cmGeneratorTarget: Compute target objects on demand

Add a ComputeObjectMapping method to compute the object
names.  It takes mapping to populate as an out-parameter so
that it can be extended in the future with parameters
relevant to generator expression evaluation.

Remove the supporting cmGeneratorTarget::AddObject method. It is
no longer needed as the container member is populated directly.

The ComputeObjectMapping method is called whenever objects are
requested from the cmGeneratorTarget.  Because the Xcode generator
makes no such request, explicitly invoke the method from that
generator so that the logic of checking for bad sources in object
libraries is executed.

In a follow-up, the UseObjectLibraries usage may be replaced by a
true generator expression evaluator for TARGET_OBJECTS. That
will require generators to use cmGeneratorTarget::GetExternalObjects
which is not currently the case for Xcode and VS generators.

1 files changed, 25 insertions, 6 deletions

diff --git a/Source/cmGeneratorTarget.cxx b/Source/cmGeneratorTarget.cxx
index 64ca863..321dd42 100644
--- a/Source/cmGeneratorTarget.cxx
+++ b/Source/cmGeneratorTarget.cxx
@@ -311,18 +311,36 @@ cmGeneratorTarget
 ::GetObjectSources(std::vector<cmSourceFile const*> &data) const
 {
   IMPLEMENT_VISIT(ObjectSources);
+
+  if (!this->Objects.empty())
+    {
+    return;
+    }
+
+  for(std::vector<cmSourceFile const*>::const_iterator it = data.begin();
+      it != data.end(); ++it)
+    {
+    this->Objects[*it];
+    }
+
+  this->LocalGenerator->ComputeObjectFilenames(this->Objects, this);
 }
 
-//----------------------------------------------------------------------------
-const std::string& cmGeneratorTarget::GetObjectName(cmSourceFile const* file)
+void cmGeneratorTarget::ComputeObjectMapping()
 {
-  return this->Objects[file];
+  if(!this->Objects.empty())
+    {
+    return;
+    }
+  std::vector<cmSourceFile const*> sourceFiles;
+  this->GetObjectSources(sourceFiles);
 }
 
-void cmGeneratorTarget::AddObject(cmSourceFile const* sf,
-                                  std::string const&name)
+//----------------------------------------------------------------------------
+const std::string& cmGeneratorTarget::GetObjectName(cmSourceFile const* file)
 {
-    this->Objects[sf] = name;
+  this->ComputeObjectMapping();
+  return this->Objects[file];
 }
 
 //----------------------------------------------------------------------------
@@ -334,6 +352,7 @@ void cmGeneratorTarget::AddExplicitObjectName(cmSourceFile const* sf)
 //----------------------------------------------------------------------------
 bool cmGeneratorTarget::HasExplicitObjectName(cmSourceFile const* file) const
 {
+  const_cast<cmGeneratorTarget*>(this)->ComputeObjectMapping();
   std::set<cmSourceFile const*>::const_iterator it
                                         = this->ExplicitObjectName.find(file);
   return it != this->ExplicitObjectName.end();