Remove some things from `IProjectSnapshot` for cohostings benefit (#10831)

Chris found these to be problematic in his branch where he enabled the
source generator, but fortunately they're simply unnecessary in
cohosting.

src/Razor/src/Microsoft.CodeAnalysis.Razor.Workspaces/ProjectSystem/IDocumentSnapshotExtensions.cs

@@ -27,12 +27,6 @@ internal static class IDocumentSnapshotExtensions
 
         var project = documentSnapshot.Project;
 
-        // If the document is an import document, then it can't be a component
-        if (project.IsImportDocument(documentSnapshot))
-        {
-            return null;
-        }
-
         // If we got this far, we can check for tag helpers
         var tagHelpers = await project.GetTagHelpersAsync(cancellationToken).ConfigureAwait(false);
         foreach (var tagHelper in tagHelpers)

src/Razor/src/Microsoft.CodeAnalysis.Razor.Workspaces/ProjectSystem/IProjectSnapshot.cs

@@ -39,14 +39,4 @@ internal interface IProjectSnapshot
     RazorProjectEngine GetProjectEngine();
     IDocumentSnapshot? GetDocument(string filePath);
     bool TryGetDocument(string filePath, [NotNullWhen(true)] out IDocumentSnapshot? document);
-    bool IsImportDocument(IDocumentSnapshot document);
-
-    /// <summary>
-    /// If the provided document is an import document, gets the other documents in the project
-    /// that include directives specified by the provided document. Otherwise returns an empty
-    /// list.
-    /// </summary>
-    /// <param name="document">The document.</param>
-    /// <returns>A list of related documents.</returns>
-    ImmutableArray<IDocumentSnapshot> GetRelatedDocuments(IDocumentSnapshot document);
 }

src/Razor/src/Microsoft.CodeAnalysis.Razor.Workspaces/ProjectSystem/IProjectSnapshotExtensions.cs

@@ -1,6 +1,7 @@
 // Copyright (c) .NET Foundation. All rights reserved.
 // Licensed under the MIT license. See License.txt in the project root for license information.
 
+using System;
 using System.Collections.Immutable;
 using System.Diagnostics;
 using System.Threading;
@@ -50,4 +51,14 @@ internal static class IProjectSnapshotExtensions
         return tagHelperTask.Result;
 #pragma warning restore VSTHRD002 // Avoid problematic synchronous waits
     }
+
+    public static ImmutableArray<IDocumentSnapshot> GetRelatedDocuments(this IProjectSnapshot projectSnapshot, IDocumentSnapshot document)
+    {
+        if (projectSnapshot is not ProjectSnapshot project)
+        {
+            throw new InvalidOperationException("This method can only be called with a ProjectSnapshot.");
+        }
+
+        return project.GetRelatedDocuments(document);
+    }
 }

src/Razor/src/Microsoft.CodeAnalysis.Razor.Workspaces/ProjectSystem/ProjectSnapshot.cs

@@ -79,16 +79,11 @@ internal class ProjectSnapshot : IProjectSnapshot
         return document is not null;
     }
 
-    public bool IsImportDocument(IDocumentSnapshot document)
-    {
-        if (document is null)
-        {
-            throw new ArgumentNullException(nameof(document));
-        }
-
-        return document.TargetPath is { } targetPath && State.ImportsToRelatedDocuments.ContainsKey(targetPath);
-    }
-
+    /// <summary>
+    /// If the provided document is an import document, gets the other documents in the project
+    /// that include directives specified by the provided document. Otherwise returns an empty
+    /// list.
+    /// </summary>
     public ImmutableArray<IDocumentSnapshot> GetRelatedDocuments(IDocumentSnapshot document)
     {
         if (document is null)

src/Razor/src/Microsoft.CodeAnalysis.Remote.Razor/ProjectSystem/RemoteProjectSnapshot.cs

@@ -11,7 +11,6 @@ using System.Threading;
 using System.Threading.Tasks;
 using Microsoft.AspNetCore.Razor;
 using Microsoft.AspNetCore.Razor.Language;
-using Microsoft.AspNetCore.Razor.PooledObjects;
 using Microsoft.AspNetCore.Razor.ProjectEngineHost;
 using Microsoft.AspNetCore.Razor.ProjectSystem;
 using Microsoft.AspNetCore.Razor.Telemetry;
@@ -32,7 +31,6 @@ internal class RemoteProjectSnapshot : IProjectSnapshot
     private readonly ITelemetryReporter _telemetryReporter;
     private readonly Lazy<RazorConfiguration> _lazyConfiguration;
     private readonly Lazy<RazorProjectEngine> _lazyProjectEngine;
-    private readonly Lazy<ImmutableDictionary<string, ImmutableArray<string>>> _importsToRelatedDocumentsLazy;
 
     private ImmutableArray<TagHelperDescriptor> _tagHelpers;
 
