Add suppression ability

src/Analyzer/ReferenceTrimmerAnalyzer.cs

@@ -91,13 +91,14 @@ private static void DumpUsedReferences(CompilationAnalysisContext context)
         }
 
         Dictionary<string, List<string>> packageAssembliesDict = new(StringComparer.OrdinalIgnoreCase);
+        Dictionary<string, string> packageNoWarn = new(StringComparer.OrdinalIgnoreCase);
         foreach (DeclaredReference declaredReference in declaredReferences.References)
         {
             switch (declaredReference.Kind)
             {
                 case DeclaredReferenceKind.Reference:
                 {
-                    if (!usedReferences.Contains(declaredReference.AssemblyName))
+                    if (!usedReferences.Contains(declaredReference.AssemblyName) && !declaredReference.NoWarn.Contains(RT0001Descriptor.Id))
                     {
                         context.ReportDiagnostic(Diagnostic.Create(RT0001Descriptor, Location.None, declaredReference.Spec));
                     }
@@ -106,7 +107,7 @@ private static void DumpUsedReferences(CompilationAnalysisContext context)
                 }
                 case DeclaredReferenceKind.ProjectReference:
                 {
-                    if (!usedReferences.Contains(declaredReference.AssemblyName))
+                    if (!usedReferences.Contains(declaredReference.AssemblyName) && !declaredReference.NoWarn.Contains(RT0002Descriptor.Id))
                     {
                         context.ReportDiagnostic(Diagnostic.Create(RT0002Descriptor, Location.None, declaredReference.Spec));
                     }
@@ -122,6 +123,7 @@ private static void DumpUsedReferences(CompilationAnalysisContext context)
                     }
 
                     packageAssemblies.Add(declaredReference.AssemblyName);
+                    packageNoWarn[declaredReference.Spec] = declaredReference.NoWarn;
                     break;
                 }
             }
@@ -132,7 +134,7 @@ private static void DumpUsedReferences(CompilationAnalysisContext context)
         {
             string packageName = kvp.Key;
             List<string> packageAssemblies = kvp.Value;
-            if (!packageAssemblies.Any(usedReferences.Contains))
+            if (!packageAssemblies.Any(usedReferences.Contains) && !packageNoWarn[packageName].Contains(RT0003Descriptor.Id))
             {
                 context.ReportDiagnostic(Diagnostic.Create(RT0003Descriptor, Location.None, packageName));
             }

src/E2ETests/E2ETests.cs

@@ -47,6 +47,14 @@ public void UnusedProjectReference()
             });
     }
 
+    [TestMethod]
+    public void UnusedProjectReferenceNoWarn()
+    {
+        RunMSBuild(
+            projectFile: "Library/Library.csproj",
+            expectedWarnings: Array.Empty<Warning>());
+    }
+
     [TestMethod]
     public void UnusedTransitiveProjectReference()
     {
@@ -114,6 +122,19 @@ public void UnusedReferenceHintPath()
             });
     }
 
+    [TestMethod]
+    public void UnusedReferenceHintPathNoWarn()
+    {
+        // For direct references, MSBuild can't determine build order so we need to ensure the dependency is already built
+        RunMSBuild(
+            projectFile: "Dependency/Dependency.csproj",
+            expectedWarnings: Array.Empty<Warning>());
+
+        RunMSBuild(
+            projectFile: "Library/Library.csproj",
+            expectedWarnings: Array.Empty<Warning>());
+    }
+
     [TestMethod]
     public void UnusedReferenceItemSpec()
     {
@@ -134,6 +155,19 @@ public void UnusedReferenceItemSpec()
             });
     }
 
+    [TestMethod]
+    public void UnusedReferenceItemSpecNoWarn()
+    {
+        // For direct references, MSBuild can't determine build order so we need to ensure the dependency is already built
+        RunMSBuild(
+            projectFile: "Dependency/Dependency.csproj",
+            expectedWarnings: Array.Empty<Warning>());
+
+        RunMSBuild(
+            projectFile: "Library/Library.csproj",
+            expectedWarnings: Array.Empty<Warning>());
+    }
+
     [TestMethod]
     public void UsedPackageReference()
     {
@@ -161,6 +195,14 @@ public void UnusedPackageReference()
             });
     }
 
