add CMake exported interface library and Config detection file

.gitignore

@@ -33,3 +33,5 @@ MANIFEST
 /cmake/
 .cache/
 sosize-*.txt
+pybind11Config*.cmake
+pybind11Targets.cmake

CMakeLists.txt

@@ -180,6 +180,7 @@ if (PYBIND11_TEST)
 endif()
 
 include(GNUInstallDirs)
+include(CMakePackageConfigHelpers)
 
 # extract project version from source
 file(STRINGS "${PYBIND11_INCLUDE_DIR}/pybind11/common.h" pybind11_version_defines
@@ -191,10 +192,40 @@ foreach(ver ${pybind11_version_defines})
 endforeach()
 set(${PROJECT_NAME}_VERSION ${PYBIND11_VERSION_MAJOR}.${PYBIND11_VERSION_MINOR}.${PYBIND11_VERSION_PATCH})
 
+if(NOT (CMAKE_VERSION VERSION_LESS 3.0))  # CMake >= 3.0
+  # Build an interface library target:
+  add_library(pybind11 INTERFACE)
+  target_include_directories(pybind11 INTERFACE $<BUILD_INTERFACE:${PYBIND11_INCLUDE_DIR}>
+                                                $<INSTALL_INTERFACE:${CMAKE_INSTALL_INCLUDEDIR}>)
+  if(APPLE)
+      target_link_libraries(pybind11 INTERFACE "-undefined dynamic_lookup")
+  endif()
+endif()
+
 if (PYBIND11_INSTALL)
   install(FILES ${PYBIND11_HEADERS}
           DESTINATION ${CMAKE_INSTALL_INCLUDEDIR}/pybind11)
   # GNUInstallDirs "DATADIR" wrong here; CMake search path wants "share".
   set(PYBIND11_CMAKECONFIG_INSTALL_DIR "share/cmake/${PROJECT_NAME}" CACHE STRING "install path for pybind11Config.cmake")
 
+  configure_package_config_file(tools/${PROJECT_NAME}Config.cmake.in
+                                "${CMAKE_CURRENT_BINARY_DIR}/${PROJECT_NAME}Config.cmake"
+                                INSTALL_DESTINATION ${PYBIND11_CMAKECONFIG_INSTALL_DIR})
+  write_basic_package_version_file(${CMAKE_CURRENT_BINARY_DIR}/${PROJECT_NAME}ConfigVersion.cmake
+                                   VERSION ${${PROJECT_NAME}_VERSION}
+                                   COMPATIBILITY AnyNewerVersion)
+  install(FILES ${CMAKE_CURRENT_BINARY_DIR}/${PROJECT_NAME}Config.cmake
+                ${CMAKE_CURRENT_BINARY_DIR}/${PROJECT_NAME}ConfigVersion.cmake
+                tools/FindPythonLibsNew.cmake
+                tools/pybind11Tools.cmake
+          DESTINATION ${PYBIND11_CMAKECONFIG_INSTALL_DIR})
+
+  if(NOT (CMAKE_VERSION VERSION_LESS 3.0))
+    install(TARGETS pybind11
+            EXPORT "${PROJECT_NAME}Targets")
+    install(EXPORT "${PROJECT_NAME}Targets"
+            NAMESPACE "${PROJECT_NAME}::"
+            DESTINATION ${PYBIND11_CMAKECONFIG_INSTALL_DIR})
+    message(STATUS "Exporting ${PROJECT_NAME}::pybind11 interface library target version ${${PROJECT_NAME}_VERSION}")
+  endif()
 endif()

docs/compiling.rst

@@ -51,3 +51,67 @@ A working sample project, including a way to invoke CMake from :file:`setup.py`
 PyPI integration, can be found in the [cmake_example]_  repository.
 
