cmake: Add options for parallel builds to --build mode

While we already support `cmake --build . -- -j`, the options after `--`
are specific to the native build tool.  Add new options `--parallel
[<N>]` and `-j [<N>]` to abstract this and map to the proper option
for the native build tool.

1 files changed, 7 insertions, 1 deletions

diff --git a/Source/cmGlobalNinjaGenerator.cxx b/Source/cmGlobalNinjaGenerator.cxx
index c19a61c..69bc3be 100644
--- a/Source/cmGlobalNinjaGenerator.cxx
+++ b/Source/cmGlobalNinjaGenerator.cxx
@@ -674,7 +674,7 @@ void cmGlobalNinjaGenerator::GenerateBuildCommand(
   std::vector<std::string>& makeCommand, const std::string& makeProgram,
   const std::string& /*projectName*/, const std::string& /*projectDir*/,
   const std::string& targetName, const std::string& /*config*/, bool /*fast*/,
-  bool verbose, std::vector<std::string> const& makeOptions)
+  int jobs, bool verbose, std::vector<std::string> const& makeOptions)
 {
   makeCommand.push_back(this->SelectMakeProgram(makeProgram));
 
@@ -682,6 +682,12 @@ void cmGlobalNinjaGenerator::GenerateBuildCommand(
     makeCommand.push_back("-v");
   }
 
+  if ((jobs != cmake::NO_BUILD_PARALLEL_LEVEL) &&
+      (jobs != cmake::DEFAULT_BUILD_PARALLEL_LEVEL)) {
+    makeCommand.push_back("-j");
+    makeCommand.push_back(std::to_string(jobs));
+  }
+
   makeCommand.insert(makeCommand.end(), makeOptions.begin(),
                      makeOptions.end());
   if (!targetName.empty()) {