Automatically detect target dependencies

[TheLartians]

Perhaps this is possible using FeatureSummary as suggested on the CMake slack.

[ClausKlein]

Great idea!

with this code appended to test/CMakeLists.txt

include(FeatureSummary)
feature_summary(
  WHAT ALL
  FILENAME ${CMAKE_CURRENT_SOURCE_DIR}/FeatureSummary.log)

I will get his file contents:

The following REQUIRED packages have been found:

 * dependency (required version >= 1.2)
 * namespaced_dependency (required version >= 4.5.6)
 * transitive_dependency (required version >= 7.8.9)

[ClausKlein]

This version seems better to parse and get only the list of required packages found:

include(FeatureSummary)
feature_summary(
  WHAT REQUIRED_PACKAGES_FOUND
  QUIET_ON_EMPTY
  DESCRIPTION ""
  FILENAME ${CMAKE_CURRENT_SOURCE_DIR}/RequiredPackagesFound.log)

[ClausKlein]

@TheLartians This seems a good starting point:

set(current_targets main)
get_property(
  _depends
  TARGET ${current_targets}
  PROPERTY INTERFACE_LINK_LIBRARIES
)
message(STATUS "${current_targets}: ${_depends}\n")

set(_property "PACKAGES_FOUND")
set(_currentFeatureText "")
get_property(_EnabledFeatures GLOBAL PROPERTY ${_property})
if(_EnabledFeatures)
  list(REMOVE_DUPLICATES _EnabledFeatures)
endif()
message(STATUS "${_property}: ${_EnabledFeatures}")

set(_currentFeature PACKAGES_FOUND)
get_property(
  _importedTargets
  DIRECTORY ${CMAKE_CURRENT_SORUCE_DIR}
  PROPERTY IMPORTED_TARGETS
)
foreach(_target ${_importedTargets})
  list(FIND _depends ${_target} _indexInList)
  if(NOT "${_indexInList}" STREQUAL "-1")
    # NOTE: we need the unalias target name! CK
    string(REGEX REPLACE "([^:]+::)" "" _targetName ${_target})

    get_property(_version GLOBAL PROPERTY _CMAKE_${_targetName}_REQUIRED_VERSION)
    message(STATUS "IMPORTED_TARGETS: ${_targetName} ${_version}")
  endif()
endforeach()

# _CMAKE_dependency_REQUIRED_VERSION: >= 1.2
# _CMAKE_namespaced_dependency_REQUIRED_VERSION: >= 4.5.6
# _CMAKE_transitive_dependency_REQUIRED_VERSION: >= 7.8.9
# -- main: dependency;ns::namespaced_dependency;transitive_dependency::transitive_dependency
#
# -- PACKAGES_FOUND: dependency;namespaced_dependency;fmt;cxxopts;transitive_dependency
# -- IMPORTED_TARGETS: dependency >= 1.2
# -- IMPORTED_TARGETS: namespaced_dependency >= 4.5.6
# -- IMPORTED_TARGETS: transitive_dependency >= 7.8.9