Apply expression-body transform to indexers as well.

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

@@ -101,12 +101,15 @@ namespace ICSharpCode.Decompiler.Tests.TestCases.Pretty.CustomAttributeSamples
 		}
 
 		[Obsolete("reason")]
+#if ROSLYN
+		public int this[int i] => 0;
+#else
 		public int this[int i] {
 			get {
 				return 0;
 			}
 		}
-
+#endif
 		[MyAttribute]
 		public event EventHandler MyEvent;
 
@@ -254,11 +257,15 @@ namespace ICSharpCode.Decompiler.Tests.TestCases.Pretty.CustomAttributeSamples
 
 	public class MyClass11
 	{
+#if ROSLYN
+		public int this[[MyAttribute] string s] => 3;
+#else
 		public int this[[MyAttribute] string s] {
 			get {
 				return 3;
 			}
 		}
+#endif
 	}
 
 	public class MyClass12

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

@@ -27,11 +27,15 @@ namespace ICSharpCode.Decompiler.Tests.TestCases.Pretty
 		public class IndexerNonDefaultName
 		{
 			[IndexerName("Foo")]
+#if ROSLYN
+			public int this[int index] => 0;
+#else
 			public int this[int index] {
 				get {
 					return 0;
 				}
 			}
+#endif
 		}
 
 		[DefaultMember("Bar")]

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

@@ -31,11 +31,7 @@ namespace ICSharpCode.Decompiler.Tests.TestCases.Pretty
 				get;
 				set;
 			}
-			public MyClass this[int index] {
-				get {
-					return null;
-				}
-			}
+			public MyClass this[int index] => null;
 			public MyClass Method(int arg)
 			{
 				return null;
@@ -52,11 +48,7 @@ namespace ICSharpCode.Decompiler.Tests.TestCases.Pretty
 			public MyClass Field;
 			public MyStruct? Property1 => null;
 			public MyStruct Property2 => default(MyStruct);
-			public MyStruct? this[int index] {
-				get {
-					return null;
-				}
-			}
+			public MyStruct? this[int index] => null;
 			public MyStruct? Method1(int arg)
 			{
 				return null;

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

@@ -84,16 +84,10 @@
             instance class ICSharpCode.Decompiler.Tests.TestCases.Pretty.NullPropagation/MyClass 
             get_Item(int32 index) cil managed
     {
-      // Code size       7 (0x7)
-      .maxstack  1
-      .locals init (class ICSharpCode.Decompiler.Tests.TestCases.Pretty.NullPropagation/MyClass V_0)
-      IL_0000:  nop
-      IL_0001:  ldnull
-      IL_0002:  stloc.0
-      IL_0003:  br.s       IL_0005
-
-      IL_0005:  ldloc.0
-      IL_0006:  ret
+      // Code size       2 (0x2)
+      .maxstack  8
+      IL_0000:  ldnull
+      IL_0001:  ret
     } // end of method MyClass::get_Item
 
     .method public hidebysig instance class ICSharpCode.Decompiler.Tests.TestCases.Pretty.NullPropagation/MyClass 
@@ -180,19 +174,13 @@
             instance valuetype [mscorlib]System.Nullable`1<valuetype ICSharpCode.Decompiler.Tests.TestCases.Pretty.NullPropagation/MyStruct> 
             get_Item(int32 index) cil managed
     {
-      // Code size       15 (0xf)
+      // Code size       10 (0xa)
       .maxstack  1
-      .locals init (valuetype [mscorlib]System.Nullable`1<valuetype ICSharpCode.Decompiler.Tests.TestCases.Pretty.NullPropagation/MyStruct> V_0,
-               valuetype [mscorlib]System.Nullable`1<valuetype ICSharpCode.Decompiler.Tests.TestCases.Pretty.NullPropagation/MyStruct> V_1)
-      IL_0000:  nop
-      IL_0001:  ldloca.s   V_0
-      IL_0003:  initobj    valuetype [mscorlib]System.Nullable`1<valuetype ICSharpCode.Decompiler.Tests.TestCases.Pretty.NullPropagation/MyStruct>
-      IL_0009:  ldloc.0
-      IL_000a:  stloc.1
-      IL_000b:  br.s       IL_000d
-
-      IL_000d:  ldloc.1
-      IL_000e:  ret
+      .locals init (valuetype [mscorlib]System.Nullable`1<valuetype ICSharpCode.Decompiler.Tests.TestCases.Pretty.NullPropagation/MyStruct> V_0)
+      IL_0000:  ldloca.s   V_0
+      IL_0002:  initobj    valuetype [mscorlib]System.Nullable`1<valuetype ICSharpCode.Decompiler.Tests.TestCases.Pretty.NullPropagation/MyStruct>
+      IL_0008:  ldloc.0
+      IL_0009:  ret
     } // end of method MyStruct::get_Item
 
     .method public hidebysig instance valuetype [mscorlib]System.Nullable`1<valuetype ICSharpCode.Decompiler.Tests.TestCases.Pretty.NullPropagation/MyStruct> 

ICSharpCode.Decompiler/CSharp/Transforms/NormalizeBlockStatements.cs

@@ -130,10 +130,28 @@ namespace ICSharpCode.Decompiler.CSharp.Transforms
 			base.VisitPropertyDeclaration(propertyDeclaration);
 		}
 
+		public override void VisitIndexerDeclaration(IndexerDeclaration indexerDeclaration)
+		{
+			if (context.Settings.UseExpressionBodyForCalculatedGetterOnlyProperties) {
+				SimplifyIndexerDeclaration(indexerDeclaration);
+			}
+			base.VisitIndexerDeclaration(indexerDeclaration);
+		}
+
 		static readonly PropertyDeclaration CalculatedGetterOnlyPropertyPattern = new PropertyDeclaration() {
 			Attributes = { new Repeat(new AnyNode()) },
 			Modifiers = Modifiers.Any,
 			Name = Pattern.AnyString,
+			PrivateImplementationType = new AnyNodeOrNull(),
+			ReturnType = new AnyNode(),
+			Getter = new Accessor() { Body = new BlockStatement() { new ReturnStatement(new AnyNode("expression")) } }
+		};
+
+		static readonly IndexerDeclaration CalculatedGetterOnlyIndexerPattern = new IndexerDeclaration() {
+			Attributes = { new Repeat(new AnyNode()) },
+			Modifiers = Modifiers.Any,
+			PrivateImplementationType = new AnyNodeOrNull(),
+			Parameters = { new Repeat(new AnyNode()) },
 			ReturnType = new AnyNode(),
 			Getter = new Accessor() { Body = new BlockStatement() { new ReturnStatement(new AnyNode("expression")) } }
 		};
@@ -146,5 +164,14 @@ namespace ICSharpCode.Decompiler.CSharp.Transforms
 			propertyDeclaration.ExpressionBody = m.Get<Expression>("expression").Single().Detach();
 			propertyDeclaration.Getter.Remove();
 		}
+
+		void SimplifyIndexerDeclaration(IndexerDeclaration indexerDeclaration)
+		{
+			var m = CalculatedGetterOnlyIndexerPattern.Match(indexerDeclaration);
+			if (!m.Success)
+				return;
+			indexerDeclaration.ExpressionBody = m.Get<Expression>("expression").Single().Detach();
+			indexerDeclaration.Getter.Remove();
+		}
 	}
 }