VS: Add option to select the version of the toolset used by VS 2017

Add new `version=` parameter in the toolset setting to select the
version.  Add variable `CMAKE_VS_PLATFORM_TOOLSET_VERSION` to hold the
version, if one is set (blank indicates default).

Fixes: #17549

1 files changed, 19 insertions, 0 deletions

diff --git a/Source/cmGlobalVisualStudio15Generator.cxx b/Source/cmGlobalVisualStudio15Generator.cxx
index 014d93d..6af5793 100644
--- a/Source/cmGlobalVisualStudio15Generator.cxx
+++ b/Source/cmGlobalVisualStudio15Generator.cxx
@@ -158,6 +158,25 @@ bool cmGlobalVisualStudio15Generator::GetVSInstance(std::string& dir) const
   return vsSetupAPIHelper.GetVSInstanceInfo(dir);
 }
 
+std::string cmGlobalVisualStudio15Generator::GetAuxiliaryToolset() const
+{
+  const char* version = this->GetPlatformToolsetVersion();
+  if (version) {
+    std::string instancePath;
+    GetVSInstance(instancePath);
+    std::stringstream path;
+    path << instancePath;
+    path << "/VC/Auxiliary/Build/";
+    path << version;
+    path << "/Microsoft.VCToolsVersion." << version << ".props";
+
+    std::string toolsetPath = path.str();
+    cmSystemTools::ConvertToUnixSlashes(toolsetPath);
+    return toolsetPath;
+  }
+  return {};
+}
+
 bool cmGlobalVisualStudio15Generator::InitializeWindows(cmMakefile* mf)
 {
   // If the Win 8.1 SDK is installed then we can select a SDK matching