Remove compilation error support from Startup error page

Fixes #510

src/Microsoft.AspNet.Hosting/Internal/HostingEngine.cs

@@ -168,13 +168,8 @@ namespace Microsoft.AspNet.Hosting.Internal
 
                 return builder.Build();
             }
-            catch (Exception ex)
+            catch (Exception ex) when (_captureStartupErrors)
             {
-                if (!_captureStartupErrors)
-                {
-                    throw;
-                }
-
                 // EnsureApplicationServices may have failed due to a missing or throwing Startup class.
                 if (_applicationServices == null)
                 {

src/Microsoft.AspNet.Hosting/Startup/StartupExceptionPage.cs

@@ -12,72 +12,38 @@ using System.Runtime.CompilerServices;
 using System.Runtime.ExceptionServices;
 using System.Text;
 using System.Text.Encodings.Web;
-using Microsoft.Extensions.CompilationAbstractions;
 using Microsoft.Extensions.PlatformAbstractions;
 
 namespace Microsoft.AspNet.Hosting.Startup
 {
     internal static class StartupExceptionPage
     {
-        private const int MaxCompilationErrorsToShow = 20;
-
         private static readonly string _errorPageFormatString = GetResourceString("GenericError.html", escapeBraces: true);
         private static readonly string _errorMessageFormatString = GetResourceString("GenericError_Message.html");
         private static readonly string _errorExceptionFormatString = GetResourceString("GenericError_Exception.html");
         private static readonly string _errorFooterFormatString = GetResourceString("GenericError_Footer.html");
-        private static readonly string _compilationExceptionFormatString = GetResourceString("Compilation_Exception.html");
 
-        public static byte[] GenerateErrorHtml(bool showDetails, IRuntimeEnvironment runtimeEnvironment, params object[] errorDetails)
+        public static byte[] GenerateErrorHtml(bool showDetails, IRuntimeEnvironment runtimeEnvironment, Exception exception)
         {
-            if (!showDetails)
-            {
-                errorDetails = new[] { "An error occurred while starting the application." };
-            }
-
             // Build the message for each error
-            var wasSourceCodeWrittenOntoPage = false;
             var builder = new StringBuilder();
             var rawExceptionDetails = new StringBuilder();
 
-            foreach (object error in errorDetails ?? new object[0])
+            if (!showDetails)
             {
-                var ex = error as Exception;
+                WriteMessage("An error occurred while starting the application.", builder);
-                if (ex == null && error is ExceptionDispatchInfo)
+            }
+            else
+            {
+                Debug.Assert(exception != null);
+                var wasSourceCodeWrittenOntoPage = false;
+                var flattenedExceptions = FlattenAndReverseExceptionTree(exception);
+                foreach (var innerEx in flattenedExceptions)
                 {
-                    ex = ((ExceptionDispatchInfo)error).SourceException;
+                    WriteException(innerEx, builder, ref wasSourceCodeWrittenOntoPage);
                 }
 
-                if (ex != null)
+                WriteRawExceptionDetails("Show raw exception details", exception.ToString(), rawExceptionDetails);
-                {
-                    var flattenedExceptions = FlattenAndReverseExceptionTree(ex);
-
-                    var compilationException = flattenedExceptions.OfType<ICompilationException>()
-                                                                  .FirstOrDefault();
-                    if (compilationException != null)
-                    {
-                        WriteException(compilationException, builder, ref wasSourceCodeWrittenOntoPage);
-
-                        var compilationErrorMessages = compilationException.CompilationFailures
-                            .SelectMany(f => f.Messages.Select(m => m.FormattedMessage))
-                            .Take(MaxCompilationErrorsToShow);
-
-                        WriteRawExceptionDetails("Show raw compilation error details", compilationErrorMessages, rawExceptionDetails);
-                    }
-                    else
-                    {
-                        foreach (var innerEx in flattenedExceptions)
-                        {
-                            WriteException(innerEx, builder, ref wasSourceCodeWrittenOntoPage);
-                        }
-
-                        WriteRawExceptionDetails("Show raw exception details", new[] { ex.ToString() }, rawExceptionDetails);
-                    }
-                }
-                else
-                {
-                    var message = Convert.ToString(error, CultureInfo.InvariantCulture);
-                    WriteMessage(message, builder);
-                }
             }
 
             // Generate the footer
@@ -171,84 +137,13 @@ namespace Microsoft.AspNet.Hosting.Startup
 
         private static string BuildMethodParametersUnescaped(MethodBase method)
         {
-            return "(" + string.Join(", ", method.GetParameters().Select(p => {
+            return "(" + string.Join(", ", method.GetParameters().Select(p =>
+            {
                 Type parameterType = p.ParameterType;
                 return ((parameterType != null) ? PrettyPrintTypeName(parameterType) : "?") + " " + p.Name;
             })) + ")";
         }
 
