Allow Razor to get diagnostics for cohosting

src/LanguageServer/Protocol/Extensions/ProtocolConversions.Diagnostics.cs

@@ -0,0 +1,275 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using System.Collections.Immutable;
+using System.Linq;
+using Microsoft.CodeAnalysis.Diagnostics;
+using Microsoft.CodeAnalysis.LanguageServer.Features.Diagnostics;
+using Microsoft.CodeAnalysis.LanguageServer.Handler.Diagnostics;
+using Microsoft.CodeAnalysis.Options;
+using Microsoft.CodeAnalysis.PooledObjects;
+using Roslyn.LanguageServer.Protocol;
+using Roslyn.Utilities;
+using LSP = Roslyn.LanguageServer.Protocol;
+
+namespace Microsoft.CodeAnalysis.LanguageServer;
+
+internal static partial class ProtocolConversions
+{
+    /// <summary>
+    /// Converts from <see cref="DiagnosticData"/> to <see cref="LSP.Diagnostic"/>
+    /// </summary>
+    /// <param name="diagnosticData">The diagnostic to convert</param>
+    /// <param name="supportsVisualStudioExtensions">Whether the client is Visual Studio</param>
+    /// <param name="project">The project the diagnostic is relevant to</param>
+    /// <param name="isLiveSource">Whether the diagnostic is considered "live" and should supersede others</param>
+    /// <param name="potentialDuplicate">Whether the diagnostic is potentially a duplicate to a build diagnostic</param>
+    /// <param name="globalOptionService">The global options service</param>
+    public static ImmutableArray<LSP.Diagnostic> ConvertDiagnostic(DiagnosticData diagnosticData, bool supportsVisualStudioExtensions, Project project, bool isLiveSource, bool potentialDuplicate, IGlobalOptionService globalOptionService)
+    {
+        if (!ShouldIncludeHiddenDiagnostic(diagnosticData, supportsVisualStudioExtensions))
+        {
+            return [];
+        }
+
+        var diagnostic = CreateLspDiagnostic(diagnosticData, project, isLiveSource, potentialDuplicate, supportsVisualStudioExtensions);
+
+        // Check if we need to handle the unnecessary tag (fading).
+        if (!diagnosticData.CustomTags.Contains(WellKnownDiagnosticTags.Unnecessary))
+        {
+            return [diagnostic];
+        }
+
+        // DiagnosticId supports fading, check if the corresponding VS option is turned on.
+        if (!SupportsFadingOption(diagnosticData, globalOptionService))
+        {
+            return [diagnostic];
+        }
+
+        // Check to see if there are specific locations marked to fade.
+        if (!diagnosticData.TryGetUnnecessaryDataLocations(out var unnecessaryLocations))
+        {
+            // There are no specific fading locations, just mark the whole diagnostic span as unnecessary.
+            // We should always have at least one tag (build or intellisense error).
+            Contract.ThrowIfNull(diagnostic.Tags, $"diagnostic {diagnostic.Identifier} was missing tags");
+            diagnostic.Tags = diagnostic.Tags.Append(DiagnosticTag.Unnecessary);
+            return [diagnostic];
+        }
+
+        if (supportsVisualStudioExtensions)
+        {
+            // Roslyn produces unnecessary diagnostics by using additional locations, however LSP doesn't support tagging
+            // additional locations separately.  Instead we just create multiple hidden diagnostics for unnecessary squiggling.
+            using var _ = ArrayBuilder<LSP.Diagnostic>.GetInstance(out var diagnosticsBuilder);
+            diagnosticsBuilder.Add(diagnostic);
+            foreach (var location in unnecessaryLocations)
+            {
+                var additionalDiagnostic = CreateLspDiagnostic(diagnosticData, project, isLiveSource, potentialDuplicate, supportsVisualStudioExtensions);
+                additionalDiagnostic.Severity = LSP.DiagnosticSeverity.Hint;
+                additionalDiagnostic.Range = GetRange(location);
+                additionalDiagnostic.Tags = [DiagnosticTag.Unnecessary, VSDiagnosticTags.HiddenInEditor, VSDiagnosticTags.HiddenInErrorList, VSDiagnosticTags.SuppressEditorToolTip];
+                diagnosticsBuilder.Add(additionalDiagnostic);
+            }
+
+            return diagnosticsBuilder.ToImmutableArray();
+        }
+        else
+        {
+            diagnostic.Tags = diagnostic.Tags != null ? diagnostic.Tags.Append(DiagnosticTag.Unnecessary) : [DiagnosticTag.Unnecessary];
+            var diagnosticRelatedInformation = unnecessaryLocations.Value.Select(l => new DiagnosticRelatedInformation
+            {
+                Location = new LSP.Location
+                {
+                    Range = GetRange(l),
+                    Uri = ProtocolConversions.CreateAbsoluteUri(l.UnmappedFileSpan.Path)
+                },
+                Message = diagnostic.Message
+            }).ToArray();
+            diagnostic.RelatedInformation = diagnosticRelatedInformation;
+            return [diagnostic];
+        }
+    }
+
+    private static LSP.VSDiagnostic CreateLspDiagnostic(
+        DiagnosticData diagnosticData,
+        Project project,
+        bool isLiveSource,
+        bool potentialDuplicate,
+        bool supportsVisualStudioExtensions)
+    {
+        Contract.ThrowIfNull(diagnosticData.Message, $"Got a document diagnostic that did not have a {nameof(diagnosticData.Message)}");
+
+        // We can just use VSDiagnostic as it doesn't have any default properties set that
+        // would get automatically serialized.
