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.

19 files changed, 353 insertions, 15 deletions

diff --git a/Source/cmAddDependenciesCommand.cxx b/Source/cmAddDependenciesCommand.cxx
index 04a304e..e4d7f7f 100644
--- a/Source/cmAddDependenciesCommand.cxx
+++ b/Source/cmAddDependenciesCommand.cxx
@@ -24,6 +24,13 @@ bool cmAddDependenciesCommand
     }
 
   std::string target_name = args[0];
+  if(this->Makefile->IsAlias(target_name.c_str()))
+    {
+    cmOStringStream e;
+    e << "Cannot add target-level dependencies to alias target \""
+      << target_name << "\".\n";
+    this->Makefile->IssueMessage(cmake::FATAL_ERROR, e.str());
+    }
   if(cmTarget* target = this->Makefile->FindTargetToUse(target_name.c_str()))
     {
     std::vector<std::string>::const_iterator s = args.begin();
diff --git a/Source/cmAddExecutableCommand.cxx b/Source/cmAddExecutableCommand.cxx
index 6dd8e5c..5785259 100644
--- a/Source/cmAddExecutableCommand.cxx
+++ b/Source/cmAddExecutableCommand.cxx
@@ -30,6 +30,7 @@ bool cmAddExecutableCommand
   bool excludeFromAll = false;
   bool importTarget = false;
   bool importGlobal = false;
+  bool isAlias = false;
   while ( s != args.end() )
     {
     if (*s == "WIN32")
@@ -57,6 +58,11 @@ bool cmAddExecutableCommand
       ++s;
       importGlobal = true;
       }
+    else if(*s == "ALIAS")
+      {
+      ++s;
+      isAlias = true;
+      }
     else
       {
       break;
@@ -83,6 +89,72 @@ bool cmAddExecutableCommand
       }
     return false;
     }
+  if (isAlias)
+    {
+    if(!cmGeneratorExpression::IsValidTargetName(exename.c_str()))
+      {
+      this->SetError(("Invalid name for ALIAS: " + exename).c_str());
+      return false;
+      }
+    if(excludeFromAll)
+      {
+      this->SetError("EXCLUDE_FROM_ALL with ALIAS makes no sense.");
+      return false;
+      }
+    if(importTarget || importGlobal)
+      {
+      this->SetError("IMPORTED with ALIAS is not allowed.");
+      return false;
+      }
+    if(args.size() != 3)
+      {
+      cmOStringStream e;
+      e << "ALIAS requires exactly one target argument.";
+      this->SetError(e.str().c_str());
+      return false;
+      }
+
+    const char *aliasedName = s->c_str();
+    if(this->Makefile->IsAlias(aliasedName))
+      {
+      cmOStringStream e;
+      e << "cannot create ALIAS target \"" << exename
+        << "\" because target \"" << aliasedName << "\" is itself an ALIAS.";
+      this->SetError(e.str().c_str());
+      return false;
+      }
+    cmTarget *aliasedTarget =
+                    this->Makefile->FindTargetToUse(aliasedName, true);
+    if(!aliasedTarget)
+      {
+      cmOStringStream e;
+      e << "cannot create ALIAS target \"" << exename
+        << "\" because target \"" << aliasedName << "\" does not already "
+        "exist.";
+      this->SetError(e.str().c_str());
+      return false;
+      }
+    cmTarget::TargetType type = aliasedTarget->GetType();
+    if(type != cmTarget::EXECUTABLE)
+      {
+      cmOStringStream e;
+      e << "cannot create ALIAS target \"" << exename
+        << "\" because target \"" << aliasedName << "\" is not an "
+        "executable.";
+      this->SetError(e.str().c_str());
+      return false;
+      }
+    if(aliasedTarget->IsImported())
+      {
+      cmOStringStream e;
+      e << "cannot create ALIAS target \"" << exename
+        << "\" because target \"" << aliasedName << "\" is IMPORTED.";
+      this->SetError(e.str().c_str());
+      return false;
+      }
+    this->Makefile->AddAlias(exename.c_str(), aliasedTarget);
+    return true;
+    }
 
