Generate an expression to create line mappings for ModelChunk directives

src/Microsoft.AspNet.Mvc.Razor.Host/MvcCSharpCodeGenerator.cs

@@ -67,6 +67,29 @@ namespace Microsoft.AspNet.Mvc.Razor
             return csharpCodeVisitor;
         }
 
+        protected override CSharpDesignTimeCodeVisitor CreateCSharpDesignTimeCodeVisitor(
+            CSharpCodeVisitor csharpCodeVisitor,
+            CSharpCodeWriter writer,
+            CodeGeneratorContext context)
+        {
+            if (csharpCodeVisitor == null)
+            {
+                throw new ArgumentNullException(nameof(csharpCodeVisitor));
+            }
+
+            if (writer == null)
+            {
+                throw new ArgumentNullException(nameof(writer));
+            }
+
+            if (context == null)
+            {
+                throw new ArgumentNullException(nameof(context));
+            }
+
+            return new MvcCSharpDesignTimeCodeVisitor(csharpCodeVisitor, writer, context);
+        }
+
         protected override void BuildConstructor(CSharpCodeWriter writer)
         {
             if (writer == null)

src/Microsoft.AspNet.Mvc.Razor.Host/MvcCSharpDesignTimeCodeVisitor.cs

@@ -0,0 +1,70 @@
+// 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 System.Diagnostics;
+using Microsoft.AspNet.Razor.Chunks;
+using Microsoft.AspNet.Razor.CodeGenerators;
+using Microsoft.AspNet.Razor.CodeGenerators.Visitors;
+
+namespace Microsoft.AspNet.Mvc.Razor
+{
+    public class MvcCSharpDesignTimeCodeVisitor : CSharpDesignTimeCodeVisitor
+    {
+        private const string ModelVariable = "__modelHelper";
+        private ModelChunk _modelChunk;
+
+        public MvcCSharpDesignTimeCodeVisitor(
+            CSharpCodeVisitor csharpCodeVisitor,
+            CSharpCodeWriter writer,
+            CodeGeneratorContext context)
+            : base(csharpCodeVisitor, writer, context)
+        {
+        }
+
+        protected override void AcceptTreeCore(ChunkTree tree)
+        {
+            base.AcceptTreeCore(tree);
+
+            if (_modelChunk != null)
+            {
+                WriteModelChunkLineMapping();
+            }
+        }
+
+        public override void Accept(Chunk chunk)
+        {
+            if (chunk is ModelChunk)
+            {
+                Visit((ModelChunk)chunk);
+            }
+
+            base.Accept(chunk);
+        }
+
+        private void Visit(ModelChunk chunk)
+        {
+            Debug.Assert(chunk != null);
+            _modelChunk = chunk;
+        }
+
+        private void WriteModelChunkLineMapping()
+        {
+            Debug.Assert(Context.Host.DesignTimeMode);
+
+            using (var lineMappingWriter =
+                Writer.BuildLineMapping(_modelChunk.Start, _modelChunk.ModelType.Length, Context.SourceFile))
+            {
+                // var __modelHelper = default(MyModel);
+                Writer.Write("var ")
+                    .Write(ModelVariable)
+                    .Write(" = default(");
+
+                lineMappingWriter.MarkLineMappingStart();
+                Writer.Write(_modelChunk.ModelType);
+                lineMappingWriter.MarkLineMappingEnd();
+
+                Writer.WriteLine(");");
+            }
+        }
+    }
+}

src/Microsoft.AspNet.Mvc.Razor.Host/MvcRazorHost.cs

@@ -45,7 +45,10 @@ namespace Microsoft.AspNet.Mvc.Razor
             new SetBaseTypeChunk
             {
                 // Microsoft.Aspnet.Mvc.Razor.RazorPage<TModel>
-                TypeName = BaseType + ChunkHelper.TModelToken
+                TypeName = BaseType + ChunkHelper.TModelToken,
+                // Set the Start to Undefined to prevent Razor design time code generation from rendering a line mapping
+                // for this chunk.
+                Start = SourceLocation.Undefined
             }
         };
 

