Drop compatibility with CMake < 2.4

Drop all behavior activated by setting CMAKE_BACKWARDS_COMPATIBILITY to
a value lower than 2.4, and generate an error when projects or the user
attempt to do so.  In the error suggest using a CMake 2.8.x release.

Teach cmake_minimum_required to warn about projects that do not require
at least CMake 2.4.  They are not supported by CMake >= 3.0.

Replace the documentation of CMAKE_BACKWARDS_COMPATIBILITY with a
reference to policy CMP0001.

1 files changed, 0 insertions, 30 deletions

diff --git a/Source/cmake.cxx b/Source/cmake.cxx
index 6822fe1..186d4e6 100644
--- a/Source/cmake.cxx
+++ b/Source/cmake.cxx
@@ -99,30 +99,6 @@
 static bool cmakeCheckStampFile(const char* stampName);
 static bool cmakeCheckStampList(const char* stampName);
 
-void cmNeedBackwardsCompatibility(const std::string& variable,
-  int access_type, void*, const char*, const cmMakefile*)
-{
-#ifdef CMAKE_BUILD_WITH_CMAKE
-  if (access_type == cmVariableWatch::UNKNOWN_VARIABLE_READ_ACCESS)
-    {
-    std::string message = "An attempt was made to access a variable: ";
-    message += variable;
-    message +=
-      " that has not been defined. Some variables were always defined "
-      "by CMake in versions prior to 1.6. To fix this you might need to set "
-      "the cache value of CMAKE_BACKWARDS_COMPATIBILITY to 1.4 or less. If "
-      "you are writing a CMakeLists file, (or have already set "
-      "CMAKE_BACKWARDS_COMPATIBILITY to 1.4 or less) then you probably need "
-      "to include a CMake module to test for the feature this variable "
-      "defines.";
-    cmSystemTools::Error(message.c_str());
-    }
-#else
-  (void)variable;
-  (void)access_type;
-#endif
-}
-
 void cmWarnUnusedCliWarning(const std::string& variable,
   int, void* ctx, const char*, const cmMakefile*)
 {
@@ -169,12 +145,6 @@ cmake::cmake()
 
 #ifdef CMAKE_BUILD_WITH_CMAKE
   this->VariableWatch = new cmVariableWatch;
-  this->VariableWatch->AddWatch("CMAKE_WORDS_BIGENDIAN",
-                            cmNeedBackwardsCompatibility);
-  this->VariableWatch->AddWatch("CMAKE_SIZEOF_INT",
-                            cmNeedBackwardsCompatibility);
-  this->VariableWatch->AddWatch("CMAKE_X_LIBS",
-                            cmNeedBackwardsCompatibility);
 #endif
 
   this->AddDefaultGenerators();