Cannot pin NETStandard.Library = 1.6.0

Description

Similar to #2289, I seeming cannot install packages when I pin NETStandard.Library 1.6.0. This is required by AWS Lambda, but most recent Microsoft.* packages require version 1.6.1. I keep getting the Paket may still find a valid resolution, but this might take a while message but I never waited long enough for it to finish.

Here’s my intended dependencies file.

source https://www.nuget.org/api/v2/

nuget xunit >= 2.3 prerelease
nuget FakeItEasy
nuget FluentAssertions
nuget Microsoft.NET.Test.Sdk
nuget xunit.extensibility.execution >= 2.3 prerelease
nuget xunit.runner.visualstudio >= 2.3 prerelease
nuget Microsoft.AspNetCore.Mvc.Core
nuget Amazon.Lambda.Core
nuget Amazon.Lambda.Serialization.Json
nuget Amazon.Lambda.APIGatewayEvents
nuget Microsoft.AspNetCore.Server.Kestrel
nuget Microsoft.Extensions.Configuration.EnvironmentVariables
nuget Microsoft.Extensions.Configuration.FileExtensions
nuget Microsoft.Extensions.Configuration.Json
nuget Microsoft.Extensions.Logging
nuget Microsoft.Extensions.Options.ConfigurationExtensions
nuget AWSSDK.S3
nuget AWSSDK.Extensions.NETCore.Setup
nuget Amazon.Lambda.Logging.AspNetCore
nuget Amazon.Lambda.AspNetCoreServer
nuget NETStandard.Library 1.6.0

Repro steps

Use the above dependencies file and paket install

Expected behavior

Should resolve older versions of packages which don’t require NETStandard.Library: >= 1.6.1

Actual behavior

It takes very long

Known workarounds

It is seemingly possible to pin all packages and their transitive dependencies but there are loads of them.

I also tried with groups but it keeps telling me that install fails because my project references two version of the NETStandard.Library package.

[matthid]

After #2307

source https://www.nuget.org/api/v2/

nuget NETStandard.Library <= 1.6.0
nuget Microsoft.AspNetCore.Mvc.Core

Locked version resolution written to C:\PROJ\paket.test\paket.lock
1 minute, 8 seconds - ready.

source https://www.nuget.org/api/v2/

nuget xunit >= 2.3 prerelease
nuget FakeItEasy
nuget FluentAssertions
nuget Microsoft.NET.Test.Sdk
nuget xunit.extensibility.execution >= 2.3 prerelease
nuget xunit.runner.visualstudio >= 2.3 prerelease
nuget Microsoft.AspNetCore.Mvc.Core
nuget Amazon.Lambda.Core
nuget Amazon.Lambda.Serialization.Json
nuget Amazon.Lambda.APIGatewayEvents
nuget Microsoft.AspNetCore.Server.Kestrel
nuget Microsoft.Extensions.Configuration.EnvironmentVariables
nuget Microsoft.Extensions.Configuration.FileExtensions
nuget Microsoft.Extensions.Configuration.Json
nuget Microsoft.Extensions.Logging
nuget Microsoft.Extensions.Options.ConfigurationExtensions
nuget AWSSDK.S3
nuget AWSSDK.Extensions.NETCore.Setup
nuget Amazon.Lambda.Logging.AspNetCore
nuget Amazon.Lambda.AspNetCoreServer
nuget NETStandard.Library 1.6.0

Locked version resolution written to C:\PROJ\paket.test\paket.lock
1 minute, 39 seconds - ready.

With the min workaround

strategy: min
lowest_matching: true

Locked version resolution written to C:\PROJ\paket.test\paket.lock
1 minute, 49 seconds - ready.

So that one is actually slower now 😛

[matthid]

Just to note https://github.com/fsprojects/Paket/issues/2294#issuecomment-298084016 from @cloudRoutine is just a workaround for now. IMHO the resolver should be smart enough to be able to find something with default settings as well…