From 7fcbc98082c83e9c45b3bbfe3bbc3065e95b1f2d Mon Sep 17 00:00:00 2001
From: Jan Jones <janjones@microsoft.com>
Date: Thu, 10 Apr 2025 23:03:56 +0200
Subject: [PATCH] Check CSS scope when comparing source generator items

---
 .../SourceGeneratorProjectItem.cs             | 10 ++++--
 .../RazorSourceGeneratorTests.cs              | 32 +++++++++++++++++++
 2 files changed, 40 insertions(+), 2 deletions(-)

diff --git a/src/Compiler/Microsoft.CodeAnalysis.Razor.Compiler/src/SourceGenerators/SourceGeneratorProjectItem.cs b/src/Compiler/Microsoft.CodeAnalysis.Razor.Compiler/src/SourceGenerators/SourceGeneratorProjectItem.cs
index 2c98017e827..b2ec91d063f 100644
--- a/src/Compiler/Microsoft.CodeAnalysis.Razor.Compiler/src/SourceGenerators/SourceGeneratorProjectItem.cs
+++ b/src/Compiler/Microsoft.CodeAnalysis.Razor.Compiler/src/SourceGenerators/SourceGeneratorProjectItem.cs
@@ -54,7 +54,13 @@ public override Stream Read()
 
         public bool Equals(SourceGeneratorProjectItem? other)
         {
-            if (ReferenceEquals(AdditionalText, other?.AdditionalText))
+            if (other is null ||
+                CssScope != other.CssScope)
+            {
+                return false;
+            }
+
+            if (ReferenceEquals(AdditionalText, other.AdditionalText))
             {
                 return true;
             }
@@ -64,7 +70,7 @@ public bool Equals(SourceGeneratorProjectItem? other)
             // It's technically possible for these hashes to collide, but other things would
             // also break in those cases, so for now we're okay with this.
             var thisHash = AdditionalText.GetText()?.GetContentHash() ?? [];
-            var otherHash = other?.AdditionalText.GetText()?.GetContentHash() ?? [];
+            var otherHash = other.AdditionalText.GetText()?.GetContentHash() ?? [];
             return thisHash.SequenceEqual(otherHash);
         }
 
diff --git a/src/Compiler/test/Microsoft.NET.Sdk.Razor.SourceGenerators.Tests/RazorSourceGeneratorTests.cs b/src/Compiler/test/Microsoft.NET.Sdk.Razor.SourceGenerators.Tests/RazorSourceGeneratorTests.cs
index 52e355e0e9a..c1d87adbfee 100644
--- a/src/Compiler/test/Microsoft.NET.Sdk.Razor.SourceGenerators.Tests/RazorSourceGeneratorTests.cs
+++ b/src/Compiler/test/Microsoft.NET.Sdk.Razor.SourceGenerators.Tests/RazorSourceGeneratorTests.cs
@@ -1203,6 +1203,38 @@ protected override void BuildRenderTree(RenderTreeBuilder builder) {}
             }
         }
 
+        [Fact]
+        public async Task IncrementalCompilation_RazorFiles_CssScopeRemoved()
+        {
+            // Compile with CssScope set.
+            var project = CreateTestProject(new()
+            {
+                ["Pages/Index.razor"] = "<h1>Hello world</h1>",
+            });
+            var compilation = await project.GetCompilationAsync();
+            var (driver, _, options) = await GetDriverWithAdditionalTextAndProviderAsync(project, static options =>
+            {
+                options.AdditionalTextOptions["Pages/Index.razor"]["build_metadata.AdditionalFiles.CssScope"] = "test-css-scope";
+            });
+
+            var result = RunGenerator(compilation!, ref driver);
+            result.Diagnostics.Verify();
+
+            // CSS isolation is enabled.
+            Assert.Contains("<h1 test-css-scope>Hello world</h1>", result.GeneratedSources.Single().SourceText.ToString());
+
+            // Unset CssScope.
+            options = options.Clone();
+            options.AdditionalTextOptions["Pages/Index.razor"].Options.Remove("build_metadata.AdditionalFiles.CssScope");
+            driver = driver.WithUpdatedAnalyzerConfigOptions(options);
+
+            result = RunGenerator(compilation!, ref driver);
+            result.Diagnostics.Verify();
+
+            // CSS isolation is disabled.
+            Assert.Contains("<h1>Hello world</h1>", result.GeneratedSources.Single().SourceText.ToString());
+        }
+
         [Fact]
         public async Task SourceGenerator_CshtmlFiles_Works()
         {