Add command line parsing and handling for output and log files

eng/Versions.props

@@ -41,7 +41,6 @@
   <PropertyGroup>
     <BasicUndoVersion>0.9.3</BasicUndoVersion>
     <BenchmarkDotNetVersion>0.11.4</BenchmarkDotNetVersion>
-    <CommandLineParserVersion>2.0.273-beta</CommandLineParserVersion>
     <DiffPlexVersion>1.4.4</DiffPlexVersion>
     <DropAppVersion>17.144.28413-buildid7983345</DropAppVersion>
     <EnvDTEVersion>8.0.2</EnvDTEVersion>
@@ -179,8 +178,7 @@
     <RoslynMicrosoftVisualStudioExtensionManagerVersion>0.0.4</RoslynMicrosoftVisualStudioExtensionManagerVersion>
     <SourceBrowserVersion>1.0.21</SourceBrowserVersion>
     <SystemBuffersVersion>4.5.0</SystemBuffersVersion>
-    <SystemCommandLineExperimentalVersion>0.1.0-alpha-63729-01</SystemCommandLineExperimentalVersion>
-    <SystemCommandLineRenderingVersion>0.1.0-alpha-63729-01</SystemCommandLineRenderingVersion>
+    <SystemCommandLineExperimentalVersion>0.3.0-alpha.19577.1</SystemCommandLineExperimentalVersion>
     <SystemComponentModelCompositionVersion>4.5.0</SystemComponentModelCompositionVersion>
     <SystemDrawingCommonVersion>4.5.0</SystemDrawingCommonVersion>
     <SystemIOFileSystemVersion>4.3.0</SystemIOFileSystemVersion>

src/Features/Lsif/Generator/.editorconfig

+# This .editorconfig customizes some diagnostic rules that are specific to this project.
+
+[*.cs]
+dotnet_diagnostic.CA2007.severity = none # Disable warnings about ConfigureAwait, since this is a console app
+dotnet_diagnostic.VSTHRD111.severity = none # Disable warnings about ConfigureAwait, since this is a console app
\ No newline at end of file

src/Features/Lsif/Generator/Microsoft.CodeAnalysis.Lsif.Generator.csproj

@@ -12,4 +12,11 @@
     <RuntimeIdentifiers>$(RoslynPortableRuntimeIdentifiers)</RuntimeIdentifiers>
     <Nullable>enable</Nullable>
   </PropertyGroup>
+  <ItemGroup>
+    <PackageReference Include="System.CommandLine.Experimental" Version="$(SystemCommandLineExperimentalVersion)" />
+  </ItemGroup>
+  <ItemGroup>
+    <None Include=".editorconfig" />
+    <None Include="README.md" />
+  </ItemGroup>
 </Project>
\ No newline at end of file

src/Features/Lsif/Generator/Program.cs

 // Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the Apache License, Version 2.0.  See License.txt in the project root for license information.
 
+using System;
+using System.CommandLine;
+using System.CommandLine.Builder;
+using System.CommandLine.Invocation;
+using System.IO;
+using System.Threading.Tasks;
+
 namespace Microsoft.CodeAnalysis.Lsif.Generator
 {
     internal static class Program
     {
-        public static void Main(string[] args)
+        public static Task Main(string[] args)
+        {
+            var generateCommand = new RootCommand("generates an LSIF file")
+            {
+                new Option("--output", "file to write the LSIF output to, instead of the console") { Argument = new Argument<string?>(defaultValue: () => null).LegalFilePathsOnly() },
+                new Option("--log", "file to write a log to") { Argument = new Argument<string?>(defaultValue: () => null).LegalFilePathsOnly() }
+            };
+
+            generateCommand.Handler = CommandHandler.Create((Func<string?, string?, Task>)GenerateAsync);
+
+            return generateCommand.InvokeAsync(args);
+        }
+
+        private static async Task GenerateAsync(string? output, string? log)
+        {
+            // If we have an output file, we'll write to that, else we'll use Console.Out
+            using StreamWriter? outputFile = output != null ? new StreamWriter(output) : null;
+            TextWriter outputWriter = outputFile ?? Console.Out;
+
+            using TextWriter logFile = log != null ? new StreamWriter(log) : TextWriter.Null;
+
+            try
+            {
+                await GenerateAsync(outputWriter, logFile);
+            }
+            catch (Exception e)
+            {
+                // If it failed, write out to the logs and error, but propagate the error too
+                var message = "Unhandled exception: " + e.ToString();
+                await logFile.WriteLineAsync(message);
+                Console.Error.WriteLine(message);
+                throw;
+            }
+
+            await logFile.WriteLineAsync("Generation complete.");
+        }
+
+        private static Task GenerateAsync(TextWriter outputWriter, TextWriter logFile)
         {
+            return Task.CompletedTask;
         }
     }
 }