Fix #1743: Add pattern for struct constructor initializers.

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

@@ -20,6 +20,22 @@ namespace ICSharpCode.Decompiler.Tests.TestCases.Pretty
 {
 	public class ConstructorInitializers
 	{
+		public struct Issue1743
+		{
+			public int Leet;
+
+			public Issue1743(int dummy)
+				: this(dummy, dummy)
+			{
+				Leet += dummy;
+			}
+
+			public Issue1743(int dummy1, int dummy2)
+			{
+				Leet = dummy1 + dummy2;
+			}
+		}
+
 		public struct SimpleStruct
 		{
 			public int Field1;

ICSharpCode.Decompiler/CSharp/Transforms/ConvertConstructorCallIntoInitializer.cs

@@ -58,13 +58,19 @@ namespace ICSharpCode.Decompiler.CSharp.Transforms
 		
 		public override void VisitConstructorDeclaration(ConstructorDeclaration constructorDeclaration)
 		{
-			var stmt = constructorDeclaration.Body.Statements.FirstOrDefault() as ExpressionStatement;
+			if (!(constructorDeclaration.Body.Statements.FirstOrDefault() is ExpressionStatement stmt))
-			if (stmt == null)
 				return;
-			if (!(stmt.Expression is InvocationExpression invocation))
+			var currentCtor = (IMethod)constructorDeclaration.GetSymbol();
+			ConstructorInitializer ci;
+			switch (stmt.Expression) {
+				// Pattern for reference types:
+				// this..ctor(...);
+				case InvocationExpression invocation:
+					if (!(invocation.Target is MemberReferenceExpression mre) || mre.MemberName != ".ctor")
 						return;
-			if (invocation.Target is MemberReferenceExpression mre && mre.MemberName == ".ctor") {
+					if (!(invocation.GetSymbol() is IMethod ctor && ctor.IsConstructor))
-				ConstructorInitializer ci = new ConstructorInitializer();
+						return;
+					ci = new ConstructorInitializer();
 					var target = mre.Target;
 					// Ignore casts, those might be added if references are missing.
 					if (target is CastExpression cast)
@@ -82,6 +88,25 @@ namespace ICSharpCode.Decompiler.CSharp.Transforms
 						constructorDeclaration.Initializer = ci.CopyAnnotationsFrom(invocation);
 					// Remove the statement:
 					stmt.Remove();
+					break;
+				// Pattern for value types:
+				// this = new TSelf(...);
+				case AssignmentExpression assignment:
+					if (!(assignment.Right is ObjectCreateExpression oce && oce.GetSymbol() is IMethod ctor2 && ctor2.DeclaringTypeDefinition == currentCtor.DeclaringTypeDefinition))
+						return;
+					ci = new ConstructorInitializer();
+					if (assignment.Left is ThisReferenceExpression)
+						ci.ConstructorInitializerType = ConstructorInitializerType.This;
+					else
+						return;
+					// Move arguments from invocation to initializer:
+					oce.Arguments.MoveTo(ci.Arguments);
+					// Add the initializer: (unless it is the default 'base()')
+					if (!(ci.ConstructorInitializerType == ConstructorInitializerType.Base && ci.Arguments.Count == 0))
+						constructorDeclaration.Initializer = ci.CopyAnnotationsFrom(oce);
+					// Remove the statement:
+					stmt.Remove();
+					break;
 			}
 		}