C#: Add compound assignment operator QL classes.

csharp/ql/lib/semmle/code/csharp/Callable.qll

@@ -611,7 +611,8 @@ class ExtensionOperator extends ExtensionCallableImpl, Operator {
 class UnaryOperator extends Operator {
   UnaryOperator() {
     this.getNumberOfParameters() = 1 and
-    not this instanceof ConversionOperator
+    not this instanceof ConversionOperator and
+    not this instanceof CompoundAssignmentOperator
   }
 }
 
@@ -784,7 +785,7 @@ class TrueOperator extends UnaryOperator {
  * A user-defined binary operator.
  *
  * Either an addition operator (`AddOperator`), a checked addition operator
- * (`CheckedAddOperator`) a subtraction operator (`SubOperator`), a checked
+ * (`CheckedAddOperator`), a subtraction operator (`SubOperator`), a checked
  * subtraction operator (`CheckedSubOperator`), a multiplication operator
  * (`MulOperator`), a checked multiplication operator (`CheckedMulOperator`),
  * a division operator (`DivOperator`), a checked division operator
@@ -795,10 +796,16 @@ class TrueOperator extends UnaryOperator {
  * operator(`UnsignedRightShiftOperator`), an equals operator (`EQOperator`),
  * a not equals operator (`NEOperator`), a lesser than operator (`LTOperator`),
  * a greater than operator (`GTOperator`), a less than or equals operator
- * (`LEOperator`), or a greater than or equals operator (`GEOperator`).
+ * (`LEOperator`), a greater than or equals operator (`GEOperator`), or
+ * a compound assignment operator (`CompoundAssignmentOperator`).
  */
 class BinaryOperator extends Operator {
-  BinaryOperator() { this.getNumberOfParameters() = 2 }
+  BinaryOperator() {
+    this.getNumberOfParameters() = 2
+    or
+    // Instance compound assignment operators only have one parameter.
+    this.getNumberOfParameters() = 1 and not this.isStatic()
+  }
 }
 
 /**
@@ -1184,6 +1191,249 @@ class CheckedExplicitConversionOperator extends ConversionOperator {
   override string getAPrimaryQlClass() { result = "CheckedExplicitConversionOperator" }
 }
 
