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, 2 insertions, 2 deletions

diff --git a/Source/cmSearchPath.h b/Source/cmSearchPath.h
index fd0c7c52ed..2a576ed59b 100644
--- a/Source/cmSearchPath.h
+++ b/Source/cmSearchPath.h
@@ -39,10 +39,10 @@ public:
   void AddCMakePrefixPath(const std::string& variable);
   void AddEnvPrefixPath(const std::string& variable, bool stripBin = false);
   void AddSuffixes(const std::vector<std::string>& suffixes);
-
-protected:
   void AddPrefixPaths(const std::vector<std::string>& paths,
                       const char* base = nullptr);
+
+protected:
   void AddPathInternal(const std::string& path, const char* base = nullptr);
 
   cmFindCommon* FC;