refactor: simplify usage of "Nullable" (#708)

vbreuss · web-flow · commit 10baccae08f3 · 2026-04-29T05:18:52.000+02:00
This pull request refactors how nullable reference type attributes are handled across the codebase. The main focus is on removing the internal polyfill for the `NotNullWhenAttribute` and instead relying on the external `Nullable` NuGet package where needed. This simplifies the code and reduces duplication. Additionally, related method signatures are updated to remove the use of the `[NotNullWhen]` attribute in internal APIs.
diff --git a/Source/Directory.Build.props b/Source/Directory.Build.props
@@ -47,10 +47,6 @@
 	</PropertyGroup>
 
 	<ItemGroup>
-		<PackageReference Include="Nullable">
-			<PrivateAssets>all</PrivateAssets>
-			<IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
-		</PackageReference>
 		<PackageReference Include="Microsoft.SourceLink.GitHub" PrivateAssets="all"/>
 	</ItemGroup>
 
diff --git a/Source/Mockolate.Analyzers/MockabilityAnalyzer.cs b/Source/Mockolate.Analyzers/MockabilityAnalyzer.cs
@@ -293,7 +293,7 @@ private static bool NeedsRefStructPipeline(ITypeSymbol type)
 	}
 
 	private static bool TryGetRefStructIssue(IMethodSymbol method, string? pipelineUnsupportedReason,
-		[NotNullWhen(true)] out string? issue)
+		out string? issue)
 	{
 		bool hasRefStructParam = false;
 		foreach (IParameterSymbol p in method.Parameters)
@@ -334,7 +334,7 @@ private static bool TryGetRefStructIssue(IMethodSymbol method, string? pipelineU
 	}
 
 	private static bool TryGetRefStructIssueForIndexer(IPropertySymbol indexer, string? pipelineUnsupportedReason,
-		[NotNullWhen(true)] out string? issue)
+		out string? issue)
 	{
 		if (!indexer.Parameters.Any(p => NeedsRefStructPipeline(p.Type)))
 		{
@@ -422,7 +422,7 @@ private static void AnalyzeImplementing(SyntaxNodeAnalysisContext context,
 	private static bool IsInMockolateNamespace(ISymbol symbol)
 		=> symbol.ContainingNamespace is { Name: "Mockolate", ContainingNamespace.IsGlobalNamespace: true, };
 
-	private static bool IsMockable(ITypeSymbol typeSymbol, [NotNullWhen(false)] out string? reason)
+	private static bool IsMockable(ITypeSymbol typeSymbol, out string? reason)
 	{
 		if (typeSymbol.TypeKind == TypeKind.Struct)
 		{
diff --git a/Source/Mockolate.Analyzers/Mockolate.Analyzers.csproj b/Source/Mockolate.Analyzers/Mockolate.Analyzers.csproj
@@ -41,8 +41,4 @@
 		</Compile>
 	</ItemGroup>
 
-	<ItemGroup>
-		<PackageReference Remove="Nullable"/>
-	</ItemGroup>
-
 </Project>
diff --git a/Source/Mockolate.Analyzers/Polyfills/NotNullWhenAttribute.cs b/Source/Mockolate.Analyzers/Polyfills/NotNullWhenAttribute.cs
diff --git a/Source/Mockolate.SourceGenerators/Entities/Class.cs b/Source/Mockolate.SourceGenerators/Entities/Class.cs
@@ -232,7 +232,7 @@ private string GetTypeName(ITypeSymbol type)
 
 			if (TryExtractSpecialName(namedType, out string? name))
 			{
-				return name;
+				return name!;
 			}
 		}
 
@@ -265,14 +265,14 @@ string GetPrefix(ITypeSymbol s)
 
 			if (TryExtractSpecialName(namedType, out string? name))
 			{
-				return name;
+				return name!;
 			}
 		}
 
 		return GetPrefix(type) + type.Name;
 	}
 
-	private static bool TryExtractSpecialName(INamedTypeSymbol namedType, [NotNullWhen(true)] out string? specialName)
+	private static bool TryExtractSpecialName(INamedTypeSymbol namedType, out string? specialName)
 	{
 		(specialName, bool hasSpecialType) = namedType.SpecialType switch
 		{
diff --git a/Source/Mockolate.SourceGenerators/MockGeneratorHelpers.cs b/Source/Mockolate.SourceGenerators/MockGeneratorHelpers.cs
@@ -145,7 +145,7 @@ internal static IEnumerable<MockClass> ExtractMockOrMockFactoryCreateSyntaxOrDef
 
 				if (IsMockable(rootType))
 				{
-					yield return new MockClass([rootType, ..collectedTypes,], sourceAssembly);
+					yield return new MockClass([rootType!, ..collectedTypes,], sourceAssembly);
 				}
 			}
 		}
@@ -180,7 +180,7 @@ private static IEnumerable<MockClass> DiscoverMockableTypes(IEnumerable<ITypeSym
 		}
 	}
 
