CMake: Add -T option to choose a generator toolset

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_TOOLSET and associated variable documentation to
hold the value persistently.

Add a RunCMake.GeneratorToolset test to cover basic "-T" option cases.
Verify that CMAKE_GENERATOR_TOOLSET is empty without -T, that -T is
rejected when the generator doesn't support it, and that two -T options
are always rejected.

1 files changed, 14 insertions, 0 deletions

diff --git a/Source/cmGlobalGenerator.cxx b/Source/cmGlobalGenerator.cxx
index d2baf53..d8afa53 100644
--- a/Source/cmGlobalGenerator.cxx
+++ b/Source/cmGlobalGenerator.cxx
@@ -79,6 +79,20 @@ cmGlobalGenerator::~cmGlobalGenerator()
   this->ClearGeneratorTargets();
 }
 
+bool cmGlobalGenerator::SetGeneratorToolset(std::string const& ts)
+{
+  cmOStringStream e;
+  e <<
+    "Generator\n"
+    "  " << this->GetName() << "\n"
+    "does not support toolset specification, but toolset\n"
+    "  " << ts << "\n"
+    "was specified.";
+  this->CMakeInstance->IssueMessage(cmake::FATAL_ERROR, e.str(),
+                                    cmListFileBacktrace());
+  return false;
+}
+
 void cmGlobalGenerator::ResolveLanguageCompiler(const std::string &lang,
                                                 cmMakefile *mf,
                                                 bool optional)