   // Handle imported target creation.
   if(importTarget)
diff --git a/Source/cmAddExecutableCommand.h b/Source/cmAddExecutableCommand.h
index 1e9f9b3..2774ce8 100644
--- a/Source/cmAddExecutableCommand.h
+++ b/Source/cmAddExecutableCommand.h
@@ -107,6 +107,19 @@ public:
       "(and its per-configuration version IMPORTED_LOCATION_<CONFIG>) "
       "which specifies the location of the main executable file on disk.  "
       "See documentation of the IMPORTED_* properties for more information."
+      "\n"
+      "The signature\n"
+      "  add_executable(<name> ALIAS <target>)\n"
+      "creates an alias, such that <name> can be used to refer to <target> "
+      "in subsequent commands.  The <name> does not appear in the generated "
+      "buildsystem as a make target.  The <target> may not be an IMPORTED "
+      "target or an ALIAS.  Alias targets can be used as linkable targets, "
+      "targets to read properties from, executables for custom commands and "
+      "custom targets.  They can also be tested for existance with the "
+      "regular if(TARGET) subcommand.  The <name> may not be used to modify "
+      "properties of <target>, that is, it may not be used as the operand of "
+      "set_property, set_target_properties, target_link_libraries etc.  An "
+      "ALIAS target may not be installed of exported."
       ;
     }
 
diff --git a/Source/cmAddLibraryCommand.cxx b/Source/cmAddLibraryCommand.cxx
index fd39eec..cbc6ed1 100644
--- a/Source/cmAddLibraryCommand.cxx
+++ b/Source/cmAddLibraryCommand.cxx
@@ -43,6 +43,7 @@ bool cmAddLibraryCommand
   // the type of library.  Otherwise, it is treated as a source or
   // source list name. There may be two keyword arguments, check for them
   bool haveSpecifiedType = false;
+  bool isAlias = false;
   while ( s != args.end() )
     {
     std::string libType = *s;
@@ -76,6 +77,11 @@ bool cmAddLibraryCommand
       type = cmTarget::UNKNOWN_LIBRARY;
       haveSpecifiedType = true;
       }
+    else if(libType == "ALIAS")
+      {
+      ++s;
+      isAlias = true;
+      }
     else if(*s == "EXCLUDE_FROM_ALL")
       {
       ++s;
@@ -96,6 +102,80 @@ bool cmAddLibraryCommand
       break;
       }
     }
+  if (isAlias)
+    {
+    if(!cmGeneratorExpression::IsValidTargetName(libName.c_str()))
+      {
+      this->SetError(("Invalid name for ALIAS: " + libName).c_str());
+      return false;
+      }
+    if(excludeFromAll)
+      {
+      this->SetError("EXCLUDE_FROM_ALL with ALIAS makes no sense.");
+      return false;
+      }
+    if(importTarget || importGlobal)
+      {
+      this->SetError("IMPORTED with ALIAS is not allowed.");
+      return false;
+      }
+    if(args.size() != 3)
+      {
+      cmOStringStream e;
+      e << "ALIAS requires exactly one target argument.";
+      this->SetError(e.str().c_str());
+      return false;
+      }
+
+    const char *aliasedName = s->c_str();
+    if(this->Makefile->IsAlias(aliasedName))
+      {
+      cmOStringStream e;
+      e << "cannot create ALIAS target \"" << libName
+        << "\" because target \"" << aliasedName << "\" is itself an ALIAS.";
+      this->SetError(e.str().c_str());
+      return false;
+      }
+    cmTarget *aliasedTarget =
+                    this->Makefile->FindTargetToUse(aliasedName, true);
+    if(!aliasedTarget)
+      {
+      cmOStringStream e;
+      e << "cannot create ALIAS target \"" << libName
+        << "\" because target \"" << aliasedName << "\" does not already "
+        "exist.";
+      this->SetError(e.str().c_str());
+      return false;
+      }
+    cmTarget::TargetType aliasedType = aliasedTarget->GetType();
+    if(aliasedType != cmTarget::SHARED_LIBRARY
+        && aliasedType != cmTarget::STATIC_LIBRARY
+        && aliasedType != cmTarget::MODULE_LIBRARY
+        && aliasedType != cmTarget::OBJECT_LIBRARY)
+      {
+      cmOStringStream e;
+      e << "cannot create ALIAS target \"" << libName
+        << "\" because target \"" << aliasedName << "\" is not a library.";
+      this->SetError(e.str().c_str());
+      return false;
+      }
+    if(aliasedTarget->IsImported())
+      {
+      cmOStringStream e;
+      e << "cannot create ALIAS target \"" << libName
+        << "\" because target \"" << aliasedName << "\" is IMPORTED.";
+      this->SetError(e.str().c_str());
+      return false;
+      }
+    this->Makefile->AddAlias(libName.c_str(), aliasedTarget);
+    return true;
+    }
+
+  if(importTarget && excludeFromAll)
+    {
+    this->SetError("excludeFromAll with IMPORTED target makes no sense.");
+    return false;
+    }
 
