[Python] Remove readline module

[JDevlieghere]

Summary

Todd added this empty readline module to workaround an issue with an old version of Python on Ubuntu in 2014 (18841). In the meantime, Python seems to have fixed the underlying issue, and indeed, I wasn't able to reproduce this. I propose to remove this.

[mgorny]

WFM. We've been stripping it in Gentoo since the inception.

[labath]

Wohoo, it's great to be able to get rid of that. Judging by the bug reports, it looks like what actually happened is that libedit fixed some readline incompatibilities, instead of python fixing stuff. But the end result is the same.

lldb/trunk/scripts/CMakeLists.txt

if(NOT LLDB_BUILD_FRAMEWORK)
   endif()
 
   set(SWIG_PYTHON_DIR ${LLVM_LIBRARY_OUTPUT_INTDIR}/${swig_python_subdir})
   set(SWIG_INSTALL_DIR lib${LLVM_LIBDIR_SUFFIX})
 
   # Install the LLDB python module
   install(DIRECTORY ${SWIG_PYTHON_DIR} DESTINATION ${SWIG_INSTALL_DIR})
 endif()
-
-# build Python modules
-add_subdirectory(Python/modules)

lldb/trunk/scripts/Python/modules/CMakeLists.txt

-# Disable some warnings triggered by Python's headers.
-check_cxx_compiler_flag("-Wno-macro-redefined"
-                        CXX_SUPPORTS_NO_MACRO_REDEFINED)
-if (CXX_SUPPORTS_NO_MACRO_REDEFINED)
-  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wno-macro-redefined")
-endif ()
-
-# build the Python readline suppression module only on Linux
-if("${CMAKE_SYSTEM_NAME}" MATCHES "Linux" OR "${CMAKE_SYSTEM_NAME}" STREQUAL "GNU" OR "${CMAKE_SYSTEM_NAME}" STREQUAL "kFreeBSD")
-   add_subdirectory(readline)
-endif()

lldb/trunk/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)
-
-# 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
-                             PRIVATE
-                               ${libedit_INCLUDE_DIRS})
-  target_link_libraries(readline ${libedit_LIBRARIES})
-endif()
-
-# FIXME: the LIBRARY_OUTPUT_PATH seems to be ignored - this is not a
-# functional issue for the build dir, though, since the shared lib dir
-# for the build is in the python shared library load path, and thus
-# python finds it when loading the python readline module.
-set_target_properties(readline PROPERTIES
-                               PREFIX ""
-                               LIBRARY_OUTPUT_PATH ${CMAKE_CURRENT_BINARY_DIR}/lib${LLVM_LIBDIR_SUFFIX}/${PYTHON_DIRECTORY})
-
-# Install the readline module.
-install(TARGETS readline LIBRARY DESTINATION ${CMAKE_INSTALL_PREFIX}/lib${LLVM_LIBDIR_SUFFIX}/${PYTHON_DIRECTORY})

lldb/trunk/scripts/Python/modules/readline/readline.cpp

-// NOTE: Since Python may define some pre-processor definitions which affect the
-// standard headers on some systems, you must include Python.h before any
-// standard headers are included.
-#include "Python.h"
-
-#include <stdio.h>
-
-#ifndef LLDB_DISABLE_LIBEDIT
-#include <editline/readline.h>
-#endif
-
-// Simple implementation of the Python readline module using libedit.
-// In the event that libedit is excluded from the build, this turns
-// back into a null implementation that blocks the module from pulling
-// in the GNU readline shared lib, which causes linkage confusion when
-// both readline and libedit's readline compatibility symbols collide.
-//
-// Currently it only installs a PyOS_ReadlineFunctionPointer, without
-// implementing any of the readline module methods. This is meant to
-// work around LLVM pr18841 to avoid seg faults in the stock Python
-// readline.so linked against GNU readline.
-
-#ifndef LLDB_DISABLE_LIBEDIT
-PyDoc_STRVAR(moduleDocumentation,
-             "Simple readline module implementation based on libedit.");
-#else
-PyDoc_STRVAR(moduleDocumentation,
-             "Stub module meant to avoid linking GNU readline.");
-#endif
-
-#if PY_MAJOR_VERSION >= 3
-static struct PyModuleDef readline_module = {
-    PyModuleDef_HEAD_INIT, // m_base
-    "readline",            // m_name
-    moduleDocumentation,   // m_doc
-    -1,                    // m_size
-    nullptr,               // m_methods
-    nullptr,               // m_reload
-    nullptr,               // m_traverse
-    nullptr,               // m_clear
-    nullptr,               // m_free
-};
-#else
-static struct PyMethodDef moduleMethods[] = {{nullptr, nullptr, 0, nullptr}};
-#endif
-
-#ifndef LLDB_DISABLE_LIBEDIT
-static char *
-#if PY_MAJOR_VERSION >= 3
-simple_readline(FILE *stdin, FILE *stdout, const char *prompt)
-#else
-simple_readline(FILE *stdin, FILE *stdout, char *prompt)
-#endif
-{
-  rl_instream = stdin;
-  rl_outstream = stdout;
-  char *line = readline(prompt);
-  if (!line) {
-    char *ret = (char *)PyMem_Malloc(1);
-    if (ret != NULL)
-      *ret = '\0';
-    return ret;
-  }
-  if (*line)
-    add_history(line);
-  int n = strlen(line);
-  char *ret = (char *)PyMem_Malloc(n + 2);
-  strncpy(ret, line, n);
-  free(line);
-  ret[n] = '\n';
-  ret[n + 1] = '\0';
-  return ret;
-}
-#endif
-
-PyMODINIT_FUNC initreadline(void) {
-#ifndef LLDB_DISABLE_LIBEDIT
-  PyOS_ReadlineFunctionPointer = simple_readline;
-#endif
-
-#if PY_MAJOR_VERSION >= 3
-  return PyModule_Create(&readline_module);
-#else
-  Py_InitModule4("readline", moduleMethods, moduleDocumentation,
-                 static_cast<PyObject *>(NULL), PYTHON_API_VERSION);
-#endif
-}