find_package: Use PackageName_ROOT variables as search prefixes

This feature was originally added by commit v3.9.0-rc1~71^2~2 (find_*:
Add a new PackageRoot search path group, 2017-05-03) and documented by
commit v3.9.0-rc1~71^2 (find_*: Add docs for PackageRoot search path
group, 2017-05-03).  However, we had to disable the feature and remove
the documentation in commit v3.9.1~2^2 (find_*: Disable the PACKAGE_ROOT
search path group for CMake 3.9, 2017-08-08) due to breaking projects
that used `PackageName_ROOT` variables themselves.

Add policy `CMP0074` to restore the `PackageName_ROOT` variable behavior
in a compatible way.  Also revise the stack of root paths to store the
paths themselves rather than the package names.  This way the policy can
be considered at the `find_package` call site instead of individual
`find_` calls inside a find module.

Co-Author: Chuck Atkins <chuck.atkins@kitware.com>
Issue: #17144

1 files changed, 0 insertions, 3 deletions

diff --git a/Source/cmFindCommon.h b/Source/cmFindCommon.h
index b237f1b..89ff174 100644
--- a/Source/cmFindCommon.h
+++ b/Source/cmFindCommon.h
@@ -84,9 +84,6 @@ protected:
   /** Compute final search path list (reroot + trailing slash).  */
   void ComputeFinalPaths();
 
-  /** Decide whether to enable the PACKAGE_ROOT search entries.  */
-  void SelectDefaultNoPackageRootPath();
-
   /** Compute the current default root path mode.  */
   void SelectDefaultRootPathMode();