Commit 049dbdd3 authored by Craig Scott's avatar Craig Scott

Help: Document that <PackageName>_ROOT applies to config packages too

The original intent of <PackageName>_ROOT may have been for it
to apply only to Find modules, but the implementation of the
find_package() command treats modules and config packages the
same. Both result in a <PackageName>_ROOT variable being
pushed onto the stack of package roots. A config package can
also call other find_...() commands, the behavior doesn't apply
just to find modules.
parent 92780281
......@@ -79,15 +79,16 @@ If ``NO_DEFAULT_PATH`` is not specified, the search process is as follows:
|prefix_XXX_SUBDIR| for each ``<prefix>`` in
:variable:`CMAKE_SYSTEM_PREFIX_PATH`
1. If called from within a find module loaded by
1. If called from within a find module or any other script loaded by a call to
:command:`find_package(<PackageName>)`, search prefixes unique to the
current package being found. Specifically look in the
current package being found. Specifically, look in the
:variable:`<PackageName>_ROOT` CMake variable and the
:envvar:`<PackageName>_ROOT` environment variable.
The package root variables are maintained as a stack so if called from
nested find modules, root paths from the parent's find module will be
searched after paths from the current module,
i.e. ``<CurrentPackage>_ROOT``, ``ENV{<CurrentPackage>_ROOT}``,
The package root variables are maintained as a stack, so if called from
nested find modules or config packages, root paths from the parent's find
module or config package will be searched after paths from the current
module or package. In other words, the search order would be
``<CurrentPackage>_ROOT``, ``ENV{<CurrentPackage>_ROOT}``,
``<ParentPackage>_ROOT``, ``ENV{<ParentPackage>_ROOT}``, etc.
This can be skipped if ``NO_PACKAGE_ROOT_PATH`` is passed or by setting
the :variable:`CMAKE_FIND_USE_PACKAGE_ROOT_PATH` to ``FALSE``.
......
......@@ -7,9 +7,9 @@ In CMake 3.12 and above the :command:`find_package(<PackageName>)` command now
searches prefixes specified by the :variable:`<PackageName>_ROOT` CMake
variable and the :envvar:`<PackageName>_ROOT` environment variable.
Package roots are maintained as a stack so nested calls to all ``find_*``
commands inside find modules also search the roots as prefixes. This policy
provides compatibility with projects that have not been updated to avoid using
``<PackageName>_ROOT`` variables for other purposes.
commands inside find modules and config packages also search the roots as
prefixes. This policy provides compatibility with projects that have not been
updated to avoid using ``<PackageName>_ROOT`` variables for other purposes.
The ``OLD`` behavior for this policy is to ignore ``<PackageName>_ROOT``
variables. The ``NEW`` behavior for this policy is to use
......
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