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, 6 insertions, 6 deletions

diff --git a/Source/cmPolicies.h b/Source/cmPolicies.h
index 68745da..7e976d6 100644
--- a/Source/cmPolicies.h
+++ b/Source/cmPolicies.h
@@ -38,12 +38,12 @@ public:
   enum PolicyStatus { OLD, WARN, NEW, REQUIRED_IF_USED, REQUIRED_ALWAYS };
   static const char* PolicyStatusNames[];
 
-  enum PolicyID {CMP_0000, CMP_POLICY_SPECIFICATION = CMP_0000,
-                 CMP_0001, CMP_TARGET_NAMES_WITH_SLASHES = CMP_0001,
-                 CMP_0002, CMP_REQUIRE_UNIQUE_TARGET_NAMES = CMP_0002,
-                 CMP_0003, CMP_CONFIGURE_FILE_IMMEDIATE = CMP_0003
-                 };
-
+  enum PolicyID
+  {
+    CMP_0000, // Policy version specification
+    CMP_0001, // Ignore old compatibility variable
+    CMP_0002
+  };
 
   ///! convert a string policy ID into a number
   bool GetPolicyID(const char *id, /* out */ cmPolicies::PolicyID &pid);