Keep track of CPS files we have imported in CMake's state, and use this
(instead of the prior, temporary work-around that used `<name>_CONFIG`)
as a guard for trying to import more than once from the same file. This
has two advantages; first, it is robust against finding the same package
name in different locations in alternating searches, and second, it
allows us to load additional appendices associated with a root package
that has already been loaded.
Fixes: #26731
Do not try to load a CPS file if we've already loaded the same file.
This only works if the current `find_package` call selects the same file
as the previous most recent call, and if the user has not meddled with
the `<name>_CONFIG` variable.
Issue: #26731
Fix two minor issues with how default configurations are set from CPS
packages. First, imported configurations were (appropriately) being
converted to upper case, but default configurations weren't. Second,
default configurations were being set only after importing components
from the root package configuration file, resulting in configurations
specified in the root file preceding the default configurations.
Modify how CMake handles required components of a CPS transitive
dependency to not pass them as COMPONENTS if a CMake-script package is
found as the resolved dependency. This is necessary as many CMake-script
package description files do not treat component requests as target
requests (which, in CPS-land, they effectively are), but do implement
logic to mark themselves 'not found' if requested components are
missing. As a result, passing in the required targets as required
components is likely to cause the dependency to be spuriously not found
if it is only available via a CMake-script package configuration file.
Fix this by introducing a new 'required targets' concept, and by passing
CPS component requirements as both required targets and optional
components. The latter serves as a hint for packages that might provide
only a subset of themselves. The former is used to post-validate a
CMake-script package, or is folded on-the-fly into required components
when considering CPS packages.
Note that this functionality is not exposed to the user at this time,
and is only used when resolving transitive dependencies for a CPS
package.
Update cmPackageInfoReader's version parsing to more fully conform to
the specification and to reject non-conforming version strings. Start
adding framework to support version schemas other than "simple". Fix how
cmFindPackageCommand extracts version parts to not fail if more than
four parts are present.
Modify cmPackageInfoReader to not require schema_version in supplemental
files (i.e. appendices and/or configuration-specific files). This is
important as our own generation is not including cps_version in
supplemental files, and it is forbidden in the same according to a
strict reading of the specification.
Implement finding components of CPS packages. Specifically, reject any
candidate packages that don't provide all required components, and
ignore appendices that don't provide requested (required or optional)
components. This applies to both top-level searches and also searching
for package dependencies.
Implement finding dependencies of CPS packages. This is done by setting
up additional `cmFindPackageCommand` instances which are used to look
for a parent package's dependencies.
Rewrite how cmPackageInfoReader parses "includes" to also support
language-specific includes (i.e. map-of-string-to-list-of-string).
Previously, we only supported the simpler list-of-string shorthand for
"includes" that do not have any language-specific includes.
Rewrite cmPackageInfoReader's parsing of the "definitions" attribute.
The old logic (having been originally adapted from proof-of-concept
parsing code circa 2023) was parsing the attribute according to its
specification as of CPS 0.11, but the representation was changed in
CPS 0.12. Add a test to verify that definitions are being imported
correctly. Remove unnecessary setting and resetting of CMAKE_PREFIX_PATH
in the test.
Implement logic (partly adapted from the 2023 proof-of-concept) to
actually parse CPS files and generate imported targets. Implement logic
to locate and load supplemental files. Adjust prefix handling to require
that the CPS file provides sufficient information to translate the
prefix placeholder into a meaningful path. (Note that this corresponds
to a change in the specification.)
Add a helper class to read CPS files. Use this to teach find_package how
to consider and accept .cps files in its search. (Note that no version
testing is performed at this time.) Add a simple test that we can find a
package from a .cps file and correctly extract the version information.
Note that this doesn't actually import anything from CPS yet.
