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Fix ParentFlags propagating in TryEmitNewExpression #493

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Fix ParentFlags propagating in TryEmitNewExpression #493

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0457a35
Add test suite for constructor call expression
exyi Jan 21, 2026
62bde56
Fix ParentFlags handling in TryEmitNewExpression
exyi Jan 21, 2026
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27 changes: 19 additions & 8 deletions src/FastExpressionCompiler/FastExpressionCompiler.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -2430,7 +2430,7 @@ private static bool TryEmitNew(Expression expr, IReadOnlyList<PE> paramExprs, IL
CompilerFlags setup, ParentFlags parent)
#endif
{
parent |= ParentFlags.CtorCall;
var flags = ParentFlags.CtorCall;
var newExpr = (NewExpression)expr;
#if SUPPORTS_ARGUMENT_PROVIDER
var argExprs = (IArgumentProvider)newExpr;
Expand All @@ -2449,15 +2449,15 @@ private static bool TryEmitNew(Expression expr, IReadOnlyList<PE> paramExprs, IL
// see the #488 for the details.
if (argCount == 1)
{
if (!TryEmit(argExprs.GetArgument(0), paramExprs, il, ref closure, setup, parent, pars[0].ParameterType.IsByRef ? 0 : -1))
if (!TryEmit(argExprs.GetArgument(0), paramExprs, il, ref closure, setup, flags, pars[0].ParameterType.IsByRef ? 0 : -1))
return false;
}
else
{
if (!closure.ArgsContainingComplexExpression.Map.ContainsKey(newExpr))
{
for (var i = 0; i < argCount; ++i)
if (!TryEmit(argExprs.GetArgument(i), paramExprs, il, ref closure, setup, parent, pars[i].ParameterType.IsByRef ? i : -1))
if (!TryEmit(argExprs.GetArgument(i), paramExprs, il, ref closure, setup, flags, pars[i].ParameterType.IsByRef ? i : -1))
return false;
}
else
Expand All @@ -2467,7 +2467,7 @@ private static bool TryEmitNew(Expression expr, IReadOnlyList<PE> paramExprs, IL
{
var argExpr = argExprs.GetArgument(i);
var parType = pars[i].ParameterType;
if (!TryEmit(argExpr, paramExprs, il, ref closure, setup, parent, parType.IsByRef ? i : -1))
if (!TryEmit(argExpr, paramExprs, il, ref closure, setup, flags, parType.IsByRef ? i : -1))
return false;
argVars.Add(EmitStoreLocalVariable(il, parType));
}
Expand All @@ -2476,21 +2476,32 @@ private static bool TryEmitNew(Expression expr, IReadOnlyList<PE> paramExprs, IL
}
}
}
var newType = newExpr.Type;
// ReSharper disable once ConditionIsAlwaysTrueOrFalse
if (ctor != null)
il.Demit(OpCodes.Newobj, ctor);
else if (newExpr.Type.IsValueType)
else if (newType.IsValueType)
{
ctor = newExpr.Type.GetConstructor(
ctor = newType.GetConstructor(
BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic,
default, CallingConventions.Any, Tools.Empty<Type>(), default);
if (ctor != null)
il.Demit(OpCodes.Newobj, ctor);
else
EmitLoadLocalVariable(il, InitValueTypeVariable(il, newExpr.Type));
EmitLoadLocalVariable(il, InitValueTypeVariable(il, newType));
}
else
return false;

closure.LastEmitIsAddress = newType.IsValueType && (parent & ParentFlags.InstanceAccess) != 0 && !parent.IgnoresResult();
if (closure.LastEmitIsAddress)
{
EmitStoreAndLoadLocalVariableAddress(il, newType);
}

if (parent.IgnoresResult())
il.Demit(OpCodes.Pop);

return true;
}

Expand Down Expand Up @@ -5081,7 +5092,7 @@ public static bool TryEmitMemberGet(MemberExpression expr,
// if the field is not used as an index, #302
// or if the field is not accessed from the just constructed object `new Widget().DodgyValue`, #333
if (((parent & ParentFlags.InstanceAccess) != 0 &
(parent & (ParentFlags.IndexAccess | ParentFlags.Ctor)) == 0) && field.FieldType.IsValueType)
(parent & ParentFlags.IndexAccess) == 0) && field.FieldType.IsValueType)
isByAddress = true;

// we don't need to duplicate the instance if we are working with the field address to save to it directly,
Expand Down
2 changes: 2 additions & 0 deletions test/FastExpressionCompiler.TestsRunner/Program.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -98,6 +98,8 @@ void Run(Func<int> run, string name = null)
Run(new LightExpression.UnitTests.ConvertOperatorsTests().Run);
Run(new DefaultTests().Run);
Run(new LightExpression.UnitTests.DefaultTests().Run);
Run(new ConstructorCallTests().Run);
Run(new LightExpression.UnitTests.ConstructorCallTests().Run);
Run(new EqualityOperatorsTests().Run);
Run(new LightExpression.UnitTests.EqualityOperatorsTests().Run);
Run(new GotoTests().Run);
Expand Down
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