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, 12 insertions, 0 deletions

diff --git a/Source/cmGeneratorExpressionEvaluator.cxx b/Source/cmGeneratorExpressionEvaluator.cxx
index d0b6190..e0c8c9e 100644
--- a/Source/cmGeneratorExpressionEvaluator.cxx
+++ b/Source/cmGeneratorExpressionEvaluator.cxx
@@ -747,6 +747,18 @@ static const struct TargetPropertyNode : public cmGeneratorExpressionNode
                       "Target name not supported.");
         return std::string();
         }
+      if(propertyName == "ALIASED_TARGET")
+        {
+        if(context->Makefile->IsAlias(targetName.c_str()))
+          {
+          if(cmTarget* tgt =
+                      context->Makefile->FindTargetToUse(targetName.c_str()))
+            {
+            return tgt->GetName();
+            }
+          }
+        return "";
+        }
       target = context->Makefile->FindTargetToUse(
                                                 targetName.c_str());