@@ -56,18 +54,6 @@ internal class RemoteProjectSnapshot : IProjectSnapshot
                     builder.SetSupportLocalizedComponentNames();
                 });
         });
-
-        _importsToRelatedDocumentsLazy = new Lazy<ImmutableDictionary<string, ImmutableArray<string>>>(() =>
-        {
-            var importsToRelatedDocuments = ImmutableDictionary.Create<string, ImmutableArray<string>>(FilePathNormalizingComparer.Instance);
-            foreach (var documentFilePath in DocumentFilePaths)
-            {
-                var importTargetPaths = ProjectState.GetImportDocumentTargetPaths(documentFilePath, FileKinds.GetFileKindFromFilePath(documentFilePath), _lazyProjectEngine.Value);
-                importsToRelatedDocuments = ProjectState.AddToImportsToRelatedDocuments(importsToRelatedDocuments, documentFilePath, importTargetPaths);
-            }
-
-            return importsToRelatedDocuments;
-        });
     }
 
     public RazorConfiguration Configuration => throw new InvalidOperationException("Should not be called for cohosted projects.");
@@ -154,34 +140,6 @@ internal class RemoteProjectSnapshot : IProjectSnapshot
     /// <returns></returns>
     internal RazorProjectEngine GetProjectEngine_CohostOnly() => _lazyProjectEngine.Value;
 
-    public ImmutableArray<IDocumentSnapshot> GetRelatedDocuments(IDocumentSnapshot document)
-    {
-        var targetPath = document.TargetPath.AssumeNotNull();
-
-        if (!_importsToRelatedDocumentsLazy.Value.TryGetValue(targetPath, out var relatedDocuments))
-        {
-            return [];
-        }
-
-        using var builder = new PooledArrayBuilder<IDocumentSnapshot>(relatedDocuments.Length);
-
-        foreach (var relatedDocumentFilePath in relatedDocuments)
-        {
-            if (TryGetDocument(relatedDocumentFilePath, out var relatedDocument))
-            {
-                builder.Add(relatedDocument);
-            }
-        }
-
-        return builder.DrainToImmutable();
-    }
-
-    public bool IsImportDocument(IDocumentSnapshot document)
-    {
-        return document.TargetPath is { } targetPath &&
-               _importsToRelatedDocumentsLazy.Value.ContainsKey(targetPath);
-    }
-
     private RazorConfiguration CreateRazorConfiguration()
     {
         // See RazorSourceGenerator.RazorProviders.cs

src/Razor/src/Microsoft.VisualStudio.LegacyEditor.Razor/EphemeralProjectSnapshot.cs

@@ -72,26 +72,6 @@ internal class EphemeralProjectSnapshot : IProjectSnapshot
         return false;
     }
 
-    public bool IsImportDocument(IDocumentSnapshot document)
-    {
-        if (document is null)
-        {
-            throw new ArgumentNullException(nameof(document));
-        }
-
-        return false;
-    }
-
-    public ImmutableArray<IDocumentSnapshot> GetRelatedDocuments(IDocumentSnapshot document)
-    {
-        if (document is null)
-        {
-            throw new ArgumentNullException(nameof(document));
-        }
-
-        return ImmutableArray<IDocumentSnapshot>.Empty;
-    }
-
     public RazorProjectEngine GetProjectEngine()
     {
         return _projectEngine.Value;

src/Razor/test/Microsoft.CodeAnalysis.Razor.Workspaces.Test/ProjectSystem/DefaultProjectSnapshotTest.cs

@@ -61,43 +61,6 @@ public class DefaultProjectSnapshotTest : WorkspaceTestBase
             d => Assert.Same(d.Value, snapshot.GetDocument(d.Key)));
     }
 
-    [Fact]
-    public void IsImportDocument_NonImportDocument_ReturnsFalse()
-    {
-        // Arrange
-        var state = ProjectState.Create(ProjectEngineFactoryProvider, _hostProject, _projectWorkspaceState)
-            .WithAddedHostDocument(_documents[0], DocumentState.EmptyLoader);
-        var snapshot = new ProjectSnapshot(state);
-
-        var document = snapshot.GetDocument(_documents[0].FilePath);
-        Assert.NotNull(document);
-
-        // Act
-        var result = snapshot.IsImportDocument(document);
-
-        // Assert
-        Assert.False(result);
-    }
-
-    [Fact]
-    public void IsImportDocument_ImportDocument_ReturnsTrue()
-    {
-        // Arrange
-        var state = ProjectState.Create(ProjectEngineFactoryProvider, _hostProject, _projectWorkspaceState)
-            .WithAddedHostDocument(_documents[0], DocumentState.EmptyLoader)
-            .WithAddedHostDocument(TestProjectData.SomeProjectImportFile, DocumentState.EmptyLoader);
-        var snapshot = new ProjectSnapshot(state);
-
-        var document = snapshot.GetDocument(TestProjectData.SomeProjectImportFile.FilePath);
-        Assert.NotNull(document);
-
-        // Act
-        var result = snapshot.IsImportDocument(document);
-
-        // Assert
-        Assert.True(result);
-    }
-
     [Fact]
     public void GetRelatedDocuments_NonImportDocument_ReturnsEmpty()
     {

src/Razor/test/Microsoft.VisualStudio.LanguageServices.Razor.Test/Cohost/CohostUriPresentationEndpointTest.cs

@@ -97,6 +97,26 @@ public class CohostUriPresentationEndpointTest(ITestOutputHelper testOutputHelpe
             expected: "<Component />");
     }
 
+    [Fact]
+    public async Task ImportsFile()
+    {
+        await VerifyUriPresentationAsync(
+            input: """
+                This is a Razor document.
+
+                <div>
+                    [||]
+                </div>
+
+                The end.
+                """,
+            additionalFiles: [
+                (File("_Imports.razor"), "")
+            ],
+            uris: [FileUri("_Imports.razor")],
+            expected: null);
+    }
+
     [Fact]
     public async Task Html_IntoCSharp_NoTag()
     {