update pybind cmake files

python/FindPythonLibsNew.cmake

@@ -52,151 +52,236 @@
 
 # Checking for the extension makes sure that `LibsNew` was found and not just `Libs`.
 if(PYTHONLIBS_FOUND AND PYTHON_MODULE_EXTENSION)
-    return()
+  return()
 endif()
 
-# Use the Python interpreter to find the libs.
-if(PythonLibsNew_FIND_REQUIRED)
-    find_package(PythonInterp ${PythonLibsNew_FIND_VERSION} REQUIRED)
+if(PythonLibsNew_FIND_QUIETLY)
+  set(_pythonlibs_quiet QUIET)
 else()
-    find_package(PythonInterp ${PythonLibsNew_FIND_VERSION})
+  set(_pythonlibs_quiet "")
+endif()
+
+if(PythonLibsNew_FIND_REQUIRED)
+  set(_pythonlibs_required REQUIRED)
+endif()
+
+# Check to see if the `python` command is present and from a virtual
+# environment, conda, or GHA activation - if it is, try to use that.
+
+if(NOT DEFINED PYTHON_EXECUTABLE)
+  if(DEFINED ENV{VIRTUAL_ENV})
+    find_program(
+      PYTHON_EXECUTABLE python
+      PATHS "$ENV{VIRTUAL_ENV}" "$ENV{VIRTUAL_ENV}/bin"
+      NO_DEFAULT_PATH)
+  elseif(DEFINED ENV{CONDA_PREFIX})
+    find_program(
+      PYTHON_EXECUTABLE python
+      PATHS "$ENV{CONDA_PREFIX}" "$ENV{CONDA_PREFIX}/bin"
+      NO_DEFAULT_PATH)
+  elseif(DEFINED ENV{pythonLocation})
+    find_program(
+      PYTHON_EXECUTABLE python
+      PATHS "$ENV{pythonLocation}" "$ENV{pythonLocation}/bin"
+      NO_DEFAULT_PATH)
+  endif()
+  if(NOT PYTHON_EXECUTABLE)
+    unset(PYTHON_EXECUTABLE)
+  endif()
+endif()
+
+# Use the Python interpreter to find the libs.
+if(NOT PythonLibsNew_FIND_VERSION)
+  set(PythonLibsNew_FIND_VERSION "3.6")
 endif()
 
+find_package(PythonInterp ${PythonLibsNew_FIND_VERSION} ${_pythonlibs_required}
+             ${_pythonlibs_quiet})
+
 if(NOT PYTHONINTERP_FOUND)
-    set(PYTHONLIBS_FOUND FALSE)
-    set(PythonLibsNew_FOUND FALSE)
-    return()
+  set(PYTHONLIBS_FOUND FALSE)
+  set(PythonLibsNew_FOUND FALSE)
+  return()
 endif()
 
-# According to http://stackoverflow.com/questions/646518/python-how-to-detect-debug-interpreter
+# According to https://stackoverflow.com/questions/646518/python-how-to-detect-debug-interpreter
 # testing whether sys has the gettotalrefcount function is a reliable, cross-platform
 # way to detect a CPython debug interpreter.
 #
 # The library suffix is from the config var LDVERSION sometimes, otherwise
 # VERSION. VERSION will typically be like "2.7" on unix, and "27" on windows.
-execute_process(COMMAND "${PYTHON_EXECUTABLE}" "-c"
-    "from distutils import sysconfig as s;import sys;import struct;
+execute_process(
+  COMMAND
+    "${PYTHON_EXECUTABLE}" "-c" "
+import sys;import struct;
+import sysconfig as s
+USE_SYSCONFIG = sys.version_info >= (3, 10)
+if not USE_SYSCONFIG:
+    from distutils import sysconfig as ds
 print('.'.join(str(v) for v in sys.version_info));
 print(sys.prefix);
-print(s.get_python_inc(plat_specific=True));
-print(s.get_python_lib(plat_specific=True));
-print(s.get_config_var('SO'));
+if USE_SYSCONFIG:
+    scheme = s.get_default_scheme()
+    if scheme == 'posix_local':
+        # Debian's default scheme installs to /usr/local/ but we want to find headers in /usr/
+        scheme = 'posix_prefix'
+    print(s.get_path('platinclude', scheme))
+    print(s.get_path('platlib'))
+    print(s.get_config_var('EXT_SUFFIX') or s.get_config_var('SO'))
+else:
+    print(ds.get_python_inc(plat_specific=True));
+    print(ds.get_python_lib(plat_specific=True));
+    print(ds.get_config_var('EXT_SUFFIX') or ds.get_config_var('SO'));
 print(hasattr(sys, 'gettotalrefcount')+0);
 print(struct.calcsize('@P'));
 print(s.get_config_var('LDVERSION') or s.get_config_var('VERSION'));
 print(s.get_config_var('LIBDIR') or '');
 print(s.get_config_var('MULTIARCH') or '');
 "
-    RESULT_VARIABLE _PYTHON_SUCCESS
-    OUTPUT_VARIABLE _PYTHON_VALUES
-    ERROR_VARIABLE _PYTHON_ERROR_VALUE)
+  RESULT_VARIABLE _PYTHON_SUCCESS
+  OUTPUT_VARIABLE _PYTHON_VALUES
+  ERROR_VARIABLE _PYTHON_ERROR_VALUE)
 
