Modernize cmake build

Add a CMake super project that includes the shiboken2, PySide2 and
pyside2-tools subprojects, so that it's possible to build everything
from Qt Creator (or any other IDE that supports CMake)
with minimal set up effort, and thus inform the IDE CMake integration
of all relevant files, for easier code editing, navigation and
refactoring.

This also lays the foundation for allowing 3rd parties to use the
shiboken2 generator to generate custom modules. This is
achieved by eliminating various hardcoded paths for libraries and
include directories.

Start using CMake targets throughout the build code to correctly
propagate link flags and include dirs for libshiboken and
shiboken2 executable targets. Same for the libpyside target.

Generate two separate cmake config files (build-tree / install-tree)
that can be used with find_package(Shiboken2), to make sure that
the PySide2 project can be built as part of the super project build.
This is currently the only way I've found to allow the super build
to work.
Note that for the build-tree find_package() to work, the
CMAKE_MODULE_PATH has to be adjusted in the super project file.

The generated config files contain variables and logic that allow
usage of the installed shiboken package in downstream projects
(PySide2). This involves things like getting the includes and
libraries for the currently found python interpreter, the shiboken
build type (release or debug), was shiboken built with limited
api support, etc.

Generate 2 separate (build-tree and install-tree) config files
for PySide2, similar to how it's done for the shiboken case, for
pyside2-tools to build correctly.

Install shiboken2 target files using install(EXPORT)
to allow building PySide2 with an installed Shiboken2 package
(as opposed to one that is built as part of the super project).
Same with PySide2 targets for pyside2-tools subproject.

Make sure not to redefine uninstall targets if they are already
defined.

Add a --shorter-paths setup.py option, which would be used by
the Windows CI, to circumvent creating paths that are too long,
and thus avoiding build issues.

Output the build characteristics / classifiers into the generated
build_history/YYYY-MM-DD_AAAAAA/build_dir.txt file, so it can be
used by the test runner to properly filter out blacklisted
tests. This was necessary due to the shorter paths options.

Fix various issues regarding target includes and library
dependencies.

Remove certain duplicated cmake code (like limited api check and build
type checks) in PySide2, given that that information will now be
present in the exported shiboken2 config file.

Include a short README.cmake.md file that describes how to build
the super project.

References used
https://rix0r.nl/blog/2015/08/13/cmake-guide/
https://pabloariasal.github.io/2018/02/19/its-time-to-do-cmake-right/
https://gist.github.com/mbinna/c61dbb39bca0e4fb7d1f73b0d66a4fd1
https://cliutils.gitlab.io/modern-cmake/chapters/basics/functions.html
https://cmake.org/cmake/help/v3.0/manual/cmake-packages.7.html
https://github.com/ComicSansMS/libstratcom/blob/master/CMakeLists.txt

Abandoned approach using ExternalProject references:
https://cmake.org/cmake/help/latest/module/ExternalProject.html
https://stackoverflow.com/questions/44990964/how-to-perform-cmakefind-package-at-build-stage-only

Fixes: PYSIDE-919
Change-Id: Iaa15d20b279a04c5e16ce2795d03f912bc44a389
Reviewed-by: Cristian Maureira-Fredes <cristian.maureira-fredes@qt.io>

1 files changed, 23 insertions, 73 deletions

diff --git a/sources/shiboken2/CMakeLists.txt b/sources/shiboken2/CMakeLists.txt
index 01efddaa5..1e52c4297 100644
--- a/sources/shiboken2/CMakeLists.txt
+++ b/sources/shiboken2/CMakeLists.txt
@@ -5,14 +5,14 @@ include(CheckIncludeFileCXX)
 cmake_minimum_required(VERSION 3.1)
 cmake_policy(VERSION 3.1)
 
-set(CMAKE_MODULE_PATH ${CMAKE_SOURCE_DIR}/../cmake_helpers/
-                      ${CMAKE_MODULE_PATH})
+list(APPEND CMAKE_MODULE_PATH "${CMAKE_CURRENT_SOURCE_DIR}/../cmake_helpers/")
+list(APPEND CMAKE_MODULE_PATH "${CMAKE_CURRENT_SOURCE_DIR}/data/")
+
 include(helpers)
+include(shiboken_helpers)
 
 find_package(Qt5 5.12 REQUIRED COMPONENTS Core Xml XmlPatterns)
 
-add_definitions(${Qt5Core_DEFINITIONS})
-
 option(BUILD_TESTS "Build tests." TRUE)
 option(USE_PYTHON_VERSION "Use specific python version to build shiboken2." "")
 
