Add a helper diagnostic for enforcing IDE0005 (remove unnecessary usi…

src/Analyzers/Core/Analyzers/AnalyzersResources.resx

@@ -352,6 +352,27 @@
   <data name="Simplify_LINQ_expression" xml:space="preserve">
     <value>Simplify LINQ expression</value>
   </data>
+  <data name="Set_MSBuild_Property_GenerateDocumentationFile_to_true" xml:space="preserve">
+    <value>Set MSBuild property 'GenerateDocumentationFile' to 'true'</value>
+  </data>
+  <data name="Set_MSBuild_Property_GenerateDocumentationFile_to_true_in_project_file_to_enable_IDE0005_Remove_unnecessary_usings_imports_on_build" xml:space="preserve">
+    <value>Set MSBuild property 'GenerateDocumentationFile' to 'true' in project file to enable IDE0005 (Remove unnecessary usings/imports) on build</value>
+  </data>
+  <data name="Add_the_following_PropertyGroup_to_your_MSBuild_project_file_to_enable_IDE0005_Remove_unnecessary_usings_imports_on_build" xml:space="preserve">
+    <value>Add the following PropertyGroup to your MSBuild project file to enable IDE0005 (Remove unnecessary usings/imports) on build:
+  &lt;PropertyGroup&gt;
+    &lt;!--
+      Make sure any documentation comments which are included in code get checked for syntax during the build, but do
+      not report warnings for missing comments.
+      CS1573: Parameter 'parameter' has no matching param tag in the XML comment for 'parameter' (but other parameters do)
+      CS1591: Missing XML comment for publicly visible type or member 'Type_or_Member'
+      CS1712: Type parameter 'type_parameter' has no matching typeparam tag in the XML comment on 'type_or_member' (but other type parameters do)
+    --&gt;
+    &lt;GenerateDocumentationFile&gt;True&lt;/GenerateDocumentationFile&gt;
+    &lt;NoWarn&gt;$(NoWarn),1573,1591,1712&lt;/NoWarn&gt;
+  &lt;/PropertyGroup&gt;
+    </value>
+  </data>
   <data name="Fix_formatting" xml:space="preserve">
     <value>Fix formatting</value>
   </data>
@@ -376,4 +397,4 @@
   <data name="Simplify_check" xml:space="preserve">
     <value>Simplify check</value>
   </data>
-</root>
+</root>

src/Analyzers/Core/Analyzers/RemoveUnnecessaryImports/AbstractRemoveUnnecessaryImportsDiagnosticAnalyzer.cs

@@ -19,12 +19,30 @@ internal abstract class AbstractRemoveUnnecessaryImportsDiagnosticAnalyzer<TSynt
         AbstractBuiltInUnnecessaryCodeStyleDiagnosticAnalyzer
         where TSyntaxNode : SyntaxNode
     {
+        // NOTE: This is a special helper diagnostic ID which is reported when the remove unnecesssary diagnostic ID (IDE0005) is
+        // ecalated to a warning or an error, but 'GenerateDocumentationFile' is false, which leads to IDE0005 not being reported
+        // on command line builds. See https://github.com/dotnet/roslyn/issues/41640 for more details.
+        internal const string EnableGenerateDocumentationFileId = "EnableGenerateDocumentationFile";
+
         // The NotConfigurable custom tag ensures that user can't turn this diagnostic into a warning / error via
         // ruleset editor or solution explorer. Setting messageFormat to empty string ensures that we won't display
         // this diagnostic in the preview pane header.
         private static readonly DiagnosticDescriptor s_fixableIdDescriptor = CreateDescriptorWithId(
             RemoveUnnecessaryImportsConstants.DiagnosticFixableId, EnforceOnBuild.Never, "", "", isConfigurable: false);
 
+#pragma warning disable RS0030 // Do not used banned APIs - Special diagnostic with 'Warning' default severity.
+        private static readonly DiagnosticDescriptor s_enableGenerateDocumentationFileIdDescriptor = new(
+            EnableGenerateDocumentationFileId,
+            title: AnalyzersResources.Set_MSBuild_Property_GenerateDocumentationFile_to_true,
+            messageFormat: AnalyzersResources.Set_MSBuild_Property_GenerateDocumentationFile_to_true_in_project_file_to_enable_IDE0005_Remove_unnecessary_usings_imports_on_build,
+            category: DiagnosticCategory.Style,
+            defaultSeverity: DiagnosticSeverity.Warning,
+            isEnabledByDefault: true,
+            helpLinkUri: "https://github.com/dotnet/roslyn/issues/41640",
+            description: AnalyzersResources.Add_the_following_PropertyGroup_to_your_MSBuild_project_file_to_enable_IDE0005_Remove_unnecessary_usings_imports_on_build,
+            customTags: DiagnosticCustomTags.Microsoft.Concat(EnforceOnBuild.Never.ToCustomTag()).ToArray());
+#pragma warning restore RS0030 // Do not used banned APIs
+
         private readonly DiagnosticDescriptor _classificationIdDescriptor;
         private readonly DiagnosticDescriptor _generatedCodeClassificationIdDescriptor;
 
@@ -39,7 +57,7 @@ private static ImmutableArray<DiagnosticDescriptor> GetDescriptors(LocalizableSt
         {
             classificationIdDescriptor = CreateDescriptorWithId(IDEDiagnosticIds.RemoveUnnecessaryImportsDiagnosticId, EnforceOnBuildValues.RemoveUnnecessaryImports, titleAndMessage, isUnnecessary: true);
             generatedCodeClassificationIdDescriptor = CreateDescriptorWithId(IDEDiagnosticIds.RemoveUnnecessaryImportsDiagnosticId + "_gen", EnforceOnBuild.Never, titleAndMessage, isUnnecessary: true, isConfigurable: false);
-            return ImmutableArray.Create(s_fixableIdDescriptor, classificationIdDescriptor, generatedCodeClassificationIdDescriptor);
+            return ImmutableArray.Create(s_fixableIdDescriptor, s_enableGenerateDocumentationFileIdDescriptor, classificationIdDescriptor, generatedCodeClassificationIdDescriptor);
         }
 
         protected abstract ISyntaxFacts SyntaxFacts { get; }
@@ -84,6 +102,20 @@ private void AnalyzeSemanticModel(SemanticModelAnalysisContext context)
                 {
                     context.ReportDiagnostic(diagnostic);
                 }
+
+                // Due to https://github.com/dotnet/roslyn/issues/41640, enabling this analyzer (IDE0005) on build requires users
+                // to enable generation of XML documentation comments. We detect if generation of XML documentation comments
+                // is disabled for this tree and IDE0005 diagnostics are being reported with effective severity "Warning" or "Error".
+                // If so, we report a special diagnostic that recommends the users to set "GenerateDocumentationFile" to "true"
+                // in their project file to enable IDE0005 on build.
+                if (tree.Options.DocumentationMode == DocumentationMode.Parse)
+                {
+                    var effectiveSeverity = descriptor.GetEffectiveSeverity(context.SemanticModel.Compilation.Options, tree, context.Options);
+                    if (effectiveSeverity is ReportDiagnostic.Warn or ReportDiagnostic.Error)
+                    {
+                        context.ReportDiagnostic(Diagnostic.Create(s_enableGenerateDocumentationFileIdDescriptor, diagnostics.First().Location));
+                    }
+                }
             }
         }