add test for #117626

tests/ui/pattern/issue-117626.rs

@@ -0,0 +1,21 @@
+// check-pass
+
+#[derive(PartialEq)]
+struct NonMatchable;
+
+impl Eq for NonMatchable {}
+
+#[derive(PartialEq, Eq)]
+enum Foo {
+    A(NonMatchable),
+    B(*const u8),
+}
+
+const CONST: Foo = Foo::B(std::ptr::null());
+
+fn main() {
+    match CONST {
+        CONST => 0,
+        _ => 1,
+    };
+}