@@ -36,11 +36,9 @@ if (QUIET_BUILD)
 endif()
 
 if (USE_PYTHON_VERSION)
-    find_package(PythonInterp ${USE_PYTHON_VERSION} REQUIRED)
-    find_package(PythonLibs ${USE_PYTHON_VERSION} REQUIRED)
+    shiboken_find_required_python(${USE_PYTHON_VERSION})
 else()
-    find_package(PythonInterp 2.7)
-    find_package(PythonLibs 2.7)
+    shiboken_find_required_python()
 endif()
 
 macro(get_python_arch)
@@ -153,7 +151,7 @@ if (NOT CLANG_INCLUDE_FOUND)
         package? (e.g. libclang-6.0-dev)")
 endif()
 
-set(SHIBOKEN_VERSION_FILE_PATH "${CMAKE_SOURCE_DIR}/shiboken_version.py")
+set(SHIBOKEN_VERSION_FILE_PATH "${CMAKE_CURRENT_SOURCE_DIR}/shiboken_version.py")
 set_property(DIRECTORY APPEND PROPERTY CMAKE_CONFIGURE_DEPENDS
   ${SHIBOKEN_VERSION_FILE_PATH}
 )
@@ -219,34 +217,7 @@ endif()
 option(FORCE_LIMITED_API "Enable the limited API." "yes")
 set(PYTHON_LIMITED_API 0)
 
-# On Windows, PYTHON_LIBRARIES can be a list. Example:
-#    optimized;C:/Python36/libs/python36.lib;debug;C:/Python36/libs/python36_d.lib
-# On other platforms, this result is not used at all.
-execute_process(
-    COMMAND ${PYTHON_EXECUTABLE} -c "if True:
-        for lib in '${PYTHON_LIBRARIES}'.split(';'):
-            if '/' in lib:
-                prefix, py = lib.rsplit('/', 1)
-                if py.startswith('python3'):
-                    print(prefix + '/python3.lib')
-                    break
-        "
-    OUTPUT_VARIABLE PYTHON_LIMITED_LIBRARIES
-    OUTPUT_STRIP_TRAILING_WHITESPACE)
-
-if(FORCE_LIMITED_API STREQUAL "yes")
-    if (${PYTHON_VERSION_MAJOR} EQUAL 3 AND ${PYTHON_VERSION_MINOR} GREATER 4)
-        # GREATER_EQUAL is available only from cmake 3.7 on. We mean python 3.5 .
-        add_definitions("-DPy_LIMITED_API=0x03050000")
-        set(PYTHON_LIMITED_API 1)
-    endif()
-    if(WIN32)
-        if (${PYTHON_VERSION_MAJOR} EQUAL 3 AND ${PYTHON_VERSION_MINOR} GREATER 4)
-            # PYSIDE-560: XXX maybe add an option to setup.py as override
-            set(SBK_PYTHON_LIBRARIES ${PYTHON_LIMITED_LIBRARIES})
-        endif()
-    endif()
-endif()
+shiboken_check_if_limited_api()
 
 if (PYTHON_LIMITED_API)
     if (WIN32 AND NOT EXISTS "${PYTHON_LIMITED_LIBRARIES}")
@@ -270,8 +241,10 @@ if (NOT PYTHON_CONFIG_SUFFIX)
           else()
               set(PYTHON_EXTENSION_SUFFIX ".abi3")
           endif()
+          set(PYTHON_CONFIG_SUFFIX ".abi3")
+      else()
+          set(PYTHON_CONFIG_SUFFIX "${PYTHON_EXTENSION_SUFFIX}")
       endif()
-      set(PYTHON_CONFIG_SUFFIX "${PYTHON_EXTENSION_SUFFIX}")
   endif()
 endif()
 
@@ -285,6 +258,10 @@ if (NOT PYTHON_SHARED_LIBRARY_SUFFIX)
   endif()
 endif()
 
+if (NOT PYTHON_CONFIG_SUFFIX)
+    message(FATAL_ERROR
+        "PYTHON_CONFIG_SUFFIX is empty. It should never be empty. Please file a bug report.")
+endif()
 
 message(STATUS "PYTHON_EXTENSION_SUFFIX:      ${PYTHON_EXTENSION_SUFFIX}")
 message(STATUS "PYTHON_CONFIG_SUFFIX:         ${PYTHON_CONFIG_SUFFIX}")
@@ -318,7 +295,6 @@ else()
     set(CMAKE_CXX_FLAGS_DEBUG "-g")
     option(ENABLE_GCC_OPTIMIZATION "Enable specific GCC flags to optimization library size and performance. Only available on Release Mode" 0)
     if(ENABLE_GCC_OPTIMIZATION)
-        set(CMAKE_BUILD_TYPE Release)
         set(CMAKE_CXX_FLAGS_RELEASE "-DNDEBUG -Os -Wl,-O1")
         if(NOT CMAKE_HOST_APPLE)
             set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wl,--hash-style=gnu")
@@ -334,7 +310,8 @@ set(CMAKE_CXX_STANDARD 11)
 set(CMAKE_CXX_STANDARD_REQUIRED ON)
 