 if(NOT _PYTHON_SUCCESS MATCHES 0)
-    if(PythonLibsNew_FIND_REQUIRED)
-        message(FATAL_ERROR
-            "Python config failure:\n${_PYTHON_ERROR_VALUE}")
-    endif()
-    set(PYTHONLIBS_FOUND FALSE)
-    set(PythonLibsNew_FOUND FALSE)
-    return()
+  if(PythonLibsNew_FIND_REQUIRED)
+    message(FATAL_ERROR "Python config failure:\n${_PYTHON_ERROR_VALUE}")
+  endif()
+  set(PYTHONLIBS_FOUND FALSE)
+  set(PythonLibsNew_FOUND FALSE)
+  return()
 endif()
 
+option(
+  PYBIND11_PYTHONLIBS_OVERWRITE
+  "Overwrite cached values read from Python library (classic search). Turn off if cross-compiling and manually setting these values."
+  ON)
+# Can manually set values when cross-compiling
+macro(_PYBIND11_GET_IF_UNDEF lst index name)
+  if(PYBIND11_PYTHONLIBS_OVERWRITE OR NOT DEFINED "${name}")
+    list(GET "${lst}" "${index}" "${name}")
+  endif()
+endmacro()
+
 # Convert the process output into a list
 if(WIN32)
-    string(REGEX REPLACE "\\\\" "/" _PYTHON_VALUES ${_PYTHON_VALUES})
+  string(REGEX REPLACE "\\\\" "/" _PYTHON_VALUES ${_PYTHON_VALUES})
 endif()
 string(REGEX REPLACE ";" "\\\\;" _PYTHON_VALUES ${_PYTHON_VALUES})
 string(REGEX REPLACE "\n" ";" _PYTHON_VALUES ${_PYTHON_VALUES})
-list(GET _PYTHON_VALUES 0 _PYTHON_VERSION_LIST)
-list(GET _PYTHON_VALUES 1 PYTHON_PREFIX)
-list(GET _PYTHON_VALUES 2 PYTHON_INCLUDE_DIR)
-list(GET _PYTHON_VALUES 3 PYTHON_SITE_PACKAGES)
-list(GET _PYTHON_VALUES 4 PYTHON_MODULE_EXTENSION)
-list(GET _PYTHON_VALUES 5 PYTHON_IS_DEBUG)
-list(GET _PYTHON_VALUES 6 PYTHON_SIZEOF_VOID_P)
-list(GET _PYTHON_VALUES 7 PYTHON_LIBRARY_SUFFIX)
-list(GET _PYTHON_VALUES 8 PYTHON_LIBDIR)
-list(GET _PYTHON_VALUES 9 PYTHON_MULTIARCH)
+_pybind11_get_if_undef(_PYTHON_VALUES 0 _PYTHON_VERSION_LIST)
+_pybind11_get_if_undef(_PYTHON_VALUES 1 PYTHON_PREFIX)
+_pybind11_get_if_undef(_PYTHON_VALUES 2 PYTHON_INCLUDE_DIR)
+_pybind11_get_if_undef(_PYTHON_VALUES 3 PYTHON_SITE_PACKAGES)
+_pybind11_get_if_undef(_PYTHON_VALUES 4 PYTHON_MODULE_EXTENSION)
+_pybind11_get_if_undef(_PYTHON_VALUES 5 PYTHON_IS_DEBUG)
+_pybind11_get_if_undef(_PYTHON_VALUES 6 PYTHON_SIZEOF_VOID_P)
+_pybind11_get_if_undef(_PYTHON_VALUES 7 PYTHON_LIBRARY_SUFFIX)
+_pybind11_get_if_undef(_PYTHON_VALUES 8 PYTHON_LIBDIR)
+_pybind11_get_if_undef(_PYTHON_VALUES 9 PYTHON_MULTIARCH)
 