+abstract private class CompoundAssignmentOperatorImpl extends BinaryOperator { }
+
+/**
+ * A user-defined compound assignment operator.
+ *
+ * Either an addition operator (`AddCompoundAssignmentOperator`), a checked addition operator
+ * (`CheckedAddCompoundAssignmentOperator`), a subtraction operator (`SubCompoundAssignmentOperator`), a checked
+ * subtraction operator (`CheckedSubCompoundAssignmentOperator`), a multiplication operator
+ * (`MulCompoundAssignmentOperator`), a checked multiplication operator (`CheckedMulCompoundAssignmentOperator`),
+ * a division operator (`DivCompoundAssignmentOperator`), a checked division operator
+ * (`CheckedDivCompoundAssignmentOperator`), a remainder operator (`RemCompoundAssignmentOperator`), an and
+ * operator (`AndCompoundAssignmentOperator`), an or operator (`OrCompoundAssignmentOperator`), an xor
+ * operator (`XorCompoundAssignmentOperator`), a left shift operator (`LeftShiftCompoundAssignmentOperator`),
+ * a right shift operator (`RightShiftCompoundAssignmentOperator`), or an unsigned right shift
+ * operator(`UnsignedRightShiftCompoundAssignmentOperator`).
+ */
+final class CompoundAssignmentOperator = CompoundAssignmentOperatorImpl;
+
+/**
+ * A user-defined compound assignment addition operator (`+=`), for example
+ *
+ * ```csharp
+ * public void operator checked +=(Widget w) {
+ *   ...
+ * }
+ * ```
+ */
+class AddCompoundAssignmentOperator extends CompoundAssignmentOperatorImpl {
+  AddCompoundAssignmentOperator() { this.getName() = "+=" }
+
+  override string getAPrimaryQlClass() { result = "AddCompoundAssignmentOperator" }
+}
+
+/**
+ * A user-defined checked compound assignment addition operator (`checked +=`), for example
+ *
+ * ```csharp
+ * public void operator checked +=(Widget w) {
+ *   ...
+ * }
+ * ```
+ */
+class CheckedAddCompoundAssignmentOperator extends CompoundAssignmentOperatorImpl {
+  CheckedAddCompoundAssignmentOperator() { this.getName() = "checked +=" }
+
+  override string getAPrimaryQlClass() { result = "CheckedAddCompoundAssignmentOperator" }
+}
+
+/**
+ * A user-defined compound assignment subtraction operator (`-=`), for example
+ *
+ * ```csharp
+ * public void operator -=(Widget w) {
+ *   ...
+ * }
+ * ```
+ */
+class SubCompoundAssignmentOperator extends CompoundAssignmentOperatorImpl {
+  SubCompoundAssignmentOperator() { this.getName() = "-=" }
+
+  override string getAPrimaryQlClass() { result = "SubCompoundAssignmentOperator" }
+}
+
+/**
+ * A user-defined checked compound assignment subtraction operator (`checked -=`), for example
+ *
+ * ```csharp
+ * public void operator checked -=(Widget w) {
+ *   ...
+ * }
+ * ```
+ */
+class CheckedSubCompoundAssignmentOperator extends CompoundAssignmentOperatorImpl {
+  CheckedSubCompoundAssignmentOperator() { this.getName() = "checked -=" }
+
+  override string getAPrimaryQlClass() { result = "CheckedSubCompoundAssignmentOperator" }
+}
+
+/**
+ * A user-defined compound assignment multiplication operator (`*=`), for example
+ *
+ * ```csharp
+ * public void operator *=(Widget w) {
+ *   ...
+ * }
+ * ```
+ */
+class MulCompoundAssignmentOperator extends CompoundAssignmentOperatorImpl {
+  MulCompoundAssignmentOperator() { this.getName() = "*=" }
+
+  override string getAPrimaryQlClass() { result = "MulCompoundAssignmentOperator" }
+}
+
+/**
+ * A user-defined checked compound assignment multiplication operator (`checked *=`), for example
+ *
+ * ```csharp
+ * public void operator checked *=(Widget w) {
+ *   ...
+ * }
+ * ```
+ */
+class CheckedMulCompoundAssignmentOperator extends CompoundAssignmentOperatorImpl {
+  CheckedMulCompoundAssignmentOperator() { this.getName() = "checked *=" }
+
+  override string getAPrimaryQlClass() { result = "CheckedMulCompoundAssignmentOperator" }
+}
+
+/**
+ * A user-defined compound assignment division operator (`/=`), for example
+ *
+ * ```csharp
+ * public void operator /=(Widget w) {
+ *   ...
+ * }
+ * ```
+ */