test/Microsoft.AspNet.Mvc.Razor.Host.Test/MvcRazorHostTest.cs

@@ -137,18 +137,18 @@ namespace Microsoft.AspNet.Mvc.Razor
                     generatedCharacterIndex: 14,
                     contentLength: 85),
                 BuildLineMapping(
-                    documentAbsoluteIndex: 0,
+                    documentAbsoluteIndex: 7,
                     documentLineIndex: 0,
-                    documentCharacterIndex: 0,
+                    documentCharacterIndex: 7,
-                    generatedAbsoluteIndex: 910,
+                    generatedAbsoluteIndex: 938,
                     generatedLineIndex: 25,
-                    generatedCharacterIndex: 0,
+                    generatedCharacterIndex: 28,
-                    contentLength: 46),
+                    contentLength: 8),
                 BuildLineMapping(
                     documentAbsoluteIndex: 139,
                     documentLineIndex: 4,
                     documentCharacterIndex: 17,
-                    generatedAbsoluteIndex: 2371,
+                    generatedAbsoluteIndex: 2338,
                     generatedLineIndex: 54,
                     generatedCharacterIndex: 95,
                     contentLength: 3),
@@ -156,16 +156,17 @@ namespace Microsoft.AspNet.Mvc.Razor
                     documentAbsoluteIndex: 166,
                     documentLineIndex: 5,
                     documentCharacterIndex: 18,
-                    generatedAbsoluteIndex: 2684,
+                    generatedAbsoluteIndex: 2651,
                     generatedLineIndex: 60,
                     generatedCharacterIndex: 87,
                     contentLength: 5),
             };
 
             // Act and Assert
-            RunDesignTimeTest(host,
+            RunDesignTimeTest(
-                              testName: "ModelExpressionTagHelper",
+                host,
-                              expectedLineMappings: expectedLineMappings);
+                testName: "ModelExpressionTagHelper",
+                expectedLineMappings: expectedLineMappings);
         }
 
