Move to .NET SDK 9.0.300 (#2208)

Unit tests now run on net9.0 (and continue to run on net8.0, net472, and UWP)
Removed .net6.0 and .net7.0 targets from test runner because those runtimes are out of support
Removed dependency on MSBuild.SDK.Extras

Author: idg10

Rx.NET/Documentation/adr/0003-uap-targets.md

@@ -34,7 +34,18 @@
 # reported as unnecessary on ObservableEx, but it is, so we've squelched it.
 # IL2060 is considered unnecessary on targets that don't support trimming, but we don't want to wrap every
 # single one in a conditional, so we also suppress warnings about unnecessary suppressions on those.
-dotnet_remove_unnecessary_suppression_exclusions = CA1704,CA1711,IL2060
+#
+# dotnet_remove_unnecessary_suppression_exclusions = CA1704,CA1711,IL2060
+#
+# Since moving to .NET SDK 9.0, we now get a lot more of these inexplicable IDE0079 warnings, where
+# if we remove the suppression that it complains about, we immediately get the warning that the suppression
+# is there to prevent. As far as I can tell, every suppression now causes a spurious IDE0079, so we
+# just have to disable IDE0079. Presumably there's something odd about this codebase that is confusing
+# the IDE0079 diagnostic - it can't be completely broken for everyone, because someone would have
+# noticed. I guess this may be related to the curse placed on this codebase by The Great Unification,
+# and in particular the corresponding requirement for putting a uap10.0.xxxx TFM on packages that
+# really shouldn't have them.
+dotnet_diagnostic.IDE0079.severity = silent
 
 
 # Prevent IDE1006 (Naming rule violation) errors for non-public fields.
@@ -68,3 +79,5 @@ dotnet_naming_symbols.protected_field_symbols.applicable_accessibilities = prote
 dotnet_naming_rule.protected_instance_fields_must_be_camel_cased_underscore_prefix.symbols  = protected_field_symbols
 dotnet_naming_rule.protected_instance_fields_must_be_camel_cased_underscore_prefix.style    = camel_case_and_prefix_with_underscore_style
 dotnet_naming_rule.protected_instance_fields_must_be_camel_cased_underscore_prefix.severity = none
+
+dotnet_style_require_accessibility_modifiers = for_non_interface_members

Rx.NET/Source/src/.editorconfig renamed to Rx.NET/Source/.editorconfig

@@ -39,7 +39,7 @@
     -->
     <PackageReference
       Include="Nerdbank.GitVersioning"
-      Version="3.6.128"
+      Version="3.6.143"
       PrivateAssets="all"
       Condition="$(ProjectName) != 'Tests.System.Reactive.Uwp.DeviceRunner'" />
   </ItemGroup>
@@ -52,6 +52,27 @@
     <PackageReference Include="coverlet.collector" Version="3.2.0" />
   </ItemGroup>
 
+
+  <PropertyGroup Condition="'$(TargetFramework)'=='uap10.0.18362'">
+    <!--
+    See 0003-uap-targets.md ADR in documentation for the reasons behind these settings.
+    -->
+    <NoStdLib>True</NoStdLib>
+
+    <TargetPlatformMinVersion>10.0.18362</TargetPlatformMinVersion>
+    <TargetPlatformVersion>10.0.18362.0</TargetPlatformVersion>
+
+    <TargetPlatformIdentifier>UAP</TargetPlatformIdentifier>
+    <TargetFrameworkMoniker>.NETCore,Version=v5.0</TargetFrameworkMoniker>
+    <TargetFrameworkIdentifier>.NETCore</TargetFrameworkIdentifier>
+    <TargetFrameworkVersion>v5.0</TargetFrameworkVersion>
+    <NugetTargetMoniker>UAP,Version=v10.0</NugetTargetMoniker>
+
+    <DefineConstants>$(DefineConstants);WINDOWS_UWP</DefineConstants>
+
+  </PropertyGroup>
+
+
   <PropertyGroup>
     <AnalysisLevelDesign>7.0-default</AnalysisLevelDesign>
     <AnalysisLevelNaming>7.0-all</AnalysisLevelNaming>
@@ -72,9 +93,16 @@
                 a chance to shut down. Each of these likely needs individual review:
                 https://github.com/dotnet/reactive/issues/1927
 
+    IDE0028 - Suggests Collection expressions in place of construction, e.g. replaces new List<int>(x)
+              [.. x]. To me, this is less readable, and it doesn't improve performance, as far as we know.
+              Annoyingly, we don't seem to be able to configure this to apply only when it would not
+              introduce a spread.
     IDE0056 - Use of index/range syntax - relevant types not available on all targets, so we can't
     IDE0057     do this.
 
