Fix user-defined op_Addition 'p += 1;' being turned into 'p++;'

ICSharpCode.Decompiler.Tests/TestCases/Pretty/CompoundAssignmentTest.cs

@@ -134,6 +134,10 @@ namespace ICSharpCode.Decompiler.Tests.TestCases.Pretty
 			{
 				throw new NotImplementedException();
 			}
+			public static CustomClass operator +(CustomClass lhs, int rhs)
+			{
+				throw new NotImplementedException();
+			}
 			public static CustomClass operator -(CustomClass lhs, CustomClass rhs)
 			{
 				throw new NotImplementedException();
@@ -4499,6 +4503,13 @@ namespace ICSharpCode.Decompiler.Tests.TestCases.Pretty
 		}
 		#endregion
 
+		public static void AddOneToCustomClass(ref CustomClass c)
+		{
+			// This should not be turned into post-increment:
+			c += 1;
+			c.CustomClassProp += 1;
+		}
+
 		private static Item GetItem(object obj)
 		{
 			return null;

ICSharpCode.Decompiler.Tests/TestCases/Pretty/CompoundAssignmentTest.il

@@ -522,6 +522,18 @@
       IL_0006:  throw
     } // end of method CustomClass::op_Addition
 
+    .method public hidebysig specialname static 
+            class ICSharpCode.Decompiler.Tests.TestCases.Pretty.CompoundAssignmentTest/CustomClass 
+            op_Addition(class ICSharpCode.Decompiler.Tests.TestCases.Pretty.CompoundAssignmentTest/CustomClass lhs,
+                        int32 rhs) cil managed
+    {
+      // Code size       7 (0x7)
+      .maxstack  8
+      IL_0000:  nop
+      IL_0001:  newobj     instance void [mscorlib]System.NotImplementedException::.ctor()
+      IL_0006:  throw
+    } // end of method CustomClass::op_Addition
+
     .method public hidebysig specialname static 
             class ICSharpCode.Decompiler.Tests.TestCases.Pretty.CompoundAssignmentTest/CustomClass 
             op_Subtraction(class ICSharpCode.Decompiler.Tests.TestCases.Pretty.CompoundAssignmentTest/CustomClass lhs,
@@ -21354,6 +21366,30 @@
     IL_018e:  ret
   } // end of method CompoundAssignmentTest::CustomStructPreDecTest
 
+  .method public hidebysig static void  AddOneToCustomClass(class ICSharpCode.Decompiler.Tests.TestCases.Pretty.CompoundAssignmentTest/CustomClass& c) cil managed
+  {
+    // Code size       32 (0x20)
+    .maxstack  8
+    IL_0000:  nop
+    IL_0001:  ldarg.0
+    IL_0002:  dup
+    IL_0003:  ldind.ref
+    IL_0004:  ldc.i4.1
+    IL_0005:  call       class ICSharpCode.Decompiler.Tests.TestCases.Pretty.CompoundAssignmentTest/CustomClass ICSharpCode.Decompiler.Tests.TestCases.Pretty.CompoundAssignmentTest/CustomClass::op_Addition(class ICSharpCode.Decompiler.Tests.TestCases.Pretty.CompoundAssignmentTest/CustomClass,
+                                                                                                                                                                                                              int32)
+    IL_000a:  stind.ref
+    IL_000b:  ldarg.0
+    IL_000c:  ldind.ref
+    IL_000d:  dup
+    IL_000e:  callvirt   instance class ICSharpCode.Decompiler.Tests.TestCases.Pretty.CompoundAssignmentTest/CustomClass ICSharpCode.Decompiler.Tests.TestCases.Pretty.CompoundAssignmentTest/CustomClass::get_CustomClassProp()
+    IL_0013:  ldc.i4.1
+    IL_0014:  call       class ICSharpCode.Decompiler.Tests.TestCases.Pretty.CompoundAssignmentTest/CustomClass ICSharpCode.Decompiler.Tests.TestCases.Pretty.CompoundAssignmentTest/CustomClass::op_Addition(class ICSharpCode.Decompiler.Tests.TestCases.Pretty.CompoundAssignmentTest/CustomClass,
+                                                                                                                                                                                                              int32)
+    IL_0019:  callvirt   instance void ICSharpCode.Decompiler.Tests.TestCases.Pretty.CompoundAssignmentTest/CustomClass::set_CustomClassProp(class ICSharpCode.Decompiler.Tests.TestCases.Pretty.CompoundAssignmentTest/CustomClass)
+    IL_001e:  nop
+    IL_001f:  ret
+  } // end of method CompoundAssignmentTest::AddOneToCustomClass
+
   .method private hidebysig static class ICSharpCode.Decompiler.Tests.TestCases.Pretty.CompoundAssignmentTest/Item 
           GetItem(object obj) cil managed
   {

