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, 13 deletions

diff --git a/Source/cmFindBase.cxx b/Source/cmFindBase.cxx
index 14987ac..f5f1430 100644
--- a/Source/cmFindBase.cxx
+++ b/Source/cmFindBase.cxx
@@ -109,19 +109,7 @@ bool cmFindBase::ParseArguments(std::vector<std::string> const& argsIn)
   // CMake versions below 2.3 did not search all these extra
   // locations.  Preserve compatibility unless a modern argument is
   // passed.
-  bool compatibility = false;
-  const char* versionValue =
-    this->Makefile->GetDefinition("CMAKE_BACKWARDS_COMPATIBILITY");
-  int major = 0;
-  int minor = 0;
-  if(versionValue && sscanf(versionValue, "%d.%d", &major, &minor) != 2)
-    {
-    versionValue = 0;
-    }
-  if(versionValue && (major < 2 || major == 2 && minor < 3))
-    {
-    compatibility = true;
-    }
+  bool compatibility = this->Makefile->NeedBackwardsCompatibility(2,3);
 
   // copy argsIn into args so it can be modified,
   // in the process extract the DOC "documentation"