Rust: Add DerefExpr class.

Author: geoffw0

rust/ql/lib/codeql/rust/elements/DerefExpr.qll

@@ -0,0 +1,13 @@
+/**
+ * Provides classes for deref expressions (`*`).
+ */
+
+private import codeql.rust.elements.PrefixExpr
+private import codeql.rust.elements.Operation
+
+/**
+ * A dereference expression, `*`.
+ */
+final class DerefExpr extends PrefixExpr, Operation {
+  DerefExpr() { this.getOperatorName() = "*" }
+}

rust/ql/lib/rust.qll

@@ -8,6 +8,7 @@ import codeql.rust.elements.ArithmeticOperation
 import codeql.rust.elements.AssignmentOperation
 import codeql.rust.elements.BitwiseOperation
 import codeql.rust.elements.ComparisonOperation
+import codeql.rust.elements.DerefExpr
 import codeql.rust.elements.LiteralExprExt
 import codeql.rust.elements.LogicalOperation
 import codeql.rust.elements.AsyncBlockExpr

rust/ql/test/library-tests/operations/Operations.ql

@@ -45,6 +45,8 @@ string describe(Expr op) {
   op instanceof BinaryBitwiseOperation and result = "BinaryBitwiseOperation"
   or
   op instanceof AssignBitwiseOperation and result = "AssignBitwiseOperation"
+  or
+  op instanceof DerefExpr and result = "DerefExpr"
 }
 
 module OperationsTest implements TestSig {

rust/ql/test/library-tests/operations/test.rs

@@ -49,7 +49,7 @@ fn test_operations(
 	x >>= y; // $ Operation Op=>>= Operands=2 AssignmentOperation BinaryExpr BitwiseOperation AssignBitwiseOperation
 
 	// miscellaneous expressions that might be operations
-	*ptr; // $ Operation Op=* Operands=1 PrefixExpr
+	*ptr; // $ Operation Op=* Operands=1 PrefixExpr DerefExpr
 	&x; // $ RefExpr
 	res?;