Fix #1059 and #1060

src/Microsoft.AspNetCore.Razor.Language/DefaultRazorIRLoweringPhase.cs

@@ -17,6 +17,9 @@ namespace Microsoft.AspNetCore.Razor.Language
             var syntaxTree = codeDocument.GetSyntaxTree();
             ThrowForMissingDependency(syntaxTree);
 
+            // This might not have been set if there are no tag helpers.
+            var tagHelperContext = codeDocument.GetTagHelperContext();
+
             var builder = RazorIRBuilder.Document();
             var document = (DocumentIRNode)builder.Current;
 
@@ -46,7 +49,7 @@ namespace Microsoft.AspNetCore.Razor.Language
                 }
             }
 
-            var tagHelperPrefix = codeDocument.GetTagHelperPrefix();
+            var tagHelperPrefix = tagHelperContext?.Prefix;
             var visitor = new MainSourceVisitor(document, builder, namespaces, tagHelperPrefix)
             {
                 FileName = syntaxTree.Source.FileName,

src/Microsoft.AspNetCore.Razor.Language/RazorCodeDocumentExtensions.cs

@@ -31,26 +31,6 @@ namespace Microsoft.AspNetCore.Razor.Language
             document.Items[typeof(TagHelperDocumentContext)] = context;
         }
 
-        public static string GetTagHelperPrefix(this RazorCodeDocument document)
-        {
-            if (document == null)
-            {
-                throw new ArgumentNullException(nameof(document));
-            }
-
-            return document.Items[TagHelperPrefixKey] as string;
-        }
-
-        public static void SetTagHelperPrefix(this RazorCodeDocument document, string tagHelperPrefix)
-        {
-            if (document == null)
-            {
-                throw new ArgumentNullException(nameof(document));
-            }
-
-            document.Items[TagHelperPrefixKey] = tagHelperPrefix;
-        }
-
         public static RazorSyntaxTree GetSyntaxTree(this RazorCodeDocument document)
         {
             if (document == null)

src/Microsoft.AspNetCore.Razor.Language/TagHelperBinderSyntaxTreePass.cs

@@ -106,7 +106,6 @@ namespace Microsoft.AspNetCore.Razor.Language
 
             if (!string.IsNullOrEmpty(prefix))
             {
-                codeDocument.SetTagHelperPrefix(prefixDirective.DirectiveText);
                 return prefixDirective.DirectiveText;
             }
 

test/Microsoft.AspNetCore.Razor.Language.Test/IntegrationTests/CodeGenerationIntegrationTest.cs

@@ -691,7 +691,7 @@ namespace Microsoft.AspNetCore.Razor.Language.IntegrationTests
         public void BasicTagHelpers_Prefixed_Runtime()
         {
             // Arrange, Act & Assert
-            RunRuntimeTagHelpersTest(TestTagHelperDescriptors.DefaultPAndInputTagHelperDescriptors, tagHelperPrefix: "THS");
+            RunRuntimeTagHelpersTest(TestTagHelperDescriptors.DefaultPAndInputTagHelperDescriptors);
         }
 
         [Fact]
@@ -1535,7 +1535,7 @@ namespace Microsoft.AspNetCore.Razor.Language.IntegrationTests
         public void BasicTagHelpers_Prefixed_DesignTime()
         {
             // Arrange, Act & Assert
-            RunDesignTimeTagHelpersTest(TestTagHelperDescriptors.DefaultPAndInputTagHelperDescriptors, tagHelperPrefix: "THS");
+            RunDesignTimeTagHelpersTest(TestTagHelperDescriptors.DefaultPAndInputTagHelperDescriptors);
         }
 
         [Fact]
@@ -1630,20 +1630,16 @@ namespace Microsoft.AspNetCore.Razor.Language.IntegrationTests
         }
         #endregion
 
-        private void RunRuntimeTagHelpersTest(IEnumerable<TagHelperDescriptor> descriptors, string tagHelperPrefix = null)
+        private void RunRuntimeTagHelpersTest(IEnumerable<TagHelperDescriptor> descriptors)
         {
             // Arrange
-            var engine = RazorEngine.Create(
+            var engine = RazorEngine.Create(builder =>
-                builder =>
-                {
-                    builder.Features.Add(new ApiSetsIRTestAdapter());
-                    builder.AddTagHelpers(descriptors);
-                });
-            var document = CreateCodeDocument();
-            if (tagHelperPrefix != null)
             {
-                document.SetTagHelperPrefix(tagHelperPrefix);
+                builder.Features.Add(new ApiSetsIRTestAdapter());
-            }
+                builder.AddTagHelpers(descriptors);
+            });
+
+            var document = CreateCodeDocument();
 
             // Act
             engine.Process(document);
@@ -1653,20 +1649,16 @@ namespace Microsoft.AspNetCore.Razor.Language.IntegrationTests
             AssertCSharpDocumentMatchesBaseline(document.GetCSharpDocument());
         }
 
-        private void RunDesignTimeTagHelpersTest(IEnumerable<TagHelperDescriptor> descriptors, string tagHelperPrefix = null)
+        private void RunDesignTimeTagHelpersTest(IEnumerable<TagHelperDescriptor> descriptors)
         {
             // Arrange
-            var engine = RazorEngine.CreateDesignTime(
+            var engine = RazorEngine.CreateDesignTime(builder =>
-                builder =>
-                {
-                    builder.Features.Add(new ApiSetsIRTestAdapter());
-                    builder.AddTagHelpers(descriptors);
-                });
-            var document = CreateCodeDocument();
-            if (tagHelperPrefix != null)
             {
-                document.SetTagHelperPrefix(tagHelperPrefix);
+                builder.Features.Add(new ApiSetsIRTestAdapter());
-            }
+                builder.AddTagHelpers(descriptors);
+            });
+
+            var document = CreateCodeDocument();
 
             // Act
             engine.Process(document);

test/Microsoft.AspNetCore.Razor.Language.Test/TagHelperBinderSyntaxTreePassTest.cs

@@ -877,7 +877,7 @@ namespace Microsoft.AspNetCore.Razor.Language
 
         [Theory]
         [MemberData(nameof(ProcessTagHelperPrefixData))]
-        public void ProcessTagHelperPrefix_ParsesPrefixFromDirectives_SetsOnCodeDocument(
+        public void ProcessTagHelperPrefix_ParsesPrefixFromDirectives(
             object directiveDescriptors,
             string expectedPrefix)
         {
@@ -892,7 +892,6 @@ namespace Microsoft.AspNetCore.Razor.Language
             // Assert
             Assert.Empty(errorSink.Errors);
             Assert.Equal(expectedPrefix, prefix);
-            Assert.Equal(expectedPrefix, document.GetTagHelperPrefix());
         }
 
         public static TheoryData ProcessDirectivesData

test/Microsoft.AspNetCore.Razor.Performance/CodeGenerationBenchmark.cs

@@ -15,7 +15,7 @@ namespace Microsoft.AspNetCore.Razor.Performance
     {
         public CodeGenerationBenchmark()
         {
-            var current = new DirectoryInfo(Environment.CurrentDirectory);
+            var current = new DirectoryInfo(AppContext.BaseDirectory);
             while  (current != null && !File.Exists(Path.Combine(current.FullName, "MSN.cshtml")))
             {
                 current = current.Parent;