 set(LIB_SUFFIX "" CACHE STRING "Define suffix of directory name (32/64)" )
-set(LIB_INSTALL_DIR "${CMAKE_INSTALL_PREFIX}/lib${LIB_SUFFIX}" CACHE PATH "The subdirectory relative to the install prefix where libraries will be installed (default is /lib${LIB_SUFFIX})" FORCE)
+set(LIB_INSTALL_DIR "lib${LIB_SUFFIX}" CACHE PATH "The subdirectory relative to the install prefix where libraries will be installed (default is /lib${LIB_SUFFIX})" FORCE)
+set(BIN_INSTALL_DIR "bin" CACHE PATH "The subdirectory relative to the install prefix where dlls will be installed (default is /bin)" FORCE)
 
 if (WIN32)
     set(PATH_SEP "\;")
@@ -408,16 +385,15 @@ execute_process(
     OUTPUT_VARIABLE PYTHON_WITH_COUNT_ALLOCS
     OUTPUT_STRIP_TRAILING_WHITESPACE)
 
-set(SHIBOKEN_BUILD_TYPE "Release")
-
-# We do not want to link against the python shared / static library on Linux and macOS.
-# The dynamic linker will pick up the python symbols at runtime automatically.
-# On Windows we do need to link against the python.lib import library.
-if (NOT SBK_PYTHON_LIBRARIES)
-    set(SBK_PYTHON_LIBRARIES "")
+if(NOT CMAKE_BUILD_TYPE)
+    set(CMAKE_BUILD_TYPE Release)
 endif()
 
+set(SHIBOKEN_BUILD_TYPE "Release")
+
 if(CMAKE_BUILD_TYPE STREQUAL "Debug")
+    set(SHIBOKEN_BUILD_TYPE "Debug")
+
     if(NOT PYTHON_DEBUG_LIBRARIES)
         message(WARNING "Python debug shared library not found; assuming python was built with shared library support disabled.")
     endif()
@@ -425,38 +401,12 @@ if(CMAKE_BUILD_TYPE STREQUAL "Debug")
     if(NOT PYTHON_WITH_DEBUG)
         message(WARNING "Compiling shiboken2 with debug enabled, but the python executable was not compiled with debug support.")
     else()
-        add_definitions("-DPy_DEBUG")
-        set(SBK_ADD_PY_DEBUG_DEFINITION "add_definitions(\"-DPy_DEBUG\")")
         set(SBK_PKG_CONFIG_PY_DEBUG_DEFINITION " -DPy_DEBUG")
     endif()
 
     if (PYTHON_WITH_COUNT_ALLOCS)
-        add_definitions("-DCOUNT_ALLOCS")
-        set(SBK_ADD_PY_DEBUG_DEFINITION "${SBK_ADD_PY_DEBUG_DEFINITION} \nadd_definitions(\"-DCOUNT_ALLOCS\")")
         set(SBK_PKG_CONFIG_PY_DEBUG_DEFINITION "${SBK_PKG_CONFIG_PY_DEBUG_DEFINITION} -DCOUNT_ALLOCS")
     endif()
-
-    if(WIN32 AND NOT SBK_PYTHON_LIBRARIES)
-        set(SBK_PYTHON_LIBRARIES ${PYTHON_DEBUG_LIBRARIES})
-    endif()
-    set(SHIBOKEN_BUILD_TYPE "Debug")
-endif()
-
-if(CMAKE_BUILD_TYPE STREQUAL "Release")
-    add_definitions("-DNDEBUG")
-    if(WIN32 AND NOT SBK_PYTHON_LIBRARIES)
-        set(SBK_PYTHON_LIBRARIES ${PYTHON_LIBRARIES})
-    endif()
-endif()
-
-
-if(APPLE)
-    set(SBK_PYTHON_LIBRARIES "-undefined dynamic_lookup")
-endif()
-if(CMAKE_VERSION VERSION_LESS 2.8)
-    set(SBK_PYTHON_INCLUDE_DIR ${PYTHON_INCLUDE_PATH})
-else()
-    set(SBK_PYTHON_INCLUDE_DIR ${PYTHON_INCLUDE_DIRS})
 endif()
 
 add_subdirectory(ApiExtractor)