+        var diagnostic = new LSP.VSDiagnostic
+        {
+            Code = diagnosticData.Id,
+            CodeDescription = ProtocolConversions.HelpLinkToCodeDescription(diagnosticData.GetValidHelpLinkUri()),
+            Message = diagnosticData.Message,
+            Severity = ConvertDiagnosticSeverity(diagnosticData.Severity, supportsVisualStudioExtensions),
+            Tags = ConvertTags(diagnosticData, isLiveSource, potentialDuplicate),
+            DiagnosticRank = ConvertRank(diagnosticData),
+            Range = GetRange(diagnosticData.DataLocation)
+        };
+
+        if (supportsVisualStudioExtensions)
+        {
+            var expandedMessage = string.IsNullOrEmpty(diagnosticData.Description) ? null : diagnosticData.Description;
+            var informationService = project.Solution.Services.GetRequiredService<IDiagnosticProjectInformationService>();
+
+            diagnostic.DiagnosticType = diagnosticData.Category;
+            diagnostic.ExpandedMessage = expandedMessage;
+            diagnostic.Projects = [informationService.GetDiagnosticProjectInformation(project)];
+
+            // Defines an identifier used by the client for merging diagnostics across projects. We want diagnostics
+            // to be merged from separate projects if they have the same code, filepath, range, and message.
+            //
+            // Note: LSP pull diagnostics only operates on unmapped locations.
+            diagnostic.Identifier = (diagnostic.Code, diagnosticData.DataLocation.UnmappedFileSpan.Path, diagnostic.Range, diagnostic.Message)
+                .GetHashCode().ToString();
+        }
+
+        return diagnostic;
+    }
+
+    private static LSP.Range GetRange(DiagnosticDataLocation dataLocation)
+    {
+        // We currently do not map diagnostics spans as
+        //   1.  Razor handles span mapping for razor files on their side.
+        //   2.  LSP does not allow us to report document pull diagnostics for a different file path.
+        //   3.  The VS LSP client does not support document pull diagnostics for files outside our content type.
+        //   4.  This matches classic behavior where we only squiggle the original location anyway.
+
+        // We also do not adjust the diagnostic locations to ensure they are in bounds because we've
+        // explicitly requested up to date diagnostics as of the snapshot we were passed in.
+        return new LSP.Range
+        {
+            Start = new Position
+            {
+                Character = dataLocation.UnmappedFileSpan.StartLinePosition.Character,
+                Line = dataLocation.UnmappedFileSpan.StartLinePosition.Line,
+            },
+            End = new Position
+            {
+                Character = dataLocation.UnmappedFileSpan.EndLinePosition.Character,
+                Line = dataLocation.UnmappedFileSpan.EndLinePosition.Line,
+            }
+        };
+    }
+
+    private static bool ShouldIncludeHiddenDiagnostic(DiagnosticData diagnosticData, bool supportsVisualStudioExtensions)
+    {
+        // VS can handle us reporting any kind of diagnostic using VS custom tags.
+        if (supportsVisualStudioExtensions == true)
+        {
+            return true;
+        }
+
+        // Diagnostic isn't hidden - we should report this diagnostic in all scenarios.
+        if (diagnosticData.Severity != DiagnosticSeverity.Hidden)
+        {
+            return true;
+        }
+
+        // Roslyn creates these for example in remove unnecessary imports, see RemoveUnnecessaryImportsConstants.DiagnosticFixableId.
+        // These aren't meant to be visible in anyway, so we can safely exclude them.
+        // TODO - We should probably not be creating these as separate diagnostics or have a 'really really' hidden tag.