   /* ideally we should check whether for the linker language of the target
     CMAKE_${LANG}_CREATE_SHARED_LIBRARY is defined and if not default to
diff --git a/Source/cmAddLibraryCommand.h b/Source/cmAddLibraryCommand.h
index e5f27cb..59354b0 100644
--- a/Source/cmAddLibraryCommand.h
+++ b/Source/cmAddLibraryCommand.h
@@ -138,6 +138,19 @@ public:
       "Some native build systems may not like targets that have only "
       "object files, so consider adding at least one real source file "
       "to any target that references $<TARGET_OBJECTS:objlib>."
+      "\n"
+      "The signature\n"
+      "  add_library(<name> ALIAS <target>)\n"
+      "creates an alias, such that <name> can be used to refer to <target> "
+      "in subsequent commands.  The <name> does not appear in the generated "
+      "buildsystem as a make target.  The <target> may not be an IMPORTED "
+      "target or an ALIAS.  Alias targets can be used as linkable targets, "
+      "targets to read properties from.  They can also be tested for "
+      "existance with the "
+      "regular if(TARGET) subcommand.  The <name> may not be used to modify "
+      "properties of <target>, that is, it may not be used as the operand of "
+      "set_property, set_target_properties, target_link_libraries etc.  An "
+      "ALIAS target may not be installed of exported."
       ;
     }
 
diff --git a/Source/cmExportCommand.cxx b/Source/cmExportCommand.cxx
index 9c3f314..f059ceb 100644
--- a/Source/cmExportCommand.cxx
+++ b/Source/cmExportCommand.cxx
@@ -114,6 +114,15 @@ bool cmExportCommand
       currentTarget != this->Targets.GetVector().end();
       ++currentTarget)
     {
+    if (this->Makefile->IsAlias(currentTarget->c_str()))
+      {
+      cmOStringStream e;
+      e << "given ALIAS target \"" << *currentTarget
+        << "\" which may not be exported.";
+      this->SetError(e.str().c_str());
+      return false;
+      }
+
     if(cmTarget* target =
        this->Makefile->GetLocalGenerator()->
        GetGlobalGenerator()->FindTarget(0, currentTarget->c_str()))
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());
 
diff --git a/Source/cmGetPropertyCommand.cxx b/Source/cmGetPropertyCommand.cxx
index 985dc50..faba7cd 100644
--- a/Source/cmGetPropertyCommand.cxx
+++ b/Source/cmGetPropertyCommand.cxx
@@ -288,6 +288,18 @@ bool cmGetPropertyCommand::HandleTargetMode()
     return false;
     }
 
+  if(this->PropertyName == "ALIASED_TARGET")
+    {
+    if(this->Makefile->IsAlias(this->Name.c_str()))
+      {
+      if(cmTarget* target =
+                          this->Makefile->FindTargetToUse(this->Name.c_str()))
+        {
+        return this->StoreResult(target->GetName());
+        }
+      }
+    return false;
+    }
   if(cmTarget* target = this->Makefile->FindTargetToUse(this->Name.c_str()))
     {
     return this->StoreResult(target->GetProperty(this->PropertyName.c_str()));
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;
 }
diff --git a/Source/cmGlobalGenerator.cxx b/Source/cmGlobalGenerator.cxx
index 9b6ac93..7f2b592 100644
--- a/Source/cmGlobalGenerator.cxx
+++ b/Source/cmGlobalGenerator.cxx
@@ -1769,10 +1769,22 @@ cmLocalGenerator* cmGlobalGenerator::FindLocalGenerator(const char* start_dir)
   return 0;
 }
 
+//----------------------------------------------------------------------------
+void cmGlobalGenerator::AddAlias(const char *name, cmTarget *tgt)
+{
+  this->AliasTargets[name] = tgt;
+}
+
+//----------------------------------------------------------------------------
+bool cmGlobalGenerator::IsAlias(const char *name)
+{
+  return this->AliasTargets.find(name) != this->AliasTargets.end();
+}
 