 # Make sure the Python has the same pointer-size as the chosen compiler
 # Skip if CMAKE_SIZEOF_VOID_P is not defined
-if(CMAKE_SIZEOF_VOID_P AND (NOT "${PYTHON_SIZEOF_VOID_P}" STREQUAL "${CMAKE_SIZEOF_VOID_P}"))
-    if(PythonLibsNew_FIND_REQUIRED)
-        math(EXPR _PYTHON_BITS "${PYTHON_SIZEOF_VOID_P} * 8")
-        math(EXPR _CMAKE_BITS "${CMAKE_SIZEOF_VOID_P} * 8")
-        message(FATAL_ERROR
-            "Python config failure: Python is ${_PYTHON_BITS}-bit, "
-            "chosen compiler is  ${_CMAKE_BITS}-bit")
-    endif()
-    set(PYTHONLIBS_FOUND FALSE)
-    set(PythonLibsNew_FOUND FALSE)
-    return()
+# This should be skipped for (non-Apple) cross-compiles (like EMSCRIPTEN)
+if(NOT CMAKE_CROSSCOMPILING
+   AND CMAKE_SIZEOF_VOID_P
+   AND (NOT "${PYTHON_SIZEOF_VOID_P}" STREQUAL "${CMAKE_SIZEOF_VOID_P}"))
+  if(PythonLibsNew_FIND_REQUIRED)
+    math(EXPR _PYTHON_BITS "${PYTHON_SIZEOF_VOID_P} * 8")
+    math(EXPR _CMAKE_BITS "${CMAKE_SIZEOF_VOID_P} * 8")
+    message(FATAL_ERROR "Python config failure: Python is ${_PYTHON_BITS}-bit, "
+                        "chosen compiler is  ${_CMAKE_BITS}-bit")
+  endif()
+  set(PYTHONLIBS_FOUND FALSE)
+  set(PythonLibsNew_FOUND FALSE)
+  return()
 endif()
 
 # The built-in FindPython didn't always give the version numbers
 string(REGEX REPLACE "\\." ";" _PYTHON_VERSION_LIST ${_PYTHON_VERSION_LIST})
 list(GET _PYTHON_VERSION_LIST 0 PYTHON_VERSION_MAJOR)
 list(GET _PYTHON_VERSION_LIST 1 PYTHON_VERSION_MINOR)
 list(GET _PYTHON_VERSION_LIST 2 PYTHON_VERSION_PATCH)
+set(PYTHON_VERSION "${PYTHON_VERSION_MAJOR}.${PYTHON_VERSION_MINOR}.${PYTHON_VERSION_PATCH}")
 
 # Make sure all directory separators are '/'
 string(REGEX REPLACE "\\\\" "/" PYTHON_PREFIX "${PYTHON_PREFIX}")
 string(REGEX REPLACE "\\\\" "/" PYTHON_INCLUDE_DIR "${PYTHON_INCLUDE_DIR}")
 string(REGEX REPLACE "\\\\" "/" PYTHON_SITE_PACKAGES "${PYTHON_SITE_PACKAGES}")
 
-if(CMAKE_HOST_WIN32 AND NOT (MINGW AND DEFINED ENV{MSYSTEM}))
-    set(PYTHON_LIBRARY
-        "${PYTHON_PREFIX}/libs/Python${PYTHON_LIBRARY_SUFFIX}.lib")
-
-    # when run in a venv, PYTHON_PREFIX points to it. But the libraries remain in the
-    # original python installation. They may be found relative to PYTHON_INCLUDE_DIR.
-    if(NOT EXISTS "${PYTHON_LIBRARY}")
-        get_filename_component(_PYTHON_ROOT ${PYTHON_INCLUDE_DIR} DIRECTORY)
-        set(PYTHON_LIBRARY
-            "${_PYTHON_ROOT}/libs/Python${PYTHON_LIBRARY_SUFFIX}.lib")
-    endif()
+if(DEFINED PYTHON_LIBRARY)
+  # Don't write to PYTHON_LIBRARY if it's already set
+elseif(CMAKE_HOST_WIN32)
+  set(PYTHON_LIBRARY "${PYTHON_PREFIX}/libs/python${PYTHON_LIBRARY_SUFFIX}.lib")
 
-    # raise an error if the python libs are still not found.
-    if(NOT EXISTS "${PYTHON_LIBRARY}")
-        message(FATAL_ERROR "Python libraries not found")
-    endif()
+  # when run in a venv, PYTHON_PREFIX points to it. But the libraries remain in the
+  # original python installation. They may be found relative to PYTHON_INCLUDE_DIR.
+  if(NOT EXISTS "${PYTHON_LIBRARY}")
+    get_filename_component(_PYTHON_ROOT ${PYTHON_INCLUDE_DIR} DIRECTORY)
+    set(PYTHON_LIBRARY "${_PYTHON_ROOT}/libs/python${PYTHON_LIBRARY_SUFFIX}.lib")
+  endif()
 
