Replace timestamp with hash in generated files

Some of our generators were embedding timestamps in the output files as comments.  This was indirectly preventing us from producing determistic builds as every rebuild came from different content.

Issue #7270 is tracking changing determinism to not be influenced by the comments.  Short term though changing this from using a time stamp (which changes and doesn't have meaning between machines) to outputing the checksum of the input file it ran against.

src/Tools/Source/CompilerGeneratorTools/Source/VisualBasicSyntaxGenerator/Program.vb

@@ -4,6 +4,7 @@ Imports System.IO
 Imports System.Collections.Generic
 Imports System.Console
 Imports System.Runtime.InteropServices
+Imports System.Security.Cryptography
 
 ''' <summary>
 ''' Contains the startup code, command line argument processing, and driving the execution of the tool.
@@ -19,7 +20,7 @@ Friend Module Program
             Dim outputKind As String = Nothing
             Dim paths As New List(Of String)()
 
-            For Each arg in args
+            For Each arg In args
                 Dim c = arg.ToLowerInvariant()
                 If c = "/test" OrElse c = "/source" OrElse c = "/gettext" Then
                     If outputKind IsNot Nothing Then
@@ -27,7 +28,7 @@ Friend Module Program
                         Return exitWithErrors
                     End If
                     outputKind = c
-                Else If c = "/?" Then
+                ElseIf c = "/?" Then
                     PrintUsage()
                     Return exitWithErrors
                 Else
@@ -54,7 +55,8 @@ Friend Module Program
                 Return exitWithErrors
             End If
 
-            WriteOutput(outputFile, definition, outputKind)
+            Dim checksum = GetChecksum(inputFile)
+            WriteOutput(outputFile, definition, outputKind, checksum)
 
             Return exitWithoutErrors
 
@@ -67,6 +69,14 @@ Friend Module Program
 
     End Function
 
+    Private Function GetChecksum(filePath As String) As String
+        Dim fileBytes = File.ReadAllBytes(filePath)
+        Dim func = SHA256.Create()
+        Dim hashBytes = func.ComputeHash(fileBytes)
+        Dim data = BitConverter.ToString(hashBytes)
+        Return data.Replace("-", "")
+    End Function
+
     Private Sub PrintUsage()
         WriteLine("VBSyntaxGenerator.exe input output [/source] [/test]")
         WriteLine("  /source        Generates syntax model source code.")
@@ -84,11 +94,11 @@ Friend Module Program
         Return True
     End Function
 
-    Public Sub WriteOutput(outputFile As String, definition As ParseTree, outputKind As String)
+    Public Sub WriteOutput(outputFile As String, definition As ParseTree, outputKind As String, checksum As String)
 
         Using output As New StreamWriter(outputFile)
             output.WriteLine("' Definition of syntax model.")
-            output.WriteLine("' Generated by a tool on {0:g}", Date.Now)
+            output.WriteLine("' Generated by a tool from SHA256 content {0}", checksum)
             output.WriteLine("' DO NOT HAND EDIT")
 
 
@@ -102,7 +112,7 @@ Friend Module Program
                     output.WriteLine("Imports Roslyn.Utilities")
                     output.WriteLine("Imports Xunit")
 
-                    Dim testWriter As New TestWriter(definition)
+                    Dim testWriter As New TestWriter(definition, checksum)
                     testWriter.WriteTestCode(output)
 
                 Case "/gettext"

src/Tools/Source/CompilerGeneratorTools/Source/VisualBasicSyntaxGenerator/Tests/TestWriter.vb

@@ -11,12 +11,14 @@ Imports System.IO
 Public Class TestWriter
     Inherits WriteUtils
 
+    Private ReadOnly _checksum As String
     Private _writer As TextWriter    'output is sent here.
     Private Const s_externalSourceDirectiveString As String = "ExternalSourceDirective"
 
     ' Initialize the class with the parse tree to write.
-    Public Sub New(parseTree As ParseTree)
+    Public Sub New(parseTree As ParseTree, checksum As String)
         MyBase.New(parseTree)
+        _checksum = checksum
     End Sub
 
     ' Write out the code defining the tree to the give file.
@@ -28,7 +30,7 @@ Public Class TestWriter
 
     Private Sub GenerateFile()
         _writer.WriteLine("' Tests for parse trees.")
-        _writer.WriteLine("' Generated by a tool on {0:g}", DateTime.Now)
+        _writer.WriteLine("' Generated by a tool from SHA256 content {0}", _checksum)
         _writer.WriteLine("' DO NOT HAND EDIT")
         _writer.WriteLine()
 

src/Tools/Source/CompilerGeneratorTools/Source/VisualBasicSyntaxGenerator/Util/WriteDumper.vb

@@ -11,10 +11,12 @@ Imports System.IO
 Friend Class WriteDumper
     Inherits WriteUtils
 
+    Private ReadOnly _checksum As String
     Private _writer As TextWriter    'output is sent here.
 
-    Public Sub New(parseTree As ParseTree)
+    Public Sub New(parseTree As ParseTree, checksum As String)
         MyBase.New(parseTree)
+        _checksum = checksum
     End Sub
 
     ' Write the dumper utility function to the given file.
@@ -29,7 +31,7 @@ Friend Class WriteDumper
     ' Write the whole contents of the file.
     Private Sub GenerateFile()
         _writer.WriteLine("' Definition of parse trees dumper.")
-        _writer.WriteLine("' Generated by a tool on {0:g}", DateTime.Now)
+        _writer.WriteLine("' Generated by a tool from SHA256 content {0}", _checksum)
         _writer.WriteLine("' DO NOT HAND EDIT")
         _writer.WriteLine()