 //----------------------------------------------------------------------------
 cmTarget*
-cmGlobalGenerator::FindTarget(const char* project, const char* name)
+cmGlobalGenerator::FindTarget(const char* project, const char* name,
+                              bool excludeAliases)
 {
   // if project specific
   if(project)
@@ -1780,7 +1792,8 @@ cmGlobalGenerator::FindTarget(const char* project, const char* name)
     std::vector<cmLocalGenerator*>* gens = &this->ProjectMap[project];
     for(unsigned int i = 0; i < gens->size(); ++i)
       {
-      cmTarget* ret = (*gens)[i]->GetMakefile()->FindTarget(name);
+      cmTarget* ret = (*gens)[i]->GetMakefile()->FindTarget(name,
+                                                            excludeAliases);
       if(ret)
         {
         return ret;
@@ -1790,6 +1803,15 @@ cmGlobalGenerator::FindTarget(const char* project, const char* name)
   // if all projects/directories
   else
     {
+    if (!excludeAliases)
+      {
+      std::map<cmStdString, cmTarget*>::iterator ai
+                                              = this->AliasTargets.find(name);
+      if (ai != this->AliasTargets.end())
+        {
+        return ai->second;
+        }
+      }
     std::map<cmStdString,cmTarget *>::iterator i =
       this->TotalTargets.find ( name );
     if ( i != this->TotalTargets.end() )
diff --git a/Source/cmGlobalGenerator.h b/Source/cmGlobalGenerator.h
index 2fcdc43..18aba24 100644
--- a/Source/cmGlobalGenerator.h
+++ b/Source/cmGlobalGenerator.h
@@ -196,7 +196,11 @@ public:
   void FindMakeProgram(cmMakefile*);
 
   ///! Find a target by name by searching the local generators.
-  cmTarget* FindTarget(const char* project, const char* name);
+  cmTarget* FindTarget(const char* project, const char* name,
+                       bool excludeAliases = false);
+
+  void AddAlias(const char *name, cmTarget *tgt);
+  bool IsAlias(const char *name);
 
   /** Determine if a name resolves to a framework on disk or a built target
       that is a framework. */
@@ -347,6 +351,7 @@ protected:
 
   // All targets in the entire project.
   std::map<cmStdString,cmTarget *> TotalTargets;
+  std::map<cmStdString,cmTarget *> AliasTargets;
   std::map<cmStdString,cmTarget *> ImportedTargets;
   std::vector<cmGeneratorExpressionEvaluationFile*> EvaluationFiles;
 
diff --git a/Source/cmInstallCommand.cxx b/Source/cmInstallCommand.cxx
index 0faf1d4..3c76bd6 100644
--- a/Source/cmInstallCommand.cxx
+++ b/Source/cmInstallCommand.cxx
@@ -362,6 +362,15 @@ bool cmInstallCommand::HandleTargetsMode(std::vector<std::string> const& args)
       targetIt!=targetList.GetVector().end();
       ++targetIt)
     {
+
+    if (this->Makefile->IsAlias(targetIt->c_str()))
+      {
+      cmOStringStream e;
+      e << "TARGETS given target \"" << (*targetIt)
+        << "\" which is an alias.";
+      this->SetError(e.str().c_str());
+      return false;
+      }
     // Lookup this target in the current directory.
     if(cmTarget* target=this->Makefile->FindTarget(targetIt->c_str()))
       {
diff --git a/Source/cmMakefile.cxx b/Source/cmMakefile.cxx
index 1920cc0..aae92dd 100644
--- a/Source/cmMakefile.cxx
+++ b/Source/cmMakefile.cxx
@@ -41,6 +41,7 @@
 
 #include <stack>
 #include <ctype.h> // for isspace
+#include <assert.h>
 
 class cmMakefile::Internals
 {
@@ -1437,6 +1438,14 @@ void cmMakefile::AddLinkDirectoryForTarget(const char *target,
   cmTargets::iterator i = this->Targets.find(target);
   if ( i != this->Targets.end())
     {
+    if(this->IsAlias(target))
+      {
+      cmOStringStream e;
+      e << "ALIAS target \"" << target << "\" "
+        << "may not be linked into another target.";
+      this->IssueMessage(cmake::FATAL_ERROR, e.str().c_str());
+      return;
+      }
     i->second.AddLinkDirectory( d );
     }
   else
@@ -1923,6 +1932,12 @@ void cmMakefile::AddGlobalLinkInformation(const char* name, cmTarget& target)
 }
 
