Add the ALIAS target concept for libraries and executables.

* The ALIAS name must match a validity regex.
* Executables and libraries may be aliased.
* An ALIAS acts immutable. It can not be used as the lhs
  of target_link_libraries or other commands.
* An ALIAS can be used with add_custom_command, add_custom_target,
  and add_test in the same way regular targets can.
* The target of an ALIAS can be retrieved with the ALIASED_TARGET
  target property.
* An ALIAS does not appear in the generated buildsystem. It
  is kept separate from cmMakefile::Targets for that reason.
* A target may have multiple aliases.
* An ALIAS target may not itself have an alias.
* An IMPORTED target may not have an alias.
* An ALIAS may not be exported or imported.

1 files changed, 19 insertions, 6 deletions

diff --git a/Source/cmGetTargetPropertyCommand.cxx b/Source/cmGetTargetPropertyCommand.cxx
index 1947139..02f00a5 100644
--- a/Source/cmGetTargetPropertyCommand.cxx
+++ b/Source/cmGetTargetPropertyCommand.cxx
@@ -22,17 +22,30 @@ bool cmGetTargetPropertyCommand
     }
   std::string var = args[0].c_str();
   const char* targetName = args[1].c_str();
+  const char *prop = 0;
 
-  if(cmTarget* tgt = this->Makefile->FindTargetToUse(targetName))
+  if(args[2] == "ALIASED_TARGET")
     {
-    cmTarget& target = *tgt;
-    const char *prop = target.GetProperty(args[2].c_str());
-    if (prop)
+    if(this->Makefile->IsAlias(targetName))
       {
-      this->Makefile->AddDefinition(var.c_str(), prop);
-      return true;
+      if(cmTarget* target =
+                          this->Makefile->FindTargetToUse(targetName))
+        {
+        prop = target->GetName();
+        }
       }
     }
+  else if(cmTarget* tgt = this->Makefile->FindTargetToUse(targetName))
+    {
+    cmTarget& target = *tgt;
+    prop = target.GetProperty(args[2].c_str());
+    }
+
+  if (prop)
+    {
+    this->Makefile->AddDefinition(var.c_str(), prop);
+    return true;
+    }
   this->Makefile->AddDefinition(var.c_str(), (var+"-NOTFOUND").c_str());
   return true;
 }