Clean up FindPythonInterp and FindPythonLibs usage

[lanza]

Summary

LLDBStandalone was calling FindPythonInterp with 3.x enabled which
runs into an issue with all threads stuck waiting on Darwin and Linux.
The quick fix is to disable finding python3.x.

While restructuring Python, I figured I'd clean up the
FindPython{Interp,Libs} usage throughout the project.

[mgorny]

scripts/Python/modules/readline/CMakeLists.txt

1

See https://stackoverflow.com/questions/1242904/finding-python-site-packages-directory-with-cmake

If we can use CMake 3.12, use FindPython. If we can't, use execute_process.

cmake/modules/LLDBConfig.cmake

function(find_python_libs_windows)
   set (PYTHON_INCLUDE_DIRS ${PYTHON_INCLUDE_DIRS} PARENT_SCOPE)
 
   message("-- LLDB Found PythonExecutable: ${PYTHON_RELEASE_EXE} and ${PYTHON_DEBUG_EXE}")
   message("-- LLDB Found PythonLibs: ${PYTHON_RELEASE_LIB} and ${PYTHON_DEBUG_LIB}")
   message("-- LLDB Found PythonDLL: ${PYTHON_RELEASE_DLL} and ${PYTHON_DEBUG_DLL}")
   message("-- LLDB Found PythonIncludeDirs: ${PYTHON_INCLUDE_DIRS}")
 endfunction(find_python_libs_windows)
 
+set(Python_ADDITIONAL_VERSIONS 2.7 2.6 2.5)
+find_package(PythonInterp)
+if (NOT PYTHONINTERP_FOUND)
+  message(FATAL_ERROR
+          "Unable to find Python interpreter, required for builds and testing.
+          Please install Python or specify the PYTHON_EXECUTABLE CMake variable.")
+endif()
+
 if (NOT LLDB_DISABLE_PYTHON)
 
   if ("${CMAKE_SYSTEM_NAME}" STREQUAL "Windows")
     find_python_libs_windows()
 
     if (NOT LLDB_RELOCATABLE_PYTHON)
       file(TO_CMAKE_PATH "${PYTHON_HOME}" LLDB_PYTHON_HOME)
       add_definitions( -DLLDB_PYTHON_HOME="${LLDB_PYTHON_HOME}" )
     endif()
   else()
-    find_package(PythonLibs REQUIRED)
+    find_package(PythonLibs ${PYTHON_VERSION_STRING} REQUIRED)
   endif()
-  
   if (PYTHON_INCLUDE_DIRS)
     include_directories(${PYTHON_INCLUDE_DIRS})
   endif()
 endif()
 
 if (LLDB_DISABLE_PYTHON)
-  unset(PYTHON_INCLUDE_DIRS)
-  unset(PYTHON_LIBRARY)
-  add_definitions( -DLLDB_DISABLE_PYTHON )
+  add_definitions(-DLLDB_DISABLE_PYTHON)
 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")

cmake/modules/LLDBStandalone.cmake

else()
     set(LLVM_SHLIB_OUTPUT_INTDIR ${LLVM_LIBRARY_OUTPUT_INTDIR})
   endif()
 
   include(AddLLVM)
   include(TableGen)
   include(HandleLLVMOptions)
   include(CheckAtomic)
 
-  if (PYTHON_EXECUTABLE STREQUAL "")
-    set(Python_ADDITIONAL_VERSIONS 3.5 3.4 3.3 3.2 3.1 3.0 2.7 2.6 2.5)
-    include(FindPythonInterp)
-    if( NOT PYTHONINTERP_FOUND )
-      message(FATAL_ERROR
-              "Unable to find Python interpreter, required for builds and testing.
-               Please install Python or specify the PYTHON_EXECUTABLE CMake variable.")
-    endif()
-  else()
-    message("-- Found PythonInterp: ${PYTHON_EXECUTABLE}")
-  endif()
-
   # Import CMake library targets from LLVM and Clang.
   include("${LLVM_OBJ_ROOT}/lib${LLVM_LIBDIR_SUFFIX}/cmake/llvm/LLVMConfig.cmake")
   if (EXISTS "${LLVM_OBJ_ROOT}/lib${LLVM_LIBDIR_SUFFIX}/cmake/clang/ClangConfig.cmake")
     include("${LLVM_OBJ_ROOT}/lib${LLVM_LIBDIR_SUFFIX}/cmake/clang/ClangConfig.cmake")
   endif()
 
   set(PACKAGE_VERSION "${LLVM_PACKAGE_VERSION}")
   set(LLVM_INCLUDE_TESTS ON CACHE INTERNAL "")

docs/CMakeLists.txt

if(DOXYGEN_FOUND)
 
   add_custom_target(lldb-cpp-doc
     ${DOXYGEN_EXECUTABLE} ${CMAKE_CURRENT_BINARY_DIR}/doxygen.cfg
     WORKING_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}
     COMMENT "Generating LLDB C++ API reference with Doxygen" VERBATIM
   )
 endif(DOXYGEN_FOUND)
 
-find_package(PythonInterp REQUIRED)
 find_program(EPYDOC_EXECUTABLE NAMES epydoc epydoc.py)
 if(EPYDOC_EXECUTABLE)
   find_program(DOT_EXECUTABLE dot)
     if(DOT_EXECUTABLE)
       set(EPYDOC_OPTIONS ${EPYDOC_OPTIONS} --graph all --dotpath ${DOT_EXECUTABLE})
     endif()
     set(DOC_DIR "${CMAKE_CURRENT_SOURCE_DIR}/doc")
     file(MAKE_DIRECTORY "${DOC_DIR}")

scripts/CMakeLists.txt

 file(GLOB SWIG_INTERFACES interface/*.i)
 file(GLOB_RECURSE SWIG_SOURCES *.swig)
 set(SWIG_HEADERS
   ${LLDB_SOURCE_DIR}/include/lldb/API/SBDefines.h
   ${LLDB_SOURCE_DIR}/include/lldb/lldb-defines.h
   ${LLDB_SOURCE_DIR}/include/lldb/lldb-enumerations.h
   ${LLDB_SOURCE_DIR}/include/lldb/lldb-forward.h
   ${LLDB_SOURCE_DIR}/include/lldb/lldb-types.h
   ${LLDB_SOURCE_DIR}/include/lldb/lldb-versioning.h
 )
 
-include(FindPythonInterp)
-
 if(LLDB_BUILD_FRAMEWORK)
   set(framework_arg --framework --target-platform Darwin)
 endif()
 
 find_package(SWIG REQUIRED)
 add_custom_command(
   OUTPUT ${CMAKE_CURRENT_BINARY_DIR}/LLDBWrapPython.cpp
   OUTPUT ${CMAKE_CURRENT_BINARY_DIR}/lldb.py

scripts/Python/modules/readline/CMakeLists.txt

-# FIXME: if a non-standard version of python is requested, the cmake macro
-# below will need Python_ADDITIONAL_VERSIONS set in order to find it.
-include(FindPythonInterp)
-SET(PYTHON_DIRECTORY python${PYTHON_VERSION_MAJOR}.${PYTHON_VERSION_MINOR}/site-packages)
+set(PYTHON_DIRECTORY python${PYTHON_VERSION_MAJOR}.${PYTHON_VERSION_MINOR}/site-packages)
 
 # Build the readline python module
 include_directories(${PYTHON_INCLUDE_DIR})
 add_library(readline SHARED readline.cpp)
 target_link_libraries(readline ${PYTHON_LIBRARY})
 
 if (NOT LLDB_DISABLE_LIBEDIT)
   target_include_directories(readline