 
+void cmMakefile::AddAlias(const char* lname, cmTarget *tgt)
+{
+  this->AliasTargets[lname] = tgt;
+  this->LocalGenerator->GetGlobalGenerator()->AddAlias(lname, tgt);
+}
+
 cmTarget* cmMakefile::AddLibrary(const char* lname, cmTarget::TargetType type,
                             const std::vector<std::string> &srcs,
                             bool excludeFromAll)
@@ -3758,8 +3773,17 @@ const char* cmMakefile::GetFeature(const char* feature, const char* config)
   return 0;
 }
 
-cmTarget* cmMakefile::FindTarget(const char* name)
+cmTarget* cmMakefile::FindTarget(const char* name, bool excludeAliases)
 {
+  if (!excludeAliases)
+    {
+    std::map<std::string, cmTarget*>::iterator i
+                                              = this->AliasTargets.find(name);
+    if (i != this->AliasTargets.end())
+      {
+      return i->second;
+      }
+    }
   cmTargets& tgts = this->GetTargets();
 
   cmTargets::iterator i = tgts.find ( name );
@@ -4184,7 +4208,7 @@ cmMakefile::AddImportedTarget(const char* name, cmTarget::TargetType type,
 }
 
 //----------------------------------------------------------------------------
-cmTarget* cmMakefile::FindTargetToUse(const char* name)
+cmTarget* cmMakefile::FindTargetToUse(const char* name, bool excludeAliases)
 {
   // Look for an imported target.  These take priority because they
   // are more local in scope and do not have to be globally unique.
@@ -4196,15 +4220,25 @@ cmTarget* cmMakefile::FindTargetToUse(const char* name)
     }
 
   // Look for a target built in this directory.
-  if(cmTarget* t = this->FindTarget(name))
+  if(cmTarget* t = this->FindTarget(name, excludeAliases))
     {
     return t;
     }
 
   // Look for a target built in this project.
-  return this->LocalGenerator->GetGlobalGenerator()->FindTarget(0, name);
+  return this->LocalGenerator->GetGlobalGenerator()->FindTarget(0, name,
+                                                              excludeAliases);
 }
 
+//----------------------------------------------------------------------------
+bool cmMakefile::IsAlias(const char *name)
+{
+  if (this->AliasTargets.find(name) != this->AliasTargets.end())
+    return true;
+  return this->GetLocalGenerator()->GetGlobalGenerator()->IsAlias(name);
+}
+
+//----------------------------------------------------------------------------
 cmGeneratorTarget* cmMakefile::FindGeneratorTargetToUse(const char* name)
 {
   cmTarget *t = this->FindTargetToUse(name);
@@ -4215,6 +4249,14 @@ cmGeneratorTarget* cmMakefile::FindGeneratorTargetToUse(const char* name)
 bool cmMakefile::EnforceUniqueName(std::string const& name, std::string& msg,
                                    bool isCustom)
 {
+  if(this->IsAlias(name.c_str()))
+    {
+    cmOStringStream e;
+    e << "cannot create target \"" << name
+      << "\" because an alias with the same name already exists.";
+    msg = e.str();
+    return false;
+    }
   if(cmTarget* existing = this->FindTargetToUse(name.c_str()))
     {
     // The name given conflicts with an existing target.  Produce an
diff --git a/Source/cmMakefile.h b/Source/cmMakefile.h
index 871fa1b..711a208 100644
--- a/Source/cmMakefile.h
+++ b/Source/cmMakefile.h
@@ -337,6 +337,7 @@ public:
   cmTarget* AddLibrary(const char *libname, cmTarget::TargetType type,
                   const std::vector<std::string> &srcs,
                   bool excludeFromAll = false);
+  void AddAlias(const char *libname, cmTarget *tgt);
 
 #if defined(CMAKE_BUILD_WITH_CMAKE)
   /**
@@ -536,11 +537,12 @@ public:
       this->GeneratorTargets = targets;
     }
 
-  cmTarget* FindTarget(const char* name);
+  cmTarget* FindTarget(const char* name, bool excludeAliases = false);
 
