Add support for user defined compound assignment operators to syntax generator

src/Workspaces/CSharp/Portable/CodeGeneration/CSharpSyntaxGenerator.cs

@@ -341,6 +341,17 @@ private static string GetOperatorName(OperatorKind kind)
             OperatorKind.True => WellKnownMemberNames.TrueOperatorName,
             OperatorKind.UnaryNegation => WellKnownMemberNames.UnaryNegationOperatorName,
             OperatorKind.UnaryPlus => WellKnownMemberNames.UnaryPlusOperatorName,
+            OperatorKind.AdditionAssignment => WellKnownMemberNames.AdditionAssignmentOperatorName,
+            OperatorKind.SubtractionAssignment => WellKnownMemberNames.SubtractionAssignmentOperatorName,
+            OperatorKind.MultiplicationAssignment => WellKnownMemberNames.MultiplicationAssignmentOperatorName,
+            OperatorKind.DivisionAssignment => WellKnownMemberNames.DivisionAssignmentOperatorName,
+            OperatorKind.ModulusAssignment => WellKnownMemberNames.ModulusAssignmentOperatorName,
+            OperatorKind.ExclusiveOrAssignment => WellKnownMemberNames.ExclusiveOrAssignmentOperatorName,
+            OperatorKind.BitwiseAndAssignment => WellKnownMemberNames.BitwiseAndAssignmentOperatorName,
+            OperatorKind.BitwiseOrAssignment => WellKnownMemberNames.BitwiseOrAssignmentOperatorName,
+            OperatorKind.LeftShiftAssignment => WellKnownMemberNames.LeftShiftAssignmentOperatorName,
+            OperatorKind.RightShiftAssignment => WellKnownMemberNames.RightShiftAssignmentOperatorName,
+            OperatorKind.UnsignedRightShiftAssignment => WellKnownMemberNames.UnsignedRightShiftAssignmentOperatorName,
             _ => throw new ArgumentException("Unknown operator kind."),
         };
 
@@ -3349,6 +3360,7 @@ public override SyntaxNode TypeExpression(SpecialType specialType)
             SpecialType.System_UInt16 => UShortKeyword,
             SpecialType.System_UInt32 => UIntKeyword,
             SpecialType.System_UInt64 => ULongKeyword,
+            SpecialType.System_Void => VoidKeyword,
             _ => throw new NotSupportedException("Unsupported SpecialType"),
         });
 

src/Workspaces/CSharpTest/CodeGeneration/SyntaxGeneratorTests.cs

@@ -968,6 +968,70 @@ public void TestOperatorDeclaration()
             "explicit operator bool (global::System.Int32 p0, global::System.String p1)\r\n{\r\n}");
     }
 
+    [Fact]
+    public void TestInstanceOperatorsDeclaration()
+    {
+        var returnType = Generator.TypeExpression(SpecialType.System_Void);
+
+        VerifySyntax<OperatorDeclarationSyntax>(
+            Generator.OperatorDeclaration(OperatorKind.Increment, [], returnType),
+            "void operator ++()\r\n{\r\n}");
+
+        VerifySyntax<OperatorDeclarationSyntax>(
+            Generator.OperatorDeclaration(OperatorKind.Decrement, [], returnType),
+            "void operator --()\r\n{\r\n}");
+
+        var parameterTypes = new[]
+        {
+            _emptyCompilation.GetSpecialType(SpecialType.System_Int32)
+        };
+        var parameters = parameterTypes.Select((t, i) => Generator.ParameterDeclaration("p" + i, Generator.TypeExpression(t))).ToList();
+
+        VerifySyntax<OperatorDeclarationSyntax>(
+            Generator.OperatorDeclaration(OperatorKind.AdditionAssignment, parameters, returnType),
+            "void operator +=(global::System.Int32 p0)\r\n{\r\n}");
+
+        VerifySyntax<OperatorDeclarationSyntax>(
+            Generator.OperatorDeclaration(OperatorKind.SubtractionAssignment, parameters, returnType),
+            "void operator -=(global::System.Int32 p0)\r\n{\r\n}");
+
+        VerifySyntax<OperatorDeclarationSyntax>(
+            Generator.OperatorDeclaration(OperatorKind.MultiplicationAssignment, parameters, returnType),
+            "void operator *=(global::System.Int32 p0)\r\n{\r\n}");
+
+        VerifySyntax<OperatorDeclarationSyntax>(
+            Generator.OperatorDeclaration(OperatorKind.DivisionAssignment, parameters, returnType),
+            "void operator /=(global::System.Int32 p0)\r\n{\r\n}");
+
+        VerifySyntax<OperatorDeclarationSyntax>(
+            Generator.OperatorDeclaration(OperatorKind.ModulusAssignment, parameters, returnType),
+            "void operator %=(global::System.Int32 p0)\r\n{\r\n}");
+
+        VerifySyntax<OperatorDeclarationSyntax>(
+            Generator.OperatorDeclaration(OperatorKind.ExclusiveOrAssignment, parameters, returnType),
+            "void operator ^=(global::System.Int32 p0)\r\n{\r\n}");
+
+        VerifySyntax<OperatorDeclarationSyntax>(
+            Generator.OperatorDeclaration(OperatorKind.BitwiseAndAssignment, parameters, returnType),
+            "void operator &=(global::System.Int32 p0)\r\n{\r\n}");
+
+        VerifySyntax<OperatorDeclarationSyntax>(
+            Generator.OperatorDeclaration(OperatorKind.BitwiseOrAssignment, parameters, returnType),
+            "void operator |=(global::System.Int32 p0)\r\n{\r\n}");
+
+        VerifySyntax<OperatorDeclarationSyntax>(
+            Generator.OperatorDeclaration(OperatorKind.LeftShiftAssignment, parameters, returnType),
+            "void operator <<=(global::System.Int32 p0)\r\n{\r\n}");
+
+        VerifySyntax<OperatorDeclarationSyntax>(
+            Generator.OperatorDeclaration(OperatorKind.RightShiftAssignment, parameters, returnType),
+            "void operator >>=(global::System.Int32 p0)\r\n{\r\n}");
+
+        VerifySyntax<OperatorDeclarationSyntax>(
+            Generator.OperatorDeclaration(OperatorKind.UnsignedRightShiftAssignment, parameters, returnType),
+            "void operator >>>=(global::System.Int32 p0)\r\n{\r\n}");
+    }
+
     [Fact, WorkItem(63410, "https://github.com/dotnet/roslyn/issues/63410")]
     public void TestCheckedOperator()
     {