         [Theory]
@@ -197,28 +198,20 @@ namespace Microsoft.AspNet.Mvc.Razor
             host.NamespaceImports.Clear();
             var expectedLineMappings = new[]
             {
-                BuildLineMapping(
-                    documentAbsoluteIndex: 0,
-                    documentLineIndex: 0,
-                    documentCharacterIndex: 0,
-                    generatedAbsoluteIndex: 343,
-                    generatedLineIndex: 11,
-                    generatedCharacterIndex: 0,
-                    contentLength: 45),
                 BuildLineMapping(
                     documentAbsoluteIndex: 13,
                     documentLineIndex: 0,
                     documentCharacterIndex: 13,
-                    generatedAbsoluteIndex: 1412,
+                    generatedAbsoluteIndex: 1269,
-                    generatedLineIndex: 37,
+                    generatedLineIndex: 32,
                     generatedCharacterIndex: 13,
                     contentLength: 4),
                 BuildLineMapping(
                     documentAbsoluteIndex: 43,
                     documentLineIndex: 2,
                     documentCharacterIndex: 5,
-                    generatedAbsoluteIndex: 1496,
+                    generatedAbsoluteIndex: 1353,
-                    generatedLineIndex: 42,
+                    generatedLineIndex: 37,
                     generatedCharacterIndex: 6,
                     contentLength: 21),
             };
@@ -247,20 +240,12 @@ namespace Microsoft.AspNet.Mvc.Razor
                     generatedLineIndex: 3,
                     generatedCharacterIndex: 0,
                     contentLength: 17),
-                BuildLineMapping(
-                    documentAbsoluteIndex: 0,
-                    documentLineIndex: 0,
-                    documentCharacterIndex: 0,
-                    generatedAbsoluteIndex: 443,
-                    generatedLineIndex: 17,
-                    generatedCharacterIndex: 0,
-                    contentLength: 45),
                 BuildLineMapping(
                     documentAbsoluteIndex: 28,
                     documentLineIndex: 1,
                     documentCharacterIndex: 8,
-                    generatedAbsoluteIndex: 850,
+                    generatedAbsoluteIndex: 706,
-                    generatedLineIndex: 31,
+                    generatedLineIndex: 26,
                     generatedCharacterIndex: 8,
                     contentLength: 20),
             };
@@ -282,18 +267,18 @@ namespace Microsoft.AspNet.Mvc.Razor
             var expectedLineMappings = new[]
             {
                 BuildLineMapping(
-                    documentAbsoluteIndex: 0,
+                    documentAbsoluteIndex: 7,
                     documentLineIndex: 0,
-                    documentCharacterIndex: 0,
+                    documentCharacterIndex: 7,
-                    generatedAbsoluteIndex: 363,
+                    generatedAbsoluteIndex: 391,
                     generatedLineIndex: 11,
-                    generatedCharacterIndex: 0,
+                    generatedCharacterIndex: 28,
-                    contentLength: 45),
+                    contentLength: 7),
                 BuildLineMapping(
                     documentAbsoluteIndex: 24,
                     documentLineIndex: 1,
                     documentCharacterIndex: 8,
-                    generatedAbsoluteIndex: 788,
+                    generatedAbsoluteIndex: 755,
                     generatedLineIndex: 25,
                     generatedCharacterIndex: 8,
                     contentLength: 20),
@@ -301,7 +286,7 @@ namespace Microsoft.AspNet.Mvc.Razor
                     documentAbsoluteIndex: 54,
                     documentLineIndex: 2,
                     documentCharacterIndex: 8,
-                    generatedAbsoluteIndex: 1014,
+                    generatedAbsoluteIndex: 981,
                     generatedLineIndex: 33,
                     generatedCharacterIndex: 8,
                     contentLength: 23),
@@ -324,18 +309,18 @@ namespace Microsoft.AspNet.Mvc.Razor
             var expectedLineMappings = new[]
             {
                 BuildLineMapping(
-                    documentAbsoluteIndex: 0,
+                    documentAbsoluteIndex: 7,
                     documentLineIndex: 0,
-                    documentCharacterIndex: 0,
+                    documentCharacterIndex: 7,
-                    generatedAbsoluteIndex: 371,
+                    generatedAbsoluteIndex: 399,
                     generatedLineIndex: 11,
-                    generatedCharacterIndex: 0,
+                    generatedCharacterIndex: 28,
-                    contentLength: 45),
+                    contentLength: 7),
                 BuildLineMapping(
                     documentAbsoluteIndex: 24,
                     documentLineIndex: 1,
                     documentCharacterIndex: 8,
-                    generatedAbsoluteIndex: 804,
+                    generatedAbsoluteIndex: 771,
                     generatedLineIndex: 25,
                     generatedCharacterIndex: 8,
                     contentLength: 20),
@@ -343,7 +328,7 @@ namespace Microsoft.AspNet.Mvc.Razor
                     documentAbsoluteIndex: 58,
                     documentLineIndex: 2,
                     documentCharacterIndex: 8,
-                    generatedAbsoluteIndex: 1034,
+                    generatedAbsoluteIndex: 1001,
                     generatedLineIndex: 33,
                     generatedCharacterIndex: 8,
                     contentLength: 23),
@@ -351,7 +336,7 @@ namespace Microsoft.AspNet.Mvc.Razor
                     documentAbsoluteIndex: 93,
                     documentLineIndex: 3,
                     documentCharacterIndex: 8,
-                    generatedAbsoluteIndex: 1267,
+                    generatedAbsoluteIndex: 1234,
                     generatedLineIndex: 41,
                     generatedCharacterIndex: 8,
                     contentLength: 21),
@@ -359,7 +344,7 @@ namespace Microsoft.AspNet.Mvc.Razor
                     documentAbsoluteIndex: 129,
                     documentLineIndex: 4,
                     documentCharacterIndex: 8,
-                    generatedAbsoluteIndex: 1498,
+                    generatedAbsoluteIndex: 1465,
                     generatedLineIndex: 49,
                     generatedCharacterIndex: 8,
                     contentLength: 24),
@@ -382,19 +367,51 @@ namespace Microsoft.AspNet.Mvc.Razor
             var expectedLineMappings = new[]
             {
                 BuildLineMapping(
-                    documentAbsoluteIndex: 0,
+                    documentAbsoluteIndex: 7,
                     documentLineIndex: 0,
-                    documentCharacterIndex: 0,
+                    documentCharacterIndex: 7,
-                    generatedAbsoluteIndex: 366,
+                    generatedAbsoluteIndex: 394,
                     generatedLineIndex: 11,
-                    generatedCharacterIndex: 0,
+                    generatedCharacterIndex: 28,
-                    contentLength: 68),
+                    contentLength: 30),
             };
 
