Merge pull request #10678 from tamasvajk/kotlin-type-param-modifiers

Kotlin: Extract type parameter modifiers (`reified`, `in`, `out`)

java/downgrades/709f1d1fd04ffd9bbcf242f17b120f8a389949bd/hasModifier.ql

@@ -0,0 +1,19 @@
+class Modifier extends @modifier {
+  string toString() { none() }
+}
+
+class TypeVariable extends @typevariable {
+  string toString() { none() }
+}
+
+class Modified extends @modifiable {
+  Modified() { hasModifier(this, _) }
+
+  string toString() { none() }
+}
+
+from Modified m1, Modifier m2
+where
+  hasModifier(m1, m2) and
+  not m1 instanceof TypeVariable
+select m1, m2

java/downgrades/709f1d1fd04ffd9bbcf242f17b120f8a389949bd/modifiers.ql

@@ -0,0 +1,11 @@
+class Modifier extends @modifier {
+  string toString() { none() }
+
+  string getName() { modifiers(this, result) }
+}
+
+from Modifier m, string s
+where
+  s = m.getName() and
+  not s in ["in", "out", "reified"]
+select m, m.getName()

java/downgrades/709f1d1fd04ffd9bbcf242f17b120f8a389949bd/upgrade.properties

@@ -0,0 +1,4 @@
+description: Remove type parameters from modifiable entities
+compatibility: backwards
+hasModifier.rel: run hasModifier.qlo
+modifiers.rel: run modifiers.qlo

java/kotlin-extractor/src/main/kotlin/KotlinFileExtractor.kt

@@ -206,6 +206,16 @@ open class KotlinFileExtractor(
                 }
             }
 
+            if (tp.isReified) {
+                addModifiers(id, "reified")
+            }
+
+            if (tp.variance == Variance.IN_VARIANCE) {
+                addModifiers(id, "in")
+            } else if (tp.variance == Variance.OUT_VARIANCE) {
+                addModifiers(id, "out")
+            }
+
             return id
         }
     }

java/ql/lib/change-notes/2022-10-11-modifiable-type-variable.md

@@ -0,0 +1,4 @@
+---
+category: minorAnalysis
+---
+* The class `TypeVariable` now also extends `Modifiable`.

java/ql/lib/config/semmlecode.dbscheme

@@ -1033,7 +1033,7 @@ javadocText(
                     @boundedtype | @array | @localvar | @expr | @stmt | @import | @fielddecl | @kt_type | @kt_type_alias |
                     @kt_property;
 
-@modifiable = @member_modifiable| @param | @localvar ;
+@modifiable = @member_modifiable| @param | @localvar | @typevariable;
 
 @member_modifiable = @class | @interface | @method | @constructor | @field | @kt_property;
 

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

@@ -137,7 +137,7 @@ abstract class BoundedType extends RefType, @boundedtype {
  * For example, `T` is a type parameter in
  * `class X<T> { }` and in `<T> void m() { }`.
  */
-class TypeVariable extends BoundedType, @typevariable {
+class TypeVariable extends BoundedType, Modifiable, @typevariable {
   /** Gets the generic type that is parameterized by this type parameter, if any. */
   GenericType getGenericType() { typeVars(this, _, _, _, result) }
 

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

@@ -96,4 +96,13 @@ abstract class Modifiable extends Element {
 
   /** Holds if this element has a `lateinit` modifier. */
   predicate isLateinit() { this.hasModifier("lateinit") }
+
+  /** Holds if this element has a `reified` modifier. */
+  predicate isReified() { this.hasModifier("reified") }
+
+  /** Holds if this element has an `in` modifier. */
+  predicate isIn() { this.hasModifier("in") }
+
+  /** Holds if this element has an `out` modifier. */
+  predicate isOut() { this.hasModifier("out") }
 }

java/ql/lib/upgrades/ecb42310286011ada450ff65b9b417509863549f/upgrade.properties

@@ -0,0 +1,2 @@
+description: Make type parameters modifiable
+compatibility: backwards