ICSharpCode.Decompiler.Tests/TestCases/Pretty/CompoundAssignmentTest.opt.il

@@ -454,6 +454,17 @@
       IL_0005:  throw
     } // end of method CustomClass::op_Addition
 
+    .method public hidebysig specialname static 
+            class ICSharpCode.Decompiler.Tests.TestCases.Pretty.CompoundAssignmentTest/CustomClass 
+            op_Addition(class ICSharpCode.Decompiler.Tests.TestCases.Pretty.CompoundAssignmentTest/CustomClass lhs,
+                        int32 rhs) cil managed
+    {
+      // Code size       6 (0x6)
+      .maxstack  8
+      IL_0000:  newobj     instance void [mscorlib]System.NotImplementedException::.ctor()
+      IL_0005:  throw
+    } // end of method CustomClass::op_Addition
+
     .method public hidebysig specialname static 
             class ICSharpCode.Decompiler.Tests.TestCases.Pretty.CompoundAssignmentTest/CustomClass 
             op_Subtraction(class ICSharpCode.Decompiler.Tests.TestCases.Pretty.CompoundAssignmentTest/CustomClass lhs,
@@ -19660,6 +19671,28 @@
     IL_0188:  ret
   } // end of method CompoundAssignmentTest::CustomStructPreDecTest
 
+  .method public hidebysig static void  AddOneToCustomClass(class ICSharpCode.Decompiler.Tests.TestCases.Pretty.CompoundAssignmentTest/CustomClass& c) cil managed
+  {
+    // Code size       30 (0x1e)
+    .maxstack  8
+    IL_0000:  ldarg.0
+    IL_0001:  dup
+    IL_0002:  ldind.ref
+    IL_0003:  ldc.i4.1
+    IL_0004:  call       class ICSharpCode.Decompiler.Tests.TestCases.Pretty.CompoundAssignmentTest/CustomClass ICSharpCode.Decompiler.Tests.TestCases.Pretty.CompoundAssignmentTest/CustomClass::op_Addition(class ICSharpCode.Decompiler.Tests.TestCases.Pretty.CompoundAssignmentTest/CustomClass,
+                                                                                                                                                                                                              int32)
+    IL_0009:  stind.ref
+    IL_000a:  ldarg.0
+    IL_000b:  ldind.ref
+    IL_000c:  dup
+    IL_000d:  callvirt   instance class ICSharpCode.Decompiler.Tests.TestCases.Pretty.CompoundAssignmentTest/CustomClass ICSharpCode.Decompiler.Tests.TestCases.Pretty.CompoundAssignmentTest/CustomClass::get_CustomClassProp()
+    IL_0012:  ldc.i4.1
+    IL_0013:  call       class ICSharpCode.Decompiler.Tests.TestCases.Pretty.CompoundAssignmentTest/CustomClass ICSharpCode.Decompiler.Tests.TestCases.Pretty.CompoundAssignmentTest/CustomClass::op_Addition(class ICSharpCode.Decompiler.Tests.TestCases.Pretty.CompoundAssignmentTest/CustomClass,
+                                                                                                                                                                                                              int32)
+    IL_0018:  callvirt   instance void ICSharpCode.Decompiler.Tests.TestCases.Pretty.CompoundAssignmentTest/CustomClass::set_CustomClassProp(class ICSharpCode.Decompiler.Tests.TestCases.Pretty.CompoundAssignmentTest/CustomClass)
+    IL_001d:  ret
+  } // end of method CompoundAssignmentTest::AddOneToCustomClass
+
   .method private hidebysig static class ICSharpCode.Decompiler.Tests.TestCases.Pretty.CompoundAssignmentTest/Item 
           GetItem(object obj) cil managed
   {

