Add ParamValue.ToString into ArgumentException message

[JesOb]

An element with the same key already exists in the dictionary.

This message says nothing when meet in log. Adding key.ToString into it will fix issue:

An element with the same key: 56 already exists in the dictionary.
An element with the same key: Bla already exists in the dictionary.
An element with the same key: WhateverReturnsFromToString already exists in the dictionary.

or

An element with the same key already exists in the dictionary. ParamValue is 56
An element with the same key already exists in the dictionary. ParamValue is Bla
An element with the same key already exists in the dictionary. ParamValue is WhateverReturnsFromToString

And so on.

[stephentoub]

Dup of dotnet/corefx#1187

[JesOb]

There is about dicitonary problem resolution but I say about ArgumentException itself for every case where we can use it.

[stephentoub]

I see. ArgumentException doesn't accept nor store anything about the incorrect argument's value (other than in whatever message the caller constructs and provides), so this would be more than just an implementation change to ArgumentException: it'd actually need new API surface area, and all consumers of ArgumentException that wanted the value traced out as part of the message would need to use that new surface area. If that's what you're asking for, then it'd be helpful for you to propose the exact surface area you're interested in seeing added, at which point it can be evaluated.

[JesOb]

Argument Exception can be overriden to have additional Ctor with ActualValue and pass value to Exception on creation of exception like in ArgumentOutOfRange exception.

And mark ctor with ParamName but without actualValue with ObsoleteAttribute to stimulate providing actualValue for Exception.

ActualValue.ToString can be surrounded with try catch and if ToString will fail we just see some info about fail and type fo Value ActualValue.GetType().FullName.

This is mostly useful in ArgumentException s in collections but actually needed everywhere.

[JesOb]

The same in: InvalidCastException: Cannot cast from source type to destination type.
Show me source and destination type

Most of the time destination type I know but source type not.

[stephentoub]

InvalidCastException is usually not explicitly thrown in code; rather, it's typically generated by the runtime when an invalid cast occurs. Such a feature request should be filed over on the https://github.com/dotnet/coreclr repo.

[terrajobst]

We reviewed this item and it looks like a dupe.

@stephentoub, could you verify and close?

[stephentoub]

The same in: InvalidCastException: Cannot cast from source type to destination type. Show me source and destination type

It typically does. For example, this code:

object i = new Queue<int>();
Queue<double> j = (Queue<double>)i;

results in this exception message:

Unhandled Exception: System.InvalidCastException: Unable to cast object of type 'System.Collections.Generic.Queue`1[System.Int32]' to type 'System.Collections.Generic.Queue`1[System.Double]'.

and:

object i = "hello";
char[] arr = (char[])i;

results in the message:

Unhandled Exception: System.InvalidCastException: Unable to cast object of type 'System.String' to type 'System.Char[]'.

The source/destination types were previously left out of cast messages when unboxing, but that was recently addressed at dotnet/coreclr#1543.

Dictionary is being addressed here: dotnet/coreclr#1452 for Dictionary

And of course for your own exception throwing, you can derive whatever exceptions you like and include any additional information you desire.

With that, I don't believe there's anything else concrete and actionable on this thread, so I'm going to go ahead and close it. Thanks for opening the discussion. If subsequently there's another specific case you think needs to be addressed (i.e. somewhere an exception is being thrown where you believe it's missing important info that could/should be included), please go ahead and open another issue for that case.