Kotlin: Add support for more type operators

java/ql/lib/config/semmlecode.dbscheme

@@ -667,6 +667,8 @@ case @expr.kind of
 | 74  = @errorexpr
 | 75  = @whenexpr
 | 76  = @getclassexpr
+| 77  = @safecastexpr
+| 78  = @notinstanceofexpr
 ;
 
 /** Holds if this `when` expression was written as an `if` expression. */

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

@@ -448,8 +448,12 @@ private module ControlFlowGraphImpl {
       or
       this instanceof CastExpr
       or
+      this instanceof SafeCastExpr
+      or
       this instanceof InstanceOfExpr and not this.(InstanceOfExpr).isPattern()
       or
+      this instanceof NotInstanceOfExpr
+      or
       this instanceof LocalVariableDeclExpr and
       not this = any(InstanceOfExpr ioe).getLocalVariableDeclExpr()
       or
@@ -526,8 +530,12 @@ private module ControlFlowGraphImpl {
       or
       index = 0 and result = this.(CastExpr).getExpr()
       or
+      index = 0 and result = this.(SafeCastExpr).getExpr()
+      or
       index = 0 and result = this.(InstanceOfExpr).getExpr()
       or
+      index = 0 and result = this.(NotInstanceOfExpr).getExpr()
+      or
       index = 0 and result = this.(LocalVariableDeclExpr).getInit()
       or
       index = 0 and result = this.(RValue).getQualifier() and not result instanceof TypeAccess
@@ -599,6 +607,8 @@ private module ControlFlowGraphImpl {
     or
     result = first(n.(InstanceOfExpr).getExpr())
     or
+    result = first(n.(NotInstanceOfExpr).getExpr())
+    or
     result = first(n.(SynchronizedStmt).getExpr())
     or
     result = n and

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

@@ -123,6 +123,18 @@ class CastConversionContext extends ConversionSite {
   override string kind() { result = "cast context" }
 }
 
+class SafeCastConversionContext extends ConversionSite {
+  SafeCastExpr c;
+
+  CastConversionContext() { this = c.getExpr() }
+
+  override Type getConversionTarget() { result = c.getType() }
+
+  override predicate isImplicit() { none() }
+
+  override string kind() { result = "safe cast context" }
+}
+
 /**
  * A numeric conversion. For example, `a * b` converts `a` and
  * `b` to have an appropriate numeric type.

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

@@ -1152,6 +1152,21 @@ class CastExpr extends Expr, @castexpr {
   override string getAPrimaryQlClass() { result = "CastExpr" }
 }
 
+// TODO: Would this be better as a predicate on CastExpr?
+/** A safe cast expression. */
+class SafeCastExpr extends Expr, @safecastexpr {
+  /** Gets the target type of this cast expression. */
+  Expr getTypeExpr() { result.isNthChildOf(this, 0) }
+
+  /** Gets the expression to which the cast operator is applied. */
+  Expr getExpr() { result.isNthChildOf(this, 1) }
+
+  /** Gets a printable representation of this expression. */
+  override string toString() { result = "... as? ..." }
+
+  override string getAPrimaryQlClass() { result = "SafeCastExpr" }
+}
+
 /** A class instance creation expression. */
 class ClassInstanceExpr extends Expr, ConstructorCall, @classinstancexpr {
   /** Gets the number of arguments provided to the constructor of the class instance creation expression. */
@@ -1442,6 +1457,28 @@ class InstanceOfExpr extends Expr, @instanceofexpr {
   override string getAPrimaryQlClass() { result = "InstanceOfExpr" }
 }
 
+// TODO: Should this be desugared into instanceof.not()?
+// Note expressions/IrTypeOperatorCall.kt says:
+//     NOT_INSTANCEOF, // TODO drop and replace with `INSTANCEOF<T>(x).not()`?
+/** An `instanceof` expression. */
+class NotInstanceOfExpr extends Expr, @notinstanceofexpr {
+  /** Gets the expression on the left-hand side of the `!is` operator. */
+  Expr getExpr() {
+    result.isNthChildOf(this, 0)
+  }
+
+  /** Gets the access to the type on the right-hand side of the `!is` operator. */
+  Expr getTypeName() { result.isNthChildOf(this, 1) }
+
+  /** Gets the type this `!is` expression checks for. */
+  RefType getCheckedType() { result = getTypeName().getType() }
+
+  /** Gets a printable representation of this expression. */
+  override string toString() { result = "... !is ..." }
+
+  override string getAPrimaryQlClass() { result = "NotInstanceOfExpr" }
+}
+
 /**
  * A local variable declaration expression.
  *

java/ql/lib/semmle/code/java/dataflow/RangeAnalysis.qll

@@ -360,8 +360,8 @@ private predicate safeCast(Type fromtyp, Type totyp) {
 /**
  * A cast that can be ignored for the purpose of range analysis.
  */
-private class SafeCastExpr extends CastExpr {
-  SafeCastExpr() { safeCast(getExpr().getType(), getType()) }
+private class RangeAnalysisSafeCastExpr extends CastExpr {
+  RangeAnalysisSafeCastExpr() { safeCast(getExpr().getType(), getType()) }
 }
 
 /**
@@ -382,7 +382,7 @@ private predicate typeBound(Type typ, int lowerbound, int upperbound) {
  */
 private class NarrowingCastExpr extends CastExpr {
   NarrowingCastExpr() {
-    not this instanceof SafeCastExpr and
+    not this instanceof RangeAnalysisSafeCastExpr and
     typeBound(getType(), _, _)
   }
 
@@ -412,7 +412,7 @@ private predicate boundFlowStep(Expr e2, Expr e1, int delta, boolean upper) {
   valueFlowStep(e2, e1, delta) and
   (upper = true or upper = false)
   or
-  e2.(SafeCastExpr).getExpr() = e1 and
+  e2.(RangeAnalysisSafeCastExpr).getExpr() = e1 and
   delta = 0 and
   (upper = true or upper = false)
   or

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

@@ -54,8 +54,15 @@
 | exprs.kt:40:5:40:22 | b6 | LocalVariableDeclExpr |
 | exprs.kt:40:14:40:15 | i1 | VarAccess |
 | exprs.kt:40:14:40:22 | ...instanceof... | InstanceOfExpr |
+| exprs.kt:40:14:40:22 | int | TypeAccess |
 | exprs.kt:41:5:41:23 | b7 | LocalVariableDeclExpr |
+| exprs.kt:41:14:41:15 | i1 | VarAccess |
+| exprs.kt:41:14:41:23 | ... !is ... | NotInstanceOfExpr |
+| exprs.kt:41:14:41:23 | int | TypeAccess |
 | exprs.kt:42:5:42:26 | b8 | LocalVariableDeclExpr |
+| exprs.kt:42:14:42:15 | b7 | VarAccess |
+| exprs.kt:42:14:42:26 | (...)... | CastExpr |
+| exprs.kt:42:14:42:26 | boolean | TypeAccess |
 | exprs.kt:43:5:43:35 | str1 | LocalVariableDeclExpr |
 | exprs.kt:43:25:43:34 | string lit | StringLiteral |
 | exprs.kt:44:5:44:36 | str2 | LocalVariableDeclExpr |
@@ -74,4 +81,3 @@
 | exprs.kt:53:9:53:18 | n | VarAccess |
 | exprs.kt:54:27:54:31 | new C(...) | ClassInstanceExpr |
 | exprs.kt:54:29:54:30 | 42 | IntegerLiteral |
-| file://:0:0:0:0 | int | TypeAccess |