fix: relink pybind11::embed after partial FindPython

tests/test_cmake_build/installed_embed/CMakeLists.txt

@@ -2,9 +2,32 @@ cmake_minimum_required(VERSION 3.15...4.2)
 
 project(test_installed_embed CXX)
 
+if(PYBIND11_FINDPYTHON)
+  find_package(
+    Python
+    COMPONENTS Interpreter
+    REQUIRED)
+endif()
 find_package(pybind11 CONFIG REQUIRED)
 message(STATUS "Found pybind11 v${pybind11_VERSION}: ${pybind11_INCLUDE_DIRS}")
 
+if(PYBIND11_FINDPYTHON)
+  if(CMAKE_VERSION VERSION_LESS 3.18)
+    find_package(Python REQUIRED COMPONENTS Development)
+  else()
+    find_package(
+      Python REQUIRED
+      COMPONENTS Development.Module
+      OPTIONAL_COMPONENTS Development.Embed)
+  endif()
+
+  get_target_property(_pybind11_embed_links pybind11::embed INTERFACE_LINK_LIBRARIES)
+  if(TARGET Python::Python AND NOT "Python::Python" IN_LIST _pybind11_embed_links)
+    message(
+      FATAL_ERROR "pybind11::embed must link to Python::Python when Python::Python is available")
+  endif()
+endif()
+
 add_executable(test_installed_embed ../embed.cpp)
 target_link_libraries(test_installed_embed PRIVATE pybind11::embed)
 set_target_properties(test_installed_embed PROPERTIES OUTPUT_NAME test_cmake_build)

tests/test_cmake_build/subdirectory_embed/CMakeLists.txt

@@ -2,6 +2,13 @@ cmake_minimum_required(VERSION 3.15...4.2)
 
 project(test_subdirectory_embed CXX)
 
+if(PYBIND11_FINDPYTHON)
+  find_package(
+    Python
+    COMPONENTS Interpreter
+    REQUIRED)
+endif()
+
 set(PYBIND11_INSTALL
     ON
     CACHE BOOL "")
@@ -15,6 +22,23 @@ endif()
 
 add_subdirectory("${pybind11_SOURCE_DIR}" pybind11)
 
+if(PYBIND11_FINDPYTHON)
+  if(CMAKE_VERSION VERSION_LESS 3.18)
+    find_package(Python REQUIRED COMPONENTS Development)
+  else()
+    find_package(
+      Python REQUIRED
+      COMPONENTS Development.Module
+      OPTIONAL_COMPONENTS Development.Embed)
+  endif()
+
+  get_target_property(_pybind11_embed_links pybind11::embed INTERFACE_LINK_LIBRARIES)
+  if(TARGET Python::Python AND NOT "Python::Python" IN_LIST _pybind11_embed_links)
+    message(
+      FATAL_ERROR "pybind11::embed must link to Python::Python when Python::Python is available")
+  endif()
+endif()
+
 # Test basic target functionality
 add_executable(test_subdirectory_embed ../embed.cpp)
 target_link_libraries(test_subdirectory_embed PRIVATE pybind11::embed)

tools/pybind11NewTools.cmake

@@ -18,14 +18,48 @@ else()
   set(_pybind11_quiet "")
 endif()
 
-if(NOT Python_FOUND AND NOT Python3_FOUND)
-  if(NOT DEFINED Python_FIND_IMPLEMENTATIONS)
-    set(Python_FIND_IMPLEMENTATIONS CPython PyPy)
+if(Python_FOUND)
+  set(_pybind11_findpython_package Python)
+elseif(Python3_FOUND)
+  set(_pybind11_findpython_package Python3)
+else()
+  set(_pybind11_findpython_package Python)
+endif()
+
+set(_pybind11_findpython_required FALSE)
+if(DEFINED ${_pybind11_findpython_package}_FOUND)
+  if(${_pybind11_findpython_package}_FOUND)
+    if(NOT _PYBIND11_CROSSCOMPILING AND NOT DEFINED ${_pybind11_findpython_package}_EXECUTABLE)
+      set(_pybind11_findpython_required TRUE)
+    endif()
+
+    if(CMAKE_VERSION VERSION_LESS 3.18) # Development.Module is not available yet
+      if(NOT DEFINED ${_pybind11_findpython_package}_INCLUDE_DIRS
+         OR NOT TARGET ${_pybind11_findpython_package}::Python)
+        set(_pybind11_findpython_required TRUE)
+      endif()
+    else()
+      if(NOT DEFINED ${_pybind11_findpython_package}_INCLUDE_DIRS
+         OR NOT TARGET ${_pybind11_findpython_package}::Module
+         OR NOT TARGET ${_pybind11_findpython_package}::Python)
+        set(_pybind11_findpython_required TRUE)
+      endif()
+    endif()
+  else()
+    set(_pybind11_findpython_required TRUE)
+  endif()
+else()
+  set(_pybind11_findpython_required TRUE)
+endif()
+
+if(_pybind11_findpython_required)
+  if(NOT DEFINED ${_pybind11_findpython_package}_FIND_IMPLEMENTATIONS)
+    set(${_pybind11_findpython_package}_FIND_IMPLEMENTATIONS CPython PyPy)
   endif()
 
