Use normalized paths as keys in project snapshots

src/Razor/src/Microsoft.AspNetCore.Razor.ProjectEngineHost/Utilities/FilePathNormalizer.cs

@@ -3,14 +3,27 @@
 
 using System;
 using System.Buffers;
+using System.Collections.Generic;
+using System.Diagnostics.CodeAnalysis;
 using System.Runtime.CompilerServices;
 using System.Runtime.InteropServices;
 using Microsoft.CodeAnalysis.Razor;
+using Microsoft.Extensions.Internal;
 
 namespace Microsoft.AspNetCore.Razor.Utilities;
 
 internal static class FilePathNormalizer
 {
+    private static Lazy<IEqualityComparer<string>> _lazyComparer = new Lazy<IEqualityComparer<string>>(() => new FilePathNormalizingComparer());
+    public static IEqualityComparer<string> Comparer => _lazyComparer.Value;
+
+    private class FilePathNormalizingComparer : IEqualityComparer<string>
+    {
+        public bool Equals(string? x, string? y) => FilePathNormalizer.FilePathsEquivalent(x, y);
+
+        public int GetHashCode([DisallowNull] string obj) => FilePathNormalizer.GetHashCode(obj);
+    }
+
     public static string NormalizeDirectory(string? directoryFilePath)
     {
         if (directoryFilePath.IsNullOrEmpty())
@@ -118,6 +131,28 @@ internal static class FilePathNormalizer
         return normalizedSpan1.Equals(normalizedSpan2, FilePathComparison.Instance);
     }
 
+    public static int GetHashCode(string filePath)
+    {
+        if (filePath.Length == 0)
+        {
+            return filePath.GetHashCode();
+        }
+
+        var filePathSpan = filePath.AsSpanOrDefault();
+
+        using var _ = ArrayPool<char>.Shared.GetPooledArray(filePathSpan.Length, out var array1);
+        var normalizedSpan = NormalizeCoreAndGetSpan(filePathSpan, array1);
+
+        var hashCombiner = HashCodeCombiner.Start();
+
+        foreach (var ch in normalizedSpan)
+        {
+            hashCombiner.Add(ch);
+        }
+
+        return hashCombiner.CombinedHash;
+    }
+
     private static ReadOnlySpan<char> NormalizeCoreAndGetSpan(ReadOnlySpan<char> source, Span<char> destination)
     {
         var (start, length) = NormalizeCore(source, destination);

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

@@ -8,6 +8,7 @@ using Microsoft.AspNetCore.Razor;
 using Microsoft.AspNetCore.Razor.Language;
 using Microsoft.AspNetCore.Razor.PooledObjects;
 using Microsoft.AspNetCore.Razor.ProjectSystem;
+using Microsoft.AspNetCore.Razor.Utilities;
 using Microsoft.CodeAnalysis.CSharp;
 
 namespace Microsoft.CodeAnalysis.Razor.ProjectSystem;
@@ -23,7 +24,7 @@ internal class ProjectSnapshot : IProjectSnapshot
         State = state ?? throw new ArgumentNullException(nameof(state));
 
         _lock = new object();
-        _documents = new Dictionary<string, DocumentSnapshot>(FilePathComparer.Instance);
+        _documents = new Dictionary<string, DocumentSnapshot>(FilePathNormalizer.Comparer);
     }
 
     public ProjectKey Key => State.HostProject.Key;

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

@@ -11,6 +11,7 @@ using System.Linq;
 using System.Threading.Tasks;
 using Microsoft.AspNetCore.Razor.Language;
 using Microsoft.AspNetCore.Razor.ProjectSystem;
+using Microsoft.AspNetCore.Razor.Utilities;
 using Microsoft.CodeAnalysis.CSharp;
 using Microsoft.CodeAnalysis.Host;
 using Microsoft.CodeAnalysis.Text;
@@ -31,8 +32,8 @@ internal class ProjectState
         ProjectDifference.DocumentAdded |
         ProjectDifference.DocumentRemoved;
 
-    private static readonly ImmutableDictionary<string, DocumentState> s_emptyDocuments = ImmutableDictionary.Create<string, DocumentState>(FilePathComparer.Instance);
-    private static readonly ImmutableDictionary<string, ImmutableArray<string>> s_emptyImportsToRelatedDocuments = ImmutableDictionary.Create<string, ImmutableArray<string>>(FilePathComparer.Instance);
+    private static readonly ImmutableDictionary<string, DocumentState> s_emptyDocuments = ImmutableDictionary.Create<string, DocumentState>(FilePathNormalizer.Comparer);
+    private static readonly ImmutableDictionary<string, ImmutableArray<string>> s_emptyImportsToRelatedDocuments = ImmutableDictionary.Create<string, ImmutableArray<string>>(FilePathNormalizer.Comparer);
     private readonly object _lock;
 
     private RazorProjectEngine _projectEngine;
@@ -337,7 +338,7 @@ internal class ProjectState
             return this;
         }
 
-        var documents = Documents.ToImmutableDictionary(kvp => kvp.Key, kvp => kvp.Value.WithConfigurationChange(), FilePathComparer.Instance);
+        var documents = Documents.ToImmutableDictionary(kvp => kvp.Key, kvp => kvp.Value.WithConfigurationChange(), FilePathNormalizer.Comparer);
 
         // If the host project has changed then we need to recompute the imports map
         var importsToRelatedDocuments = s_emptyImportsToRelatedDocuments;
@@ -365,7 +366,7 @@ internal class ProjectState
         }
 
         var difference = ProjectDifference.ProjectWorkspaceStateChanged;
-        var documents = Documents.ToImmutableDictionary(kvp => kvp.Key, kvp => kvp.Value.WithProjectWorkspaceStateChange(), FilePathComparer.Instance);
+        var documents = Documents.ToImmutableDictionary(kvp => kvp.Key, kvp => kvp.Value.WithProjectWorkspaceStateChange(), FilePathNormalizer.Comparer);
         var state = new ProjectState(this, difference, HostProject, projectWorkspaceState, documents, ImportsToRelatedDocuments);
         return state;
     }
@@ -435,7 +436,7 @@ internal class ProjectState
         {
             var itemTargetPath = importItem.FilePath.Replace('/', '\\').TrimStart('\\');
 
-            if (FilePathComparer.Instance.Equals(itemTargetPath, hostDocument.TargetPath))
+            if (FilePathNormalizer.Comparer.Equals(itemTargetPath, hostDocument.TargetPath))
             {
                 // We've normalized the original importItem.FilePath into the HostDocument.TargetPath. For instance, if the HostDocument.TargetPath
                 // was '/_Imports.razor' it'd be normalized down into '_Imports.razor'. The purpose of this method is to get the associated document