This change make DacTableGen work for VS2017

There was a issue (see https://github.com/dotnet/coreclr/issues/11305) where
a tool used in the CoreCLR build called DacTableGen requires a old version of the
msdia120.dll.   The symptom is that this tool would fail with a class not registered errror.

This tool comes from a very old nuget package microsoft.dotnet.buildtools.coreclr, which
we no longer can build easly.    Our guidance now is to move tools that are only used in
one repository (like this one) out of nuget packages and simply build them as part of the build.

This change makes a step in that direction.  The DacTableGen code actually was already
in the CoreCLR repo, so this change

1. Fixes the source of DacTableGen so that tool no longer needs a com object to be registered
    (but it DOES need msdia140.dll to be on the path.  This is true for VS2017.
2.  Turns on the build of DacTableGen
3. Change the build use the built DacTableGen (unless running on VS2017, in that case we use the
    the version in the tool package.
4.) Remove the hack that warns people to register msdia120 (since you don't need to anymore)

There is also an unrelated addition to the docs.

This change should still work for VS2015 (because it falls back to the old DacTableGen in that case)

Finally we should move to using the Linux method of creating the DAC, and so all these tools and
their nuget package can be removed.

4 files changed, 39 insertions, 6 deletions

diff --git a/src/ToolBox/SOS/CMakeLists.txt b/src/ToolBox/SOS/CMakeLists.txt
index 9380dc1de6..212f4eebd7 100644
--- a/src/ToolBox/SOS/CMakeLists.txt
+++ b/src/ToolBox/SOS/CMakeLists.txt
@@ -1,3 +1,4 @@
 if(WIN32)
+    add_subdirectory(DacTableGen)
     add_subdirectory(Strike)
 endif(WIN32)
diff --git a/src/ToolBox/SOS/DacTableGen/CMakeLists.txt b/src/ToolBox/SOS/DacTableGen/CMakeLists.txt
index 01ee51f7a4..c980cc2ff8 100644
--- a/src/ToolBox/SOS/DacTableGen/CMakeLists.txt
+++ b/src/ToolBox/SOS/DacTableGen/CMakeLists.txt
@@ -7,13 +7,13 @@ set(DACTABLEGEN_SOURCES
 
 # Cmake does not support csharp sources so add custom command
 add_custom_target(dactablegen ALL 
-    COMMAND csc.exe /t:exe /platform:anycpu /r:System.dll /r:$<TARGET_FILE:dialib_dll> /out:${CMAKE_CURRENT_BINARY_DIR}/dactablegen.exe ${DACTABLEGEN_SOURCES}
-    COMMAND ${CMAKE_COMMAND} -E copy $<TARGET_FILE:dialib_dll> $<TARGET_FILE_DIR:dactablegen_exe>
-    DEPENDS ${DACTABLEGEN_SOURCES}  dialib
+    COMMAND csc.exe /t:exe /platform:anycpu32bitpreferred /r:System.dll /r:DiaLib.dll /out:${CMAKE_CURRENT_BINARY_DIR}/dactablegen.exe ${DACTABLEGEN_SOURCES}
+    COMMAND ${CMAKE_COMMAND} -E copy DIAlib.dll ${CMAKE_CURRENT_BINARY_DIR}
+    DEPENDS ${DACTABLEGEN_SOURCES} DIAlib.dll
     WORKING_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}
 )
 
 # In order to use dactablegen as an executable target it needs to be imported. 
 # Target is used in dll/mscoree/coreclr/cmakelists.txt
 add_executable(dactablegen_exe IMPORTED GLOBAL)
-set_property(TARGET dactablegen_exe PROPERTY IMPORTED_LOCATION ${CMAKE_CURRENT_BINARY_DIR}/dactablegen.exe)
\ No newline at end of file
+set_property(TARGET dactablegen_exe PROPERTY IMPORTED_LOCATION ${CMAKE_CURRENT_BINARY_DIR}/dactablegen.exe)
diff --git a/src/ToolBox/SOS/DacTableGen/DIALib.dll b/src/ToolBox/SOS/DacTableGen/DIALib.dll
new file mode 100644
index 0000000000..06665740dc
--- /dev/null
+++ b/src/ToolBox/SOS/DacTableGen/DIALib.dll
diff --git a/src/ToolBox/SOS/DacTableGen/diautil.cs b/src/ToolBox/SOS/DacTableGen/diautil.cs
index d0e9c811a7..f0937b190e 100644
--- a/src/ToolBox/SOS/DacTableGen/diautil.cs
+++ b/src/ToolBox/SOS/DacTableGen/diautil.cs
@@ -97,7 +97,7 @@ class Util
 
 public class DiaFile
 {
-    DiaSourceClass  m_dsc;
+    IDiaDataSource  m_dsc;
     IDiaSession     m_session;
     DiaSymbol       m_global;
     IDiaEnumSymbols m_publicsEnum;
@@ -106,7 +106,7 @@ public class DiaFile
 
     public DiaFile(String pdbFile, String dllFile)
     {
-        m_dsc = new DiaSourceClass();
+        m_dsc = GetDiaSourceClass();
         string pdbPath = System.IO.Path.GetDirectoryName(pdbFile);
 
         // Open the PDB file, validating it matches the supplied DLL file
@@ -414,6 +414,37 @@ public class DiaFile
         E_PDB_SYMSRV_CACHE_FULL     ,
         E_PDB_MAX           
     }
+
+    // Get the DiaSourceClass from the msdia140.dll in the app directory without using COM activation
+    static IDiaDataSource GetDiaSourceClass() {
+	    // This is Class ID for the DiaSourceClass used by msdia140.  
+	    var diaSourceClassGuid = new Guid("{e6756135-1e65-4d17-8576-610761398c3c}");
+	    var comClassFactory = (IClassFactory)DllGetClassObject(diaSourceClassGuid, typeof(IClassFactory).GUID);
+       
+	    // As the DLL to create a new instance of it
+	    object comObject = null;
+	    Guid iDiaDataSourceGuid = typeof(IDiaDataSource).GUID;
+	    comClassFactory.CreateInstance(null, ref iDiaDataSourceGuid, out comObject);
+
+	    // And return it as the type we expect
+	    return (comObject as IDiaDataSource);
+    }
+
+    [return: MarshalAs(UnmanagedType.Interface)]
+    [DllImport("msdia140.dll", CharSet = CharSet.Unicode, ExactSpelling = true, PreserveSig = false)]
+    private static extern object DllGetClassObject(
+        [In, MarshalAs(UnmanagedType.LPStruct)] Guid rclsid,
+        [In, MarshalAs(UnmanagedType.LPStruct)] Guid riid);
+
+    [ComImport, ComVisible(false), Guid("00000001-0000-0000-C000-000000000046"),
+     InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
+    private interface IClassFactory
+    {
+	    void CreateInstance([MarshalAs(UnmanagedType.Interface)] object aggregator,
+		    ref Guid refiid,
+	        [MarshalAs(UnmanagedType.Interface)] out object createdObject);
+	    void LockServer(bool incrementRefCount);
+    }
 }
 
 /***************************************************************************************
@@ -806,4 +837,5 @@ public class DiaDataSymbol : DiaSymbol
     }
 }
 
+
 } // Namespace Dia.Util