LL |             Some(_) => {}
    |             ^^^^^^^
    |
    = note: matches no values because `Void` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error: unreachable pattern
   --> $DIR/impl-trait.rs:48:13
@@ -42,6 +45,7 @@ LL |             Some(_) => {}
    |             ^^^^^^^
    |
    = note: matches no values because `Void` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error: unreachable pattern
   --> $DIR/impl-trait.rs:62:13
@@ -58,6 +62,7 @@ LL |         _ => {}
    |         ^
    |
    = note: matches no values because `Void` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error: unreachable pattern
   --> $DIR/impl-trait.rs:85:9
@@ -74,6 +79,7 @@ LL |             _ => {}
    |             ^
    |
    = note: matches no values because `Void` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error: unreachable pattern
   --> $DIR/impl-trait.rs:104:9
@@ -98,6 +104,7 @@ LL |             _ => {}
    |             ^
    |
    = note: matches no values because `SecretelyVoid` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error: unreachable pattern
   --> $DIR/impl-trait.rs:150:13
@@ -106,6 +113,7 @@ LL |             _ => {}
    |             ^
    |
    = note: matches no values because `SecretelyDoubleVoid` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error[E0004]: non-exhaustive patterns: type `impl Copy` is non-empty
   --> $DIR/impl-trait.rs:22:11
diff --git a/tests/ui/reachable/unreachable-loop-patterns.stderr b/tests/ui/reachable/unreachable-loop-patterns.stderr
index 9781a976686..f34ca3258ca 100644
--- a/tests/ui/reachable/unreachable-loop-patterns.stderr
+++ b/tests/ui/reachable/unreachable-loop-patterns.stderr
@@ -5,6 +5,7 @@ LL |     for _ in unimplemented!() as Void {}
    |         ^
    |
    = note: matches no values because `Void` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 note: the lint level is defined here
   --> $DIR/unreachable-loop-patterns.rs:3:9
    |
diff --git a/tests/ui/reachable/unreachable-try-pattern.stderr b/tests/ui/reachable/unreachable-try-pattern.stderr
index 83040d35c0f..2ead661a658 100644
--- a/tests/ui/reachable/unreachable-try-pattern.stderr
+++ b/tests/ui/reachable/unreachable-try-pattern.stderr
@@ -20,6 +20,7 @@ LL |     let y = (match x { Ok(n) => Ok(n as u32), Err(e) => Err(e) })?;
    |                        ^^^^^
    |
    = note: matches no values because `!` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 note: the lint level is defined here
   --> $DIR/unreachable-try-pattern.rs:4:9
    |
@@ -33,6 +34,7 @@ LL |     let y = (match x { Ok(n) => Ok(n), Err(e) => Err(e) })?;
    |                                        ^^^^^^
    |
    = note: matches no values because `Void` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 warning: 3 warnings emitted
 
diff --git a/tests/ui/rfcs/rfc-0000-never_patterns/unreachable.stderr b/tests/ui/rfcs/rfc-0000-never_patterns/unreachable.stderr
index be8b38f6942..b7a5f3e5513 100644
--- a/tests/ui/rfcs/rfc-0000-never_patterns/unreachable.stderr
+++ b/tests/ui/rfcs/rfc-0000-never_patterns/unreachable.stderr
@@ -5,6 +5,7 @@ LL |         Err(!),
    |         ^^^^^^
    |
    = note: matches no values because `Void` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 note: the lint level is defined here
   --> $DIR/unreachable.rs:4:9
    |
@@ -18,6 +19,7 @@ LL |     let (Ok(_x) | Err(!)) = res_void;
    |                   ^^^^^^
    |
    = note: matches no values because `Void` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error: unreachable pattern
   --> $DIR/unreachable.rs:19:12
@@ -26,6 +28,7 @@ LL |     if let Err(!) = res_void {}
    |            ^^^^^^
    |
    = note: matches no values because `Void` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error: unreachable pattern
   --> $DIR/unreachable.rs:21:24
@@ -34,6 +37,7 @@ LL |     if let (Ok(true) | Err(!)) = res_void {}
    |                        ^^^^^^
    |
    = note: matches no values because `Void` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error: unreachable pattern
   --> $DIR/unreachable.rs:23:23
@@ -42,6 +46,7 @@ LL |     for (Ok(mut _x) | Err(!)) in [res_void] {}
    |                       ^^^^^^
    |
    = note: matches no values because `Void` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error: unreachable pattern
   --> $DIR/unreachable.rs:27:18
@@ -50,6 +55,7 @@ LL | fn foo((Ok(_x) | Err(!)): Result<bool, Void>) {}
    |                  ^^^^^^
    |
    = note: matches no values because `Void` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error: aborting due to 6 previous errors
 
