Implement revisions

* Update Lambda1 to be invariant
* Visit descendents before deciding whether or not to parenthesize an interpolation expression
* Rename local function
* Remove branch for conditional expressions
* Handle Lambda expressions without a block body
* Check for parenthesized expressions

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

@@ -4,7 +4,11 @@
 	{
 		public static string Root => $"Prefix {(global::System.DateTime.Now)} suffix";
 		public static string Cast => $"Prefix {((int)global::System.DateTime.Now.Ticks)} suffix";
+#if CS100 && !NET40
+		public static string Lambda1 => $"Prefix {(() => global::System.DateTime.Now)} suffix";
+#else
 		public static string Lambda1 => $"Prefix {(global::System.Func<global::System.DateTime>)(() => global::System.DateTime.Now)} suffix";
+#endif
 		public static string Lambda2 => $"Prefix {((global::System.Func<global::System.DateTime>)(() => global::System.DateTime.Now))()} suffix";
 		public static string Method1 => $"Prefix {M(global::System.DateTime.Now)} suffix";
 		public static string Method2 => $"Prefix {(global::System.DateTime.Now.Ticks)} suffix";

ICSharpCode.Decompiler/CSharp/OutputVisitor/InsertParenthesesVisitor.cs

@@ -392,28 +392,30 @@ namespace ICSharpCode.Decompiler.CSharp.OutputVisitor
 
 		public override void VisitInterpolation(Interpolation interpolation)
 		{
+			// Need to do this first, in case the descendents parenthesize themselves.
+			base.VisitInterpolation(interpolation);
+
 			// If an interpolation contains global::, we need to parenthesize the expression.
-			if (InterpolationNeedsParenthesized(interpolation))
+			if (InterpolationNeedsParenthesis(interpolation))
 				Parenthesize(interpolation.Expression);
-			base.VisitInterpolation(interpolation);
 
-			static bool InterpolationNeedsParenthesized(AstNode node)
+			static bool InterpolationNeedsParenthesis(AstNode node)
 			{
 				if (node is MemberType { IsDoubleColon: true })
 					return true;
 
-				if (node is ConditionalExpression)
-					return false; // Conditional expressions are parenthesized in their own visit method.
-				if (node is AnonymousMethodExpression or LambdaExpression)
+				if (node is ParenthesizedExpression)
+					return false;
+				if (node is AnonymousMethodExpression or LambdaExpression { Body: BlockStatement })
 					return false;
 				if (node is InvocationExpression invocation)
-					return InterpolationNeedsParenthesized(invocation.Target);
+					return InterpolationNeedsParenthesis(invocation.Target);
 				if (node is CastExpression cast)
-					return InterpolationNeedsParenthesized(cast.Expression);
+					return InterpolationNeedsParenthesis(cast.Expression);
 
 				foreach (var child in node.Children)
 				{
-					if (InterpolationNeedsParenthesized(child))
+					if (InterpolationNeedsParenthesis(child))
 						return true;
 				}
 				return false;