Commit Graph

11 Commits

Author SHA1 Message Date
Brad King c4275592a8 Modules: Include builtin FindPackageHandleStandardArgs directly
The FindPackageHandleStandardArgs module was originally created outside
of CMake.  It was added for CMake 2.6.0 by commit e118a627 (add a macro
FIND_PACKAGE_HANDLE_STANDARD_ARGS..., 2007-07-18).  However, it also
proliferated into a number of other projects that at the time required
only CMake 2.4 and thus could not depend on CMake to provide the module.
CMake's own find modules started using the module in commit b5f656e0
(use the new FIND_PACKAGE_HANDLE_STANDARD_ARGS in some of the FindXXX
modules..., 2007-07-18).

Then commit d358cf5c (add 2nd, more powerful mode to
find_package_handle_standard_args, 2010-07-29) added a new feature to
the interface of the module that was fully optional and backward
compatible with all existing users of the module.  Later commit 5f183caa
(FindZLIB: use the FPHSA version mode, 2010-08-04) and others shortly
thereafter started using the new interface in CMake's own find modules.
This change was also backward compatible because it was only an
implementation detail within each module.

Unforutnately these changes introduced a problem for projects that still
have an old copy of FindPackageHandleStandardArgs in CMAKE_MODULE_PATH.
When any such project uses one of CMake's builtin find modules the line

  include(FindPackageHandleStandardArgs)

loads the copy from the project which does not have the new interface!
Then the including find module tries to use the new interface with the
old module and fails.

Whether this breakage can be considered a backward incompatible change
in CMake is debatable.  The situation is analagous to copying a standard
library header from one version of a compiler into a project and then
observing problems when the next version of the compiler reports errors
in its other headers that depend on its new version of the original
header.  Nevertheless it is a change to CMake that causes problems for
projects that worked with previous versions.

This problem was discovered during the 2.8.3 release candidate cycle.
It is an instance of a more general problem with projects that provide
their own versions of CMake modules when other CMake modules depend on
them.  At the time we resolved this instance of the problem with commit
b0118402 (Use absolute path to FindPackageHandleStandardArgs.cmake
everywhere, 2010-09-28) for the 2.8.3 release.

In order to address the more general problem we introduced policy
CMP0017 in commit db44848f (Prefer files from CMAKE_ROOT when including
from CMAKE_ROOT, 2010-11-17).  That change was followed by commit
ce28737c (Remove usage of CMAKE_CURRENT_LIST_DIR now that we have
CMP0017, 2010-12-20) which reverted the original workaround in favor of
using the policy.  However, existing project releases do not set the
policy behavior to NEW and therefore still exhibit the problem.

We introduced in commit a364daf1 (Allow users to specify defaults for
unset policies, 2011-01-03) an option for users to build existing
projects by adding -DCMAKE_POLICY_DEFAULT_CMP0017=NEW to the command
line.  Unfortunately this solution still does not allow such projects to
build out of the box, and there is no good way to suggest the use of the
new option.

The only remaining solution to keep existing projects that exhibit this
problem building is to restore the change originally made in commit
b0118402 (Use absolute path to FindPackageHandleStandardArgs.cmake
everywhere, 2010-09-28).  This also avoids policy CMP0017 warnings for
this particular instance of the problem the policy addresses.
2011-01-20 10:56:49 -05:00
Alex Neundorf ce28737c93 Remove usage of CMAKE_CURRENT_LIST_DIR now that we have CMP0017
This puts the new search behaviour for included files in action, i.e.
now when a file from Modules/ include()s another file, it also gets the
one from Modules/ included, i.e. the one it expects.

Alex
2011-01-04 08:20:08 -05:00
Alex Neundorf b01184022b Use absolute path to FindPackageHandleStandardArgs.cmake everywhere
This is to avoid getting an (older) copy of FPHSA.cmake which is
e.g. installed with KDE 4.5.0 and 4.5.1.

Alex
2010-09-28 22:30:31 +02:00
Todd Gamblin 2cde67a781 Modules: Fix spelling 'To distributed' -> 'To distribute' 2010-08-09 08:48:31 -04:00
Brad King c4bb9c9d42 Convert CMake find-modules to BSD License
This adds copyright/license notification blocks CMake's find-modules.
Many of the modules had no notices at all.  Some had notices referring
to the BSD license already.  This commit normalizes existing notices and
adds missing notices.
2009-09-28 11:45:50 -04:00
Philip Lowman 78bbf5a0de ENH: Added FindOpenSceneGraph.cmake which is intended to wrap any of the existing Findosg* modules (or even user specified modules in CMAKE_MODULE_PATH) and aggregate the include dirs & libraries while providing a COMPONENT frontend and version checking (Fixes Issue ). Also added a note to Findosg.cmake to refer new users to the module. 2009-01-30 20:09:16 -05:00
Philip Lowman 901b4b6c3f BUG: The QUIET and REQUIRED find attributes on each Findosg* module were not
being respected.
2009-01-30 14:33:08 -05:00
Philip Lowman d1640b11de BUG: Fixed Issue Bugs in Findosg*.cmake. Also added OPENTHREADS_LIBRARIES. 2009-01-19 13:33:36 -05:00
Brad King e2ec3b671b ENH: Cleanup Find* modules with new HINTS feature
- The find_* commands now provide a HINTS option.
  - The option specifies paths to be preferred over the system paths.
  - Many Find* modules were using two find calls with NO_DEFAULT_PATH
    to approximate the behavior, but that blocked users from overriding
    things with CMAKE_PREFIX_PATH.
  - This commit uses the HINTS feature to get desired behavior in
    only one find command call.
2008-06-09 16:04:06 -04:00
Brad King 52718dbbf2 BUG: Remove references to CMAKE_PREFIX_PATH variable. It should not be referenced directly by FIND_* command calls. The commands search it automatically. 2008-01-15 21:20:11 -05:00
Eric Wing a5b3ab4eee BUG: Fixed modules to set FOO_FOUND when both headers and libraries are found.
BUG: FindSDL now has flag it responds to so it will not find/link against SDLmain. This is required to build libraries instead of applications since they don't have main().
ENH: All modules have a predictable search order, where environmental variables are searched before system paths. This is designed to make automation easier for those that need to automatically build projects without intervention but may be using alternative install locations for isolated testing.
ENH: New modules for OpenSceneGraph, Freetype, GDAL, Lua, QuickTime, GIFLIB, Producer, OpenThreads.
STYLE: Added documentation explaining peculuar SDL_LIBRARY_TEMP variable in SDL
  module when library find is incomplete.
2007-12-20 20:59:44 -05:00