             // Act and Assert
             RunDesignTimeTest(host, "Model", expectedLineMappings);
         }
 
+        [Fact]
+        public void ModelVisitor_GeneratesLineMappingsForLastModel_WhenMultipleModelsArePresent()
+        {
+            // Arrange
+            var fileProvider = new TestFileProvider();
+            var host = new MvcRazorHostWithNormalizedNewLine(new DefaultChunkTreeCache(fileProvider))
+            {
+                DesignTimeMode = true
+            };
+            host.NamespaceImports.Clear();
+            var inputFile = "TestFiles/Input/MultipleModels.cshtml";
+            var outputFile = "TestFiles/Output/DesignTime/MultipleModels.cs";
+            var expectedCode = ResourceFile.ReadResource(_assembly, outputFile, sourceFile: false);
+
+            // Act
+            GeneratorResults results;
+            using (var stream = ResourceFile.GetResourceStream(_assembly, inputFile, sourceFile: true))
+            {
+                results = host.GenerateCode(inputFile, stream);
+            }
+
+            // Assert
+            Assert.False(results.Success);
+            var parserError = Assert.Single(results.ParserErrors);
+            Assert.Equal("Only one 'model' statement is allowed in a file.", parserError.Message);
+#if GENERATE_BASELINES
+            ResourceFile.UpdateFile(_assembly, outputFile, expectedCode, results.GeneratedCode);
+#else
+            Assert.Equal(expectedCode, results.GeneratedCode, ignoreLineEndingDifferences: true);
+#endif
+        }
+
         private static void RunRuntimeTest(
             MvcRazorHost host,
             string testName)

test/Microsoft.AspNet.Mvc.Razor.Host.Test/TestFiles/Input/MultipleModels.cshtml

@@ -0,0 +1,2 @@
+@model ThisShouldNotBeGenerated
+@model System.Collections.IEnumerable

test/Microsoft.AspNet.Mvc.Razor.Host.Test/TestFiles/Output/DesignTime/Basic.cs

@@ -8,11 +8,6 @@ namespace Asp
         private void @__RazorDesignTimeHelpers__()
         {
             #pragma warning disable 219
-#line 1 "TestFiles/Input/Basic.cshtml"
-Microsoft.AspNet.Mvc.Razor.RazorPage<dynamic> __inheritsHelper = null;
-
-#line default
-#line hidden
             #pragma warning restore 219
         }
         #line hidden

test/Microsoft.AspNet.Mvc.Razor.Host.Test/TestFiles/Output/DesignTime/Inject.cs

@@ -14,11 +14,6 @@ using MyNamespace
         private void @__RazorDesignTimeHelpers__()
         {
             #pragma warning disable 219
-#line 1 "TestFiles/Input/Inject.cshtml"
-Microsoft.AspNet.Mvc.Razor.RazorPage<dynamic> __inheritsHelper = null;
-
-#line default
-#line hidden
             #pragma warning restore 219
         }
         #line hidden

test/Microsoft.AspNet.Mvc.Razor.Host.Test/TestFiles/Output/DesignTime/InjectWithModel.cs

