[cmake-developers] find_package module-only policy

[Brad King]

On 2/28/2012 8:24 AM, Brad King wrote:
> I replaced the FindPackage_ModeWarning topic on the stage with a
[snip]
> However, I'm not yet prepared to merge this to next. I'm going
> to make more significant edits to the proposed changes and post
> them as a separate topic and then report back here.

I pushed new topic

   find_package-improve-messages

that shares the beginning of FindPackage_ModeWarning but then
makes slightly different changes:

- I improved detection of options that conflict with MODULE.
CONFIG and NO_MODULE are not the only conflicts.  Other options
imply Config mode too.

- I added a test to check the major failure case message text
by actually comparing it to known output.  This is a stronger
test than your FindPackageTest change and provides a reference
for the message text of each case right in the source tree
without running anything.

- I decided to drop the warning for MODULE or CONFIG keywords
without a sufficiently high minimum required CMake version.
We don't warn for other commands that have new options, and
the project could guard the use with its own test of the
CMake version without actually bumping the min req version
e.g. "if(NOT ${CMAKE_VERSION} VERSION_LESS 2.8.8)".  We should
not warn in such cases.

- I changed the warning text and documentation text of the
CMAKE_FIND_PACKAGE_WARN_NO_MODULE variable to change the tone
from "less ambiguous" to "more specific."

- I really don't want to ever warn in the default mode when
falling back to Config mode.  I think the new failure message
text and explicit mode keywords are sufficient to solve this
problem.  Therefore CMAKE_FIND_PACKAGE_WARN_NO_MODULE will be
required to get the warning and 2.8.8 will not warn by default.

IMO this topic is ready to be merged to 'next' for testing.

-Brad