Auto-generate Consts.cs on Windows when building from Visual Studio (#9598)

This adds a simple script for generating Consts.cs that can run on Windows, and makes it a dependency of corlib.csproj in the BCL solution file. From my initial testing this will autogenerate Consts.cs if it's missing and then corlib will successfully build.
This (mostly?) addresses issue https://github.com/mono/mono/issues/6886.

This currently has an awkward dependency on ```winsetup.bat``` and I modified it slightly to make it clearer whether the batch file succeeded.

3 files changed, 141 insertions, 12 deletions

diff --git a/msvc/scripts/genconsts.cs b/msvc/scripts/genconsts.cs
new file mode 100755
index 00000000000..1ec83657e4e
--- /dev/null
+++ b/msvc/scripts/genconsts.cs
@@ -0,0 +1,98 @@
+using System;
+using System.IO;
+using System.Reflection;
+using System.Diagnostics;
+using System.Text;
+using System.Text.RegularExpressions;
+
+public static class Program {
+    public static int Main (string[] args) {
+        var myAssembly = Assembly.GetExecutingAssembly ();
+        var codeBase = new Uri (myAssembly.CodeBase);
+        var executablePath = Path.GetFullPath (codeBase.LocalPath);
+        var executableDirectory = Path.GetDirectoryName (executablePath);
+
+        var winsetupDirectory = Path.Combine (executableDirectory, "..");
+        var winsetupPath = Path.Combine (winsetupDirectory, "winsetup.bat");
+
+        var psi = new ProcessStartInfo (winsetupPath) {
+            WorkingDirectory = winsetupDirectory,
+            UseShellExecute = false,
+            ErrorDialog = false,
+            RedirectStandardOutput = true
+        };
+
+        string monoVersion, monoCorlibVersion;
+
+        Process winsetupProcess;
+
+        try {
+            winsetupProcess = Process.Start (psi);
+        } catch (Exception exc) {
+            Console.Error.WriteLine ("Failed starting winsetup.bat");
+            Console.Error.WriteLine (exc);
+            return 1;
+        }
+
+        using (winsetupProcess) {
+            var outputBuffer = new StringBuilder ();
+
+            winsetupProcess.OutputDataReceived += (s, e) => {
+                outputBuffer.AppendLine (e.Data);
+            };
+            winsetupProcess.BeginOutputReadLine ();
+            winsetupProcess.WaitForExit ();
+
+            var output = outputBuffer.ToString ().Trim ();
+
+            if (winsetupProcess.ExitCode != 0) {
+                Console.Error.WriteLine ("Failed running winsetup.bat");
+                Console.Write (output);
+                return winsetupProcess.ExitCode;
+            } else {
+                var m = Regex.Match (output, "MONO_VERSION=([0-9.]+)");
+                if (!m.Success)
+                    return 1;
+                monoVersion = m.Groups[1].Value;
+
+                // HACK: winsetup.bat produces N.N.N instead of N.N.N.N like configure.ac,
+                //  so we add .0's to match the Consts.cs generated by make
+                while (monoVersion.Split ('.').Length < 4)
+                    monoVersion += ".0";
+
+                Console.WriteLine ($"MONO_VERSION={monoVersion}");
+                m = Regex.Match (output, "MONO_CORLIB_VERSION=([0-9]+)");
+                if (!m.Success)
+                    return 1;
+                monoCorlibVersion = m.Groups[1].Value;
+                Console.WriteLine ($"MONO_CORLIB_VERSION={monoCorlibVersion}");
+            }
+        }
+
+        var constsDirectory = Path.Combine (executableDirectory, "..", "..", "mcs", "build", "common");
+        var constsTemplatePath = Path.Combine (constsDirectory, "Consts.cs.in");        
+        if (!Directory.Exists (constsDirectory) || !File.Exists (constsTemplatePath)) {
+            Console.Error.WriteLine ($"File not found: {constsTemplatePath}");
+            return 1;
+        }
+
+        var resultPath = Path.GetFullPath (Path.Combine (constsDirectory, "Consts.cs"));
+        var templateText = File.ReadAllText (constsTemplatePath);
+
+        var resultText = templateText.Replace ("@MONO_VERSION@", monoVersion)
+            .Replace ("@MONO_CORLIB_VERSION@", monoCorlibVersion);
+
+        if (File.Exists (resultPath)) {
+            var existingText = File.ReadAllText (resultPath);
+            if (existingText.Trim () == resultText.Trim ()) {
+                Console.WriteLine ($"{resultPath} not changed");
+                return 0;
+            }
+        }
+
+        File.WriteAllText (resultPath, resultText);
+        Console.WriteLine ($"Generated {resultPath} successfully");
+
+        return 0;
+    }
+}
\ No newline at end of file
diff --git a/msvc/scripts/genconsts.csproj b/msvc/scripts/genconsts.csproj
new file mode 100755
index 00000000000..fa523495fff
--- /dev/null
+++ b/msvc/scripts/genconsts.csproj
@@ -0,0 +1,23 @@
+<?xml version="1.0" encoding="utf-8"?>

