Avoid expanding tabs to spaces in codegen

src/Compiler/Microsoft.AspNetCore.Razor.Language/src/CodeGeneration/CodeWriterExtensions.cs

@@ -68,12 +68,9 @@ int CalculatePadding()
                 {
                     break;
                 }
-                else if (@char == '\t')
-                {
-                    spaceCount += writer.TabSize;
-                }
                 else
                 {
+                    // Note that a tab is also replaced with a single space so character indices match.
                     spaceCount++;
                 }
             }

src/Compiler/Microsoft.AspNetCore.Razor.Language/test/TestFiles/IntegrationTests/CodeGenerationIntegrationTest/CodeBlockWithTextElement_DesignTime.codegen.cs

@@ -33,14 +33,14 @@ public async System.Threading.Tasks.Task ExecuteAsync()
 #nullable disable
 #nullable restore
 #line 3 "TestFiles/IntegrationTests/CodeGenerationIntegrationTest/CodeBlockWithTextElement.cshtml"
-                                __o = a+b;
+                       __o = a+b;
 
 #line default
 #line hidden
 #nullable disable
 #nullable restore
 #line 3 "TestFiles/IntegrationTests/CodeGenerationIntegrationTest/CodeBlockWithTextElement.cshtml"
-                                                 
+
 
 #line default
 #line hidden

src/Compiler/Microsoft.AspNetCore.Razor.Language/test/TestFiles/IntegrationTests/CodeGenerationIntegrationTest/CodeBlockWithTextElement_DesignTime.mappings.txt

@@ -14,13 +14,13 @@ Generated Location: (980:27,31 [22] )
 
 Source Location: (69:2,29 [3] TestFiles/IntegrationTests/CodeGenerationIntegrationTest/CodeBlockWithTextElement.cshtml)
 |a+b|
-Generated Location: (1211:35,38 [3] )
+Generated Location: (1202:35,29 [3] )
 |a+b|
 
 Source Location: (80:2,40 [2] TestFiles/IntegrationTests/CodeGenerationIntegrationTest/CodeBlockWithTextElement.cshtml)
 |
 |
-Generated Location: (1435:42,49 [2] )
+Generated Location: (1417:42,40 [2] )
 |
 |
 

src/Compiler/Microsoft.AspNetCore.Razor.Language/test/TestFiles/IntegrationTests/CodeGenerationIntegrationTest/FunctionsBlockMinimal_DesignTime.codegen.cs

@@ -19,7 +19,7 @@ public async System.Threading.Tasks.Task ExecuteAsync()
         #pragma warning restore 1998
 #nullable restore
 #line 3 "TestFiles/IntegrationTests/CodeGenerationIntegrationTest/FunctionsBlockMinimal.cshtml"
-               
+
 string foo(string input) {
 	return input + "!";
 }

src/Compiler/Microsoft.AspNetCore.Razor.Language/test/TestFiles/IntegrationTests/CodeGenerationIntegrationTest/FunctionsBlockMinimal_DesignTime.mappings.txt

@@ -4,7 +4,7 @@ string foo(string input) {
 	return input + "!";
 }
 |
-Generated Location: (817:21,15 [55] )
+Generated Location: (814:21,12 [55] )
 |
 string foo(string input) {
 	return input + "!";

src/Compiler/Microsoft.AspNetCore.Razor.Language/test/TestFiles/IntegrationTests/CodeGenerationIntegrationTest/FunctionsBlockMinimal_Runtime.codegen.cs

@@ -16,7 +16,7 @@ public async System.Threading.Tasks.Task ExecuteAsync()
         #pragma warning restore 1998
 #nullable restore
 #line 3 "TestFiles/IntegrationTests/CodeGenerationIntegrationTest/FunctionsBlockMinimal.cshtml"
-               
+
 string foo(string input) {
 	return input + "!";
 }

src/Compiler/Microsoft.AspNetCore.Razor.Language/test/TestFiles/IntegrationTests/CodeGenerationIntegrationTest/SimpleUnspacedIf_DesignTime.codegen.cs

@@ -26,7 +26,7 @@ public async System.Threading.Tasks.Task ExecuteAsync()
 #nullable disable
 #nullable restore
 #line 3 "TestFiles/IntegrationTests/CodeGenerationIntegrationTest/SimpleUnspacedIf.cshtml"
-               
+
 }
 
 #line default

src/Compiler/Microsoft.AspNetCore.Razor.Language/test/TestFiles/IntegrationTests/CodeGenerationIntegrationTest/SimpleUnspacedIf_DesignTime.mappings.txt

@@ -10,7 +10,7 @@ Generated Location: (744:19,1 [15] )
 Source Location: (27:2,12 [3] TestFiles/IntegrationTests/CodeGenerationIntegrationTest/SimpleUnspacedIf.cshtml)
 |
 }|
-Generated Location: (937:28,15 [3] )
+Generated Location: (934:28,12 [3] )
 |
 }|
 

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

@@ -578,4 +578,57 @@ private static int RaiseHere()
             Assert.Equal(new TextSpan(originalIndex, snippet.Length), mappedSpan);
         }
     }
+
+    [Fact, WorkItem("https://github.com/dotnet/razor/issues/9050")]
+    public async Task LineMapping_Tabs()
+    {
+        // Arrange
+        var tab = '\t';
+        var source = $$"""
+            <div>
+            {{tab}}@if (true)
+            {{tab}}{
+            {{tab}}{{tab}}@("code")
+            {{tab}}}
+            </div>
+            """;
+        var project = CreateTestProject(new()
+        {
+            ["Shared/Component1.razor"] = source,
+        });
+        var compilation = await project.GetCompilationAsync();
+        var driver = await GetDriverAsync(project);
+
+        // Act
+        var result = RunGenerator(compilation!, ref driver);
+
+        // Assert
+        result.Diagnostics.Verify();
+
+        var original = project.AdditionalDocuments.Single();
+        var originalText = await original.GetTextAsync();
+        Assert.Equal(source, originalText.ToString());
+        var generated = result.GeneratedSources.Single();
+        var generatedText = generated.SourceText;
+        var generatedTextString = generatedText.ToString();
+
+        // Find snippets and verify their mapping.
+        var snippets = new[] { "true", "code" };
+        var expectedLines = new[] { 1, 3 };
+        var originalIndex = -1;
+        var generatedIndex = -1;
+        foreach (var (snippet, expectedLine) in snippets.Zip(expectedLines))
+        {
+            originalIndex = source.IndexOf(snippet, originalIndex + 1, StringComparison.Ordinal);
+            generatedIndex = generatedTextString.IndexOf(snippet, generatedIndex + 1, StringComparison.Ordinal);
+            var mapped = generated.SyntaxTree.GetMappedLineSpan(new TextSpan(generatedIndex, snippet.Length));
+            Assert.True(mapped.IsValid);
+            Assert.True(mapped.HasMappedPath);
+            Assert.Equal("Shared/Component1.razor", mapped.Path);
+            Assert.Equal(expectedLine, mapped.StartLinePosition.Line);
+            Assert.Equal(expectedLine, mapped.EndLinePosition.Line);
+            var mappedSpan = originalText.Lines.GetTextSpan(mapped.Span);
+            Assert.Equal(new TextSpan(originalIndex, snippet.Length), mappedSpan);
+        }
+    }
 }