@@ -9,7 +9,7 @@ namespace Asp
         {
             #pragma warning disable 219
 #line 1 "TestFiles/Input/InjectWithModel.cshtml"
-Microsoft.AspNet.Mvc.Razor.RazorPage<MyModel> __inheritsHelper = null;
+var __modelHelper = default(MyModel);
 
 #line default
 #line hidden

test/Microsoft.AspNet.Mvc.Razor.Host.Test/TestFiles/Output/DesignTime/InjectWithSemicolon.cs

@@ -9,7 +9,7 @@ namespace Asp
         {
             #pragma warning disable 219
 #line 1 "TestFiles/Input/InjectWithSemicolon.cshtml"
-Microsoft.AspNet.Mvc.Razor.RazorPage<MyModel> __inheritsHelper = null;
+var __modelHelper = default(MyModel);
 
 #line default
 #line hidden

test/Microsoft.AspNet.Mvc.Razor.Host.Test/TestFiles/Output/DesignTime/Model.cs

@@ -9,7 +9,7 @@ namespace Asp
         {
             #pragma warning disable 219
 #line 1 "TestFiles/Input/Model.cshtml"
-Microsoft.AspNet.Mvc.Razor.RazorPage<System.Collections.IEnumerable> __inheritsHelper = null;
+var __modelHelper = default(System.Collections.IEnumerable);
 
 #line default
 #line hidden

test/Microsoft.AspNet.Mvc.Razor.Host.Test/TestFiles/Output/DesignTime/ModelExpressionTagHelper.cs

@@ -23,7 +23,7 @@ namespace Asp
 #line hidden
             ;
 #line 1 "TestFiles/Input/ModelExpressionTagHelper.cshtml"
-Microsoft.AspNet.Mvc.Razor.RazorPage<DateTime> __inheritsHelper = null;
+var __modelHelper = default(DateTime);
 
 #line default
 #line hidden

test/Microsoft.AspNet.Mvc.Razor.Host.Test/TestFiles/Output/DesignTime/MultipleModels.cs

@@ -0,0 +1,40 @@
+namespace Asp
+{
+    using System.Threading.Tasks;
+
+    public class ASPV_TestFiles_Input_MultipleModels_cshtml : Microsoft.AspNet.Mvc.Razor.RazorPage<System.Collections.IEnumerable>
+    {
+        private static object @__o;
+        private void @__RazorDesignTimeHelpers__()
+        {
+            #pragma warning disable 219
+#line 2 "TestFiles/Input/MultipleModels.cshtml"
+var __modelHelper = default(System.Collections.IEnumerable);
+
+#line default
+#line hidden
+            #pragma warning restore 219
+        }
+        #line hidden
+        public ASPV_TestFiles_Input_MultipleModels_cshtml()
+        {
+        }
+        #line hidden
+        [Microsoft.AspNet.Mvc.Razor.Internal.RazorInjectAttribute]
+        public Microsoft.AspNet.Mvc.IUrlHelper Url { get; private set; }
+        [Microsoft.AspNet.Mvc.Razor.Internal.RazorInjectAttribute]
+        public Microsoft.AspNet.Mvc.IViewComponentHelper Component { get; private set; }
+        [Microsoft.AspNet.Mvc.Razor.Internal.RazorInjectAttribute]
+        public Microsoft.AspNet.Mvc.Rendering.IJsonHelper Json { get; private set; }
+        [Microsoft.AspNet.Mvc.Razor.Internal.RazorInjectAttribute]
+        public Microsoft.AspNet.Mvc.Rendering.IHtmlHelper<System.Collections.IEnumerable> Html { get; private set; }
+
+        #line hidden
+
+        #pragma warning disable 1998
+        public override async Task ExecuteAsync()
+        {
+        }
+        #pragma warning restore 1998
+    }
+}