-	private static bool IsMockable([NotNullWhen(true)] ITypeSymbol? typeSymbol)
+	private static bool IsMockable(ITypeSymbol? typeSymbol)
 		=> typeSymbol is
 		   {
 			   DeclaredAccessibility: not Accessibility.Private and not Accessibility.ProtectedAndInternal and not Accessibility.ProtectedAndFriend,
diff --git a/Source/Mockolate.SourceGenerators/Mockolate.SourceGenerators.csproj b/Source/Mockolate.SourceGenerators/Mockolate.SourceGenerators.csproj
@@ -24,8 +24,4 @@
 		<None Include="$(OutputPath)\$(AssemblyName).dll" Pack="true" PackagePath="analyzers/dotnet/cs" Visible="false"/>
 	</ItemGroup>
 
-	<ItemGroup>
-		<PackageReference Remove="Nullable"/>
-	</ItemGroup>
-
 </Project>
diff --git a/Source/Mockolate.SourceGenerators/Polyfills/NotNullWhenAttribute.cs b/Source/Mockolate.SourceGenerators/Polyfills/NotNullWhenAttribute.cs
diff --git a/Source/Mockolate/Mockolate.csproj b/Source/Mockolate/Mockolate.csproj
@@ -13,6 +13,10 @@
 			<PrivateAssets>all</PrivateAssets>
 			<IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
 		</PackageReference>
+		<PackageReference Include="Nullable">
+			<PrivateAssets>all</PrivateAssets>
+			<IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
+		</PackageReference>
 	</ItemGroup>
 
 	<ItemGroup Condition="'$(TargetFramework)' == 'netstandard2.0'">
diff --git a/Tests/Directory.Build.props b/Tests/Directory.Build.props
@@ -33,10 +33,6 @@
 			<PrivateAssets>all</PrivateAssets>
 		</PackageReference>
 		<PackageReference Include="Microsoft.NET.Test.Sdk"/>
-		<PackageReference Include="Nullable">
-			<PrivateAssets>all</PrivateAssets>
-			<IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
-		</PackageReference>
 		<PackageReference Include="coverlet.collector">
 			<IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
 			<PrivateAssets>all</PrivateAssets>
diff --git a/Tests/Mockolate.Internal.Tests/Mockolate.Internal.Tests.csproj b/Tests/Mockolate.Internal.Tests/Mockolate.Internal.Tests.csproj
@@ -7,8 +7,4 @@
 		<ProjectReference Include="..\..\Source\Mockolate.Analyzers.CodeFixers\Mockolate.Analyzers.CodeFixers.csproj" PrivateAssets="all" ReferenceOutputAssembly="false" OutputItemType="Analyzer"/>
 	</ItemGroup>
 
-	<ItemGroup>
-		<PackageReference Remove="Nullable"/>
-	</ItemGroup>
-
 </Project>
diff --git a/Tests/Mockolate.Tests/Mockolate.Tests.csproj b/Tests/Mockolate.Tests/Mockolate.Tests.csproj
@@ -6,5 +6,12 @@
 		<ProjectReference Include="..\..\Source\Mockolate.Analyzers\Mockolate.Analyzers.csproj" PrivateAssets="all" ReferenceOutputAssembly="false" OutputItemType="Analyzer"/>
 		<ProjectReference Include="..\..\Source\Mockolate.Analyzers.CodeFixers\Mockolate.Analyzers.CodeFixers.csproj" PrivateAssets="all" ReferenceOutputAssembly="false" OutputItemType="Analyzer"/>
 	</ItemGroup>
+	
+	<ItemGroup>
+		<PackageReference Include="Nullable">
+			<PrivateAssets>all</PrivateAssets>
+			<IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
+		</PackageReference>
+	</ItemGroup>
 
