Rollup merge of #144545 - ChayimFriedman2:bool-witness-order, r=Nadrieril

In rustc_pattern_analysis, put `true` witnesses before `false` witnesses

In rustc it doesn't really matter what the order of the witnesses is, but I'm planning to use the witnesses for implementing the "add missing match arms" assist in rust-analyzer, and there `true` before `false` is the natural order (like `Some` before `None`), and also what the current assist does.

The current order doesn't seem to be intentional; the code was created when bool ctors became their own thing, not just int ctors, but for integer, 0 before 1 is indeed the natural order.

r? `@Nadrieril`

6 files changed, 15 insertions, 12 deletions

diff --git a/compiler/rustc_pattern_analysis/src/constructor.rs b/compiler/rustc_pattern_analysis/src/constructor.rs
index 9a9e0db964c..12f653a1337 100644
--- a/compiler/rustc_pattern_analysis/src/constructor.rs
+++ b/compiler/rustc_pattern_analysis/src/constructor.rs
@@ -1130,16 +1130,16 @@ impl<Cx: PatCx> ConstructorSet<Cx> {
                         seen_false = true;
                     }
                 }
-                if seen_false {
-                    present.push(Bool(false));
-                } else {
-                    missing.push(Bool(false));
-                }
                 if seen_true {
                     present.push(Bool(true));
                 } else {
                     missing.push(Bool(true));
                 }
+                if seen_false {
+                    present.push(Bool(false));
+                } else {
+                    missing.push(Bool(false));
+                }
             }
             ConstructorSet::Integers { range_1, range_2 } => {
                 let seen_ranges: Vec<_> =
diff --git a/compiler/rustc_pattern_analysis/tests/exhaustiveness.rs b/compiler/rustc_pattern_analysis/tests/exhaustiveness.rs
index 14ca0d057f0..4ad64f81560 100644
--- a/compiler/rustc_pattern_analysis/tests/exhaustiveness.rs
+++ b/compiler/rustc_pattern_analysis/tests/exhaustiveness.rs
@@ -176,6 +176,9 @@ fn test_witnesses() {
         ),
         vec!["Enum::Variant1(_)", "Enum::Variant2(_)", "_"],
     );
+
+    // Assert we put `true` before `false`.
+    assert_witnesses(AllOfThem, Ty::Bool, Vec::new(), vec!["true", "false"]);
 }
 
 #[test]
diff --git a/tests/ui/pattern/deref-patterns/usefulness/non-exhaustive.rs b/tests/ui/pattern/deref-patterns/usefulness/non-exhaustive.rs
index 704cae8bdbc..bab6308223e 100644
--- a/tests/ui/pattern/deref-patterns/usefulness/non-exhaustive.rs
+++ b/tests/ui/pattern/deref-patterns/usefulness/non-exhaustive.rs
@@ -15,7 +15,7 @@ fn main() {
     }
 
     match Box::new((true, Box::new(false))) {
-        //~^ ERROR non-exhaustive patterns: `deref!((false, deref!(false)))` and `deref!((true, deref!(true)))` not covered
+        //~^ ERROR non-exhaustive patterns: `deref!((true, deref!(true)))` and `deref!((false, deref!(false)))` not covered
         (true, false) => {}
         (false, true) => {}
     }
diff --git a/tests/ui/pattern/deref-patterns/usefulness/non-exhaustive.stderr b/tests/ui/pattern/deref-patterns/usefulness/non-exhaustive.stderr
index 55fa84bafde..a1abd5f0e3f 100644
--- a/tests/ui/pattern/deref-patterns/usefulness/non-exhaustive.stderr
+++ b/tests/ui/pattern/deref-patterns/usefulness/non-exhaustive.stderr
@@ -28,11 +28,11 @@ LL ~         true => {},
 LL +         deref!(deref!(false)) => todo!()
    |
 
