Remove CMake Policy CMP0015 until it is revised

We revert commit "Create CMake Policy CMP0015 to fix set(CACHE)" because
the NEW behavior of the policy breaks a valid use case:

  # CMakeLists.txt
  option(BUILD_SHARED_LIBS "..." ON)
  add_library(mylib ...)
  set(BUILD_SHARED_LIBS OFF) # we want only mylib to be shared
  add_subdirectory(ThirdParty)

  # ThirdParty/CMakeLists.txt
  option(BUILD_SHARED_LIBS "..." ON)
  # uh, oh, with NEW behavior this dir uses shared libs!!!

We'll re-introduce the policy later with a different change in behavior
to resolve the motivating case, which was more subtle but less common.

See issue #9008.

1 files changed, 2 insertions, 4 deletions

diff --git a/Source/cmSetCommand.h b/Source/cmSetCommand.h
index 609106c..2990d24 100644
--- a/Source/cmSetCommand.h
+++ b/Source/cmSetCommand.h
@@ -64,10 +64,8 @@ public:
       "  set(<variable> <value>\n"
       "      [[CACHE <type> <docstring> [FORCE]] | PARENT_SCOPE])\n"
       "Within CMake sets <variable> to the value <value>.  <value> is expanded"
-      "  before <variable> is set to it.  If CACHE is present and <variable> "
-      "is not yet in the cache, then <variable> is put in the cache. If it is "
-      "already in the cache, <variable> is assigned the value stored in the "
-      "cache.  If CACHE is present, also <type> and <docstring> are "
+      "  before <variable> is set to it.  If CACHE is present, then the "
+      "<variable> is put in the cache. <type> and <docstring> are then "
       "required. <type> is used by the CMake GUI to choose a widget with "
       "which the user sets a value.  The value for <type> may be one of\n"
       "  FILEPATH = File chooser dialog.\n"