add more tests

Author: lcnr

src/test/ui/impl-trait/in-ctfe/array-len.rs

@@ -1,3 +1,6 @@
+// This previously compiled, but broke with #101478.
+//
+// See that PR for more details.
 trait MyTrait: Copy {
     const ASSOC: usize;
 }

src/test/ui/impl-trait/in-ctfe/enum-discr.rs

@@ -1,3 +1,6 @@
+// This previously compiled, but broke with #101478.
+//
+// See that PR for more details.
 trait MyTrait: Copy {
     const ASSOC: usize;
 }

src/test/ui/impl-trait/in-ctfe/match-arm-exhaustive.rs

@@ -0,0 +1,25 @@
+// This previously compiled, but broke with #101478.
+//
+// See that PR for more details.
+trait MyTrait: Copy {
+    const ASSOC: u8;
+}
+
+impl MyTrait for () {
+    const ASSOC: u8 = 0;
+}
+
+const fn yeet() -> impl MyTrait {}
+
+const fn output<T: MyTrait>(_: T) -> u8 {
+    <T as MyTrait>::ASSOC
+}
+
+const CT: u8 = output(yeet());
+
+fn main() {
+    match 0 {
+        CT => (),
+        1.. => (),
+    }
+}

src/test/ui/impl-trait/in-ctfe/match-arm-exhaustive.stderr

@@ -0,0 +1,14 @@
+error: constant pattern depends on a generic parameter
+  --> $DIR/match-arm-exhaustive.rs:19:9
+   |
+LL |         CT => (),
+   |         ^^
+
+error: constant pattern depends on a generic parameter
+  --> $DIR/match-arm-exhaustive.rs:19:9
+   |
+LL |         CT => (),
+   |         ^^
+
+error: aborting due to 2 previous errors
+