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`

2 files changed, 8 insertions, 5 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]