+    IDE0130 - Namespace does not match folder structure. Conforming to this would be a significant
+                upheaval, and it's not clear that it would be an improvement.
+
     IDE0290 - Primary ctors. This diagnostic suggests them in a lot of places where we don't want
                 them. E.g., in most types with multiple constructors I find I prefer not to have
                 a primary ctor. Since this is all or nothing, we turn it off.
@@ -84,11 +112,13 @@
                   [.. readyList]
               This won't improve performance as far as we know (sometimes a reason for using that
               syntax), and it's not obviously an improvement in readability.
+    IDE0306 - Suggests Collection expressions in place of construction, e.g. replaces new List<int>(x)
+              [.. x]. To me, this is less readable, and it doesn't improve performance, as far as we know.
 
     CA1510 - use ArgumentNullException.ThrowIf (not available on all targets)
     CA1513 - use ObjectDisposedException.ThrowIf (not available on all targets)
     -->
-    <NoWarn>$(NoWarn);CA1001;CA2213;CA1510;CA1513;IDE0056;IDE0057;IDE0290;IDE0305</NoWarn>
+    <NoWarn>$(NoWarn);CA1001;CA2213;CA1510;CA1513;IDE0028;IDE0056;IDE0057;IDE0130;IDE0290;IDE0305;IDE0306</NoWarn>
   </PropertyGroup>
 
   <ItemGroup>

Rx.NET/Source/Directory.build.props

@@ -11,22 +11,39 @@
   </PropertyGroup>
   <PropertyGroup Condition="'$(TargetFramework)' == 'uap10.0.18362'">
     <DefineConstants>$(DefineConstants);HAS_WINRT;WINDOWS;HAS_OS_XAML;LEGACY_WINRT;NO_NULLABLE_ATTRIBUTES</DefineConstants>
-    <TargetPlatformVersion>10.0.19041.0</TargetPlatformVersion>
   </PropertyGroup>
   <PropertyGroup Condition="'$(TargetFramework)' == 'netstandard2.0'">
     <DefineConstants>$(DefineConstants);HAS_WINRT;NO_NULLABLE_ATTRIBUTES</DefineConstants>
   </PropertyGroup>
   <PropertyGroup Condition="$(TargetFramework.StartsWith('net6.0')) or $(TargetFramework.StartsWith('net7.0')) or $(TargetFramework.StartsWith('net8.0'))">
     <DefineConstants>$(DefineConstants);HAS_TRIMMABILITY_ATTRIBUTES</DefineConstants>
   </PropertyGroup>
-  <PropertyGroup Condition="$(TargetFramework.StartsWith('net6.0-windows')) or $(TargetFramework.StartsWith('net7.0-windows')) or $(TargetFramework.StartsWith('net8.0-windows'))">
+  <PropertyGroup Condition="$(TargetFramework.StartsWith('net6.0-windows')) or $(TargetFramework.StartsWith('net8.0-windows')) or $(TargetFramework.StartsWith('net9.0-windows'))">
     <DefineConstants>$(DefineConstants);HAS_WINRT;HAS_WINFORMS;HAS_WPF;HAS_DISPATCHER;DESKTOPCLR;WINDOWS;CSWINRT</DefineConstants>
   </PropertyGroup>
 
   <ItemGroup Condition="'$(TargetFramework)' == 'net472' or '$(TargetFramework)' == 'uap10.0.18362' or '$(TargetFramework)' == 'netstandard2.0'">
     <PackageReference Include="System.Threading.Tasks.Extensions" Version="4.5.4" />
   </ItemGroup>
 
+  <ItemGroup Condition="'$(TargetFramework)'=='uap10.0.18362'">
+    <PackageReference Include="Microsoft.NETCore.UniversalWindowsPlatform"
+                    Version="6.2.14" />
+  </ItemGroup>
+
+
+  <PropertyGroup Condition="$(TargetFramework.StartsWith('net6.0-windows')) or $(TargetFramework.StartsWith('net8.0-windows')) or $(TargetFramework.StartsWith('net9.0-windows'))">
+    <!--
+    In the 9.0.100-rc.2.24474.11 SDK, the build tools attempt to perform code generation for a whole load of our types to support WinRT interop.
+    It's looking like it does this for any public type that implements IDisposable!
+    It's possible that this is a bug in the SDK, but it's also possible that this will be resolved as by design.
+    For the .NET 9.0 RC2 SDK at least, we need to opt out the CsWinRT AOT optimizer.
+    We need to check whether this is definitely OK. I think this is only meant for types that are intended to be used from WinRT,
+    which isn't the case here, but we need to verify this.
+    -->
+    <CsWinRTAotOptimizerEnabled>false</CsWinRTAotOptimizerEnabled>
+  </PropertyGroup>
+
   <Target Name="AddCommitHashToAssemblyAttributes" BeforeTargets="GetAssemblyAttributes">
     <ItemGroup>
       <AssemblyAttribute Include="System.Reflection.AssemblyMetadataAttribute" Condition=" '$(SourceRevisionId)' != '' ">