-        private static void BuildCodeSnippetDiv(CompilationFailure failure,
-                                               StringBuilder builder,
-                                               ref int totalErrorsShown)
-        {
-            const int NumContextLines = 3;
-            var fileName = failure.SourceFilePath;
-            if (totalErrorsShown < MaxCompilationErrorsToShow &&
-                !string.IsNullOrEmpty(fileName))
-            {
-                builder.Append(@"<div class=""codeSnippet"">")
-                       .AppendFormat(@"<div class=""filename""><code>{0}</code></div>", HtmlEncodeAndReplaceLineBreaks(fileName))
-                       .AppendLine();
-
-                IEnumerable<string> fileContent;
-                if (string.IsNullOrEmpty(failure.SourceFileContent))
-                {
-                    fileContent = File.ReadLines(fileName);
-                }
-                else
-                {
-                    fileContent = failure.SourceFileContent.Split(new[] { Environment.NewLine }, StringSplitOptions.None);
-                }
-                foreach (var message in failure.Messages)
-                {
-                    if (totalErrorsShown++ > MaxCompilationErrorsToShow)
-                    {
-                        break;
-                    }
-
-                    if (totalErrorsShown > 1)
-                    {
-                        builder.AppendLine("<br />");
-                    }
-
-                    builder.Append(@"<div class=""error-message"">")
-                           .Append(HtmlEncodeAndReplaceLineBreaks(message.Message))
-                           .Append("</div>");
-
-                    // StartLine and EndLine are 1-based
-                    var startLine = message.StartLine - 1;
-                    var endLine = message.EndLine - 1;
-                    var preContextIndex = Math.Max(startLine - NumContextLines, 0);
-                    var index = preContextIndex + 1;
-                    foreach (var line in fileContent.Skip(preContextIndex).Take(startLine - preContextIndex))
-                    {
-                        builder.Append(@"<div class=""line faded"">")
-                               .AppendFormat(@"<span class=""line-number"">{0}</span><code>", index++)
-                               .Append(HtmlEncodeAndReplaceLineBreaks(line))
-                               .AppendLine("</code></div>");
-                    }
-
-                    var numErrorLines = 1 + Math.Max(0, endLine - startLine);
-                    foreach (var line in fileContent.Skip(startLine).Take(numErrorLines))
-                    {
-                        builder.Append(@"<div class=""line error"">")
-                               .AppendFormat(@"<span class=""line-number"">{0}</span><code>", index++)
-                               .Append(HtmlEncodeAndReplaceLineBreaks(line))
-                               .AppendLine("</code></div>");
-                    }
-                    foreach (var line in fileContent.Skip(message.EndLine).Take(NumContextLines))
-                    {
-                        builder.Append(@"<div class=""line faded"">")
-                               .AppendFormat(@"<span class=""line-number"">{0}</span><code>", index++)
-                               .Append(HtmlEncodeAndReplaceLineBreaks(line))
-                               .AppendLine("</code></div>");
-                    }
-                }
-
-                builder.AppendLine("</div>"); // Close codeSnippet div
-            }
-        }
-
         private static string GetResourceString(string name, bool escapeBraces = false)
         {
             // '{' and '}' are special in CSS, so we use "[[[0]]]" instead for {0} (and so on).
@@ -451,7 +346,7 @@ namespace Microsoft.AspNet.Hosting.Startup
                 stackTraceBuilder);
         }
 
-        private static void WriteRawExceptionDetails(string linkText, IEnumerable<string> lines, StringBuilder rawExceptionDetails)
+        private static void WriteRawExceptionDetails(string linkText, string line, StringBuilder rawExceptionDetails)
         {
             rawExceptionDetails
                 .AppendLine("<div class=\"rawExceptionBlock\">")
@@ -460,10 +355,7 @@ namespace Microsoft.AspNet.Hosting.Startup
                 .AppendLine("    <div id=\"rawException\">")
                 .Append("        <pre>");
 
-            foreach (var line in lines)
+            rawExceptionDetails.AppendLine(line);
-            {
-                rawExceptionDetails.AppendLine(line);
-            }
 
             rawExceptionDetails
                 .AppendLine("</pre>")
@@ -471,34 +363,6 @@ namespace Microsoft.AspNet.Hosting.Startup
                 .AppendLine("</div>");
         }
 
-        private static void WriteException(ICompilationException compilationException,
-                                           StringBuilder builder,
-                                           ref bool wasSourceCodeWrittenOntoPage)
-        {
-            var totalErrorsShown = 0;
-            var inlineSourceDiv = new StringBuilder();
-            var firstStackFrame = true;
-            foreach (var failure in compilationException.CompilationFailures)
-            {
-                if (firstStackFrame)
-                {
-                    firstStackFrame = false;
-                }
-                else
-                {
-                    inlineSourceDiv.AppendLine("<br/>");
-                }
-
-                BuildCodeSnippetDiv(failure, inlineSourceDiv, ref totalErrorsShown);
-            }
-
-            wasSourceCodeWrittenOntoPage = totalErrorsShown > 0;
-
-            builder.AppendFormat(CultureInfo.InvariantCulture,
-                                 _compilationExceptionFormatString,
-                                 inlineSourceDiv);
-        }
-
         private static void WriteMessage(string message, StringBuilder builder)
         {
             // Build the <div>

src/Microsoft.AspNet.Hosting/compiler/resources/Compilation_Exception.html

@@ -1,6 +0,0 @@
-<div class="message">
-    <span class="light exception">One or more compilation errors occurred:</span><br />
-    <div class="stacktrace">
-        {0}
-    </div>
-</div>

src/Microsoft.AspNet.Hosting/compiler/resources/GenericError.html

@@ -75,11 +75,6 @@
             background-color: #f6f6f6;
         }
 
-        .codeSnippet .error-message {
-            color: red;
-            font-weight: normal;
-        }
-
         .codeSnippet div.filename {
             font-weight: bold;
             background-color: white;

src/Microsoft.AspNet.Hosting/project.json

@@ -21,7 +21,6 @@
     "Microsoft.Extensions.Configuration.Json": "1.0.0-*",
     "Microsoft.Extensions.DependencyInjection": "1.0.0-*",
     "Microsoft.Extensions.Logging": "1.0.0-*",
-    "Microsoft.Extensions.CompilationAbstractions": "1.0.0-*",
     "Microsoft.Extensions.PlatformAbstractions": "1.0.0-*",
     "System.Diagnostics.DiagnosticSource": "4.0.0-*"
   },