+    [TestMethod]
+    public void UnusedPackageReferenceNoWarn()
+    {
+        RunMSBuild(
+            projectFile: "Library/Library.csproj",
+            expectedWarnings: Array.Empty<Warning>());
+    }
+
     [TestMethod]
     public void UnusedPackageReferenceDocDisabled()
     {

src/E2ETests/TestData/UnusedPackageReferenceNoWarn/Library/Library.cs

@@ -0,0 +1,7 @@
+namespace Library
+{
+    public static class Foo
+    {
+        public static string Bar() => "Baz";
+    }
+}

src/E2ETests/TestData/UnusedPackageReferenceNoWarn/Library/Library.csproj

@@ -0,0 +1,12 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <OutputType>Library</OutputType>
+    <TargetFramework>net472</TargetFramework>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <PackageReference Include="Newtonsoft.Json" Version="13.0.2" NoWarn="RT0003"/>
+  </ItemGroup>
+
+</Project>

src/E2ETests/TestData/UnusedProjectReferenceNoWarn/Dependency/Dependency.cs

@@ -0,0 +1,7 @@
+namespace Dependency
+{
+    public static class Foo
+    {
+        public static string Bar() => "Baz";
+    }
+}

src/E2ETests/TestData/UnusedProjectReferenceNoWarn/Dependency/Dependency.csproj

@@ -0,0 +1,8 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <OutputType>Library</OutputType>
+    <TargetFramework>net472</TargetFramework>
+  </PropertyGroup>
+
+</Project>

src/E2ETests/TestData/UnusedProjectReferenceNoWarn/Library/Library.cs

@@ -0,0 +1,7 @@
+namespace Library
+{
+    public static class Foo
+    {
+        public static string Bar() => "Baz";
+    }
+}

src/E2ETests/TestData/UnusedProjectReferenceNoWarn/Library/Library.csproj

@@ -0,0 +1,12 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <OutputType>Library</OutputType>
+    <TargetFramework>net472</TargetFramework>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="../Dependency/Dependency.csproj" NoWarn="RT0002" />
+  </ItemGroup>
+
+</Project>

src/E2ETests/TestData/UnusedReferenceHintPathNoWarn/Dependency/Dependency.cs

@@ -0,0 +1,7 @@
+namespace Dependency
+{
+    public static class Foo
+    {
+        public static string Bar() => "Baz";
+    }
+}

src/E2ETests/TestData/UnusedReferenceHintPathNoWarn/Dependency/Dependency.csproj

@@ -0,0 +1,8 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <OutputType>Library</OutputType>
+    <TargetFramework>net472</TargetFramework>
+  </PropertyGroup>
+
+</Project>

src/E2ETests/TestData/UnusedReferenceHintPathNoWarn/Library/Library.cs

@@ -0,0 +1,7 @@
+namespace Library
+{
+    public static class Foo
+    {
+        public static string Bar() => "Baz";
+    }
+}

src/E2ETests/TestData/UnusedReferenceHintPathNoWarn/Library/Library.csproj

@@ -0,0 +1,15 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <OutputType>Library</OutputType>
+    <TargetFramework>net472</TargetFramework>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <Reference Include="Dependency">
+      <HintPath>..\Dependency\$(OutputPath)\Dependency.dll</HintPath>
+      <NoWarn>RT0001</NoWarn>
+    </Reference>
+  </ItemGroup>
+
+</Project>

src/E2ETests/TestData/UnusedReferenceItemSpecNoWarn/Dependency/Dependency.cs

@@ -0,0 +1,7 @@
+namespace Dependency
+{
+    public static class Foo
+    {
+        public static string Bar() => "Baz";
+    }
+}

src/E2ETests/TestData/UnusedReferenceItemSpecNoWarn/Dependency/Dependency.csproj

@@ -0,0 +1,8 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <OutputType>Library</OutputType>
+    <TargetFramework>net472</TargetFramework>
+  </PropertyGroup>
+
+</Project>