java/ql/test/kotlin/library-tests/modifiers/modifiers.expected

@@ -1,5 +1,5 @@
-| modifiers.kt:1:1:28:1 | X | Class | public |
-| modifiers.kt:1:6:28:1 | X | Constructor | public |
+| modifiers.kt:1:1:29:1 | X | Class | public |
+| modifiers.kt:1:6:29:1 | X | Constructor | public |
 | modifiers.kt:2:5:2:21 | a | Field | final |
 | modifiers.kt:2:5:2:21 | a | Field | private |
 | modifiers.kt:2:5:2:21 | a | Property | private |
@@ -45,13 +45,26 @@
 | modifiers.kt:27:12:27:49 | fn5 | Method | inline |
 | modifiers.kt:27:12:27:49 | fn5 | Method | public |
 | modifiers.kt:27:20:27:44 | f | Parameter | crossinline |
-| modifiers.kt:30:1:36:1 | LateInit | Class | final |
-| modifiers.kt:30:1:36:1 | LateInit | Class | public |
-| modifiers.kt:30:8:36:1 | LateInit | Constructor | public |
-| modifiers.kt:31:5:31:40 | test0 | Field | private |
-| modifiers.kt:31:5:31:40 | test0 | Property | lateinit |
-| modifiers.kt:31:5:31:40 | test0 | Property | private |
-| modifiers.kt:31:22:31:40 | getTest0$private | Method | private |
-| modifiers.kt:31:22:31:40 | setTest0$private | Method | private |
-| modifiers.kt:33:5:35:5 | fn | Method | public |
-| modifiers.kt:34:9:34:36 | LateInit test1 | LocalVariableDecl | lateinit |
+| modifiers.kt:28:12:28:39 | fn6 | Method | inline |
+| modifiers.kt:28:12:28:39 | fn6 | Method | public |
+| modifiers.kt:28:17:28:25 | T | TypeVariable | reified |
+| modifiers.kt:31:1:33:1 | Y | Class | final |
+| modifiers.kt:31:1:33:1 | Y | Class | public |
+| modifiers.kt:31:1:33:1 | Y | Constructor | public |
+| modifiers.kt:31:1:33:1 | Y | GenericType | final |
+| modifiers.kt:31:1:33:1 | Y | GenericType | public |
+| modifiers.kt:31:1:33:1 | Y | ParameterizedType | final |
+| modifiers.kt:31:1:33:1 | Y | ParameterizedType | public |
+| modifiers.kt:31:9:31:13 | T1 | TypeVariable | in |
+| modifiers.kt:31:16:31:21 | T2 | TypeVariable | out |
+| modifiers.kt:32:5:32:32 | foo | Method | public |
+| modifiers.kt:35:1:41:1 | LateInit | Class | final |
+| modifiers.kt:35:1:41:1 | LateInit | Class | public |
+| modifiers.kt:35:8:41:1 | LateInit | Constructor | public |
+| modifiers.kt:36:5:36:40 | test0 | Field | private |
+| modifiers.kt:36:5:36:40 | test0 | Property | lateinit |
+| modifiers.kt:36:5:36:40 | test0 | Property | private |
+| modifiers.kt:36:22:36:40 | getTest0$private | Method | private |
+| modifiers.kt:36:22:36:40 | setTest0$private | Method | private |
+| modifiers.kt:38:5:40:5 | fn | Method | public |
+| modifiers.kt:39:9:39:36 | LateInit test1 | LocalVariableDecl | lateinit |

java/ql/test/kotlin/library-tests/modifiers/modifiers.kt

@@ -25,6 +25,11 @@ open class X {
 
     inline fun fn4(noinline f: () -> Unit) { }
     inline fun fn5(crossinline f: () -> Unit) { }
+    inline fun <reified T> fn6(x: T) {}
+}
+
+class Y<in T1, out T2> {
+    fun foo(t: T1) : T2 = null!!
 }
 
 public class LateInit {