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New generic constraint error in 2.16.1

See original GitHub issue

I’m not sure what to do with this, so I figured reporting here and see if anyone knew would be my best course of action. We have a bot (renovate) that updates dependencies of projects at work, and the update from 2.16.0 to 2.16.1 of FsCheck broke our tests with the following error:

System.TypeLoadException : GenericArguments[0], 'b', on 'FsCheck.ReflectArbitrary+shrinkChildren@183-1[a]' violates the constraint of type parameter 'a'.
Stack Trace:
   at System.RuntimeMethodHandle.InvokeMethod(Object target, Object[] arguments, Signature sig, Boolean constructor)
   at System.Reflection.RuntimeMethodInfo.UnsafeInvokeInternal(Object obj, Object[] parameters, Object[] arguments)
   at System.Reflection.RuntimeMethodInfo.Invoke(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture)
   at System.Reflection.MethodBase.Invoke(Object obj, Object[] parameters)
   at FsCheck.Runner.checkMethod(Config config, MethodInfo m, FSharpOption`1 target)
   at FsCheck.Check.Method(Config config, MethodInfo methodInfo, FSharpOption`1 target)
   at <StartupCode$FsCheck-Xunit>.$PropertyAttribute.testExec@199(PropertyTestCase this, IMessageBus messageBus, Object[] constructorArguments, CancellationTokenSource cancellationTokenSource, XunitTest test, RunSummary summary, TestOutputHelper outputHelper, Unit unitVar0)
----- Inner Stack Trace -----
   at FsCheck.ReflectArbitrary.reflectShrinkObj@226-7.Invoke(FSharpFunc`2 arg00)
   at Microsoft.FSharp.Core.FSharpFunc`2.InvokeFast[V,W,X](FSharpFunc`2 func, T arg1, TResult arg2, V arg3, W arg4)
   at FsCheck.ReflectArbitrary.reflectShrink[a,a](FSharpFunc`2 getShrink, a a)
   at FsCheck.Arb.Derive@1326.Shrinker(a a)
   at FsCheck.Testable.props@143-1[a,b,c](FSharpFunc`2 shrink, FSharpFunc`2 pf, a x)
   at FsCheck.Testable.shrinking[a,b,c](FSharpFunc`2 shrink, a x, FSharpFunc`2 pf)
   at FsCheck.Testable.forAll@163-1.Invoke(a _arg1)
   at FsCheck.GenBuilder.Bind@88.Invoke(Int32 n, StdGen r0)
   at FsCheck.Runner.test@96-1.GenerateNext(IEnumerable`1& next)
   at Microsoft.FSharp.Core.CompilerServices.GeneratedSequenceBase`1.MoveNextImpl()
   at Microsoft.FSharp.Core.CompilerServices.GeneratedSequenceBase`1.System-Collections-IEnumerator-MoveNext()
   at FsCheck.Common.loop@53-1.GenerateNext(IEnumerable`1& next)
   at Microsoft.FSharp.Core.CompilerServices.GeneratedSequenceBase`1.MoveNextImpl()
   at Microsoft.FSharp.Core.CompilerServices.GeneratedSequenceBase`1.System-Collections-IEnumerator-MoveNext()
   at FsCheck.Common.takeWhilePlusLast@61.GenerateNext(IEnumerable`1& next)
   at Microsoft.FSharp.Core.CompilerServices.GeneratedSequenceBase`1.MoveNextImpl()
   at Microsoft.FSharp.Core.CompilerServices.GeneratedSequenceBase`1.System-Collections-IEnumerator-MoveNext()
   at Microsoft.FSharp.Collections.SeqModule.Fold[T,TState](FSharpFunc`2 folder, TState state, IEnumerable`1 source)
   at FsCheck.Runner.runner[a](Config config, a prop)
   at FsCheck.Runner.check[a](Config config, a p)

Issue Analytics

State:
Created 2 years ago
Reactions:1
Comments:9 (4 by maintainers)

Top GitHub Comments

3reactions

kurtschelfthoutcommented, Aug 30, 2021

Fix released in 2.16.2

1reaction

kurtschelfthoutcommented, Aug 30, 2021

It’s strange, I can’t reproduce on master but I can reproduce with the build from NuGet. Thanks for the repro I’ll investigate further.

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