+        if (string.IsNullOrEmpty(diagnosticData.Message))
+        {
+            return false;
+        }
+
+        // Hidden diagnostics that are unnecessary are visible to the user in the form of fading.
+        // We can report these diagnostics.
+        if (diagnosticData.CustomTags.Contains(WellKnownDiagnosticTags.Unnecessary))
+        {
+            return true;
+        }
+
+        // We have a hidden diagnostic that has no fading.  This diagnostic can't be visible so don't send it to the client.
+        return false;
+    }
+
+    private static VSDiagnosticRank? ConvertRank(DiagnosticData diagnosticData)
+    {
+        if (diagnosticData.Properties.TryGetValue(PullDiagnosticConstants.Priority, out var priority))
+        {
+            return priority switch
+            {
+                PullDiagnosticConstants.Low => VSDiagnosticRank.Low,
+                PullDiagnosticConstants.Medium => VSDiagnosticRank.Default,
+                PullDiagnosticConstants.High => VSDiagnosticRank.High,
+                _ => null,
+            };
+        }
+
+        return null;
+    }
+
+    private static LSP.DiagnosticSeverity ConvertDiagnosticSeverity(DiagnosticSeverity severity, bool supportsVisualStudioExtensions)
+        => severity switch
+        {
+            // Hidden is translated in ConvertTags to pass along appropriate _ms tags
+            // that will hide the item in a client that knows about those tags.
+            DiagnosticSeverity.Hidden => LSP.DiagnosticSeverity.Hint,
+            // VSCode shows information diagnostics as blue squiggles, and hint diagnostics as 3 dots.  We prefer the latter rendering so we return hint diagnostics in vscode.
+            DiagnosticSeverity.Info => supportsVisualStudioExtensions ? LSP.DiagnosticSeverity.Information : LSP.DiagnosticSeverity.Hint,
+            DiagnosticSeverity.Warning => LSP.DiagnosticSeverity.Warning,
+            DiagnosticSeverity.Error => LSP.DiagnosticSeverity.Error,
+            _ => throw ExceptionUtilities.UnexpectedValue(severity),
+        };
+
+    /// <summary>
+    /// If you make change in this method, please also update the corresponding file in
+    /// src\VisualStudio\Xaml\Impl\Implementation\LanguageServer\Handler\Diagnostics\AbstractPullDiagnosticHandler.cs
+    /// </summary>
+    private static DiagnosticTag[] ConvertTags(DiagnosticData diagnosticData, bool isLiveSource, bool potentialDuplicate)
+    {
+        using var _ = ArrayBuilder<DiagnosticTag>.GetInstance(out var result);
+
+        if (diagnosticData.Severity == DiagnosticSeverity.Hidden)
+        {
+            result.Add(VSDiagnosticTags.HiddenInEditor);
+            result.Add(VSDiagnosticTags.HiddenInErrorList);
+            result.Add(VSDiagnosticTags.SuppressEditorToolTip);
+        }
+        else
+        {
+            result.Add(VSDiagnosticTags.VisibleInErrorList);
+        }
+
+        if (diagnosticData.CustomTags.Contains(PullDiagnosticConstants.TaskItemCustomTag))
+            result.Add(VSDiagnosticTags.TaskItem);
+
+        // Let the host know that these errors represent potentially stale information from the past that should
+        // be superseded by fresher info.
+        if (potentialDuplicate)
+            result.Add(VSDiagnosticTags.PotentialDuplicate);
+
+        // Mark this also as a build error.  That way an explicitly kicked off build from a source like CPS can
+        // override it.
+        if (!isLiveSource)
+            result.Add(VSDiagnosticTags.BuildError);
+
+        result.Add(diagnosticData.CustomTags.Contains(WellKnownDiagnosticTags.Build)
+            ? VSDiagnosticTags.BuildError
+            : VSDiagnosticTags.IntellisenseError);
+
+        if (diagnosticData.CustomTags.Contains(WellKnownDiagnosticTags.EditAndContinue))
+            result.Add(VSDiagnosticTags.EditAndContinueError);
+
+        return result.ToArray();
+    }
+
+    private static bool SupportsFadingOption(DiagnosticData diagnosticData, IGlobalOptionService globalOptionService)
+    {
+        if (IDEDiagnosticIdToOptionMappingHelper.TryGetMappedFadingOption(diagnosticData.Id, out var fadingOption))
+        {
+            Contract.ThrowIfNull(diagnosticData.Language, $"diagnostic {diagnosticData.Id} is missing a language");
+            return globalOptionService.GetOption(fadingOption, diagnosticData.Language);
+        }
+
+        return true;
+    }
+}