Java: account for generic exceptions in java/unreachable-catch-clause

Author: yh-semmle

java/ql/src/Likely Bugs/Statements/PartiallyMaskedCatch.ql

@@ -47,7 +47,10 @@ RefType getAThrownExceptionType(TryStmt t) {
     t.getBlock() = call.getEnclosingStmt().getParent*() or
     t.getAResourceDecl() = call.getEnclosingStmt()
     |
-    call.getCallee().getAnException() = e and
+    (
+      call.getCallee().getAnException() = e or
+      call.(GenericCall).getATypeArgument(call.getCallee().getAnException().getType()) = e.getType()
+    ) and
     not caughtInside(t, call.getEnclosingStmt(), e.getType()) and
     result = e.getType()
   ) or

java/ql/test/query-tests/PartiallyMaskedCatch/PartiallyMaskedCatchTest.java

@@ -68,6 +68,14 @@ public static void method() {
 		} catch (IOException e) {
 			// reachable: IOException is thrown by getClosableThing()
 		}
+
+		try (ClosableThing thing = new ClosableThing()) {
+			genericThrowingMethod(IOException.class);
+		} catch (ExceptionA e) {
+			// reachable: ExceptionA is thrown by implicit invocation of CloseableThing.close()
+		} catch (IOException e) {
+			// reachable: IOException is thrown by invocation of genericThrowingMethod(IOException.class)
+		}
 	}
 
 	public static ClosableThing getClosableThing() throws IOException {
@@ -94,4 +102,6 @@ public static void throwingMethod()
 			throws ClassNotFoundException,
 			NoSuchMethodException, InstantiationException, IllegalAccessException,
 			InvocationTargetException {}
+
+	public static <E extends Exception> void genericThrowingMethod(Class<E> c) throws E {}
 }