Added support for diagnostic suppressors

build.json

@@ -49,7 +49,8 @@
         "NetCore31Project",
         "Net50Project",
         "ProjectWithAnalyzersAndEditorConfig",
-        "ProjectWithParentEditorConfig"
+        "ProjectWithParentEditorConfig",
+        "TwoProjectsWithAnalyzerSuppressor"
     ],
     "CakeTestAssets": [
         "CakeProject"

src/OmniSharp.Roslyn.CSharp/Workers/Diagnostics/CSharpDiagnosticWorkerWithAnalyzers.cs

@@ -291,6 +291,7 @@ private async Task<ImmutableArray<Diagnostic>> AnalyzeDocument(Project project,
 
                     diagnostics = semanticDiagnosticsWithAnalyzers
                         .Concat(syntaxDiagnosticsWithAnalyzers)
+                        .Where(d => !d.IsSuppressed)
                         .Concat(documentSemanticModel.GetDiagnostics())
                         .ToImmutableArray();
                 }

test-assets/test-projects/TwoProjectsWithAnalyzerSuppressor/App/App.csproj

@@ -0,0 +1,23 @@
+<Project Sdk="Microsoft.NET.Sdk">
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFramework>netcoreapp3.1</TargetFramework>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <PackageReference Include="Microsoft.CodeAnalysis.CSharp" Version="3.3.1" />
+    <PackageReference Include="StyleCop.Analyzers" Version="1.1.118">
+      <PrivateAssets>all</PrivateAssets>
+      <IncludeAssets>runtime; build; native; contentfiles; analyzers</IncludeAssets>
+    </PackageReference>
+  </ItemGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="..\Lib\Lib.csproj">
+      <ReferenceOutputAssembly>false</ReferenceOutputAssembly>
+      <OutputItemType>Analyzer</OutputItemType>
+    </ProjectReference>
+  </ItemGroup>
+
+
+</Project>

test-assets/test-projects/TwoProjectsWithAnalyzerSuppressor/App/Program.cs

@@ -0,0 +1,12 @@
+using System;
+
+namespace App
+{
+    class Program
+    {
+        static void Main(string[] args)
+        {
+            Console.WriteLine("Hello World!");
+        }
+    }
+}

test-assets/test-projects/TwoProjectsWithAnalyzerSuppressor/Lib/Class1.cs

@@ -0,0 +1,23 @@
+using Microsoft.CodeAnalysis;
+using Microsoft.CodeAnalysis.Diagnostics;
+using System.Collections.Immutable;
+
+namespace Lib
+{
+    [DiagnosticAnalyzer(LanguageNames.CSharp)]
+    public class MySuppressor : DiagnosticSuppressor
+    {
+       public override ImmutableArray<SuppressionDescriptor> SupportedSuppressions { get; } = new[]
+       {
+           new SuppressionDescriptor("SUPP3662", "SA1200", "Dummy suppression")
+       }.ToImmutableArray();
+
+       public override void ReportSuppressions(SuppressionAnalysisContext context)
+       {
+           foreach (Diagnostic diagnostic in context.ReportedDiagnostics)
+           {
+                context.ReportSuppression(Suppression.Create(SupportedSuppressions[0], diagnostic));
+           }
+       }
+    }
+}

test-assets/test-projects/TwoProjectsWithAnalyzerSuppressor/Lib/Lib.csproj

@@ -0,0 +1,11 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <TargetFramework>netstandard2.0</TargetFramework>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <PackageReference Include="Microsoft.CodeAnalysis.CSharp" Version="3.3.1" />
+  </ItemGroup>
+
+</Project>

test-assets/test-projects/TwoProjectsWithAnalyzerSuppressor/TwoProjectsWithAnalyzerSuppressor.sln

