Failed compilation with false error CS0534 ('X' does not implement inherited abstract member 'Y')

Steps to reproduce

1. Clone https://github.com/twilio/twilio-csharp
2. Checkout branch next-gen-netstandard
3. dotnet restore <-- works fine
4. dotnet build JWT <-- works fine
5. dotnet build Twilio <-- fails

Expected behavior

Should successfully compile the project. It compiles fine within Visual Studio 2015 U3.

Actual behavior

Project JWT (.NETStandard,Version=v1.1) was previously compiled. Skipping compilation.
Project Twilio (.NETStandard,Version=v1.1) will be compiled because expected outputs are missing
Compiling Twilio for .NETStandard,Version=v1.1
C:\Program Files\dotnet\dotnet.exe compile-csc @C:\Users\david\Projects\twilio-csharp\Twilio\obj\Debug\netstandard1.1\dotnet-compile.rsp returned Exit Code 1
C:\Users\david\Projects\twilio-csharp\Twilio\Http\SystemNetClient.cs(7,15): error CS0534: 'SystemNetClient' does not implement inherited abstract member 'HttpClient.MakeRequestAysnc(Request)'

Compilation failed.
    0 Warning(s)
    1 Error(s)

Time elapsed 00:00:03.9889266

The error is incorrect. The abstract member is implemented and the code compiles fine in Visual Studio 2015 U3.

Environment data

dotnet --info output:

.NET Command Line Tools (1.0.0-preview2-1-003177)

Product Information:
 Version:            1.0.0-preview2-1-003177
 Commit SHA-1 hash:  a2df9c2576

Runtime Environment:
 OS Name:     Windows
 OS Version:  10.0.14393
 OS Platform: Windows
 RID:         win10-x64

[dprothero]

@krwq Thanks for all your help troubleshooting. Finally found the problem, and it was me and my eyes… the error says SystemNetClient which was a class that already existed but was only intended for our .NET 3.5 library. I surrounded it with the appropriate precompiler checks and all is peachy.

[TheRealPiotrP]

Thanks for tracking this down, @dprothero && @krwq!