Type.IsAssignableTo

[benaadams]

Resolves #30714

[Dotnet-GitSync-Bot]

Note regarding the new-api-needs-documentation label:

This serves as a reminder for when your PR is modifying a ref *.cs file and adding/modifying public APIs, to please make sure the API implementation in the src *.cs file is documented with triple slash comments, so the PR reviewers can sign off that change.

[Dotnet-GitSync-Bot]

I couldn't figure out the best area label to add to this PR. If you have write-permissions please help me learn by adding exactly one area label.

[EgorBo]

I assume

static bool Test<T1, T2>() => typeof(T1).IsAssignableTo(typeof(T2));

is optimized to true/false for known types (except Nullable and shared generics) 🙂

[jkotas]

is optimized to true/false for known types (except Nullable and shared generics)

That would require fixes in the JIT. I do not think the existing JIT optimization will be able to cut through ? :.

[EgorBo]

Oops. sorry 🙁

[akoeplinger]

/cc @steveharter @GrabYourPitchforks as System.Reflection area owners

[jkotas]

I think this should also expand the optimizations done for IsAssignableFrom to IsAssignableTo so that the new API is no-brainer to use and people do not have to think about trade-offs. It is hard to choose between two nearly identical APIs where one has better name and the other has better optimizations.

[EgorBo]

I think this should also expand the optimizations done for IsAssignableFrom to IsAssignableTo so that the new API is no-brainer to use and people do not have to think about trade-offs. It is hard to choose between two nearly identical APIs where one has better name and the other has better optimizations.

@benaadams feel free to ping if you need any help

[jkotas]

Do we need test for the optimization, similar to src/tests/JIT/Intrinsics/TypeIntrinsics.IsAssignableFrom.cs ?

[jkotas]

And also general functional tests for the API

[benaadams]

That's a new error, don't think its from this change though

/ runtime (Libraries Build Linux x64 Debug)

Build log #L1971
Child node "4" exited prematurely. Shutting down. Diagnostic information may be found in files in "/tmp/" and will be named MSBuild_*.failure.txt. This location can be changed by setting the MSBUILDDEBUGPATH environment variable to a different directory.
/tmp/MSBuild_pid-2555_75cd8686c9e7462d87e5a643d9ee969f.failure.txt:
UNHANDLED EXCEPTIONS FROM PROCESS 2555:
=====================
08/10/2020 16:31:12
System.InvalidOperationException: Collection was modified; enumeration operation may not execute.
   at System.Collections.Generic.Dictionary`2.Enumerator.MoveNext()
   at Microsoft.Build.BackEnd.BinaryTranslator.BinaryWriteTranslator.TranslateDictionary[D,T](D& dictionary, ObjectTranslator`1 objectTranslator)
   at Microsoft.Build.Execution.ProjectItemInstance.TaskItem.Microsoft.Build.BackEnd.ITranslatable.Translate(ITranslator translator)
   at Microsoft.Build.BackEnd.BinaryTranslator.BinaryWriteTranslator.Translate[T](List`1& list, ObjectTranslator`1 objectTranslator)
   at Microsoft.Build.BackEnd.LogMessagePacket.TranslateTargetFinishedEvent(ITranslator translator, TargetFinishedEventArgs finishedEvent)
   at Microsoft.Build.Shared.LogMessagePacketBase.WriteToStream(ITranslator translator)
   at Microsoft.Build.BackEnd.NodeEndpointOutOfProcBase.RunReadLoop(Stream localReadPipe, Stream localWritePipe, ConcurrentQueue`1 localPacketQueue, AutoResetEvent localPacketAvailable, AutoResetEvent localTerminatePacketPump)
===================

[benaadams]

Added test; seems unhappy with unrelated issue

      Process: 7628 dotnet PrivateMemory: 8100003840
      Timed out at 8/10/2020 5:56:34 PM after 60000ms waiting for remote process.
      Wrote mini dump to: C:\helix\work\workitem\uploads\7628.tpwrerhj.lnu.dmp
      	Process ID: 7628
      	Handle: 1000
      	Name: dotnet
      	MainModule: C:\helix\work\correlation\dotnet.exe
      	StartTime: 8/10/2020 5:55:34 PM
      	TotalProcessorTime: 00:01:00.1875000
      	Threads:
      		Thread #1 (OS 0x6A0)   [MTA]
      			[InlinedCallFrame] (System.Buffer.__Memmove)
      			[InlinedCallFrame] (System.Buffer.__Memmove)
      			System.Buffer._Memmove(Byte*, Byte*, UIntPtr)
      			System.String.wstrcpy(Char*, Char*, Int32)
      			System.Text.StringBuilder.ThreadSafeCopy(Char*, Char[], Int32, Int32)
      			System.Text.StringBuilder.Append(Char*, Int32)
      			System.Text.StringBuilder.Append(Char[])
      			System.Text.Tests.StringBuilderTests+<>c.<FailureOnLargeString>b__168_1()
      			System.AssertExtensions.ThrowsAnyInternal(System.Action, System.Type[])
      			System.AssertExtensions.ThrowsAny[[System.__Canon, System.Private.CoreLib],[System.__Canon, System.Private.CoreLib]](System.Action)
      			System.Text.Tests.StringBuilderTests+<>c.<FailureOnLargeString>b__168_0()
      			[DebuggerU2MCatchHandlerFrame]
      			[HelperMethodFrame_PROTECTOBJ] (System.RuntimeMethodHandle.InvokeMethod)
      			System.Reflection.MethodBase.Invoke(System.Object, System.Object[])
      			Microsoft.DotNet.RemoteExecutor.Program.Main(System.String[])
      		Thread #2 (OS 0xB98) [Finalizer] [Background] [MTA]
      			[DebuggerU2MCatchHandlerFrame]
      		Thread #3 (OS 0x2210) [Thread pool worker] [Background] [MTA]
      
      Stack Trace:
        /_/src/Microsoft.DotNet.RemoteExecutor/src/RemoteInvokeHandle.cs(225,0): at Microsoft.DotNet.RemoteExecutor.RemoteInvokeHandle.Dispose(Boolean disposing)
        /_/src/Microsoft.DotNet.RemoteExecutor/src/RemoteInvokeHandle.cs(58,0): at Microsoft.DotNet.RemoteExecutor.RemoteInvokeHandle.Dispose()
        /_/src/libraries/System.Runtime/tests/System/Text/StringBuilderTests.cs(2237,0): at System.Text.Tests.StringBuilderTests.FailureOnLargeString()
  Finished:    System.Runtime.Nls.Tests

[benaadams]

runtime (CoreCLR Product Build OSX x64 checked) broke or got chopped

/ runtime (CoreCLR Product Build OSX x64 checked)

[ 77%] Building CXX object src/jit/standalone/CMakeFiles/clrjit.dir/__/lsra.cpp.o
[ 77%] Building CXX object src/vm/crossgen/CMakeFiles/cee_crossgen.dir/__/instmethhash.cpp.o
[ 77%] Building CXX object src/jit/protononjit/CMakeFiles/protononjit.dir/__/instr.cpp.o
[ 77%] Building CXX object src/vm/wks/CMakeFiles/cee_wks_core.dir/__/encee.cpp.o
[ 77%] Building CXX object src/jit/standalone/CMakeFiles/clrjit.dir/__/lsrabuild.cpp.o
##[error]The operation was canceled.
Finishing: Build CoreCLR Runtime

[benaadams]

OSX Issue is already reported #34472

[jkotas]

Thanks