 .. [cmake_example] https://github.com/pybind/cmake_example
+
+For CMake-based projects that don't include the pybind11
+repository internally, an external installation can be detected
+through `find_package(pybind11 ... CONFIG ...)`. See the `Config file
+<https://github.com/pybind/pybind11/blob/master/tools/pybind11Config.cmake.in>`_
+docstring for details of relevant CMake variables.
+
+Once detected, and after setting any variables to guide Python and C++
+standard detection, the aforementioned ``pybind11_add_module``
+wrapper to ``add_library`` can
+be employed as described above (after ``include(pybind11Tools)``). This
+procedure is available when using CMake >= 2.8.12. A
+working example can be found at [test_installed_module]_ .
+
+.. code-block:: cmake
+
+    cmake_minimum_required(VERSION 2.8.12)
+    project(example)
+
+    find_package(pybind11 REQUIRED)
+    pybind11_add_module(example example.cpp)
+
+.. [test_installed_module] https://github.com/pybind/pybind11/blob/master/tests/test_installed_module/CMakeLists.txt
+
+When using a version of CMake greater than 3.0, pybind11 can
+additionally be used as a special *interface library* following the call
+to ``find_package``. CMake
+variables to guide Python and C++ standard detection should be set
+*before* ``find_package``. When ``find_package`` returns, the target
+``pybind11::pybind11`` is available with pybind11 headers, Python headers
+and libraries as needed, and C++ compile definitions attached. This
+target is suitable for linking to an independently constructed (through
+``add_library``, not ``pybind11_add_module``) target in the consuming
+project. A working example can be found at [test_installed_target]_ .
+
+.. code-block:: cmake
+
+    cmake_minimum_required(VERSION 3.0)
+    project(example)
+
+    add_library(example MODULE main.cpp)
+
+    find_package(pybind11 REQUIRED)
+    target_link_libraries(example PRIVATE pybind11::pybind11)
+    set_target_properties(example PROPERTIES PREFIX "${PYTHON_MODULE_PREFIX}"
+                                             SUFFIX "${PYTHON_MODULE_EXTENSION}")
+
+.. warning::
+
+    Since pybind11 is a metatemplate library, it is crucial that certain
+    compiler flags are provided to ensure high quality code generation. In
+    contrast to the ``pybind11_add_module()`` command, the CMake interface
+    library only provides the *minimal* set of parameters to ensure that the
+    code using pybind11 compiles, but it does **not** pass these extra compiler
+    flags (i.e. this is up to you).
+
+    These include Link Time Optimization (``-flto`` on GCC/Clang/ICPC, ``/GL``
+    and ``/LTCG`` on Visual Studio). Default-hidden symbols on GCC/Clang/ICPC
+    (``-fvisibility=hidden``) and .OBJ files with many sections on Visual Studio
+    (``/bigobj``). The :ref:`FAQ <faq:symhidden>` contains an
+    explanation on why these are needed.
+
+.. [test_installed_target] https://github.com/pybind/pybind11/blob/master/tests/test_installed_target/CMakeLists.txt
+

docs/faq.rst

@@ -162,6 +162,8 @@ culprit is generally the generation of function signatures at compile time
 using C++14 template metaprogramming.
 
 
+.. _`faq:symhidden`:
+
 How can I create smaller binaries?
 ==================================
 