-else()
+  # if we are in MSYS & MINGW, and we didn't find windows python lib, look for system python lib
+  if(DEFINED ENV{MSYSTEM}
+     AND MINGW
+     AND NOT EXISTS "${PYTHON_LIBRARY}")
     if(PYTHON_MULTIARCH)
-        set(_PYTHON_LIBS_SEARCH "${PYTHON_LIBDIR}/${PYTHON_MULTIARCH}" "${PYTHON_LIBDIR}")
+      set(_PYTHON_LIBS_SEARCH "${PYTHON_LIBDIR}/${PYTHON_MULTIARCH}" "${PYTHON_LIBDIR}")
     else()
-        set(_PYTHON_LIBS_SEARCH "${PYTHON_LIBDIR}")
-    endif()
-    #message(STATUS "Searching for Python libs in ${_PYTHON_LIBS_SEARCH}")
-    # Probably this needs to be more involved. It would be nice if the config
-    # information the python interpreter itself gave us were more complete.
-    find_library(PYTHON_LIBRARY
-        NAMES "python${PYTHON_LIBRARY_SUFFIX}"
-        PATHS ${_PYTHON_LIBS_SEARCH}
-        NO_DEFAULT_PATH)
-
-    # If all else fails, just set the name/version and let the linker figure out the path.
-    if(NOT PYTHON_LIBRARY)
-        set(PYTHON_LIBRARY python${PYTHON_LIBRARY_SUFFIX})
+      set(_PYTHON_LIBS_SEARCH "${PYTHON_LIBDIR}")
     endif()
+    unset(PYTHON_LIBRARY)
+    find_library(
+      PYTHON_LIBRARY
+      NAMES "python${PYTHON_LIBRARY_SUFFIX}"
+      PATHS ${_PYTHON_LIBS_SEARCH}
+      NO_DEFAULT_PATH)
+  endif()
+
+  # raise an error if the python libs are still not found.
+  if(NOT EXISTS "${PYTHON_LIBRARY}")
+    message(FATAL_ERROR "Python libraries not found")
+  endif()
+
+else()
+  if(PYTHON_MULTIARCH)
+    set(_PYTHON_LIBS_SEARCH "${PYTHON_LIBDIR}/${PYTHON_MULTIARCH}" "${PYTHON_LIBDIR}")
+  else()
+    set(_PYTHON_LIBS_SEARCH "${PYTHON_LIBDIR}")
+  endif()
+  #message(STATUS "Searching for Python libs in ${_PYTHON_LIBS_SEARCH}")
+  # Probably this needs to be more involved. It would be nice if the config
+  # information the python interpreter itself gave us were more complete.
+  find_library(
+    PYTHON_LIBRARY
+    NAMES "python${PYTHON_LIBRARY_SUFFIX}"
+    PATHS ${_PYTHON_LIBS_SEARCH}
+    NO_DEFAULT_PATH)
+
+  # If all else fails, just set the name/version and let the linker figure out the path.
+  if(NOT PYTHON_LIBRARY)
+    set(PYTHON_LIBRARY python${PYTHON_LIBRARY_SUFFIX})
+  endif()
 endif()
 
-MARK_AS_ADVANCED(
-  PYTHON_LIBRARY
-  PYTHON_INCLUDE_DIR
-)
+mark_as_advanced(PYTHON_LIBRARY PYTHON_INCLUDE_DIR)
 
 # We use PYTHON_INCLUDE_DIR, PYTHON_LIBRARY and PYTHON_DEBUG_LIBRARY for the
 # cache entries because they are meant to specify the location of a single
 # library. We now set the variables listed by the documentation for this
 # module.
-SET(PYTHON_INCLUDE_DIRS "${PYTHON_INCLUDE_DIR}")
-SET(PYTHON_LIBRARIES "${PYTHON_LIBRARY}")
-SET(PYTHON_DEBUG_LIBRARIES "${PYTHON_DEBUG_LIBRARY}")
+set(PYTHON_INCLUDE_DIRS "${PYTHON_INCLUDE_DIR}")
+set(PYTHON_LIBRARIES "${PYTHON_LIBRARY}")
+if(NOT PYTHON_DEBUG_LIBRARY)
+  set(PYTHON_DEBUG_LIBRARY "")
+endif()
+set(PYTHON_DEBUG_LIBRARIES "${PYTHON_DEBUG_LIBRARY}")
 
-find_package_message(PYTHON
-    "Found PythonLibs: ${PYTHON_LIBRARY}"
-    "${PYTHON_EXECUTABLE}${PYTHON_VERSION}")
+find_package_message(PYTHON "Found PythonLibs: ${PYTHON_LIBRARIES}"
+                     "${PYTHON_EXECUTABLE}${PYTHON_VERSION_STRING}")
 
 set(PYTHONLIBS_FOUND TRUE)
 set(PythonLibsNew_FOUND TRUE)
+
+if(NOT PYTHON_MODULE_PREFIX)
+  set(PYTHON_MODULE_PREFIX "")
+endif()