+<Project ToolsVersion="14.0" DefaultTargets="Build" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">

+  <PropertyGroup>

+    <Configuration Condition=" '$(Configuration)' == '' ">Debug</Configuration>

+    <Platform Condition=" '$(Platform)' == '' ">Any CPU</Platform>

+    <OutputType>Exe</OutputType>

+    <AssemblyName>genconsts</AssemblyName>

+    <DebugSymbols>true</DebugSymbols>

+    <DebugType>full</DebugType>

+    <Optimize>false</Optimize>

+    <DefineConstants>TRACE;DEBUG</DefineConstants>

+    <OutputPath>.\</OutputPath>

+    <ProjectGuid>{702AE2C0-71DD-4112-9A06-E4FABCA59986}</ProjectGuid>

+    <RunPostBuildEvent>Always</RunPostBuildEvent>

+    <PostBuildEvent>cd $(MSBuildProjectDirectory)

+$(TargetPath)</PostBuildEvent>

+  </PropertyGroup>

+  <Import Project="$(MSBuildToolsPath)\Microsoft.CSharp.targets" />

+  <ItemGroup>

+    <Compile Include="genconsts.cs" />

+    <Reference Include="System" />

+  </ItemGroup>

+</Project>
\ No newline at end of file
diff --git a/msvc/scripts/genproj.cs b/msvc/scripts/genproj.cs
index fab5c4e6d4f..86794ed0ef5 100644..100755
--- a/msvc/scripts/genproj.cs
+++ b/msvc/scripts/genproj.cs
@@ -25,7 +25,7 @@ public enum Target {
 	Library, Exe, Module, WinExe
 }
 
-class SlnGenerator {
+public class SlnGenerator {
 	public static readonly string NewLine = "\r\n"; //Environment.NewLine; // "\n"; 
 	public SlnGenerator (string slnVersion)
 	{
@@ -53,8 +53,11 @@ class SlnGenerator {
 		"net_4_x"
 	};
 
-	const string jay_vcxproj_guid = "{5D485D32-3B9F-4287-AB24-C8DA5B89F537}";
-	const string jay_sln_guid = "{8BC9CEB8-8B4A-11D0-8D11-00A0C91BC942}";
+	public const string csproj_type_guid = "{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}";
+	public const string vcxproj_type_guid = "{8BC9CEB8-8B4A-11D0-8D11-00A0C91BC942}";
+
+	public const string jay_vcxproj_guid = "{5D485D32-3B9F-4287-AB24-C8DA5B89F537}";
+	public const string genconsts_csproj_guid = "{702AE2C0-71DD-4112-9A06-E4FABCA59986}";
 
 	public static Dictionary<string, HashSet<string>> profilesByGuid = new Dictionary<string, HashSet<string>> ();
 	public List<MsbuildGenerator.VsCsproj> libraries = new List<MsbuildGenerator.VsCsproj> ();
@@ -103,6 +106,7 @@ class SlnGenerator {
 		var relativePath = MsbuildGenerator.GetRelativePath (slnFullPath, fullProjPath);
 
 		var dependencyGuids = new string[0];
+
 		if (proj.preBuildEvent.Contains ("jay"))
 			dependencyGuids = new [] { jay_vcxproj_guid };
 