ICSharpCode.Decompiler.Tests/TestCases/Pretty/CompoundAssignmentTest.opt.roslyn.il

@@ -458,6 +458,17 @@
       IL_0005:  throw
     } // end of method CustomClass::op_Addition
 
+    .method public hidebysig specialname static 
+            class ICSharpCode.Decompiler.Tests.TestCases.Pretty.CompoundAssignmentTest/CustomClass 
+            op_Addition(class ICSharpCode.Decompiler.Tests.TestCases.Pretty.CompoundAssignmentTest/CustomClass lhs,
+                        int32 rhs) cil managed
+    {
+      // Code size       6 (0x6)
+      .maxstack  8
+      IL_0000:  newobj     instance void [mscorlib]System.NotImplementedException::.ctor()
+      IL_0005:  throw
+    } // end of method CustomClass::op_Addition
+
     .method public hidebysig specialname static 
             class ICSharpCode.Decompiler.Tests.TestCases.Pretty.CompoundAssignmentTest/CustomClass 
             op_Subtraction(class ICSharpCode.Decompiler.Tests.TestCases.Pretty.CompoundAssignmentTest/CustomClass lhs,
@@ -22967,6 +22978,28 @@
     IL_01de:  ret
   } // end of method CompoundAssignmentTest::CustomStructPreDecTest
 
+  .method public hidebysig static void  AddOneToCustomClass(class ICSharpCode.Decompiler.Tests.TestCases.Pretty.CompoundAssignmentTest/CustomClass& c) cil managed
+  {
+    // Code size       30 (0x1e)
+    .maxstack  8
+    IL_0000:  ldarg.0
+    IL_0001:  ldarg.0
+    IL_0002:  ldind.ref
+    IL_0003:  ldc.i4.1
+    IL_0004:  call       class ICSharpCode.Decompiler.Tests.TestCases.Pretty.CompoundAssignmentTest/CustomClass ICSharpCode.Decompiler.Tests.TestCases.Pretty.CompoundAssignmentTest/CustomClass::op_Addition(class ICSharpCode.Decompiler.Tests.TestCases.Pretty.CompoundAssignmentTest/CustomClass,
+                                                                                                                                                                                                              int32)
+    IL_0009:  stind.ref
+    IL_000a:  ldarg.0
+    IL_000b:  ldind.ref
+    IL_000c:  dup
+    IL_000d:  callvirt   instance class ICSharpCode.Decompiler.Tests.TestCases.Pretty.CompoundAssignmentTest/CustomClass ICSharpCode.Decompiler.Tests.TestCases.Pretty.CompoundAssignmentTest/CustomClass::get_CustomClassProp()
+    IL_0012:  ldc.i4.1
+    IL_0013:  call       class ICSharpCode.Decompiler.Tests.TestCases.Pretty.CompoundAssignmentTest/CustomClass ICSharpCode.Decompiler.Tests.TestCases.Pretty.CompoundAssignmentTest/CustomClass::op_Addition(class ICSharpCode.Decompiler.Tests.TestCases.Pretty.CompoundAssignmentTest/CustomClass,
+                                                                                                                                                                                                              int32)
+    IL_0018:  callvirt   instance void ICSharpCode.Decompiler.Tests.TestCases.Pretty.CompoundAssignmentTest/CustomClass::set_CustomClassProp(class ICSharpCode.Decompiler.Tests.TestCases.Pretty.CompoundAssignmentTest/CustomClass)
+    IL_001d:  ret
+  } // end of method CompoundAssignmentTest::AddOneToCustomClass
+
   .method private hidebysig static class ICSharpCode.Decompiler.Tests.TestCases.Pretty.CompoundAssignmentTest/Item 
           GetItem(object obj) cil managed
   {

ICSharpCode.Decompiler.Tests/TestCases/Pretty/CompoundAssignmentTest.roslyn.il

@@ -480,6 +480,18 @@
       IL_0006:  throw
     } // end of method CustomClass::op_Addition
 
