VS: Provide an option to use x64 host tools

Visual Studio provides toolchains that are themselves built for 32-bit
or 64-bit host architectures.  By default it uses the 32-bit tools, but
it can be told to prefer the 64-bit tools on 64-bit hosts.  Extend the
`CMAKE_GENERATOR_TOOLSET` specification to provide a way to request
use of the 64-bit host tools.

Closes: #15622

1 files changed, 15 insertions, 0 deletions

diff --git a/Source/cmGlobalVisualStudio12Generator.cxx b/Source/cmGlobalVisualStudio12Generator.cxx
index 5fdeec7..ec7916c 100644
--- a/Source/cmGlobalVisualStudio12Generator.cxx
+++ b/Source/cmGlobalVisualStudio12Generator.cxx
@@ -96,6 +96,21 @@ bool cmGlobalVisualStudio12Generator::MatchesGeneratorName(
   return false;
 }
 
+bool cmGlobalVisualStudio12Generator::ParseGeneratorToolset(
+  std::string const& ts, cmMakefile* mf)
+{
+  std::string::size_type ts_end = ts.size();
+  if (cmHasLiteralSuffix(ts, ",host=x64")) {
+    this->GeneratorToolsetHostArchitecture = "x64";
+    ts_end -= 9;
+  } else if (ts == "host=x64") {
+    this->GeneratorToolsetHostArchitecture = "x64";
+    ts_end = 0;
+  }
+  return this->cmGlobalVisualStudio11Generator::ParseGeneratorToolset(
+    ts.substr(0, ts_end), mf);
+}
+
 bool cmGlobalVisualStudio12Generator::InitializeWindowsPhone(cmMakefile* mf)
 {
   if (!this->SelectWindowsPhoneToolset(this->DefaultPlatformToolset)) {