From f1f1db0d8ef68ec4b34fe58d79204ffd2b99cae0 Mon Sep 17 00:00:00 2001
From: David Fowler <davidfowl@gmail.com>
Date: Fri, 6 Nov 2015 05:53:16 -0800
Subject: [PATCH] Support language version based on schema

---
 src/Microsoft.DotNet.Tools.Compiler.Csc/Program.cs | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/src/Microsoft.DotNet.Tools.Compiler.Csc/Program.cs b/src/Microsoft.DotNet.Tools.Compiler.Csc/Program.cs
index e1336db75..d748c11f8 100644
--- a/src/Microsoft.DotNet.Tools.Compiler.Csc/Program.cs
+++ b/src/Microsoft.DotNet.Tools.Compiler.Csc/Program.cs
@@ -114,7 +114,7 @@ namespace Microsoft.DotNet.Tools.Compiler.Csc
 
             if (options.LanguageVersion != null)
             {
-                commonArgs.Add($"-langversion:{options.LanguageVersion}");
+                commonArgs.Add($"-langversion:{GetLanguageVersion(options.LanguageVersion)}");
             }
 
             if (options.Platform != null)
@@ -159,6 +159,17 @@ namespace Microsoft.DotNet.Tools.Compiler.Csc
             return commonArgs;
         }
 
+        private static string GetLanguageVersion(string languageVersion)
+        {
+            // project.json supports the enum that the roslyn APIs expose
+            if (languageVersion?.StartsWith("csharp", StringComparison.OrdinalIgnoreCase) == true)
+            {
+                // We'll be left with the number csharp6 = 6
+                return languageVersion.Substring("csharp".Length);
+            }
+            return languageVersion;
+        }
+
         private static Command RunCsc(string cscArgs)
         {
             // Locate CoreRun