+class DivCompoundAssignmentOperator extends CompoundAssignmentOperatorImpl {
+  DivCompoundAssignmentOperator() { this.getName() = "/=" }
+
+  override string getAPrimaryQlClass() { result = "DivCompoundAssignmentOperator" }
+}
+
+/**
+ * A user-defined checked compound assignment division operator (`checked /=`), for example
+ *
+ * ```csharp
+ * public void operator checked /=(Widget w) {
+ *   ...
+ * }
+ * ```
+ */
+class CheckedDivCompoundAssignmentOperator extends CompoundAssignmentOperatorImpl {
+  CheckedDivCompoundAssignmentOperator() { this.getName() = "checked /=" }
+
+  override string getAPrimaryQlClass() { result = "CheckedDivCompoundAssignmentOperator" }
+}
+
+/**
+ * A user-defined compound assignment remainder operator (`%=`), for example
+ *
+ * ```csharp
+ * public void operator %=(Widget w) {
+ *   ...
+ * }
+ * ```
+ */
+class RemCompoundAssignmentOperator extends CompoundAssignmentOperatorImpl {
+  RemCompoundAssignmentOperator() { this.getName() = "%=" }
+
+  override string getAPrimaryQlClass() { result = "RemCompoundAssignmentOperator" }
+}
+
+/**
+ * A user-defined compound assignment and operator (`&=`), for example
+ *
+ * ```csharp
+ * public void operator &=(Widget w) {
+ *   ...
+ * }
+ * ```
+ */
+class AndCompoundAssignmentOperator extends CompoundAssignmentOperatorImpl {
+  AndCompoundAssignmentOperator() { this.getName() = "&=" }
+
+  override string getAPrimaryQlClass() { result = "AndCompoundAssignmentOperator" }
+}
+
+/**
+ * A user-defined compound assignment or operator (`|=`), for example
+ *
+ * ```csharp
+ * public void operator |=(Widget w) {
+ *   ...
+ * }
+ * ```
+ */
+class OrCompoundAssignmentOperator extends CompoundAssignmentOperatorImpl {
+  OrCompoundAssignmentOperator() { this.getName() = "|=" }
+
+  override string getAPrimaryQlClass() { result = "OrCompoundAssignmentOperator" }
+}
+
+/**
+ * A user-defined compound assignment xor operator (`^=`), for example
+ *
+ * ```csharp
+ * public void operator ^=(Widget w) {
+ *   ...
+ * }
+ * ```
+ */
+class XorCompoundAssignmentOperator extends CompoundAssignmentOperatorImpl {
+  XorCompoundAssignmentOperator() { this.getName() = "^=" }
+
+  override string getAPrimaryQlClass() { result = "XorCompoundAssignmentOperator" }
+}
+
+/**
+ * A user-defined compound assignment left shift operator (`<<=`), for example
+ *
+ * ```csharp
+ * public void operator <<=(Widget w) {
+ *   ...
+ * }
+ * ```
+ */
+class LeftShiftCompoundAssignmentOperator extends CompoundAssignmentOperatorImpl {
+  LeftShiftCompoundAssignmentOperator() { this.getName() = "<<=" }
+
+  override string getAPrimaryQlClass() { result = "LeftShiftCompoundAssignmentOperator" }
+}
+
+/**
+ * A user-defined compound assignment right shift operator (`>>=`), for example
+ *
+ * ```csharp
+ * public void operator >>=(Widget w) {
+ *   ...
+ * }
+ * ```
+ */
+class RightShiftCompoundAssignmentOperator extends CompoundAssignmentOperatorImpl {
+  RightShiftCompoundAssignmentOperator() { this.getName() = ">>=" }
+
+  override string getAPrimaryQlClass() { result = "RightShiftCompoundAssignmentOperator" }
+}
+
+/**
+ * A user-defined compound assignment unsigned right shift operator (`>>>=`), for example
+ *
+ * ```csharp
+ * public void operator >>>=(Widget w) {
+ *   ...
+ * }
+ * ```
+ */
+class UnsignedRightShiftCompoundAssignmentOperator extends CompoundAssignmentOperatorImpl {
+  UnsignedRightShiftCompoundAssignmentOperator() { this.getName() = ">>>=" }
+
+  override string getAPrimaryQlClass() { result = "UnsignedRightShiftCompoundAssignmentOperator" }
+}
+
 /**
  * A local function, defined within the scope of another callable.
  * For example, `Fac` on lines 2--4 in

csharp/ql/lib/semmle/code/csharp/Type.qll

@@ -1334,6 +1334,7 @@ class TypeMention extends @type_mention {
  * ```csharp
  * static class MyExtensions {
  *   extension(string s) { ... }
+ * }
  * ```
  */
 class ExtensionType extends Parameterizable, @extension_type {