Note we can't prove certain unreachable callables when 'case null' is present

Author: smowton

java/ql/test/library-tests/switch-default-impossible-dispatch/Test.java

@@ -25,7 +25,7 @@ public static void test(int unknown, int alsoUnknown) {
 
     switch(i) {
       case C1 c1 -> { }
-      case null, default -> i.take(source()); // Can't call C1.take
+      case null, default -> i.take(source()); // Can't call C1.take (but we don't currently notice)
     }
 
     switch(i) {
@@ -53,6 +53,11 @@ case WrapperWrapper(Wrapper(String s)) -> { }
       default -> i.take(source()); // Could call any implementation, because this might be a WrapperWrapper(Wrapper((Integer)) for example.
     }
 
+    switch(i) {
+      case C1 c1: break;
+      case null: default: i.take(source()); // Can't call C1.take (but we don't currently notice)
+    }
+
   }
 
 }

java/ql/test/library-tests/switch-default-impossible-dispatch/test.expected

@@ -5,6 +5,7 @@
 | Test.java:23:25:23:32 | source(...) | Test.java:8:65:8:65 | x |
 | Test.java:23:25:23:32 | source(...) | Test.java:9:74:9:74 | x |
 | Test.java:23:25:23:32 | source(...) | Test.java:10:82:10:82 | x |
+| Test.java:28:36:28:43 | source(...) | Test.java:7:65:7:65 | x |
 | Test.java:28:36:28:43 | source(...) | Test.java:8:65:8:65 | x |
 | Test.java:28:36:28:43 | source(...) | Test.java:9:74:9:74 | x |
 | Test.java:28:36:28:43 | source(...) | Test.java:10:82:10:82 | x |
@@ -25,3 +26,7 @@
 | Test.java:53:25:53:32 | source(...) | Test.java:8:65:8:65 | x |
 | Test.java:53:25:53:32 | source(...) | Test.java:9:74:9:74 | x |
 | Test.java:53:25:53:32 | source(...) | Test.java:10:82:10:82 | x |
+| Test.java:58:34:58:41 | source(...) | Test.java:7:65:7:65 | x |
+| Test.java:58:34:58:41 | source(...) | Test.java:8:65:8:65 | x |
+| Test.java:58:34:58:41 | source(...) | Test.java:9:74:9:74 | x |
+| Test.java:58:34:58:41 | source(...) | Test.java:10:82:10:82 | x |