Decouple FixAll from the workspace

src/OmniSharp.Abstractions/Models/v1/FixAll/RunFixAllRequest.cs

@@ -13,5 +13,7 @@ public class RunFixAllRequest : SimpleFileRequest
         public int Timeout { get; set; } = 3000;
         public bool WantsAllCodeActionOperations { get; set; }
         public bool WantsTextChanges { get; set; }
+        // Nullable for backcompat: null == true, for requests that don't set it
+        public bool? ApplyChanges { get; set; }
     }
 }

src/OmniSharp.Roslyn.CSharp/Helpers/CodeFixProviderExtensions.cs

@@ -0,0 +1,29 @@
+using System.Collections.Generic;
+using System.Linq;
+using Microsoft.CodeAnalysis.CodeFixes;
+
+namespace OmniSharp.Roslyn.CSharp.Helpers
+{
+    internal static class CodeFixProviderExtensions
+    {
+        // http://sourceroslyn.io/#Microsoft.VisualStudio.LanguageServices.CSharp/LanguageService/CSharpCodeCleanupFixer.cs,d9a375db0f1e430e,references
+        // CS8019 isn't directly used (via roslyn) but has an analyzer that report different diagnostic based on CS8019 to improve user experience.
+        private static readonly Dictionary<string, string> _customDiagVsFixMap = new Dictionary<string, string>
+        {
+            { "CS8019", "RemoveUnnecessaryImportsFixable" }
+        };
+
+        // Theres specific filterings between what is shown and what is fixed because of some custom mappings
+        // between diagnostics and their fixers. We dont want to show text 'RemoveUnnecessaryImportsFixable: ...'
+        // but instead 'CS8019: ...' where actual fixer is RemoveUnnecessaryImportsFixable behind the scenes.
+        public static bool HasFixForId(this CodeFixProvider provider, string diagnosticId)
+        {
+            return provider.FixableDiagnosticIds.Any(id => id == diagnosticId) && !_customDiagVsFixMap.ContainsKey(diagnosticId) || HasMappedFixAvailable(diagnosticId, provider);
+        }
+
+        private static bool HasMappedFixAvailable(string diagnosticId, CodeFixProvider provider)
+        {
+            return (_customDiagVsFixMap.ContainsKey(diagnosticId) && provider.FixableDiagnosticIds.Any(id => id == _customDiagVsFixMap[diagnosticId]));
+        }
+    }
+}

src/OmniSharp.Roslyn.CSharp/Helpers/DiagnosticExtensions.cs

@@ -35,7 +35,7 @@ internal static DiagnosticLocation ToDiagnosticLocation(this Diagnostic diagnost
         internal static IEnumerable<DiagnosticLocation> DistinctDiagnosticLocationsByProject(this IEnumerable<DocumentDiagnostics> documentDiagnostic)
         {
             return documentDiagnostic
-                .SelectMany(x => x.Diagnostics, (parent, child) => (projectName: parent.ProjectName, diagnostic: child))
+                .SelectMany(x => x.Diagnostics, (parent, child) => (projectName: parent.Project.Name, diagnostic: child))
                 .Select(x => new
                 {
                     location = x.diagnostic.ToDiagnosticLocation(),

src/OmniSharp.Roslyn.CSharp/Services/Diagnostics/CodeCheckService.cs

@@ -47,7 +47,7 @@ private static QuickFixResponse GetResponseFromDiagnostics(ImmutableArray<Docume
         {
             var diagnosticLocations = diagnostics
                 .Where(x => string.IsNullOrEmpty(fileName)
-                    || x.DocumentPath == fileName)
+                    || x.Document.FilePath == fileName)
                 .DistinctDiagnosticLocationsByProject()
                 .Where(x => x.FileName != null);
 

src/OmniSharp.Roslyn.CSharp/Services/Refactoring/GetFixAllCodeActionService.cs

@@ -1,11 +1,13 @@
 using System.Collections.Generic;
+using System.Collections.Immutable;
 using System.Composition;
 using System.Linq;
 using System.Threading.Tasks;
 using Microsoft.CodeAnalysis;
 using Microsoft.Extensions.Logging;
 using OmniSharp.Abstractions.Models.V1.FixAll;
 using OmniSharp.Mef;
+using OmniSharp.Roslyn.CSharp.Helpers;
 using OmniSharp.Roslyn.CSharp.Services.Refactoring.V2;
 using OmniSharp.Roslyn.CSharp.Workers.Diagnostics;
 using OmniSharp.Services;
@@ -28,17 +30,30 @@ CachingCodeFixProviderForProjects codeFixesForProject
 
         public override async Task<GetFixAllResponse> Handle(GetFixAllRequest request)
         {
-            var availableFixes = await GetDiagnosticsMappedWithFixAllProviders(request.Scope, request.FileName);
+            var document = Workspace.GetDocument(request.FileName);
+            if (document is null)
+            {
+                Logger.LogWarning("Could not find document for file {0}", request.FileName);
+                return new GetFixAllResponse(ImmutableArray<FixAllItem>.Empty);
+            }
 
-            var distinctDiagnosticsThatCanBeFixed = availableFixes
-                .SelectMany(x => x.FixableDiagnostics)
-                .GroupBy(x => x.id) // Distinct isn't good fit here since theres cases where Id has multiple different messages based on location, just show one of them.
-                .Select(x => x.First())
-                .Select(x => new FixAllItem(x.id, x.messsage))
+            var allDiagnostics = await GetDiagnosticsAsync(request.Scope, document);
+            var validFixes = allDiagnostics
+                .GroupBy(docAndDiag => docAndDiag.Document.Project)
+                .SelectMany(grouping =>
+                {
+                    var projectFixProviders = GetCodeFixProviders(grouping.Key);
+                    return grouping
+                        .SelectMany(docAndDiag => docAndDiag.Diagnostics)
+                        .Where(diag => projectFixProviders.Any(provider => provider.HasFixForId(diag.Id)));
+                })
+                .GroupBy(diag => diag.Id)
+                .Select(grouping => grouping.First())
+                .Select(x => new FixAllItem(x.Id, x.GetMessage()))
                 .OrderBy(x => x.Id)
                 .ToArray();
 
-            return new GetFixAllResponse(distinctDiagnosticsThatCanBeFixed);
+            return new GetFixAllResponse(validFixes);
         }
     }
-}
+}