move to a consistent langversion of 11

Directory.Build.props

@@ -7,5 +7,6 @@
       <AddSyntheticProjectReferencesForSolutionDependencies>false</AddSyntheticProjectReferencesForSolutionDependencies>
       <MSBuildEnableWorkloadResolver>false</MSBuildEnableWorkloadResolver>
       <RunApiCompat>False</RunApiCompat>
+      <LangVersion>11</LangVersion>
   </PropertyGroup>
 </Project>

build/SharedVersion.props

@@ -8,7 +8,6 @@
     <RepositoryUrl>https://github.com/AvaloniaUI/Avalonia/</RepositoryUrl>
     <GenerateDocumentationFile>true</GenerateDocumentationFile>
     <NoWarn>$(NoWarn);CS1591</NoWarn>
-    <LangVersion>preview</LangVersion>
     <PackageLicenseExpression>MIT</PackageLicenseExpression>
     <PackageIcon>Icon.png</PackageIcon>
     <PackageDescription>Avalonia is a cross-platform UI framework for .NET providing a flexible styling system and supporting a wide range of Operating Systems such as Windows, Linux, macOS and with experimental support for Android, iOS and WebAssembly.</PackageDescription>

src/Browser/Avalonia.Browser/Avalonia.Browser.csproj

@@ -1,7 +1,6 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
     <TargetFramework>net7.0</TargetFramework>
-    <LangVersion>preview</LangVersion>
     <Nullable>enable</Nullable>
     <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
   </PropertyGroup>

src/tools/DevAnalyzers/DevAnalyzers.csproj

@@ -2,7 +2,6 @@
 
   <PropertyGroup>
     <TargetFramework>netstandard2.0</TargetFramework>
-    <LangVersion>10</LangVersion>
     <Nullable>enable</Nullable>
   </PropertyGroup>
 

src/tools/DevGenerators/DevGenerators.csproj

@@ -4,7 +4,6 @@
     <TargetFramework>netstandard2.0</TargetFramework>
     <Nullable>enable</Nullable>
     <IsPackable>false</IsPackable>
-    <LangVersion>10</LangVersion>
   </PropertyGroup>
 
   <ItemGroup>

tests/Avalonia.Base.UnitTests/Avalonia.Base.UnitTests.csproj

@@ -3,7 +3,6 @@
     <TargetFramework>net6.0</TargetFramework>
     <OutputType>Library</OutputType>
     <IsTestProject>true</IsTestProject>
-    <LangVersion>latest</LangVersion>
   </PropertyGroup>
   <Import Project="..\..\build\UnitTests.NetCore.targets" />
   <Import Project="..\..\build\UnitTests.NetFX.props" />

tests/Avalonia.Controls.DataGrid.UnitTests/Avalonia.Controls.DataGrid.UnitTests.csproj

@@ -1,7 +1,6 @@
 <Project Sdk="Microsoft.NET.Sdk" ToolsVersion="15.0">
   <PropertyGroup>
     <TargetFramework>net6.0</TargetFramework>
-    <LangVersion>latest</LangVersion>
     <OutputType>Library</OutputType>
     <IsTestProject>true</IsTestProject>
   </PropertyGroup>

tests/Avalonia.Controls.UnitTests/Avalonia.Controls.UnitTests.csproj

@@ -1,7 +1,6 @@
 <Project Sdk="Microsoft.NET.Sdk" ToolsVersion="15.0">
   <PropertyGroup>
     <TargetFramework>net6.0</TargetFramework>
-    <LangVersion>latest</LangVersion>
     <OutputType>Library</OutputType>
     <IsTestProject>true</IsTestProject>
   </PropertyGroup>

tests/Avalonia.Markup.Xaml.UnitTests/Avalonia.Markup.Xaml.UnitTests.csproj

@@ -3,7 +3,6 @@
     <TargetFrameworks>net6.0;net47</TargetFrameworks>
     <OutputType>Library</OutputType>
     <IsTestProject>true</IsTestProject>
-    <LangVersion>latest</LangVersion>
   </PropertyGroup>
   <Import Project="..\..\build\UnitTests.NetCore.targets" />
   <Import Project="..\..\build\UnitTests.NetFX.props" />

tests/Avalonia.Skia.UnitTests/Avalonia.Skia.UnitTests.csproj

@@ -1,7 +1,6 @@
 <Project Sdk="Microsoft.NET.Sdk" ToolsVersion="15.0">
   <PropertyGroup>
     <TargetFramework>net6.0</TargetFramework>
-    <LangVersion>latest</LangVersion>
   </PropertyGroup>
   <Import Project="..\..\build\UnitTests.NetCore.targets" />
   <Import Project="..\..\build\Moq.props" />

tests/Avalonia.UnitTests/Avalonia.UnitTests.csproj

@@ -1,7 +1,6 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
     <TargetFrameworks>netstandard2.0</TargetFrameworks>
-    <LangVersion>latest</LangVersion>
     <GenerateAssemblyInfo>false</GenerateAssemblyInfo>
     <OutputType>Library</OutputType>
     <IsPackable>false</IsPackable>