Fix renaming file

src/Compiler/Microsoft.CodeAnalysis.Razor.Compiler/src/SourceGenerators/SourceGeneratorProjectItem.cs

@@ -61,7 +61,8 @@ public override Stream Read()
         public bool Equals(SourceGeneratorProjectItem? other)
         {
             if (other is null ||
-                CssScope != other.CssScope)
+                CssScope != other.CssScope ||
+                PhysicalPath != other.PhysicalPath)
             {
                 return false;
             }

src/Compiler/test/Microsoft.NET.Sdk.Razor.SourceGenerators.Tests/RazorSourceGeneratorTests.cs

@@ -3508,5 +3508,95 @@ protected override void BuildRenderTree(global::Microsoft.AspNetCore.Components.
 #pragma warning restore 1591
 ");
         }
+
+        [Fact]
+        public async Task IncrementalCompilation_RerunsGenerator_When_AdditionalFileRenamed()
+        {
+            // Arrange
+            using var eventListener = new RazorEventListener();
+            var project = CreateTestProject(new()
+            {
+                ["Pages/Index.razor"] = "<h1>Hello world</h1>",
+                ["Pages/Counter.razor"] = "<h1>Counter</h1>",
+            });
+            var compilation = await project.GetCompilationAsync();
+            var (driver, additionalTexts, analyzerConfigOptionProvider) = await GetDriverWithAdditionalTextAndProviderAsync(project);
+
+            var result = RunGenerator(compilation!, ref driver);
+            Assert.Empty(result.Diagnostics);
+            Assert.Equal(2, result.GeneratedSources.Length);
+
+            eventListener.Clear();
+
+            // Verify no changes when re-running
+            result = RunGenerator(compilation!, ref driver)
+                        .VerifyOutputsMatch(result);
+
+            Assert.Empty(result.Diagnostics);
+            Assert.Equal(2, result.GeneratedSources.Length);
+            Assert.Empty(eventListener.Events);
+
+            // Rename Counter.razor to NewCounter.razor by removing and re-adding with same content
+            var counterText = additionalTexts.First(f => f.Path.EndsWith("Counter.razor", StringComparison.OrdinalIgnoreCase));
+            var renamedText = new TestAdditionalText("Pages/NewCounter.razor", counterText.GetText()!);
+            driver = driver.RemoveAdditionalTexts([counterText])
+                          .AddAdditionalTexts([renamedText]);
+
+            // Update the analyzer config options with the new target path
+            analyzerConfigOptionProvider.AdditionalTextOptions[renamedText.Path] = new TestAnalyzerConfigOptions
+            {
+                ["build_metadata.AdditionalFiles.TargetPath"] = Convert.ToBase64String(Encoding.UTF8.GetBytes(renamedText.Path))
+            };
+            driver = driver.WithUpdatedAnalyzerConfigOptions(analyzerConfigOptionProvider);
+
+            result = RunGenerator(compilation!, ref driver);
+
+            Assert.Empty(result.Diagnostics);
+            Assert.Equal(2, result.GeneratedSources.Length);
+
+            // Verify the new file was processed
+            Assert.Collection(eventListener.Events,
+                    e => e.AssertSingleItem("ParseRazorDocumentStart", "Pages/NewCounter.razor"),
+                    e => e.AssertSingleItem("ParseRazorDocumentStop", "Pages/NewCounter.razor"),
+                    e => e.AssertSingleItem("GenerateDeclarationCodeStart", "/Pages/NewCounter.razor"),
+                    e => e.AssertSingleItem("GenerateDeclarationCodeStop", "/Pages/NewCounter.razor"),
+                    e => Assert.Equal("DiscoverTagHelpersFromCompilationStart", e.EventName),
+                    e => Assert.Equal("DiscoverTagHelpersFromCompilationStop", e.EventName),
+                    e => e.AssertSingleItem("RewriteTagHelpersStart", "Pages/NewCounter.razor"),
+                    e => e.AssertSingleItem("RewriteTagHelpersStop", "Pages/NewCounter.razor"),
+                    e => e.AssertSingleItem("CheckAndRewriteTagHelpersStart", "Pages/Index.razor"),
+                    e => e.AssertSingleItem("CheckAndRewriteTagHelpersStop", "Pages/Index.razor"),
+                    e => e.AssertSingleItem("CheckAndRewriteTagHelpersStart", "Pages/NewCounter.razor"),
+                    e => e.AssertSingleItem("CheckAndRewriteTagHelpersStop", "Pages/NewCounter.razor"),
+                    e => e.AssertPair("RazorCodeGenerateStart", "Pages/Index.razor", "Runtime"),
+                    e => e.AssertPair("RazorCodeGenerateStop", "Pages/Index.razor", "Runtime"),
+                    e => e.AssertPair("RazorCodeGenerateStart", "Pages/NewCounter.razor", "Runtime"),
+                    e => e.AssertPair("RazorCodeGenerateStop", "Pages/NewCounter.razor", "Runtime"),
+                    e => e.AssertSingleItem("AddSyntaxTrees", "Pages_NewCounter_razor.g.cs")
+            );
+
+            // Verify the generated source has the correct namespace and class name
+            var newCounterSource = result.GeneratedSources.FirstOrDefault(s => s.HintName.Contains("NewCounter"));
+            Assert.Contains("namespace MyApp.Pages", newCounterSource.SourceText.ToString());
+            Assert.Contains("public partial class NewCounter", newCounterSource.SourceText.ToString());
+
+            // Do a case-only rename and make sure we update the generated class name still
+            // as component names are case sensitive even on Windows.
+            var renamedText2 = new TestAdditionalText("Pages/NewCouNter.razor", counterText.GetText()!);
+            driver = driver.RemoveAdditionalTexts([renamedText])
+                          .AddAdditionalTexts([renamedText2]);
+
+            // Update the analyzer config options with the new target path
+            analyzerConfigOptionProvider.AdditionalTextOptions[renamedText2.Path] = new TestAnalyzerConfigOptions
+            {
+                ["build_metadata.AdditionalFiles.TargetPath"] = Convert.ToBase64String(Encoding.UTF8.GetBytes(renamedText2.Path))
+            };
+            driver = driver.WithUpdatedAnalyzerConfigOptions(analyzerConfigOptionProvider);
+
+            result = RunGenerator(compilation!, ref driver);
+
+            var newCouNterSource = result.GeneratedSources.FirstOrDefault(s => s.HintName.Contains("NewCouNter"));
+            Assert.Contains("public partial class NewCouNter", newCouNterSource.SourceText.ToString());
+        }
     }
 }

