CMake: Add CMAKE_GENERATOR_PLATFORM option

Reject the option by default.  It will be implemented on a per-generator
basis.  Pass the setting into try_compile project generation.  Add cache
entry CMAKE_GENERATOR_PLATFORM and associated variable documentation to
hold the value persistently.

Add a RunCMake.GeneratorPlatform test to cover basic use cases for the
option.  Verify that CMAKE_GENERATOR_PLATFORM is empty by default, and
that it is rejected when the generator does not support a user setting.

1 files changed, 29 insertions, 0 deletions

diff --git a/Source/cmGlobalGenerator.cxx b/Source/cmGlobalGenerator.cxx
index 42efec2..90fd3f3 100644
--- a/Source/cmGlobalGenerator.cxx
+++ b/Source/cmGlobalGenerator.cxx
@@ -76,6 +76,27 @@ cmGlobalGenerator::~cmGlobalGenerator()
     }
 }
 
+bool cmGlobalGenerator::SetGeneratorPlatform(std::string const& p,
+                                             cmMakefile* mf)
+{
+  if(p.empty())
+    {
+    return true;
+    }
+  else
+    {
+    cmOStringStream e;
+    e <<
+      "Generator\n"
+      "  " << this->GetName() << "\n"
+      "does not support platform specification, but platform\n"
+      "  " << p << "\n"
+      "was specified.";
+    mf->IssueMessage(cmake::FATAL_ERROR, e.str());
+    return false;
+    }
+}
+
 bool cmGlobalGenerator::SetGeneratorToolset(std::string const& ts,
                                             cmMakefile* mf)
 {
@@ -459,6 +480,14 @@ cmGlobalGenerator::EnableLanguage(std::vector<std::string>const& languages,
     return;
     }
 
+  // Tell the generator about the platform, if any.
+  std::string platform = mf->GetSafeDefinition("CMAKE_GENERATOR_PLATFORM");
+  if(!this->SetGeneratorPlatform(platform, mf))
+    {
+    cmSystemTools::SetFatalErrorOccured();
+    return;
+    }
+
   // Tell the generator about the toolset, if any.
   std::string toolset = mf->GetSafeDefinition("CMAKE_GENERATOR_TOOLSET");
   if(!this->SetGeneratorToolset(toolset, mf))