[lldb/CMake] Autodetect Python dependency

[JDevlieghere]

Summary

Python was the last remaining "optional" dependency for LLDB. This moves the code to find Python into FindPythonInterpAndLibs using the same principles as FindCursesAndPanel.

[xiaobai]

It's nice to consolidate the logic into one place. I think you will probably need to make an appropriate change on the buildbot side as well (if you haven't done that already).

Where is FindPythonInterpAndLibs being included?

[JDevlieghere]

In D72107#1802001, @xiaobai wrote:

It's nice to consolidate the logic into one place. I think you will probably need to make an appropriate change on the buildbot side as well (if you haven't done that already).

Do you mean forcing LLDB_ENABLE_PYTHON to on so that it fails in case the logic changes and Python isn't found?

Where is FindPythonInterpAndLibs being included?

It's included from the add_optional_dependency macro.

[xiaobai]

In D72107#1802029, @JDevlieghere wrote:

Do you mean forcing LLDB_ENABLE_PYTHON to on so that it fails in case the logic changes and Python isn't found?

Yes, something like that. It looks like the previous expected behavior was that python was implicitly a required dependency (unless you explicitly disabled it or were building for android/ios). Making it an optional dependency means that the buildbots should probably explicitly say that they want to enable python. You could probably not change buildbot invocations, but that means that if a buildbot fails to find python then we won't know until something goes wrong (e.g. A test fails locally on some setup that passed buildbots because buildbots weren't running python tests).

[JDevlieghere]

In D72107#1802048, @xiaobai wrote:

In D72107#1802029, @JDevlieghere wrote:

Do you mean forcing LLDB_ENABLE_PYTHON to on so that it fails in case the logic changes and Python isn't found?

Yes, something like that. It looks like the previous expected behavior was that python was implicitly a required dependency (unless you explicitly disabled it or were building for android/ios). Making it an optional dependency means that the buildbots should probably explicitly say that they want to enable python. You could probably not change buildbot invocations, but that means that if a buildbot fails to find python then we won't know until something goes wrong (e.g. A test fails locally on some setup that passed buildbots because buildbots weren't running python tests).

Yup, I've updated the config in 9a3d9b7f

[mgorny]

lldb/cmake/modules/FindPythonInterpAndLibs.cmake

2

Typo.

[labath]

Looks fine to me. Thanks for tackling this.

lldb/cmake/modules/FindPythonInterpAndLibs.cmake

+#.rst:
+# FindPythonInterpndLibs
+# -----------
+#
+# Find the python interpreter and libraries as a whole.
+
+if(PYTHON_LIBRARIES AND PYTHON_INCLUDE_DIRS AND PYTHON_EXECUTABLE)
+  set(PYTHONINTERPANDLIBS_FOUND TRUE)
+else()
+  if ("${CMAKE_SYSTEM_NAME}" STREQUAL "Windows")
+    find_package(Python3 COMPONENTS Interpreter Development QUIET)
+    if (Python3_FOUND AND Python3_Interpreter_FOUND)
+      set(PYTHON_LIBRARIES ${Python3_LIBRARIES})
+      set(PYTHON_INCLUDE_DIRS ${Python3_INCLUDE_DIRS})
+      set(PYTHON_EXECUTABLE ${Python3_EXECUTABLE})
+      mark_as_advanced(
+        PYTHON_LIBRARIES
+        PYTHON_INCLUDE_DIRS
+        PYTHON_EXECUTABLE)
+    endif()
+  else()
+    find_package(PythonInterp QUIET)
+    find_package(PythonLibs QUIET)
+    if(PYTHONINTERP_FOUND AND PYTHONLIBS_FOUND)
+      if (NOT CMAKE_CROSSCOMPILING)
+        string(REPLACE "." ";" pythonlibs_version_list ${PYTHONLIBS_VERSION_STRING})
+        list(GET pythonlibs_version_list 0 pythonlibs_major)
+        list(GET pythonlibs_version_list 1 pythonlibs_minor)
+
+        # Ignore the patch version. Some versions of macOS report a different
+        # patch version for the system provided interpreter and libraries.
+        if (CMAKE_CROSSCOMPILING OR (PYTHON_VERSION_MAJOR VERSION_EQUAL pythonlibs_major AND
+            PYTHON_VERSION_MINOR VERSION_EQUAL pythonlibs_minor))
+          mark_as_advanced(
+            PYTHON_LIBRARIES
+            PYTHON_INCLUDE_DIRS
+            PYTHON_EXECUTABLE)
+        endif()
+      endif()
+    endif()
+  endif()
+
+  include(FindPackageHandleStandardArgs)
+  find_package_handle_standard_args(PythonInterpAndLibs
+                                    FOUND_VAR
+                                      PYTHONINTERPANDLIBS_FOUND
+                                    REQUIRED_VARS
+                                      PYTHON_LIBRARIES
+                                      PYTHON_INCLUDE_DIRS
+                                      PYTHON_EXECUTABLE)
+endif()

lldb/cmake/modules/LLDBConfig.cmake

macro(add_optional_dependency variable description package found)
 
   message(STATUS "${description}: ${${variable}}")
 endmacro()
 