-error[E0004]: non-exhaustive patterns: `deref!((false, deref!(false)))` and `deref!((true, deref!(true)))` not covered
+error[E0004]: non-exhaustive patterns: `deref!((true, deref!(true)))` and `deref!((false, deref!(false)))` not covered
   --> $DIR/non-exhaustive.rs:17:11
    |
 LL |     match Box::new((true, Box::new(false))) {
-   |           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ patterns `deref!((false, deref!(false)))` and `deref!((true, deref!(true)))` not covered
+   |           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ patterns `deref!((true, deref!(true)))` and `deref!((false, deref!(false)))` not covered
    |
 note: `Box<(bool, Box<bool>)>` defined here
   --> $SRC_DIR/alloc/src/boxed.rs:LL:COL
@@ -40,7 +40,7 @@ note: `Box<(bool, Box<bool>)>` defined here
 help: ensure that all possible cases are being handled by adding a match arm with a wildcard pattern, a match arm with multiple or-patterns as shown, or multiple match arms
    |
 LL ~         (false, true) => {},
-LL +         deref!((false, deref!(false))) | deref!((true, deref!(true))) => todo!()
+LL +         deref!((true, deref!(true))) | deref!((false, deref!(false))) => todo!()
    |
 
 error[E0004]: non-exhaustive patterns: `deref!((deref!(T::C), _))` not covered
diff --git a/tests/ui/pattern/usefulness/unions.rs b/tests/ui/pattern/usefulness/unions.rs
index 80a7f36a09a..3de79c6f849 100644
--- a/tests/ui/pattern/usefulness/unions.rs
+++ b/tests/ui/pattern/usefulness/unions.rs
@@ -26,7 +26,7 @@ fn main() {
         }
         // Our approach can report duplicate witnesses sometimes.
         match (x, true) {
-            //~^ ERROR non-exhaustive patterns: `(U8AsBool { n: 0_u8 }, false)`, `(U8AsBool { b: false }, false)`, `(U8AsBool { n: 0_u8 }, false)` and 1 more not covered
+            //~^ ERROR non-exhaustive patterns: `(U8AsBool { n: 0_u8 }, false)`, `(U8AsBool { b: true }, false)`, `(U8AsBool { n: 0_u8 }, false)` and 1 more not covered
             (U8AsBool { b: true }, true) => {}
             (U8AsBool { b: false }, true) => {}
             (U8AsBool { n: 1.. }, true) => {}
diff --git a/tests/ui/pattern/usefulness/unions.stderr b/tests/ui/pattern/usefulness/unions.stderr
index 4b397dc25db..98fb6a33ae4 100644
--- a/tests/ui/pattern/usefulness/unions.stderr
+++ b/tests/ui/pattern/usefulness/unions.stderr
@@ -16,11 +16,11 @@ LL ~             U8AsBool { n: 1.. } => {},
 LL +             U8AsBool { n: 0_u8 } | U8AsBool { b: false } => todo!()
    |
 
-error[E0004]: non-exhaustive patterns: `(U8AsBool { n: 0_u8 }, false)`, `(U8AsBool { b: false }, false)`, `(U8AsBool { n: 0_u8 }, false)` and 1 more not covered
+error[E0004]: non-exhaustive patterns: `(U8AsBool { n: 0_u8 }, false)`, `(U8AsBool { b: true }, false)`, `(U8AsBool { n: 0_u8 }, false)` and 1 more not covered
   --> $DIR/unions.rs:28:15
    |
 LL |         match (x, true) {
-   |               ^^^^^^^^^ patterns `(U8AsBool { n: 0_u8 }, false)`, `(U8AsBool { b: false }, false)`, `(U8AsBool { n: 0_u8 }, false)` and 1 more not covered
+   |               ^^^^^^^^^ patterns `(U8AsBool { n: 0_u8 }, false)`, `(U8AsBool { b: true }, false)`, `(U8AsBool { n: 0_u8 }, false)` and 1 more not covered
    |
    = note: the matched value is of type `(U8AsBool, bool)`
 help: ensure that all possible cases are being handled by adding a match arm with a wildcard pattern as shown, or multiple match arms