@@ -0,0 +1,48 @@
+
+Microsoft Visual Studio Solution File, Format Version 12.00
+# Visual Studio 15
+VisualStudioVersion = 15.0.26124.0
+MinimumVisualStudioVersion = 15.0.26124.0
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Lib", "Lib\Lib.csproj", "{7120F661-4FCB-4D55-921F-6FBFC3746443}"
+EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "App", "App\App.csproj", "{8CC04E3C-AF7D-40F1-BEB4-BACF30A895C2}"
+EndProject
+Global
+	GlobalSection(SolutionConfigurationPlatforms) = preSolution
+		Debug|Any CPU = Debug|Any CPU
+		Debug|x64 = Debug|x64
+		Debug|x86 = Debug|x86
+		Release|Any CPU = Release|Any CPU
+		Release|x64 = Release|x64
+		Release|x86 = Release|x86
+	EndGlobalSection
+	GlobalSection(SolutionProperties) = preSolution
+		HideSolutionNode = FALSE
+	EndGlobalSection
+	GlobalSection(ProjectConfigurationPlatforms) = postSolution
+		{7120F661-4FCB-4D55-921F-6FBFC3746443}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{7120F661-4FCB-4D55-921F-6FBFC3746443}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{7120F661-4FCB-4D55-921F-6FBFC3746443}.Debug|x64.ActiveCfg = Debug|Any CPU
+		{7120F661-4FCB-4D55-921F-6FBFC3746443}.Debug|x64.Build.0 = Debug|Any CPU
+		{7120F661-4FCB-4D55-921F-6FBFC3746443}.Debug|x86.ActiveCfg = Debug|Any CPU
+		{7120F661-4FCB-4D55-921F-6FBFC3746443}.Debug|x86.Build.0 = Debug|Any CPU
+		{7120F661-4FCB-4D55-921F-6FBFC3746443}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{7120F661-4FCB-4D55-921F-6FBFC3746443}.Release|Any CPU.Build.0 = Release|Any CPU
+		{7120F661-4FCB-4D55-921F-6FBFC3746443}.Release|x64.ActiveCfg = Release|Any CPU
+		{7120F661-4FCB-4D55-921F-6FBFC3746443}.Release|x64.Build.0 = Release|Any CPU
+		{7120F661-4FCB-4D55-921F-6FBFC3746443}.Release|x86.ActiveCfg = Release|Any CPU
+		{7120F661-4FCB-4D55-921F-6FBFC3746443}.Release|x86.Build.0 = Release|Any CPU
+		{8CC04E3C-AF7D-40F1-BEB4-BACF30A895C2}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{8CC04E3C-AF7D-40F1-BEB4-BACF30A895C2}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{8CC04E3C-AF7D-40F1-BEB4-BACF30A895C2}.Debug|x64.ActiveCfg = Debug|Any CPU
+		{8CC04E3C-AF7D-40F1-BEB4-BACF30A895C2}.Debug|x64.Build.0 = Debug|Any CPU
+		{8CC04E3C-AF7D-40F1-BEB4-BACF30A895C2}.Debug|x86.ActiveCfg = Debug|Any CPU
+		{8CC04E3C-AF7D-40F1-BEB4-BACF30A895C2}.Debug|x86.Build.0 = Debug|Any CPU
+		{8CC04E3C-AF7D-40F1-BEB4-BACF30A895C2}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{8CC04E3C-AF7D-40F1-BEB4-BACF30A895C2}.Release|Any CPU.Build.0 = Release|Any CPU
+		{8CC04E3C-AF7D-40F1-BEB4-BACF30A895C2}.Release|x64.ActiveCfg = Release|Any CPU
+		{8CC04E3C-AF7D-40F1-BEB4-BACF30A895C2}.Release|x64.Build.0 = Release|Any CPU
+		{8CC04E3C-AF7D-40F1-BEB4-BACF30A895C2}.Release|x86.ActiveCfg = Release|Any CPU
+		{8CC04E3C-AF7D-40F1-BEB4-BACF30A895C2}.Release|x86.Build.0 = Release|Any CPU
+	EndGlobalSection
+EndGlobal

tests/OmniSharp.MSBuild.Tests/ProjectWithAnalyzersTests.cs

@@ -302,6 +302,32 @@ public async Task WhenNewAnalyzerReferenceIsAdded_ThenAutomaticallyUseItWithoutR
             }
         }
 
+        [Fact]
+        public async Task WhenProjectIsLoadedThenItRespectsDiagnosticSuppressors()
+        {
+            using (var testProject = await TestAssets.Instance.GetTestProjectAsync("TwoProjectsWithAnalyzerSuppressor"))
+            using (var host = CreateMSBuildTestHost(testProject.Directory, configurationData: TestHelpers.GetConfigurationDataWithAnalyzerConfig(roslynAnalyzersEnabled: true)))
+            {
+                var project = host.Workspace.CurrentSolution.Projects.First(p => p.Name == "App");
+
+                // by default Stylecop reported diagnostics should be:
+                //  - The file header is missing or not located at the top of the file. [App] SA1633
+                //  - Elements should be documented [App] SA1600
+                //  - Element 'Program' should declare an access modifier [App] SA1400
+                //  - Element 'Main' should declare an access modifier [App] SA1400
+                // However, SA1200 should be suppressed
+
+                var diagnostics = await host.RequestCodeCheckAsync(Path.Combine(testProject.Directory, "App", "Program.cs"));
+
+                Assert.NotEmpty(diagnostics.QuickFixes);
+
+                Assert.Contains(diagnostics.QuickFixes.OfType<DiagnosticLocation>(), x => x.Id == "SA1633" && x.LogLevel == "Warning");
+                Assert.Contains(diagnostics.QuickFixes.OfType<DiagnosticLocation>(), x => x.Id == "SA1600" && x.LogLevel == "Warning");
+                Assert.Contains(diagnostics.QuickFixes.OfType<DiagnosticLocation>(), x => x.Id == "SA1400" && x.LogLevel == "Warning");
+                Assert.DoesNotContain(diagnostics.QuickFixes.OfType<DiagnosticLocation>(), x => x.Id == "SA1200");
+            }
+        }
+
         private string ModifyXmlFileInPlace(string file, Action<XDocument> docUpdateAction)
         {
             var xmlFile = XDocument.Load(file);