ENH: Improve handling of old-style compatibility.

  - Remove CMP_0001 (no slash in target name) and restore
    old CMAKE_BACKWARDS_COMPATIBILITY check for it
  - Replace all checks of CMAKE_BACKWARDS_COMPATIBILITY
    with cmLocalGenerator::NeedBackwardsCompatibility calls
  - Create new CMP_0001 to determine whether or not
    CMAKE_BACKWARDS_COMPATIBILITY is used.
    (old = use, new = ignore)
  - Show CMAKE_BACKWARDS_COMPATIBILITY in cache only when
    CMP_0001 is set to OLD or WARN
  - Update documentation of cmake_policy and cmake_minimum_required
    to indicate their relationship and the 2.4 version boundary
  - When no cmake policy version is set in top level makefile
    implicitly call cmake_policy(VERSION 2.4) which restores
    CMAKE_BACKWARDS_COMPATIBILITY and other 2.4 compatibility
  - Fix tests MakeClean and Preprocess to call
    cmake_policy(VERSION 2.6) because they depend on new policies

1 files changed, 1 insertions, 20 deletions

diff --git a/Source/cmConfigureFileCommand.cxx b/Source/cmConfigureFileCommand.cxx
index d768886..cac2552 100644
--- a/Source/cmConfigureFileCommand.cxx
+++ b/Source/cmConfigureFileCommand.cxx
@@ -40,29 +40,10 @@ bool cmConfigureFileCommand
   this->CopyOnly = false;
   this->EscapeQuotes = false;
 
-  
   // for CMake 2.0 and earlier CONFIGURE_FILE defaults to the FinalPass,
   // after 2.0 it only does InitialPass
-  this->Immediate = false;
-  const char* versionValue
-    = this->Makefile->GetDefinition("CMAKE_BACKWARDS_COMPATIBILITY");
-  if (versionValue && atof(versionValue) > 2.0)
-  {
-    this->Immediate = true;
-  }
+  this->Immediate = !this->Makefile->NeedBackwardsCompatibility(2,0);
 
-  switch (this->Makefile->GetPolicyStatus(cmPolicies::CMP_0003))
-  {
-    case cmPolicies::WARN:
-    case cmPolicies::OLD:
-      break;
-    case cmPolicies::NEW:
-    case cmPolicies::REQUIRED_IF_USED:
-    case cmPolicies::REQUIRED_ALWAYS:
-      this->Immediate = true;
-  }
-    
-  
   this->AtOnly = false;
   for(unsigned int i=2;i < args.size();++i)
     {