IndexOutOfRangeException in TryEmitConvert on .NET Framework

[exyi]

Hello, some of our users are reporting a strange exception coming from FastExpressionCompiler FindConvertOperator method. Unfortunately, I'm unable to replicate it, as it probably only occurs on .NET Framework (or in other special circumstances). However, the compiled expression can be quite simple, on of the stack traces I have is coming from this - essentially only New(Convert(x), Convert(y)).

I think it started occuring with FEC 4.0.1 or 4.0.0, I have just asked the second user about its version, will let you know when I get a response.

I guess the only possible cause is a implicit/explicit operator with 0 arguments, which is weird. I just wanted to ask, if you have any other idea. I see you recently made some changes to this method, could this be related?

The exceptions are:

System.IndexOutOfRangeException: Index was outside the bounds of the array.

MethodInfo FastExpressionCompiler.Tools.FindConvertOperator(Type type, Type sourceType, Type targetType)
bool FastExpressionCompiler.ExpressionCompiler+EmittingVisitor.TryEmitConvert(UnaryExpression expr, IReadOnlyList<ParameterExpression> paramExprs, ILGenerator il, ref ClosureInfo closure, CompilerFlags setup, ParentFlags parent)
bool FastExpressionCompiler.ExpressionCompiler+EmittingVisitor.TryEmit(Expression expr, IReadOnlyList<ParameterExpression> paramExprs, ILGenerator il, ref ClosureInfo closure, CompilerFlags setup, ParentFlags parent, int byRefIndex)
bool FastExpressionCompiler.ExpressionCompiler+EmittingVisitor.TryEmitAssignToParameterOrVariable(ParameterExpression left, Expression right, ExpressionType nodeType, bool isPost, Type exprType, IReadOnlyList<ParameterExpression> paramExprs, ILGenerator il, ref ClosureInfo closure, CompilerFlags setup, ParentFlags parent, int resultVar)
bool FastExpressionCompiler.ExpressionCompiler+EmittingVisitor.TryEmitArithmeticAndOrAssign(Expression left, Expression right, Type exprType, ExpressionType nodeType, bool isPost, IReadOnlyList<ParameterExpression> paramExprs, ILGenerator il, ref ClosureInfo closure, CompilerFlags setup, ParentFlags parent)
bool FastExpressionCompiler.ExpressionCompiler+EmittingVisitor.TryEmit(Expression expr, IReadOnlyList<ParameterExpression> paramExprs, ILGenerator il, ref ClosureInfo closure, CompilerFlags setup, ParentFlags parent, int byRefIndex) x 2
object FastExpressionCompiler.ExpressionCompiler.TryCompileBoundToFirstClosureParam(Type delegateType, Expression bodyExpr, IReadOnlyList<ParameterExpression> paramExprs, Type[] closurePlusParamTypes, Type returnType, CompilerFlags flags)
TDelegate FastExpressionCompiler.ExpressionCompiler.CompileFast<TDelegate>(LambdaExpression lambdaExpr, bool ifFastFailedReturnNull, CompilerFlags flags)
void DotVVM.Framework.Compilation.ViewCompiler.ViewCompilingVisitor.VisitView(ResolvedTreeRoot view)

System.IndexOutOfRangeException: Index was outside the bounds of the array.

MethodInfo FastExpressionCompiler.Tools.FindConvertOperator(Type type, Type sourceType, Type targetType)
bool FastExpressionCompiler.ExpressionCompiler+EmittingVisitor.TryEmitConvert(UnaryExpression expr, IReadOnlyList<ParameterExpression> paramExprs, ILGenerator il, ref ClosureInfo closure, CompilerFlags setup, ParentFlags parent)
bool FastExpressionCompiler.ExpressionCompiler+EmittingVisitor.TryEmit(Expression expr, IReadOnlyList<ParameterExpression> paramExprs, ILGenerator il, ref ClosureInfo closure, CompilerFlags setup, ParentFlags parent, int byRefIndex)
bool FastExpressionCompiler.ExpressionCompiler+EmittingVisitor.TryEmitNew(Expression expr, IReadOnlyList<ParameterExpression> paramExprs, ILGenerator il, ref ClosureInfo closure, CompilerFlags setup, ParentFlags parent)
bool FastExpressionCompiler.ExpressionCompiler+EmittingVisitor.TryEmit(Expression expr, IReadOnlyList<ParameterExpression> paramExprs, ILGenerator il, ref ClosureInfo closure, CompilerFlags setup, ParentFlags parent, int byRefIndex)
object FastExpressionCompiler.ExpressionCompiler.TryCompileBoundToFirstClosureParam(Type delegateType, Expression bodyExpr, IReadOnlyList<ParameterExpression> paramExprs, Type[] closurePlusParamTypes, Type returnType, CompilerFlags flags)
Func<T1, T2, R> FastExpressionCompiler.ExpressionCompiler.CompileFast<T1, T2, R>(Expression<Func<T1, T2, R>> lambdaExpr, bool ifFastFailedReturnNull, CompilerFlags flags)
TValue System.Collections.Concurrent.ConcurrentDictionary<TKey, TValue>.GetOrAdd(TKey key, Func<TKey, TValue> valueFactory)
IBinding DotVVM.Framework.Binding.BindingFactory.CreateBinding(BindingCompilationService service, Type binding, object[] properties) 

[dadhi]

@exyi Related issue is #386

This issue is already fixed, the fix will be released with v4.0.2

[exyi]

Ok, great, thank you!

[dadhi]

@exyi The v4.1.0 with the fix is out on NuGet