tools/pybind11Config.cmake.in

+# pybind11Config.cmake
+# --------------------
+#
+# PYBIND11 cmake module.
+# This module sets the following variables in your project::
+#
+#   pybind11_FOUND - true if pybind11 and all required components found on the system
+#   pybind11_VERSION - pybind11 version in format Major.Minor.Release
+#   pybind11_INCLUDE_DIRS - Directories where pybind11 and python headers are located.
+#   pybind11_INCLUDE_DIR - Directory where pybind11 headers are located.
+#   pybind11_DEFINITIONS - Definitions necessary to use pybind11, namely USING_pybind11.
+#   pybind11_LIBRARIES - compile flags and python libraries (as needed) to link against.
+#   pybind11_LIBRARY - empty.
+#   CMAKE_MODULE_PATH - appends location of accompanying FindPythonLibsNew.cmake and
+#                       pybind11Tools.cmake modules.
+#
+#
+# Available components: None
+#
+#
+# Exported targets::
+#
+# If pybind11 is found, this module defines the following :prop_tgt:`IMPORTED`
+# target. Python headers, libraries (as needed by platform), and C++ standard
+# are attached to the target. Set PythonLibsNew variables to influence
+# python detection and PYBIND11_CPP_STANDARD (-std=c++11 or -std=c++14) to
+# influence standard setting. ::
+#
+#   pybind11::pybind11 - the main pybind11 interface library (i.e., headers)
+#
+#   find_package(pybind11 CONFIG REQUIRED)
+#   message(STATUS "Found pybind11: ${pybind11_INCLUDE_DIR} (found version ${pybind11_VERSION} & Py${PYTHON_VERSION_STRING})")
+#   add_library(mylib MODULE main.cpp)
+#   target_link_libraries(mylib pybind11::pybind11)
+#
+# Suggested usage::
+#
+# find_package with version info is not recommended except for release versions. ::
+#
+#   find_package(pybind11 CONFIG)
+#   find_package(pybind11 2.0 EXACT CONFIG REQUIRED)
+#
+#
+# The following variables can be set to guide the search for this package::
+#
+#   pybind11_DIR - CMake variable, set to directory containing this Config file
+#   CMAKE_PREFIX_PATH - CMake variable, set to root directory of this package
+#   PATH - environment variable, set to bin directory of this package
+#   CMAKE_DISABLE_FIND_PACKAGE_pybind11 - CMake variable, disables
+#     find_package(pybind11) when not REQUIRED, perhaps to force internal build
+
+@PACKAGE_INIT@
+
+set(PN pybind11)
+
+# location of pybind11/pybind11.h
+set(${PN}_INCLUDE_DIR "${PACKAGE_PREFIX_DIR}/@CMAKE_INSTALL_INCLUDEDIR@")
+
+set(${PN}_LIBRARY "")
+set(${PN}_DEFINITIONS USING_${PN})
+
+check_required_components(${PN})
+
+# make detectable the FindPythonLibsNew.cmake module
+list(APPEND CMAKE_MODULE_PATH ${CMAKE_CURRENT_LIST_DIR})
+
+include(pybind11Tools)
+
+if(NOT (CMAKE_VERSION VERSION_LESS 3.0))
+#-----------------------------------------------------------------------------
+# Don't include targets if this file is being picked up by another
+# project which has already built this as a subproject
+#-----------------------------------------------------------------------------
+if(NOT TARGET ${PN}::pybind11)
+    include("${CMAKE_CURRENT_LIST_DIR}/${PN}Targets.cmake")
+
+    find_package(PythonLibsNew ${PYBIND11_PYTHON_VERSION} MODULE REQUIRED)
+    set_property(TARGET ${PN}::pybind11 APPEND PROPERTY INTERFACE_INCLUDE_DIRECTORIES ${PYTHON_INCLUDE_DIRS})
+    if(WIN32 OR CYGWIN)
+      set_property(TARGET ${PN}::pybind11 APPEND PROPERTY INTERFACE_LINK_LIBRARIES ${PYTHON_LIBRARIES})
+    endif()
+
+    select_cxx_standard()
+    set_property(TARGET ${PN}::pybind11 APPEND PROPERTY INTERFACE_COMPILE_OPTIONS "${PYBIND11_CPP_STANDARD}")
+
+    get_property(_iid TARGET ${PN}::pybind11 PROPERTY INTERFACE_INCLUDE_DIRECTORIES)
+    get_property(_ill TARGET ${PN}::pybind11 PROPERTY INTERFACE_LINK_LIBRARIES)
+    get_property(_ico TARGET ${PN}::pybind11 PROPERTY INTERFACE_COMPILE_OPTIONS)
+    set(${PN}_INCLUDE_DIRS ${_iid})
+    set(${PN}_LIBRARIES ${_ico} ${_ill})
+endif()
+endif()