 </Project>

Original file line number	Diff line number	Diff line change
`@@ -293,7 +293,7 @@ private static bool NeedsRefStructPipeline(ITypeSymbol type)`
`293`	`293`	`}`
`294`	`294`
`295`	`295`	`private static bool TryGetRefStructIssue(IMethodSymbol method, string? pipelineUnsupportedReason,`
`296`		`- [NotNullWhen(true)] out string? issue)`
	`296`	`+ out string? issue)`
`297`	`297`	`{`
`298`	`298`	`bool hasRefStructParam = false;`
`299`	`299`	`foreach (IParameterSymbol p in method.Parameters)`
`@@ -334,7 +334,7 @@ private static bool TryGetRefStructIssue(IMethodSymbol method, string? pipelineU`
`334`	`334`	`}`
`335`	`335`
`336`	`336`	`private static bool TryGetRefStructIssueForIndexer(IPropertySymbol indexer, string? pipelineUnsupportedReason,`
`337`		`- [NotNullWhen(true)] out string? issue)`
	`337`	`+ out string? issue)`
`338`	`338`	`{`
`339`	`339`	`if (!indexer.Parameters.Any(p => NeedsRefStructPipeline(p.Type)))`
`340`	`340`	`{`
`@@ -422,7 +422,7 @@ private static void AnalyzeImplementing(SyntaxNodeAnalysisContext context,`
`422`	`422`	`private static bool IsInMockolateNamespace(ISymbol symbol)`
`423`	`423`	`=> symbol.ContainingNamespace is { Name: "Mockolate", ContainingNamespace.IsGlobalNamespace: true, };`
`424`	`424`
`425`		`- private static bool IsMockable(ITypeSymbol typeSymbol, [NotNullWhen(false)] out string? reason)`
	`425`	`+ private static bool IsMockable(ITypeSymbol typeSymbol, out string? reason)`
`426`	`426`	`{`
`427`	`427`	`if (typeSymbol.TypeKind == TypeKind.Struct)`
`428`	`428`	`{`
Original file line number	Diff line number	Diff line change
`@@ -232,7 +232,7 @@ private string GetTypeName(ITypeSymbol type)`
`232`	`232`
`233`	`233`	`if (TryExtractSpecialName(namedType, out string? name))`
`234`	`234`	`{`
`235`		`- return name;`
	`235`	`+ return name!;`
`236`	`236`	`}`
`237`	`237`	`}`
`238`	`238`
`@@ -265,14 +265,14 @@ string GetPrefix(ITypeSymbol s)`
`265`	`265`
`266`	`266`	`if (TryExtractSpecialName(namedType, out string? name))`
`267`	`267`	`{`
`268`		`- return name;`
	`268`	`+ return name!;`
`269`	`269`	`}`
`270`	`270`	`}`
`271`	`271`
`272`	`272`	`return GetPrefix(type) + type.Name;`
`273`	`273`	`}`
`274`	`274`
`275`		`- private static bool TryExtractSpecialName(INamedTypeSymbol namedType, [NotNullWhen(true)] out string? specialName)`
	`275`	`+ private static bool TryExtractSpecialName(INamedTypeSymbol namedType, out string? specialName)`
`276`	`276`	`{`
`277`	`277`	`(specialName, bool hasSpecialType) = namedType.SpecialType switch`
`278`	`278`	`{`
Original file line number	Diff line number	Diff line change
`@@ -145,7 +145,7 @@ internal static IEnumerable<MockClass> ExtractMockOrMockFactoryCreateSyntaxOrDef`
`145`	`145`
`146`	`146`	`if (IsMockable(rootType))`
`147`	`147`	`{`
`148`		`- yield return new MockClass([rootType, ..collectedTypes,], sourceAssembly);`
	`148`	`+ yield return new MockClass([rootType!, ..collectedTypes,], sourceAssembly);`
`149`	`149`	`}`
`150`	`150`	`}`
`151`	`151`	`}`
`@@ -180,7 +180,7 @@ private static IEnumerable<MockClass> DiscoverMockableTypes(IEnumerable<ITypeSym`
`180`	`180`	`}`
`181`	`181`	`}`
`182`	`182`
`183`		`- private static bool IsMockable([NotNullWhen(true)] ITypeSymbol? typeSymbol)`
	`183`	`+ private static bool IsMockable(ITypeSymbol? typeSymbol)`
`184`	`184`	`=> typeSymbol is`
`185`	`185`	`{`
`186`	`186`	`DeclaredAccessibility: not Accessibility.Private and not Accessibility.ProtectedAndInternal and not Accessibility.ProtectedAndFriend,`