src/E2ETests/TestData/UnusedReferenceItemSpecNoWarn/Library/Library.cs

@@ -0,0 +1,7 @@
+namespace Library
+{
+    public static class Foo
+    {
+        public static string Bar() => "Baz";
+    }
+}

src/E2ETests/TestData/UnusedReferenceItemSpecNoWarn/Library/Library.csproj

@@ -0,0 +1,12 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <OutputType>Library</OutputType>
+    <TargetFramework>net472</TargetFramework>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <Reference Include="..\Dependency\$(OutputPath)\Dependency.dll" NoWarn="RT0001"/>
+  </ItemGroup>
+
+</Project>

src/Shared/DeclaredReferences.cs

@@ -32,6 +32,8 @@ public void SaveToFile(string filePath)
             writer.Write(KindEnumToString[reference.Kind]);
             writer.Write(FieldDelimiter);
             writer.Write(reference.Spec);
+            writer.Write(FieldDelimiter);
+            writer.Write(reference.NoWarn);
             writer.WriteLine();
         }
     }
@@ -46,23 +48,23 @@ public static DeclaredReferences ReadFromFile(string filePath)
         string? line;
         while ((line = reader.ReadLine()) != null)
         {
-            string[] parts = line.Split(FieldDelimiters, 3);
-            if (parts.Length != 3)
+            string[] parts = line.Split(FieldDelimiters, 4);
+            if (parts.Length != 4)
             {
                 throw new InvalidDataException($"File '{filePath}' is invalid. Line: {references.Count + 1}");
             }
 
             string assemblyName = parts[0];
             DeclaredReferenceKind kind = KindStringToEnum[parts[1]];
             string spec = parts[2];
-            DeclaredReference reference = new(assemblyName, kind, spec);
+            DeclaredReference reference = new(assemblyName, kind, spec, parts[3]);
             references.Add(reference);
         }
 
         return new DeclaredReferences(references);
     }
 }
 
-internal record DeclaredReference(string AssemblyName, DeclaredReferenceKind Kind, string Spec);
+internal record DeclaredReference(string AssemblyName, DeclaredReferenceKind Kind, string Spec, string NoWarn);
 
 internal enum DeclaredReferenceKind { Reference, ProjectReference, PackageReference }

src/Tasks/CollectDeclaredReferencesTask.cs

@@ -116,7 +116,7 @@ public override bool Execute()
                         }
                     }
 
-                    declaredReferences.Add(new DeclaredReference(referenceAssemblyName, DeclaredReferenceKind.Reference, referenceSpec));
+                    declaredReferences.Add(new DeclaredReference(referenceAssemblyName, DeclaredReferenceKind.Reference, referenceSpec, reference.GetMetadata("NoWarn")));
                 }
             }
 
@@ -137,7 +137,7 @@ public override bool Execute()
                     string projectReferenceAssemblyName = new AssemblyName(projectReference.GetMetadata("FusionName")).Name;
                     string referenceProjectFile = projectReference.GetMetadata("OriginalProjectReferenceItemSpec");
 
-                    declaredReferences.Add(new DeclaredReference(projectReferenceAssemblyName, DeclaredReferenceKind.ProjectReference, referenceProjectFile));
+                    declaredReferences.Add(new DeclaredReference(projectReferenceAssemblyName, DeclaredReferenceKind.ProjectReference, referenceProjectFile, projectReference.GetMetadata("NoWarn")));
                 }
             }
 
@@ -160,7 +160,7 @@ public override bool Execute()
 
                     foreach (string assemblyName in packageInfo.CompileTimeAssemblies)
                     {
-                        declaredReferences.Add(new DeclaredReference(assemblyName, DeclaredReferenceKind.PackageReference, packageReference.ItemSpec));
+                        declaredReferences.Add(new DeclaredReference(assemblyName, DeclaredReferenceKind.PackageReference, packageReference.ItemSpec, packageReference.GetMetadata("NoWarn")));
                     }
                 }
             }