.net core version of System.Net.Mail is used when targeting .net461

[theimowski]

Description

I want to add Suave.Experimental and target net461 but using .net sdk-based project. When referencing System.Net.Mail.MailAddress class, a .net core package System.Net.Mail is added instead of using the standard System.dll 4.0

Repro steps

https://github.com/theimowski/repro-paket-system.net.mail

1. dotnet restore

2. dotnet build

3. dotnet run

Expected behavior

want to print:

System.Net.Mail.MailAddress, System, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089

Actual behavior

prints:

System.Net.Mail.MailAddress, System.Net.Mail, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null

Known workarounds

¯\(ツ)/¯

TBH I'm not even sure if this is Paket-related, or rather F#-specific. Same happens if I don't use Paket on F# project: https://github.com/theimowski/repro-paket-system.net.mail/tree/fsharp_nopaket However if I use C# without Paket https://github.com/theimowski/repro-paket-system.net.mail/tree/csharp , I get an error build upon dotnet build:

Program.cs(9,54): error CS0433: The type 'MailAddress' exists in both 'System.Net.Mail, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null' and 'System, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089' 

Any guidance would be helpful here

[matthid]

I think this is something interesting and might be related to what happened before regarding assembly versioning and Suave.

[matthid]

Ok maybe it is something entirely different, you can try to

• debug via msbuild https://github.com/KirillOsenkov/MSBuildStructuredLog and try to figure out what compilation flags are given to the C# and F# compiler and why
• Open an issue on dotnet-sdk/dotnet-cli with the nopaket and csharp repro. Maybe someone there immediately knows what's up

This looks like you might have hit some strange incompat between a netstandard and an existing net461 api.