   # GitHub Actions like activation
-  if(NOT DEFINED Python_ROOT_DIR AND DEFINED ENV{pythonLocation})
-    set(Python_ROOT_DIR "$ENV{pythonLocation}")
+  if(NOT DEFINED ${_pybind11_findpython_package}_ROOT_DIR AND DEFINED ENV{pythonLocation})
+    set(${_pybind11_findpython_package}_ROOT_DIR "$ENV{pythonLocation}")
   endif()
 
   # Interpreter should not be found when cross-compiling
@@ -44,46 +78,49 @@ if(NOT Python_FOUND AND NOT Python3_FOUND)
 
   # Callers need to be able to access Python_EXECUTABLE
   set(_pybind11_global_keyword "")
-  if(NOT is_config AND NOT DEFINED Python_ARTIFACTS_INTERACTIVE)
-    set(Python_ARTIFACTS_INTERACTIVE TRUE)
+  set(_pybind11_artifacts_interactive ${_pybind11_findpython_package}_ARTIFACTS_INTERACTIVE)
+  if(NOT is_config AND NOT DEFINED ${_pybind11_artifacts_interactive})
+    set(${_pybind11_artifacts_interactive} TRUE)
     if(NOT CMAKE_VERSION VERSION_LESS 3.24)
       set(_pybind11_global_keyword "GLOBAL")
     endif()
   endif()
 
   find_package(
-    Python 3.8 REQUIRED COMPONENTS ${_pybind11_interp_component} ${_pybind11_dev_component}
-                                   ${_pybind11_quiet} ${_pybind11_global_keyword})
+    ${_pybind11_findpython_package} 3.8 REQUIRED
+    COMPONENTS ${_pybind11_interp_component} ${_pybind11_dev_component} ${_pybind11_quiet}
+               ${_pybind11_global_keyword})
 
   # If we are in submodule mode, export the Python targets to global targets.
   # If this behavior is not desired, FindPython _before_ pybind11.
   if(NOT is_config
-     AND Python_ARTIFACTS_INTERACTIVE
+     AND ${_pybind11_artifacts_interactive}
      AND _pybind11_global_keyword STREQUAL "")
-    if(TARGET Python::Python)
-      set_property(TARGET Python::Python PROPERTY IMPORTED_GLOBAL TRUE)
+    if(TARGET ${_pybind11_findpython_package}::Python)
+      set_property(TARGET ${_pybind11_findpython_package}::Python PROPERTY IMPORTED_GLOBAL TRUE)
     endif()
-    if(TARGET Python::Interpreter)
-      set_property(TARGET Python::Interpreter PROPERTY IMPORTED_GLOBAL TRUE)
+    if(TARGET ${_pybind11_findpython_package}::Interpreter)
+      set_property(TARGET ${_pybind11_findpython_package}::Interpreter PROPERTY IMPORTED_GLOBAL
+                                                                                TRUE)
     endif()
-    if(TARGET Python::Module)
-      set_property(TARGET Python::Module PROPERTY IMPORTED_GLOBAL TRUE)
+    if(TARGET ${_pybind11_findpython_package}::Module)
+      set_property(TARGET ${_pybind11_findpython_package}::Module PROPERTY IMPORTED_GLOBAL TRUE)
     endif()
   endif()
 
   # Explicitly export version for callers (including our own functions)
-  if(NOT is_config AND Python_ARTIFACTS_INTERACTIVE)
-    set(Python_VERSION
-        "${Python_VERSION}"
+  if(NOT is_config AND ${_pybind11_artifacts_interactive})
+    set(${_pybind11_findpython_package}_VERSION
+        "${${_pybind11_findpython_package}_VERSION}"
         CACHE INTERNAL "")
-    set(Python_VERSION_MAJOR
-        "${Python_VERSION_MAJOR}"
+    set(${_pybind11_findpython_package}_VERSION_MAJOR
+        "${${_pybind11_findpython_package}_VERSION_MAJOR}"
         CACHE INTERNAL "")
-    set(Python_VERSION_MINOR
-        "${Python_VERSION_MINOR}"
+    set(${_pybind11_findpython_package}_VERSION_MINOR
+        "${${_pybind11_findpython_package}_VERSION_MINOR}"
         CACHE INTERNAL "")
-    set(Python_VERSION_PATCH
-        "${Python_VERSION_PATCH}"
+    set(${_pybind11_findpython_package}_VERSION_PATCH
+        "${${_pybind11_findpython_package}_VERSION_PATCH}"
         CACHE INTERNAL "")
   endif()
 endif()