Kotlin: Add support for varargs

java/ql/lib/config/semmlecode.dbscheme

@@ -694,6 +694,7 @@ case @expr.kind of
 | 78  = @notinstanceofexpr
 | 79  = @stmtexpr
 | 80  = @stringtemplateexpr
+| 81  = @varargexpr
 ;
 
 /** Holds if this `when` expression was written as an `if` expression. */

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

@@ -2267,3 +2267,26 @@ class StringTemplateExpr extends Expr, @stringtemplateexpr {
 
   override string getAPrimaryQlClass() { result = "StringTemplateExpr" }
 }
+
+/**
+ * A Kotlin(TODO: Should Java make these too?) vararg expression.
+ * This is the argument to a function that corresponds to a `vararg`
+ * parameter.
+ */
+class VarArgExpr extends Expr, @varargexpr {
+  /**
+   * Gets the `i`th component of this vararg. TODO: Is this always Expr?
+   *
+   * For example, in the string template `"foo${bar}baz"`, the 0th
+   * component is the string literal `"foo"`, the 1st component is
+   * the variable access `bar`, and the 2nd component is the string
+   * literal `"bar"`.
+   */
+  Expr getComponent(int i) { result.isNthChildOf(this, i) }
+
+  override string toString() { result = "..." }
+
+  override string getHalsteadID() { result = "VarArgExpr" }
+
+  override string getAPrimaryQlClass() { result = "VarArgExpr" }
+}

java/ql/test/kotlin/library-tests/vararg/args.expected

@@ -0,0 +1,7 @@
+| test.kt:13:5:13:34 | funWithOnlyVarArgs(...) | 0 | test.kt:13:24:13:33 | ... |
+| test.kt:14:5:14:50 | funWithArgsAndVarArgs(...) | 0 | test.kt:14:28:14:30 | foo |
+| test.kt:14:5:14:50 | funWithArgsAndVarArgs(...) | 1 | test.kt:14:34:14:37 | true |
+| test.kt:14:5:14:50 | funWithArgsAndVarArgs(...) | 2 | test.kt:14:40:14:49 | ... |
+| test.kt:15:5:15:53 | funWithMiddleVarArgs(...) | 0 | test.kt:15:27:15:29 | foo |
+| test.kt:15:5:15:53 | funWithMiddleVarArgs(...) | 1 | test.kt:15:33:15:42 | ... |
+| test.kt:15:5:15:53 | funWithMiddleVarArgs(...) | 2 | test.kt:15:49:15:52 | true |

java/ql/test/kotlin/library-tests/vararg/args.ql

@@ -0,0 +1,4 @@
+import java
+
+from Call c, int i
+select c, i, c.getArgument(i)

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

@@ -0,0 +1,17 @@
+
+fun funWithOnlyVarArgs(vararg xs: Int) {
+}
+
+fun funWithArgsAndVarArgs(x: String, y: Boolean, vararg xs: Int) {
+}
+
+fun funWithMiddleVarArgs(x: String, vararg xs: Int, y: Boolean) {
+}
+
+fun myFun() {
+    // TODO val xs = listOf(10, 11, 12)
+    funWithOnlyVarArgs(20, 21, 22)
+    funWithArgsAndVarArgs("foo", true, 30, 31, 32)
+    funWithMiddleVarArgs("foo", 41, 42, 43, y = true)
+}
+

java/ql/test/kotlin/library-tests/vararg/varargs.expected

@@ -0,0 +1,9 @@
+| test.kt:13:24:13:33 | ... | 0 | test.kt:13:24:13:25 | 20 |
+| test.kt:13:24:13:33 | ... | 1 | test.kt:13:28:13:29 | 21 |
+| test.kt:13:24:13:33 | ... | 2 | test.kt:13:32:13:33 | 22 |
+| test.kt:14:40:14:49 | ... | 0 | test.kt:14:40:14:41 | 30 |
+| test.kt:14:40:14:49 | ... | 1 | test.kt:14:44:14:45 | 31 |
+| test.kt:14:40:14:49 | ... | 2 | test.kt:14:48:14:49 | 32 |
+| test.kt:15:33:15:42 | ... | 0 | test.kt:15:33:15:34 | 41 |
+| test.kt:15:33:15:42 | ... | 1 | test.kt:15:37:15:38 | 42 |
+| test.kt:15:33:15:42 | ... | 2 | test.kt:15:41:15:42 | 43 |

java/ql/test/kotlin/library-tests/vararg/varargs.ql

@@ -0,0 +1,4 @@
+import java
+
+from VarArgExpr vae, int i
+select vae, i, vae.getComponent(i)