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Improve error reporting for dynamic method invocation via reflection #97022
Description
When we invoke a method via reflection, in case something goes wrong with type matching we get this error:
Object does not match target type.
This is a very poor message for debugging. Please give us more information. Something like:
You wanted to invoke
SomeMethodand you passedXof typeXTypewith valueXValueandYwith typeYType. These types do not match with whatSomeMethodexpects as its parametersAof typeATypeandBof typeBType.
Activity
steveharter commentedon Jan 17, 2024
The request sounds reasonable; the proposed wording seems a little verbose. Maybe shorten to something like:
It looks like the existing resource string "RFLCT_Targ_ITargMismatch" is used by the managed code in
System.Reflection.MethodInvokerCommonand by runtime code ininteroputil.cpp. To make this easier, we would likely create a new resource string for the managed code and leave the runtime\native code as-is.[-]Improve error reporting for dynamic method invokation via reflection[/-][+]Improve error reporting for dynamic method invocation via reflection[/+]Nefcanto commentedon Jan 18, 2024
@steveharter, thank you so much.
GustavoAdami commentedon Jan 24, 2024
@steveharter, I would like to take on this issue.
RutulPatel8 commentedon Feb 3, 2024
@Nefcanto or @steveharter
Can you please suggest how Can I debug runtime > Reflection code so I can fix this issue.
I tried lot but I didn't found the way.
Nefcanto commentedon Feb 4, 2024
@RutulPatel8, create a simple class with a single method that takes one parameter which is a string.
Now reflect it and call that method, but pass it a list of integers. That's how.
RutulPatel8 commentedon Feb 4, 2024
@Nefcanto Yes I know. how to reproduce this issue.
I'm talking about dotnet > Runtime > libraries > System.Reflection debugging.
Currently I clone runtime repository but I don't know which solution file needs to execute(debug) in runtime project.
In libraries, I found System.Reflection csProj but I think it is not right way to technique.
Nefcanto commentedon Feb 4, 2024
@RutulPatel8, I apologize for my misunderstanding. I don't know about that part.
RutulPatel8 commentedon Feb 4, 2024
Oh okay no issue Thanks for the help!
wcsanders1 commentedon Feb 4, 2024
I believe the solution file you're looking for is this one: https://github.com/dotnet/runtime/blob/main/src/coreclr/System.Private.CoreLib/System.Private.CoreLib.sln
AndyBevan commentedon Feb 5, 2024
I was taking a look at this and the error message gets thrown within class MethodInvokerCommon method ValidateInvokeTarget
I was unable to find any pre-existing tests for this class - am I missing them? I grepped the repo for the class name and did not find it used in anything test related.
I do find tests within \src\libraries\System.Private.CoreLib\tests\IntrinsicsInSystemPrivatecoreLibAnalyzer.Tests so would assume that somewhere under \tests\ would need a new test class adding for MethodInvokerCommon.
I tried to run the existing tests following the instructions from here -
https://github.com/dotnet/runtime/blob/main/docs/workflow/testing/libraries/testing.md#running-tests-for-a-single-library
But this doesn't appear to work for src\libraries\System.Private.CoreLib\tests\ because there is no solution like there is for something like System.Collections.Immutable which has a solution within the libraries folder.
@steveharter - are you able to give some pointers on what I might be missing in terms of how we can run the tests within visual studio for System.Private.CoreLib?
RutulPatel8 commentedon Feb 5, 2024
Which solution did you execute for debugging?
AndyBevan commentedon Feb 5, 2024
At this point I have not found any tests to execute. I'm hoping that @steveharter will give us some pointers on how to approach this because there is a solution file that contains libraries\System.Private.CoreLib but it's in coreclr (/src/coreclr/System.Private.CoreLib/System.Private.CoreLib.sln) and does not contain the tests (Maybe it should?)
Rest of my questions are in this post - #97022 (comment)
AndyBevan commentedon Feb 5, 2024
I think I figured it out - It looks like you need to use the System.Runtime solution which includes the public methods that allow access to System.Private.CoreLib.
AndyBevan commentedon Feb 7, 2024
I've been looking at this and have submitted a PR - #98129
@steveharter - I do have a few questions that I'm hoping you can help me with.
Object of type {0} does not match target type {1}.This is different from the proposed message ofSomeMethod exists on type X but an object of type Y was passed.. Because I'm not sure we know easily that the target type has SomeMethod. The problem here relates to the incorrect type being passed in so I think the error message I used adds the additional clarity we are looking for.\System.Private.CoreLib\src\System\Reflection\MethodInvokerCommon.cs). To modify MethodInvokerCommon I needed to load System.Private.CoreLib.sln, what's the easiest way to rebuild this library so that it gets pulled into for use within projects contained in the System.Runtime.sln solution. I ended up rerunningbuild.cmd clr+libs -rc Releasebut that's a big hammer for a small nut (hopefully). Is there a more efficient way to work to rebuild Private.CoreLib and then have the managed code libraries pull the new version? I hope this question makes sense. I tried just building System.Private.CoreLib.sln and that wasn't sufficient to for the projects contained in System.Runtime solution to have the new assembly.Added more verbose error message when calling method using reflection…
Added more verbose error message when calling method using reflection…