CMake target missing Python in CONFIG mode

[mablanchard]

Looking for pybind11 in CMake CONFIG mode multiple times from separate directories doesn't seem to produce the same targets. In FindPython mode, the following snippet:

find_package(
  Python
  COMPONENTS
    Interpreter Development
  QUIET)
find_package(
  pybind11 CONFIG # ${PYBIND11_VERSION} EXACT
  HINTS "${pybind11_ROOT}"
  QUIET)

get_target_property(
  __linkLibraries pybind11::embed INTERFACE_LINK_LIBRARIES)
message("pybind11::embed::INTERFACE_LINK_LIBRARIES=${__linkLibraries }")

Gives from first execution in the first directory the expected:

pybind11::embed::INTERFACE_LINK_LIBRARIES=pybind11::pybind11;Python::Python

But later gives, from the second execution in another directory, the unexpected (Python::Python missing) :

pybind11::embed::INTERFACE_LINK_LIBRARIES=pybind11::pybind11

From pybind11Common.cmake comments, pybind11 CMake script shall declare regular (ie. non-global) targets. It seems like pybind11NewTools.cmake is using a global include guard though, which explains why the second pybind11::embed targets does not get linked with Python::Python...

[mablanchard]

Possible workaround could be, with CMake >= 3.24.0 to enforce find_package() to be promoted GLOBAL. Not sure if anything is possible with older CMake.