or-tools: Missing support for .NET Framework in latest Nuget packages

@Mizux , maybe a single NetStandard 2.0 ?

.NET Framework: 4.6.1, 4.6.2, 4.7, 4.7.1, 4.7.2, 4.8 ref: https://learn.microsoft.com/en-us/dotnet/standard/net-standard?tabs=net-standard-2-0

NET Standard is a formal specification of .NET APIs that are available on multiple .NET implementations. The motivation behind .NET Standard was to establish greater uniformity in the .NET ecosystem. .NET 5 and later versions adopt a different approach to establishing uniformity that eliminates the need for .NET Standard in most scenarios. However, if you want to share code between .NET Framework and any other .NET implementation, such as .NET Core, your library should target .NET Standard 2.0. No new versions of .NET Standard will be released, but .NET 5, .NET 6, and all future versions will continue to support .NET Standard 2.1 and earlier.

The code improvements were a result of a contribution where the user spent a lot of time profiling, improving, and optimizing the code. I am not happy to throw away his code.

@lperron The code changes I have made in PR #3542 are not in any way related to code optimization. I have only reverted the use of some C# 9 syntactic sugar. Code functions exactly the same as before, it is just a change of expressing the patterns in code.

I would like to see if we can compile targeting 4.6.2 or later with some C#9 code inside with vs2019. That would solve a lot of problems.

The changes I have made have no negative impact on the ability to build on VS 2019, quite the opposite, since I would expect that C# 8 is more reliably supported on VS 2019 than is C# 9.

And yes, although not officially supported it looks like the current code builds for .NET Framework 4.6.1 and forward with language version set to 9. As a .NET Framework user I would still be concerned that the code could misbehave in scenarios not captured in compilation, but at this point I have yet no indication that it will not work.

FYI.

When manually building the Google.OrTools.csproj project for .NET Framework, I noticed that C# language version was set to 9.0 in the project file. Officially, .NET Framework is only expected to support C# up to language version 8, but I got no compilation errors when building, at least for .NET Framework 4.8.

When changing language version to 8.0 in the project file, I get the following compilation errors:

\or-tools\ortools\sat\csharp\CpModel.cs(145,33): error CS8400: Feature ‘or pattern’ is not available in C# 8.0. Please use language version 9.0 or greater. [\or-tools\build\dotnet\Google.OrTools\Google.OrTools.csproj] \or-tools\ortools\util\csharp\NestedArrayHelper.cs(61,27): error CS8400: Feature ‘not pattern’ is not available in C# 8.0. Please use language version 9.0 or greater. [\or-tools\build\dotnet\Google.OrTools\Google.OrTools.csproj] \or-tools\ortools\sat\csharp\CpModel.cs(146,33): error CS8400: Feature ‘or pattern’ is not available in C# 8.0. Please use language version 9.0 or greater. [\or-tools\build\dotnet\Google.OrTools\Google.OrTools.csproj] \or-tools\ortools\sat\csharp\CpModel.cs(165,40): error CS8400: Feature ‘or pattern’ is not available in C# 8.0. Please use language version 9.0 or greater. [\or-tools\build\dotnet\Google.OrTools\Google.OrTools.csproj] \or-tools\ortools\sat\csharp\CpModel.cs(1015,36): error CS8400: Feature ‘not pattern’ is not available in C# 8.0. Please use language version 9.0 or greater. [\or-tools\build\dotnet\Google.OrTools\Google.OrTools.csproj] \or-tools\ortools\sat\csharp\CpModel.cs(1015,81): error CS8400: Feature ‘not pattern’ is not available in C# 8.0. Please use language version 9.0 or greater. [\or-tools\build\dotnet\Google.OrTools\Google.OrTools.csproj] \or-tools\ortools\sat\csharp\CpSolver.cs(36,35): error CS8400: Feature ‘not pattern’ is not available in C# 8.0. Please use language version 9.0 or greater. [\or-tools\build\dotnet\Google.OrTools\Google.OrTools.csproj] \or-tools\ortools\sat\csharp\CpSolver.cs(40,30): error CS8400: Feature ‘not pattern’ is not available in C# 8.0. Please use language version 9.0 or greater. [\or-tools\build\dotnet\Google.OrTools\Google.OrTools.csproj] \or-tools\ortools\sat\csharp\CpSolver.cs(44,19): error CS8400: Feature ‘not pattern’ is not available in C# 8.0. Please use language version 9.0 or greater. [\or-tools\build\dotnet\Google.OrTools\Google.OrTools.csproj] \or-tools\ortools\sat\csharp\CpSolver.cs(52,19): error CS8400: Feature ‘not pattern’ is not available in C# 8.0. Please use language version 9.0 or greater. [\or-tools\build\dotnet\Google.OrTools\Google.OrTools.csproj] \or-tools\ortools\sat\csharp\CpSolver.cs(84,31): error CS8400: Feature ‘not pattern’ is not available in C# 8.0. Please use language version 9.0 or greater. [\or-tools\build\dotnet\Google.OrTools\Google.OrTools.csproj]

@Mizux @lperron Many thanks for reopening this request!

Regarding the version of .NET Framework, I would recommend that you target .NET 4.6.1 or 4.6.2. That would definitely be enough for most .NET Framework users, and it is forward compatible up to .NET Framework 4.8.

I understand your concern on the <TargetFrameworks> issue, although I believe you have some kind of solution for it? Anyway, targeting .NET Framework 4.6.1 (2), .NET Core 3.1 and .NET 6 will probably suffice for quite a while forward.

Regarding .NET Standard 2.0, that would of course be a tempting solution, but I am not sure about accessing the native x64 libraries directly from a .NET Standard assembly? It will probably be less extra work if you stick with the approach you have chosen now for .NET.

Hi guys, I’m developing a visual studio extension based on or-tools. As VS runs on .NET framework, it would be great if the newest version of or-tools could support net472. Thanks!