Java: Fix CFG for rule statements.

Author: aschackmull

java/ql/lib/semmle/code/java/ControlFlowGraph.qll

@@ -871,7 +871,13 @@ private module ControlFlowGraphImpl {
     )
     or
     // the last node in a case rule is the last node in the right-hand side
-    last(n.(SwitchCase).getRuleStatement(), last, completion)
+    // if the rhs is a statement we wrap the completion as a break
+    exists(Completion caseCompletion |
+      last(n.(SwitchCase).getRuleStatement(), last, caseCompletion) and
+      if caseCompletion instanceof NormalOrBooleanCompletion
+      then completion = anonymousBreakCompletion()
+      else completion = caseCompletion
+    )
     or
     // ...and if the rhs is an expression we wrap the completion as a yield
     exists(Completion caseCompletion |

java/ql/test/library-tests/guards12/guard.expected

@@ -1,2 +1,6 @@
 | Test.java:5:7:5:17 | case ... | Test.java:3:20:3:20 | s | Test.java:5:12:5:14 | "c" | true | true | Test.java:5:7:5:17 | case ... |
 | Test.java:6:7:6:17 | case ... | Test.java:3:20:3:20 | s | Test.java:6:12:6:14 | "d" | true | true | Test.java:6:7:6:17 | case ... |
+| Test.java:11:7:11:17 | case ... | Test.java:9:13:9:13 | s | Test.java:11:12:11:14 | "c" | true | false | Test.java:13:7:13:16 | default |
+| Test.java:11:7:11:17 | case ... | Test.java:9:13:9:13 | s | Test.java:11:12:11:14 | "c" | true | true | Test.java:11:7:11:17 | case ... |
+| Test.java:12:7:12:17 | case ... | Test.java:9:13:9:13 | s | Test.java:12:12:12:14 | "d" | true | false | Test.java:13:7:13:16 | default |
+| Test.java:12:7:12:17 | case ... | Test.java:9:13:9:13 | s | Test.java:12:12:12:14 | "d" | true | true | Test.java:12:7:12:17 | case ... |