src/Workspaces/Core/Portable/Editing/OperatorKind.cs

@@ -140,4 +140,59 @@ public enum OperatorKind
     /// The name assigned to the UnsignedRightShift operator.
     /// </summary>
     UnsignedRightShift,
+
+    /// <summary>
+    /// The name assigned to the AdditionAssignment operator.
+    /// </summary>
+    AdditionAssignment,
+
+    /// <summary>
+    /// The name assigned to the SubtractionAssignment operator.
+    /// </summary>
+    SubtractionAssignment,
+
+    /// <summary>
+    /// The name assigned to the MultiplicationAssignment operator.
+    /// </summary>
+    MultiplicationAssignment,
+
+    /// <summary>
+    /// The name assigned to the DivisionAssignment operator.
+    /// </summary>
+    DivisionAssignment,
+
+    /// <summary>
+    /// The name assigned to the ModulusAssignment operator.
+    /// </summary>
+    ModulusAssignment,
+
+    /// <summary>
+    /// The name assigned to the ExclusiveOrAssignment operator.
+    /// </summary>
+    ExclusiveOrAssignment,
+
+    /// <summary>
+    /// The name assigned to the BitwiseAndAssignment operator.
+    /// </summary>
+    BitwiseAndAssignment,
+
+    /// <summary>
+    /// The name assigned to the BitwiseOrAssignment operator.
+    /// </summary>
+    BitwiseOrAssignment,
+
+    /// <summary>
+    /// The name assigned to the LeftShiftAssignment operator.
+    /// </summary>
+    LeftShiftAssignment,
+
+    /// <summary>
+    /// The name assigned to the RightShiftAssignment operator.
+    /// </summary>
+    RightShiftAssignment,
+
+    /// <summary>
+    /// The name assigned to the UnsignedRightShiftAssignment operator.
+    /// </summary>
+    UnsignedRightShiftAssignment,
 }

src/Workspaces/Core/Portable/PublicAPI.Unshipped.txt

@@ -1,2 +1,14 @@
 *REMOVED*abstract Microsoft.CodeAnalysis.Editing.SyntaxGenerator.WithModifiers(Microsoft.CodeAnalysis.SyntaxNode declaration, Microsoft.CodeAnalysis.Editing.DeclarationModifiers modifiers) -> Microsoft.CodeAnalysis.SyntaxNode
 Microsoft.CodeAnalysis.Editing.SyntaxGenerator.WithModifiers(Microsoft.CodeAnalysis.SyntaxNode declaration, Microsoft.CodeAnalysis.Editing.DeclarationModifiers modifiers) -> Microsoft.CodeAnalysis.SyntaxNode
+
+Microsoft.CodeAnalysis.Editing.OperatorKind.AdditionAssignment = 27 -> Microsoft.CodeAnalysis.Editing.OperatorKind
+Microsoft.CodeAnalysis.Editing.OperatorKind.BitwiseAndAssignment = 33 -> Microsoft.CodeAnalysis.Editing.OperatorKind
+Microsoft.CodeAnalysis.Editing.OperatorKind.BitwiseOrAssignment = 34 -> Microsoft.CodeAnalysis.Editing.OperatorKind
+Microsoft.CodeAnalysis.Editing.OperatorKind.DivisionAssignment = 30 -> Microsoft.CodeAnalysis.Editing.OperatorKind
+Microsoft.CodeAnalysis.Editing.OperatorKind.ExclusiveOrAssignment = 32 -> Microsoft.CodeAnalysis.Editing.OperatorKind
+Microsoft.CodeAnalysis.Editing.OperatorKind.LeftShiftAssignment = 35 -> Microsoft.CodeAnalysis.Editing.OperatorKind
+Microsoft.CodeAnalysis.Editing.OperatorKind.ModulusAssignment = 31 -> Microsoft.CodeAnalysis.Editing.OperatorKind
+Microsoft.CodeAnalysis.Editing.OperatorKind.MultiplicationAssignment = 29 -> Microsoft.CodeAnalysis.Editing.OperatorKind
+Microsoft.CodeAnalysis.Editing.OperatorKind.RightShiftAssignment = 36 -> Microsoft.CodeAnalysis.Editing.OperatorKind
+Microsoft.CodeAnalysis.Editing.OperatorKind.SubtractionAssignment = 28 -> Microsoft.CodeAnalysis.Editing.OperatorKind
+Microsoft.CodeAnalysis.Editing.OperatorKind.UnsignedRightShiftAssignment = 37 -> Microsoft.CodeAnalysis.Editing.OperatorKind