Kotlin: Add FP test case for dead code queries

Author: tamasvajk

java/ql/src/DeadCode/DeadClass.ql

@@ -14,6 +14,8 @@ import semmle.code.java.deadcode.DeadCode
 
 from DeadClass c, Element origin, string reason
 where
+  not c.getFile().isKotlinSourceFile() and
+  not origin.getFile().isKotlinSourceFile() and
   if exists(DeadRoot root | root = c.getADeadRoot() | not root = c.getACallable())
   then (
     // Report a list of the dead roots.

java/ql/src/DeadCode/DeadField.ql

@@ -15,6 +15,8 @@ import semmle.code.java.deadcode.DeadCode
 
 from DeadField f, Element origin, string reason
 where
+  not f.getFile().isKotlinSourceFile() and
+  not origin.getFile().isKotlinSourceFile() and
   not f.isInDeadScope() and
   if f.getAnAccess() instanceof FieldRead
   then (

java/ql/src/DeadCode/DeadMethod.ql

@@ -15,6 +15,8 @@ import semmle.code.java.deadcode.DeadCode
 
 from DeadMethod c, Callable origin, string reason
 where
+  not c.getFile().isKotlinSourceFile() and
+  not origin.getFile().isKotlinSourceFile() and
   not c.isInDeadScope() and
   if exists(DeadRoot deadRoot | deadRoot = getADeadRoot(c) | deadRoot.getSourceDeclaration() != c)
   then (

java/ql/test/kotlin/query-tests/DeadCode/DeadClass.expected

@@ -0,0 +1,4 @@
+| Test.kt:0:0:0:0 | TestKt | The class TestKt is entirely unused. | Test.kt:0:0:0:0 | TestKt | TestKt |
+| Test.kt:1:1:1:26 | DbAddexpr | The class DbAddexpr is entirely unused. | Test.kt:1:1:1:26 | DbAddexpr | DbAddexpr |
+| Test.kt:3:1:4:1 | Label | The class Label is only used from dead code originating at $@. | Test.kt:15:1:17:1 | main1 | main1 |
+| Test.kt:19:1:27:1 | Foo | The class Foo is only used from dead code originating at $@. | Test.kt:29:1:31:1 | main2 | main2 |

java/ql/test/kotlin/query-tests/DeadCode/DeadClass.qlref

@@ -0,0 +1 @@
+DeadCode/DeadClass.ql

java/ql/test/kotlin/query-tests/DeadCode/DeadMethod.expected

@@ -0,0 +1,8 @@
+| Test.kt:0:0:0:0 | component1 | The method component1 is entirely unused. | Test.kt:0:0:0:0 | component1 | component1 |
+| Test.kt:0:0:0:0 | component2 | The method component2 is entirely unused. | Test.kt:0:0:0:0 | component2 | component2 |
+| Test.kt:0:0:0:0 | copy | The method copy is only used from dead code originating at $@. | Test.kt:0:0:0:0 | copy$default | copy$default |
+| Test.kt:0:0:0:0 | copy$default | The method copy$default is entirely unused. | Test.kt:0:0:0:0 | copy$default | copy$default |
+| Test.kt:20:10:20:41 | DC | The method DC is only used from dead code originating at $@. | Test.kt:0:0:0:0 | copy$default | copy$default |
+| Test.kt:20:10:20:41 | DC | The method DC is only used from dead code originating at $@. | Test.kt:29:1:31:1 | main2 | main2 |
+| Test.kt:20:19:20:28 | getX | The method getX is only used from dead code originating at $@. | Test.kt:29:1:31:1 | main2 | main2 |
+| Test.kt:20:31:20:40 | getY | The method getY is only used from dead code originating at $@. | Test.kt:29:1:31:1 | main2 | main2 |

java/ql/test/kotlin/query-tests/DeadCode/DeadMethod.qlref

@@ -0,0 +1 @@
+DeadCode/DeadMethod.ql

java/ql/test/kotlin/query-tests/DeadCode/Test.kt

@@ -0,0 +1,31 @@
+sealed interface DbAddexpr
+
+class Label<T> {
+}
+
+fun <T> getFreshIdLabel(): Label<T> {
+    return Label()
+}
+
+fun foo(): Label<DbAddexpr> {
+    val x = getFreshIdLabel<DbAddexpr>()
+    return x
+}
+
+fun main1() {
+    print(foo())
+}
+
+class Foo {
+    data class DC(val x: Int, val y: Int)
+
+    fun foo() {
+        val dc = DC(3, 4)
+        print(dc.x)
+        print(dc.y)
+    }
+}
+
+fun main2() {
+    Foo().foo()
+}