+    .method public hidebysig specialname static 
+            class ICSharpCode.Decompiler.Tests.TestCases.Pretty.CompoundAssignmentTest/CustomClass 
+            op_Addition(class ICSharpCode.Decompiler.Tests.TestCases.Pretty.CompoundAssignmentTest/CustomClass lhs,
+                        int32 rhs) cil managed
+    {
+      // Code size       7 (0x7)
+      .maxstack  8
+      IL_0000:  nop
+      IL_0001:  newobj     instance void [mscorlib]System.NotImplementedException::.ctor()
+      IL_0006:  throw
+    } // end of method CustomClass::op_Addition
+
     .method public hidebysig specialname static 
             class ICSharpCode.Decompiler.Tests.TestCases.Pretty.CompoundAssignmentTest/CustomClass 
             op_Subtraction(class ICSharpCode.Decompiler.Tests.TestCases.Pretty.CompoundAssignmentTest/CustomClass lhs,
@@ -25308,6 +25320,30 @@
     IL_01f8:  ret
   } // end of method CompoundAssignmentTest::CustomStructPreDecTest
 
+  .method public hidebysig static void  AddOneToCustomClass(class ICSharpCode.Decompiler.Tests.TestCases.Pretty.CompoundAssignmentTest/CustomClass& c) cil managed
+  {
+    // Code size       32 (0x20)
+    .maxstack  8
+    IL_0000:  nop
+    IL_0001:  ldarg.0
+    IL_0002:  ldarg.0
+    IL_0003:  ldind.ref
+    IL_0004:  ldc.i4.1
+    IL_0005:  call       class ICSharpCode.Decompiler.Tests.TestCases.Pretty.CompoundAssignmentTest/CustomClass ICSharpCode.Decompiler.Tests.TestCases.Pretty.CompoundAssignmentTest/CustomClass::op_Addition(class ICSharpCode.Decompiler.Tests.TestCases.Pretty.CompoundAssignmentTest/CustomClass,
+                                                                                                                                                                                                              int32)
+    IL_000a:  stind.ref
+    IL_000b:  ldarg.0
+    IL_000c:  ldind.ref
+    IL_000d:  dup
+    IL_000e:  callvirt   instance class ICSharpCode.Decompiler.Tests.TestCases.Pretty.CompoundAssignmentTest/CustomClass ICSharpCode.Decompiler.Tests.TestCases.Pretty.CompoundAssignmentTest/CustomClass::get_CustomClassProp()
+    IL_0013:  ldc.i4.1
+    IL_0014:  call       class ICSharpCode.Decompiler.Tests.TestCases.Pretty.CompoundAssignmentTest/CustomClass ICSharpCode.Decompiler.Tests.TestCases.Pretty.CompoundAssignmentTest/CustomClass::op_Addition(class ICSharpCode.Decompiler.Tests.TestCases.Pretty.CompoundAssignmentTest/CustomClass,
+                                                                                                                                                                                                              int32)
+    IL_0019:  callvirt   instance void ICSharpCode.Decompiler.Tests.TestCases.Pretty.CompoundAssignmentTest/CustomClass::set_CustomClassProp(class ICSharpCode.Decompiler.Tests.TestCases.Pretty.CompoundAssignmentTest/CustomClass)
+    IL_001e:  nop
+    IL_001f:  ret
+  } // end of method CompoundAssignmentTest::AddOneToCustomClass
+
   .method private hidebysig static class ICSharpCode.Decompiler.Tests.TestCases.Pretty.CompoundAssignmentTest/Item 
           GetItem(object obj) cil managed
   {

ICSharpCode.Decompiler/CSharp/Transforms/PrettifyAssignments.cs

@@ -58,7 +58,7 @@ namespace ICSharpCode.Decompiler.CSharp.Transforms
 				var rr = assignment.Right.GetResolveResult();
 				if (rr.IsCompileTimeConstant && rr.Type.IsCSharpPrimitiveIntegerType() && CSharpPrimitiveCast.Cast(rr.Type.GetTypeCode(), 1, false).Equals(rr.ConstantValue)) {
 					// only if it's not a custom operator
-					if (assignment.Annotation<IL.CallInstruction>() == null) {
+					if (assignment.Annotation<IL.CallInstruction>() == null && assignment.Annotation<IL.UserDefinedCompoundAssign>() == null) {
 						UnaryOperatorType type;
 						// When the parent is an expression statement, pre- or post-increment doesn't matter;
 						// so we can pick post-increment which is more commonly used (for (int i = 0; i < x; i++))