Flow parser errors over to the CSharpDocument

src/Microsoft.AspNetCore.Razor.Evolution/DefaultRazorDesignTimeCSharpLoweringPhase.cs

@@ -36,11 +36,13 @@ namespace Microsoft.AspNetCore.Razor.Evolution
             };
             var visitor = new CSharpRenderer(renderingContext);
             visitor.VisitDocument(irDocument);
+
+            var combinedErrors = syntaxTree.Diagnostics.Concat(renderingContext.ErrorSink.Errors).ToList();
             var csharpDocument = new RazorCSharpDocument()
             {
                 GeneratedCode = renderingContext.Writer.GenerateCode(),
                 LineMappings = renderingContext.LineMappings,
-                Diagnostics = renderingContext.ErrorSink.Errors
+                Diagnostics = combinedErrors
             };
 
             codeDocument.SetCSharpDocument(csharpDocument);

src/Microsoft.AspNetCore.Razor.Evolution/DefaultRazorRuntimeCSharpLoweringPhase.cs

@@ -37,11 +37,13 @@ namespace Microsoft.AspNetCore.Razor.Evolution
 
             var visitor = new CSharpRenderer(renderingContext);
             visitor.VisitDocument(irDocument);
+
+            var combinedErrors = syntaxTree.Diagnostics.Concat(renderingContext.ErrorSink.Errors).ToList();
             var csharpDocument = new RazorCSharpDocument()
             {
                 GeneratedCode = renderingContext.Writer.GenerateCode(),
                 LineMappings = renderingContext.LineMappings,
-                Diagnostics = renderingContext.ErrorSink.Errors
+                Diagnostics = combinedErrors
             };
 
             codeDocument.SetCSharpDocument(csharpDocument);

test/Microsoft.AspNetCore.Razor.Evolution.Test/IntegrationTests/BasicIntegrationTest.cs

@@ -1,6 +1,7 @@
 // Copyright (c) .NET Foundation. All rights reserved.
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
+using Microsoft.AspNetCore.Razor.Evolution.Legacy;
 using Xunit;
 
 namespace Microsoft.AspNetCore.Razor.Evolution.IntegrationTests
@@ -70,5 +71,49 @@ namespace Microsoft.AspNetCore.Razor.Evolution.IntegrationTests
             Assert.NotNull(document.GetSyntaxTree());
             Assert.NotNull(document.GetIRDocument());
         }
+
+        [Fact]
+        public void CSharpDocument_Runtime_PreservesParserErrors()
+        {
+            // Arrange
+            var engine = RazorEngine.Create();
+
+            var document = RazorCodeDocument.Create(TestRazorSourceDocument.Create("@!!!"));
+
+            // Act
+            engine.Process(document);
+
+            // Assert
+            var csharpDocument = document.GetCSharpDocument();
+            var error = Assert.Single(csharpDocument.Diagnostics);
+            Assert.Equal(
+                new RazorError(
+                    LegacyResources.FormatParseError_Unexpected_Character_At_Start_Of_CodeBlock_CS("!"),
+                    new SourceLocation(1, 0, 1),
+                    length: 1),
+                error);
+        }
+
+        [Fact]
+        public void CSharpDocument_DesignTime_PreservesParserErrors()
+        {
+            // Arrange
+            var engine = RazorEngine.CreateDesignTime();
+
+            var document = RazorCodeDocument.Create(TestRazorSourceDocument.Create("@{"));
+
+            // Act
+            engine.Process(document);
+
+            // Assert
+            var csharpDocument = document.GetCSharpDocument();
+            var error = Assert.Single(csharpDocument.Diagnostics);
+            Assert.Equal(
+                new RazorError(
+                    LegacyResources.FormatParseError_Expected_EndOfBlock_Before_EOF(LegacyResources.BlockName_Code, "}", "{"),
+                    new SourceLocation(1, 0, 1),
+                    length: 1),
+                error);
+        }
     }
 }