[pypy-issue] Issue #2134: Building cffi shared objects picks up system libpypy-c (pypy/pypy)

[Edd Barrett]

New issue 2134: Building cffi shared objects picks up system libpypy-c
https://bitbucket.org/pypy/pypy/issues/2134/building-cffi-shared-objects-picks-up

Edd Barrett:

Noticed the following warnings when building PyPy:

```
starting build_cffi_imports                                                                                                                         [27/1833]
* _audioop_build.py
 Traceback (most recent call last):
  File "<builtin>/app_main.py", line 75, in run_toplevel
  File "_audioop_build.py", line 3, in <module>
    ffi = FFI()
  File "/home/edd/research/pypy.pypy/lib_pypy/cffi/api.py", line 59, in __init__
    "version mismatch, %s != %s" % (backend.__version__, __version__)
AssertionError: version mismatch, 1.1.0 != 1.3.0

* _curses_build.py
 Traceback (most recent call last):
  File "<builtin>/app_main.py", line 75, in run_toplevel
  File "_curses_build.py", line 3, in <module>
    ffi = FFI()
  File "/home/edd/research/pypy.pypy/lib_pypy/cffi/api.py", line 59, in __init__
    "version mismatch, %s != %s" % (backend.__version__, __version__)
AssertionError: version mismatch, 1.1.0 != 1.3.0

...

/home/edd/research/pypy.pypy/pypy-c successfully built, but errors while building the above modules will be ignored
```

The problem is, the build is picking up the system libpypy-c installed by the OS package manager. Confirmed by forcing a library path:

```
$ ./pypy-c ./lib_pypy/_tkinter/tklib_build.py
Traceback (most recent call last):
  File "<builtin>/app_main.py", line 75, in run_toplevel
  File "./lib_pypy/_tkinter/tklib_build.py", line 32, in <module>
    config_ffi = FFI()
  File "/home/edd/research/pypy.pypy/lib_pypy/cffi/api.py", line 59, in __init__
    "version mismatch, %s != %s" % (backend.__version__, __version__)
AssertionError: version mismatch, 1.1.0 != 1.3.0
$ export LD_LIBRARY_PATH=`pwd`
$ ./pypy-c ./lib_pypy/_tkinter/tklib_build.py
_tkinter/tklib_cffi.c: In function '_cffi_checkfld__Tcl_Obj':
_tkinter/tklib_cffi.c:3971: warning: initialization from incompatible pointer type
_tkinter/tklib_cffi.c: In function '_cffi_checkfld__Tcl_ObjType':
_tkinter/tklib_cffi.c:3981: warning: initialization from incompatible pointer type
$ 
```

Cheers