Reuse constructor emission inside member initializers

src/FastExpressionCompiler/FastExpressionCompiler.cs

@@ -4703,17 +4703,13 @@ private static bool EmitMemberInit(MemberInitExpression expr, ILGenerator il, re
                     var argCount = argExprs.GetArgCount();
                     if (argCount > 0)
                     {
-                        var args = newExpr.Constructor.GetParameters();
-                        for (var i = 0; i < argCount; i++)
-                            if (!TryEmit(argExprs.GetArgument(i), il, ref context, parent, args[i].ParameterType.IsByRef ? i : -1))
-                                return false;
+                        if (!TryEmitNew(newExpr, il, ref context, ParentFlags.CtorCall)) return false;
+                        if (valueVarIndex != -1) EmitStoreLocalVariable(il, valueVarIndex);
                     }
-
-                    if (newExpr.Constructor != null)
+                    else if (newExpr.Constructor != null)
                     {
                         il.Demit(OpCodes.Newobj, newExpr.Constructor);
-                        if (valueVarIndex != -1)
-                            EmitStoreLocalVariable(il, valueVarIndex);
+                        if (valueVarIndex != -1) EmitStoreLocalVariable(il, valueVarIndex);
                     }
                     else if (valueVarIndex != -1)
                         InitValueTypeVariable(il, exprType, valueVarIndex);

test/FastExpressionCompiler.TestsRunner.Net472/Program.cs

@@ -78,6 +78,7 @@ static void RunLightExpressionTests(object state)
                 t.Run(new LightExpression.UnitTests.ByRefConversionRegressionTests());
                 t.Run(new LightExpression.UnitTests.PropertyGetterReceiverRegressionTests());
                 t.Run(new LightExpression.UnitTests.RuntimeTypeConstantRegressionTests());
+                t.Run(new LightExpression.UnitTests.MemberConstructorExceptionTests());
                 t.Run(new LightExpression.UnitTests.MethodBasedNotRegressionTests());
                 t.Run(new LightExpression.UnitTests.ExtensionReductionIdentityRegressionTests());
                 t.Run(new LightExpression.UnitTests.LiftedOperandEvaluationRegressionTests());
@@ -138,6 +139,7 @@ static void RunLightExpressionTests(object state)
             fecTests.Run(new ByRefConversionRegressionTests());
             fecTests.Run(new PropertyGetterReceiverRegressionTests());
             fecTests.Run(new RuntimeTypeConstantRegressionTests());
+            fecTests.Run(new MemberConstructorExceptionTests());
             fecTests.Run(new MethodBasedNotRegressionTests());
             fecTests.Run(new CustomReducibleNodeRegressionTests());
             fecTests.Run(new ExtensionReductionIdentityRegressionTests());

test/FastExpressionCompiler.TestsRunner/Program.cs

@@ -110,6 +110,7 @@ public static void Main(string[] args)
                 lt.Run(new LightExpression.UnitTests.ByRefConversionRegressionTests());
                 lt.Run(new LightExpression.UnitTests.PropertyGetterReceiverRegressionTests());
                 lt.Run(new LightExpression.UnitTests.RuntimeTypeConstantRegressionTests());
+                lt.Run(new LightExpression.UnitTests.MemberConstructorExceptionTests());
                 lt.Run(new LightExpression.UnitTests.MethodBasedNotRegressionTests());
                 lt.Run(new LightExpression.UnitTests.ExtensionReductionIdentityRegressionTests());
                 lt.Run(new LightExpression.UnitTests.LiftedOperandEvaluationRegressionTests());
@@ -157,6 +158,7 @@ public static void Main(string[] args)
             st.Run(new ByRefConversionRegressionTests());
             st.Run(new PropertyGetterReceiverRegressionTests());
             st.Run(new RuntimeTypeConstantRegressionTests());
+            st.Run(new MemberConstructorExceptionTests());
             st.Run(new MethodBasedNotRegressionTests());
             st.Run(new CustomReducibleNodeRegressionTests());
             st.Run(new ExtensionReductionIdentityRegressionTests());

test/FastExpressionCompiler.UnitTests/MemberConstructorExceptionTests.cs

@@ -0,0 +1,41 @@
+using System;
+using System.Collections.Generic;
+using S = System.Linq.Expressions.Expression;
+#if LIGHT_EXPRESSION
+using E = FastExpressionCompiler.LightExpression.Expression;
+namespace FastExpressionCompiler.LightExpression.UnitTests;
+#else
+using E = System.Linq.Expressions.Expression;
+namespace FastExpressionCompiler.UnitTests;
+#endif
+public struct MemberConstructorExceptionTests : ITestX
+{
+ public static List<int> Trace=new List<int>();
+ public sealed class Model {public int Total;public int Value;public Model(int a,int b){Trace.Add(5);Total=a+b;}}
+ public struct ValueModel {public int Total;public int Value;public ValueModel(int a,int b){Trace.Add(5);Total=a+b;Value=0;}}
+ public static int Mark(int n){Trace.Add(n);return n;}
+ public void Run(TestRun t) { Constructor_arguments_keep_order_before_bindings(t); }
+ public void Constructor_arguments_keep_order_before_bindings(TestContext t) {
+  foreach(var type in new[]{typeof(Model),typeof(ValueModel)}) {
+   var mark=typeof(MemberConstructorExceptionTests).GetMethod(nameof(Mark));
+   var created=E.New(type.GetConstructor(new[]{typeof(int),typeof(int)}),E.Call(mark,E.Constant(1)),E.TryFinally(E.Call(mark,E.Constant(2)),E.Block(E.Call(mark,E.Constant(3)),E.Empty())));
+   var tree=E.Lambda<Func<object>>(E.Convert(E.MemberInit(created,E.Bind(type.GetField("Value"),E.Call(mark,E.Constant(4)))),typeof(object)));
+#if NETFRAMEWORK
+   // Framework's System compiler rejects EH inside struct member initializers.
+   Func<object> system=type.IsValueType?FrameworkValue:(Func<object>)tree.CompileSys();
+#else
+   var system=(Func<object>)tree.CompileSys();
+#endif
+   Trace.Clear();var expected=system();var effects=string.Join(",",Trace);
+   foreach(var flags in new[]{CompilerFlags.Default,CompilerFlags.NoInvocationLambdaInlining,CompilerFlags.EnableDelegateDebugInfo}) {var fast=tree.CompileFast(true,flags);if(!t.IsNotNull(fast))return;Trace.Clear();var actual=fast();t.AreEqual(type.GetField("Total").GetValue(expected),type.GetField("Total").GetValue(actual));t.AreEqual(type.GetField("Value").GetValue(expected),type.GetField("Value").GetValue(actual));t.AreEqual(effects,string.Join(",",Trace));}
+  }
+ }
+#if NETFRAMEWORK
+ private static object FrameworkValue() {
+  var first=Mark(1);int second;
+  try{second=Mark(2);}finally{Mark(3);}
+  var result=new ValueModel(first,second);result.Value=Mark(4);return result;
+ }
+#endif
+
+}