   /** Find a target to use in place of the given name.  The target
       returned may be imported or built within the project.  */
-  cmTarget* FindTargetToUse(const char* name);
+  cmTarget* FindTargetToUse(const char* name, bool excludeAliases = false);
+  bool IsAlias(const char *name);
   cmGeneratorTarget* FindGeneratorTargetToUse(const char* name);
 
   /**
@@ -902,6 +904,7 @@ protected:
 
   // libraries, classes, and executables
   cmTargets Targets;
+  std::map<std::string, cmTarget*> AliasTargets;
   cmGeneratorTargetsType GeneratorTargets;
   std::vector<cmSourceFile*> SourceFiles;
 
diff --git a/Source/cmSetPropertyCommand.cxx b/Source/cmSetPropertyCommand.cxx
index b5e5225..4207860 100644
--- a/Source/cmSetPropertyCommand.cxx
+++ b/Source/cmSetPropertyCommand.cxx
@@ -244,6 +244,11 @@ bool cmSetPropertyCommand::HandleTargetMode()
   for(std::set<cmStdString>::const_iterator ni = this->Names.begin();
       ni != this->Names.end(); ++ni)
     {
+    if (this->Makefile->IsAlias(ni->c_str()))
+      {
+      this->SetError("can not be used on an ALIAS target.");
+      return false;
+      }
     if(cmTarget* target = this->Makefile->FindTargetToUse(ni->c_str()))
       {
       // Handle the current target.
diff --git a/Source/cmSetTargetPropertiesCommand.cxx b/Source/cmSetTargetPropertiesCommand.cxx
index a2b50a8..78ef393 100644
--- a/Source/cmSetTargetPropertiesCommand.cxx
+++ b/Source/cmSetTargetPropertiesCommand.cxx
@@ -72,6 +72,11 @@ bool cmSetTargetPropertiesCommand
   int i;
   for(i = 0; i < numFiles; ++i)
     {
+    if (this->Makefile->IsAlias(args[i].c_str()))
+      {
+      this->SetError("can not be used on an ALIAS target.");
+      return false;
+      }
     bool ret = cmSetTargetPropertiesCommand::SetOneTarget
       (args[i].c_str(),propertyPairs,this->Makefile);
     if (!ret)
diff --git a/Source/cmTarget.cxx b/Source/cmTarget.cxx
index 667c685..13cd006 100644
--- a/Source/cmTarget.cxx
+++ b/Source/cmTarget.cxx
@@ -969,6 +969,12 @@ void cmTarget::DefineProperties(cmake *cm)
      "This is the configuration-specific version of OUTPUT_NAME.");
 
   cm->DefineProperty
+    ("ALIASED_TARGET", cmProperty::TARGET,
+     "Name of target aliased by this target.",
+     "If this is an ALIAS target, this property contains the name of the "
+     "target aliased.");
+
+  cm->DefineProperty
     ("<CONFIG>_OUTPUT_NAME", cmProperty::TARGET,
      "Old per-configuration target file base name.",
      "This is a configuration-specific version of OUTPUT_NAME.  "
diff --git a/Source/cmTargetLinkLibrariesCommand.cxx b/Source/cmTargetLinkLibrariesCommand.cxx
index 0ee9420..863b391 100644
--- a/Source/cmTargetLinkLibrariesCommand.cxx
+++ b/Source/cmTargetLinkLibrariesCommand.cxx
@@ -31,6 +31,11 @@ bool cmTargetLinkLibrariesCommand
     return false;
     }
 
+  if (this->Makefile->IsAlias(args[0].c_str()))
+    {
+    this->SetError("can not be used on an ALIAS target.");
+    return false;
+    }
   // Lookup the target for which libraries are specified.
   this->Target =
     this->Makefile->GetCMakeInstance()
diff --git a/Source/cmTargetPropCommandBase.cxx b/Source/cmTargetPropCommandBase.cxx
index 37aa604..1862cb6 100644
--- a/Source/cmTargetPropCommandBase.cxx
+++ b/Source/cmTargetPropCommandBase.cxx
@@ -26,6 +26,11 @@ bool cmTargetPropCommandBase
     }
 
   // Lookup the target for which libraries are specified.
+  if (this->Makefile->IsAlias(args[0].c_str()))
+    {
+    this->SetError("can not be used on an ALIAS target.");
+    return false;
+    }
   this->Target =
     this->Makefile->GetCMakeInstance()
     ->GetGlobalGenerator()->FindTarget(0, args[0].c_str());