VS: Parameterize cmVSSetupAPIHelper instances with VS version

Source/cmCMakeHostSystemInformationCommand.cxx

@@ -141,7 +141,7 @@ bool cmCMakeHostSystemInformationCommand::GetValue(
     }
 
     // Otherwise, find a VS 15 instance ourselves.
-    cmVSSetupAPIHelper vsSetupAPIHelper;
+    cmVSSetupAPIHelper vsSetupAPIHelper(15);
     if (vsSetupAPIHelper.GetVSInstanceInfo(value)) {
       cmSystemTools::ConvertToUnixSlashes(value);
     }

Source/cmGlobalVisualStudio15Generator.cxx

@@ -79,6 +79,7 @@ cmGlobalVisualStudio15Generator::cmGlobalVisualStudio15Generator(
   cmake* cm, const std::string& name,
   std::string const& platformInGeneratorName)
   : cmGlobalVisualStudio14Generator(cm, name, platformInGeneratorName)
+  , vsSetupAPIHelper(15)
 {
   this->ExpressEdition = false;
   this->DefaultPlatformToolset = "v141";
@@ -215,7 +216,7 @@ bool cmGlobalVisualStudio15Generator::SelectWindowsStoreToolset(
 
 bool cmGlobalVisualStudio15Generator::IsWindowsDesktopToolsetInstalled() const
 {
-  return vsSetupAPIHelper.IsVS2017Installed();
+  return vsSetupAPIHelper.IsVSInstalled();
 }
 
 bool cmGlobalVisualStudio15Generator::IsWindowsStoreToolsetInstalled() const

Source/cmVSSetupHelper.cxx

@@ -57,8 +57,9 @@ std::string VSInstanceInfo::GetInstallLocation() const
   return loc;
 }
 
-cmVSSetupAPIHelper::cmVSSetupAPIHelper()
-  : setupConfig(NULL)
+cmVSSetupAPIHelper::cmVSSetupAPIHelper(unsigned int version)
+  : Version(version)
+  , setupConfig(NULL)
   , setupConfig2(NULL)
   , setupHelper(NULL)
   , initializationFailure(false)
@@ -88,7 +89,7 @@ bool cmVSSetupAPIHelper::SetVSInstance(std::string const& vsInstallLocation)
   return this->EnumerateAndChooseVSInstance();
 }
 
-bool cmVSSetupAPIHelper::IsVS2017Installed()
+bool cmVSSetupAPIHelper::IsVSInstalled()
 {
   return this->EnumerateAndChooseVSInstance();
 }
@@ -312,11 +313,11 @@ bool cmVSSetupAPIHelper::EnumerateAndChooseVSInstance()
     return false;
 
   std::string envVSCommonToolsDir;
+  std::string envVSCommonToolsDirEnvName =
+    "VS" + std::to_string(this->Version) + "0COMNTOOLS";
 
-  // FIXME: When we support VS versions beyond 2017, the version
-  // to choose will be passed in by the caller.  We need to map that
-  // to a per-version name of this environment variable.
-  if (cmSystemTools::GetEnv("VS150COMNTOOLS", envVSCommonToolsDir)) {
+  if (cmSystemTools::GetEnv(envVSCommonToolsDirEnvName.c_str(),
+                            envVSCommonToolsDir)) {
     cmSystemTools::ConvertToUnixSlashes(envVSCommonToolsDir);
   }
 
@@ -328,8 +329,7 @@ bool cmVSSetupAPIHelper::EnumerateAndChooseVSInstance()
     return false;
   }
 
-  // FIXME: Add a way for caller to specify other versions.
-  std::wstring wantVersion = std::to_wstring(15) + L'.';
+  std::wstring const wantVersion = std::to_wstring(this->Version) + L'.';
 
   SmartCOMPtr<ISetupInstance> instance;
   while (SUCCEEDED(enumInstances->Next(1, &instance, NULL)) && instance) {

Source/cmVSSetupHelper.h

@@ -120,12 +120,12 @@ struct VSInstanceInfo
 class cmVSSetupAPIHelper
 {
 public:
-  cmVSSetupAPIHelper();
+  cmVSSetupAPIHelper(unsigned int version);
   ~cmVSSetupAPIHelper();
 
   bool SetVSInstance(std::string const& vsInstallLocation);
 
-  bool IsVS2017Installed();
+  bool IsVSInstalled();
   bool GetVSInstanceInfo(std::string& vsInstallLocation);
   bool GetVCToolsetVersion(std::string& vsToolsetVersion);
   bool IsWin10SDKInstalled();
@@ -140,6 +140,8 @@ private:
   int ChooseVSInstance(const std::vector<VSInstanceInfo>& vecVSInstances);
   bool EnumerateAndChooseVSInstance();
 
+  unsigned int Version;
+
   // COM ptrs to query about VS instances
   SmartCOMPtr<ISetupConfiguration> setupConfig;
   SmartCOMPtr<ISetupConfiguration2> setupConfig2;

Source/cmake.cxx

@@ -1538,8 +1538,7 @@ void cmake::CreateDefaultGlobalGenerator()
     "\\Setup\\VC;ProductDir", //
     ";InstallDir"             //
   };
-  cmVSSetupAPIHelper vsSetupAPIHelper;
-  if (vsSetupAPIHelper.IsVS2017Installed()) {
+  if (cmVSSetupAPIHelper(15).IsVSInstalled()) {
     found = "Visual Studio 15 2017";
   } else {
     for (VSVersionedGenerator const* g = cm::cbegin(vsGenerators);