Build configuration

Roslyn and C# version constants

Before the compilation, the package reads the version of the Microsoft.CodeAnalysis package that the project references and defines constants for it, so the same code can target several versions of Roslyn:

Constant	Defined when the Roslyn version is at least
`ROSLYN_<version>_OR_GREATER`, such as `ROSLYN_4_8_OR_GREATER` or `ROSLYN_4_9_2_OR_GREATER`	That version, for the Roslyn releases from 1.0 to 5.9.
`CSHARP9_OR_GREATER`	4.2
`CSHARP10_OR_GREATER`	4.4
`CSHARP11_OR_GREATER`	4.6
`CSHARP12_OR_GREATER`	4.8
`CSHARP13_OR_GREATER`	4.14
`CSHARP14_OR_GREATER`	5.0
`CSHARP15_OR_GREATER`	5.6
`ROSLYN_WORKSPACES`	Any version, when the project references a workspaces package.

Use them in #if directives around the code that calls newer APIs. The CSHARP* constants say which C# versions the referenced compiler APIs know, such as LanguageVersion.CSharp12, not the C# version of your project.

The version is read from the PackageReference of Microsoft.CodeAnalysis.CSharp, then Microsoft.CodeAnalysis.Common, Microsoft.CodeAnalysis.Workspaces.Common and Microsoft.CodeAnalysis.CSharp.Workspaces, then from the PackageVersion items of central package management. ROSLYN_WORKSPACES is defined when the project references Microsoft.CodeAnalysis.Workspaces.Common, Microsoft.CodeAnalysis.CSharp.Workspaces, Microsoft.CodeAnalysis.VisualBasic.Workspaces or Microsoft.CodeAnalysis.Workspaces.MSBuild.

To define the constants yourself, disable this feature:

<PropertyGroup>
  <MeziantouFrameworkRoslynDefineConstants>false</MeziantouFrameworkRoslynDefineConstants>
</PropertyGroup>

Embedded types

All the types of the package are marked with [Microsoft.CodeAnalysis.Embedded], so the compiler hides them from the other assemblies. Two assemblies that use the package and see each other's internals through [InternalsVisibleTo] do not get CS0436 warnings about duplicate types.

The package declares Microsoft.CodeAnalysis.EmbeddedAttribute as an internal sealed partial class without any attribute, so it merges with the declarations that other source generators or packages emit. If your project declares the attribute in a way that conflicts, define one of these constants:

Constant	Effect
`MEZIANTOU_FRAMEWORK_ROSLYN_DISABLE_EMBEDDEDATTRIBUTE_DECLARATION`	The types are still marked as embedded, but the project must declare the attribute.
`MEZIANTOU_FRAMEWORK_ROSLYN_DISABLE_EMBEDDEDATTRIBUTE`	Neither declares the attribute nor marks the types with it.

<PropertyGroup>
  <DefineConstants>$(DefineConstants);MEZIANTOU_FRAMEWORK_ROSLYN_DISABLE_EMBEDDEDATTRIBUTE_DECLARATION</DefineConstants>
</PropertyGroup>

Compiler warnings

The helper files suppress all the compiler warnings, so they do not add warnings to your build, whatever its rules. Define MEZIANTOU_FRAMEWORK_ROSLYN_ENABLE_WARNINGS to report them:

<PropertyGroup>
  <DefineConstants>$(DefineConstants);MEZIANTOU_FRAMEWORK_ROSLYN_ENABLE_WARNINGS</DefineConstants>
</PropertyGroup>