commit 07612646fe28d86330cbd4db9cfd27be1d8fb90f
author Brad King <brad.king@kitware.com> Thu Dec 12 11:22:00 2019 -0500
committer Brad King <brad.king@kitware.com> Thu Dec 12 11:25:42 2019 -0500
tree 22fa196a5e9b46810bacb27bab524fca59b7ba91
parent 2a5e5b25ba4d6eb68dbee29381774562c98e228f

VS: Fix support for v142 toolset minor versions in VS 16.5+

The fix in commit 5117389931 (VS: Fix support for v142 toolset minor
versions, 2019-10-01, v3.15.5~6^2) worked around a bug in VS's placement
of toolset files.   VS 16.5 will fix that bug and restore the original
pattern for locations of toolset files.  Update our logic to look for
both possibilities.

Issue: #19779

Modules/CMakeDetermineCompilerId.cmake

diff --git a/Modules/CMakeDetermineCompilerId.cmake b/Modules/CMakeDetermineCompilerId.cmake
index d9002fb..edbc23b 100644
--- a/Modules/CMakeDetermineCompilerId.cmake
+++ b/Modules/CMakeDetermineCompilerId.cmake
@@ -284,10 +284,11 @@
           set(id_cl icl.exe)
         endif()
         if(CMAKE_VS_PLATFORM_TOOLSET_VERSION)
+          set(id_sep "\\")
           if(CMAKE_VS_PLATFORM_TOOLSET_VERSION VERSION_GREATER_EQUAL "14.20")
-            set(id_sep ".")
-          else()
-            set(id_sep "\\")
+            if(EXISTS "${CMAKE_GENERATOR_INSTANCE}/VC/Auxiliary/Build.${CMAKE_VS_PLATFORM_TOOLSET_VERSION}/Microsoft.VCToolsVersion.${CMAKE_VS_PLATFORM_TOOLSET_VERSION}.props")
+              set(id_sep ".")
+            endif()
           endif()
           set(id_toolset_version_props "<Import Project=\"${CMAKE_GENERATOR_INSTANCE}\\VC\\Auxiliary\\Build${id_sep}${CMAKE_VS_PLATFORM_TOOLSET_VERSION}\\Microsoft.VCToolsVersion.${CMAKE_VS_PLATFORM_TOOLSET_VERSION}.props\" />")
           unset(id_sep)

Source/cmGlobalVisualStudioVersionedGenerator.cxx

diff --git a/Source/cmGlobalVisualStudioVersionedGenerator.cxx b/Source/cmGlobalVisualStudioVersionedGenerator.cxx
index 1eca1f6..66a57eb 100644
--- a/Source/cmGlobalVisualStudioVersionedGenerator.cxx
+++ b/Source/cmGlobalVisualStudioVersionedGenerator.cxx
@@ -388,15 +388,17 @@
   if (version) {
     std::string instancePath;
     GetVSInstance(instancePath);
-    std::stringstream path;
-    path << instancePath;
-    path << "/VC/Auxiliary/Build";
-    path << (cmSystemTools::VersionCompareGreaterEq(version, "14.20") ? '.'
-                                                                      : '/');
-    path << version;
-    path << "/Microsoft.VCToolsVersion." << version << ".props";
-
-    std::string toolsetPath = path.str();
+    std::string toolsetDir = instancePath + "/VC/Auxiliary/Build";
+    char sep = '/';
+    if (cmSystemTools::VersionCompareGreaterEq(version, "14.20")) {
+      std::string toolsetDot = toolsetDir + "." + version +
+        "/Microsoft.VCToolsVersion." + version + ".props";
+      if (cmSystemTools::PathExists(toolsetDot)) {
+        sep = '.';
+      }
+    }
+    std::string toolsetPath = toolsetDir + sep + version +
+      "/Microsoft.VCToolsVersion." + version + ".props";
     cmSystemTools::ConvertToUnixSlashes(toolsetPath);
     return toolsetPath;
   }