src/Compiler/test/Microsoft.NET.Sdk.Razor.SourceGenerators.Tests/SourceGeneratorProjectItemTest.cs

@@ -1,6 +1,7 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
+using System.Text;
 using Microsoft.AspNetCore.Razor.Language;
 using Xunit;
 
@@ -115,5 +116,34 @@ public void PathWithoutExtension_ExcludesExtension(string path, string expected)
             // Assert
             Assert.Equal(expected, fileName);
         }
+
+        [Fact]
+        public void ProjectItems_WithDifferentPaths_SameContent_AreNotEqual()
+        {
+            // Two additional texts with same contents, but different paths
+            var content = "<h1>Hello World</h1>";
+            var additionalText1 = new TestAdditionalText(content, Encoding.UTF8, "File1.cshtml");
+            var additionalText2 = new TestAdditionalText(content, Encoding.UTF8, "File2.cshtml");
+
+            var projectItem1 = new SourceGeneratorProjectItem(
+                filePath: "/Views/Home/Index.cshtml",
+                basePath: "/",
+                relativePhysicalPath: "/Views/Home",
+                fileKind: RazorFileKind.Legacy,
+                additionalText: additionalText1,
+                cssScope: null);
+
+            var projectItem2 = new SourceGeneratorProjectItem(
+                filePath: "/Views/About/Index.cshtml",
+                basePath: "/",
+                relativePhysicalPath: "/Views/About",
+                fileKind: RazorFileKind.Legacy,
+                additionalText: additionalText2,
+                cssScope: null);
+
+            // Act & Assert
+            Assert.NotEqual(projectItem1, projectItem2);
+            Assert.False(projectItem1.Equals(projectItem2));
+        }
     }
 }