@@ -115,10 +119,10 @@ class SlnGenerator {
 		if (dependencyGuids.Length > 0)
 			Console.WriteLine ($"Project {fullProjPath} has {dependencyGuids.Length} dependencies: {string.Join(", ", dependencyGuids)}");
 
-		WriteProjectReference(sln, "{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}", proj.library, relativePath, proj.projectGuid, dependencyGuids);
+		WriteProjectReference(sln, csproj_type_guid, proj.library, relativePath, proj.projectGuid, dependencyGuids);
 	}
 
-	private void WriteProjectConfigurationPlatforms (StreamWriter sln, string guid, string defaultPlatform)
+	private void WriteProjectConfigurationPlatforms (StreamWriter sln, string guid, string defaultPlatform, bool forceBuild)
 	{
 		var fallbackProfileNames = new List<string> ();
 
@@ -136,8 +140,7 @@ class SlnGenerator {
 			) {
 				fallbackProfileNames.Add (platformToBuild);
 				platformToBuild = defaultPlatform;
-				// HACK: Force build for C++ executables like jay ('Win32') but not for managed assemblies
-				isBuildEnabled = (defaultPlatform == "Win32");
+				isBuildEnabled = forceBuild;
 			}
 
 			sln.WriteLine ("\t\t{0}.Debug|{1}.ActiveCfg = Debug|{2}", guid, profile, platformToBuild);
@@ -161,7 +164,10 @@ class SlnGenerator {
 			sln.WriteLine (header);
 
 			// Manually insert jay's vcxproj. We depend on jay.exe to perform build steps later.
-			WriteProjectReference (sln, jay_sln_guid, "jay", "mcs/jay/jay.vcxproj", jay_vcxproj_guid, null);
+			WriteProjectReference (sln, vcxproj_type_guid, "jay", "mcs/jay/jay.vcxproj", jay_vcxproj_guid, null);
+
+			// Manually insert genconsts. This is used to generate Consts.cs.
+			WriteProjectReference (sln, csproj_type_guid, "genconsts", "msvc/scripts/genconsts.csproj", genconsts_csproj_guid, null);
 
 			foreach (var proj in libraries) {
 				WriteProjectReference (sln, fullPath, proj);
@@ -181,11 +187,12 @@ class SlnGenerator {
 
 			sln.WriteLine ("\tGlobalSection(ProjectConfigurationPlatforms) = postSolution");
 
-			// Manually insert jay's configurations because they are different
-			WriteProjectConfigurationPlatforms (sln, jay_vcxproj_guid, "Win32");
+			// Manually insert configurations for jay and genconsts
+			WriteProjectConfigurationPlatforms (sln, jay_vcxproj_guid, "Win32", true);
+			WriteProjectConfigurationPlatforms (sln, genconsts_csproj_guid, "x86", true);
 
 			foreach (var proj in libraries) {
-				WriteProjectConfigurationPlatforms (sln, proj.projectGuid, "net_4_x");
+				WriteProjectConfigurationPlatforms (sln, proj.projectGuid, "net_4_x", false);
 			}
 
 			sln.WriteLine ("\tEndGlobalSection");
@@ -206,7 +213,7 @@ class SlnGenerator {
 	public int Count { get { return libraries.Count; } }
 }
 
-class MsbuildGenerator {
+public class MsbuildGenerator {
 	static readonly string NewLine = SlnGenerator.NewLine;
 	static XmlNamespaceManager xmlns;
 
@@ -222,6 +229,7 @@ class MsbuildGenerator {
 	};
 
 	public static readonly (string, string[])[] fixed_dependencies = new [] {
+		("corlib/corlib.csproj", new [] { SlnGenerator.genconsts_csproj_guid }),
 		("class/System.Web/System.Web.csproj", new [] { culevel_guid })
 	};