diff --git a/tests/ui/rfcs/rfc-2008-non-exhaustive/enum_same_crate_empty_match.stderr b/tests/ui/rfcs/rfc-2008-non-exhaustive/enum_same_crate_empty_match.stderr
index 06bc901ffdf..88fab333c74 100644
--- a/tests/ui/rfcs/rfc-2008-non-exhaustive/enum_same_crate_empty_match.stderr
+++ b/tests/ui/rfcs/rfc-2008-non-exhaustive/enum_same_crate_empty_match.stderr
@@ -5,6 +5,7 @@ LL |         _ => {}
    |         ^
    |
    = note: matches no values because `EmptyNonExhaustiveEnum` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 note: the lint level is defined here
   --> $DIR/enum_same_crate_empty_match.rs:1:9
    |
diff --git a/tests/ui/rfcs/rfc-2008-non-exhaustive/uninhabited/patterns_same_crate.stderr b/tests/ui/rfcs/rfc-2008-non-exhaustive/uninhabited/patterns_same_crate.stderr
index 982129046b8..5dbe7a2dc5a 100644
--- a/tests/ui/rfcs/rfc-2008-non-exhaustive/uninhabited/patterns_same_crate.stderr
+++ b/tests/ui/rfcs/rfc-2008-non-exhaustive/uninhabited/patterns_same_crate.stderr
@@ -5,6 +5,7 @@ LL |         Some(_x) => (),
    |         ^^^^^^^^
    |
    = note: matches no values because `UninhabitedEnum` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 note: the lint level is defined here
   --> $DIR/patterns_same_crate.rs:1:9
    |
@@ -18,6 +19,7 @@ LL |         Some(_x) => (),
    |         ^^^^^^^^
    |
    = note: matches no values because `UninhabitedVariants` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error: unreachable pattern
   --> $DIR/patterns_same_crate.rs:60:15
@@ -26,6 +28,7 @@ LL |     while let PartiallyInhabitedVariants::Struct { x } = partially_inhabite
    |               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = note: matches no values because `!` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error: unreachable pattern
   --> $DIR/patterns_same_crate.rs:64:15
@@ -34,6 +37,7 @@ LL |     while let Some(_x) = uninhabited_struct() {
    |               ^^^^^^^^
    |
    = note: matches no values because `UninhabitedStruct` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error: unreachable pattern
   --> $DIR/patterns_same_crate.rs:67:15
@@ -42,6 +46,7 @@ LL |     while let Some(_x) = uninhabited_tuple_struct() {
    |               ^^^^^^^^
    |
    = note: matches no values because `UninhabitedTupleStruct` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error: aborting due to 5 previous errors
 
diff --git a/tests/ui/uninhabited/uninhabited-patterns.stderr b/tests/ui/uninhabited/uninhabited-patterns.stderr
index 4bac1bc52f4..c9b9242384d 100644
--- a/tests/ui/uninhabited/uninhabited-patterns.stderr
+++ b/tests/ui/uninhabited/uninhabited-patterns.stderr
@@ -5,6 +5,7 @@ LL |         Ok(box _) => (),
    |         ^^^^^^^^^
    |
    = note: matches no values because `NotSoSecretlyEmpty` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 note: the lint level is defined here
   --> $DIR/uninhabited-patterns.rs:3:9
    |
@@ -18,6 +19,7 @@ LL |         Err(Ok(_y)) => (),
    |         ^^^^^^^^^^^
    |
    = note: matches no values because `NotSoSecretlyEmpty` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error: unreachable pattern
   --> $DIR/uninhabited-patterns.rs:41:15
@@ -26,6 +28,7 @@ LL |     while let Some(_y) = foo() {
    |               ^^^^^^^^
    |
    = note: matches no values because `NotSoSecretlyEmpty` is uninhabited
+   = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
 
 error: aborting due to 3 previous errors