 add_optional_dependency(LLDB_ENABLE_LIBEDIT "Enable editline support in LLDB" LibEdit LibEdit_FOUND)
 add_optional_dependency(LLDB_ENABLE_CURSES "Enable curses support in LLDB" CursesAndPanel CURSESANDPANEL_FOUND)
 add_optional_dependency(LLDB_ENABLE_LZMA "Enable LZMA compression support in LLDB" LibLZMA LIBLZMA_FOUND)
 add_optional_dependency(LLDB_ENABLE_LUA "Enable Lua scripting support in LLDB" Lua LUA_FOUND)
+add_optional_dependency(LLDB_ENABLE_PYTHON "Enable Python scripting support in LLDB" PythonInterpAndLibs PYTHONINTERPANDLIBS_FOUND)
 
-set(default_enable_python ON)
-
-if(CMAKE_SYSTEM_NAME MATCHES "Android")
-  set(default_enable_python OFF)
-elseif(IOS)
-  set(default_enable_python OFF)
-endif()
-
-option(LLDB_ENABLE_PYTHON "Enable Python scripting integration." ${default_enable_python})
 option(LLDB_RELOCATABLE_PYTHON "Use the PYTHONHOME environment variable to locate Python." OFF)
 option(LLDB_USE_SYSTEM_SIX "Use six.py shipped with system and do not install a copy of it" OFF)
 option(LLDB_USE_ENTITLEMENTS "When codesigning, use entitlements if available" ON)
 option(LLDB_BUILD_FRAMEWORK "Build LLDB.framework (Darwin only)" OFF)
 option(LLDB_NO_INSTALL_DEFAULT_RPATH "Disable default RPATH settings in binaries" OFF)
 option(LLDB_USE_SYSTEM_DEBUGSERVER "Use the system's debugserver for testing (Darwin only)." OFF)
 option(LLDB_SKIP_STRIP "Whether to skip stripping of binaries when installing lldb." OFF)
 
else()
     set(LLDB_HAVE_EL_RFUNC_T 1)
   endif()
   set(CMAKE_REQUIRED_LIBRARIES)
   set(CMAKE_REQUIRED_INCLUDES)
   set(CMAKE_EXTRA_INCLUDE_FILES)
 endif()
 
 if (LLDB_ENABLE_PYTHON)
-  if ("${CMAKE_SYSTEM_NAME}" STREQUAL "Windows")
-    find_package(Python3 COMPONENTS Interpreter Development REQUIRED)
-    if(Python3_VERSION VERSION_LESS 3.5)
-      message(SEND_ERROR "Python 3.5 or newer is required (found: ${Python3_VERSION}")
-    endif()
-    set(PYTHON_LIBRARIES ${Python3_LIBRARIES})
-    include_directories(${Python3_INCLUDE_DIRS})
-
-    if (NOT LLDB_RELOCATABLE_PYTHON)
-      get_filename_component(PYTHON_HOME "${Python3_EXECUTABLE}" DIRECTORY)
-      file(TO_CMAKE_PATH "${PYTHON_HOME}" LLDB_PYTHON_HOME)
-    endif()
-  else()
-    find_package(PythonInterp REQUIRED)
-    find_package(PythonLibs REQUIRED)
-
-    if (NOT CMAKE_CROSSCOMPILING)
-      string(REPLACE "." ";" pythonlibs_version_list ${PYTHONLIBS_VERSION_STRING})
-      list(GET pythonlibs_version_list 0 pythonlibs_major)
-      list(GET pythonlibs_version_list 1 pythonlibs_minor)
-
-      # Ignore the patch version. Some versions of macOS report a different patch
-      # version for the system provided interpreter and libraries.
-      if (NOT PYTHON_VERSION_MAJOR VERSION_EQUAL pythonlibs_major OR
-          NOT PYTHON_VERSION_MINOR VERSION_EQUAL pythonlibs_minor)
-        message(FATAL_ERROR "Found incompatible Python interpreter (${PYTHON_VERSION_MAJOR}.${PYTHON_VERSION_MINOR})"
-                            " and Python libraries (${pythonlibs_major}.${pythonlibs_minor})")
-      endif()
-    endif()
-
-    if (PYTHON_INCLUDE_DIR)
-      include_directories(${PYTHON_INCLUDE_DIR})
-    endif()
-  endif()
-endif()
-
-if (NOT LLDB_ENABLE_PYTHON)
-  unset(PYTHON_INCLUDE_DIR)
-  unset(PYTHON_LIBRARIES)
-  unset(PYTHON_EXECUTABLE)
+  include_directories(${PYTHON_INCLUDE_DIRS})
+    get_filename_component(PYTHON_HOME "${PYTHON_EXECUTABLE}" DIRECTORY)
 endif()
 
 if (LLVM_EXTERNAL_CLANG_SOURCE_DIR)
   include_directories(${LLVM_EXTERNAL_CLANG_SOURCE_DIR}/include)
 else ()
   include_directories(${CMAKE_SOURCE_DIR}/tools/clang/include)
 endif ()
 include_directories("${CMAKE_CURRENT_BINARY_DIR}/../clang/include")