c++ reference is accessed via pointer dereference in 0.22

[Stephan]

Hi, after upgrading cython from 0.20 to 0.22 my c++ code fails to compile. I stripped the problem down to the following code.

cdef extern from "<memory>" namespace "std":
    cdef cppclass shared_ptr[T]:
        pass

cdef extern from "rocksdb/env.h" namespace "rocksdb":
    cdef cppclass Logger:
        pass

cdef extern from "rocksdb/options.h" namespace "rocksdb":
    cdef cppclass Options:
        shared_ptr[Logger] info_log

cdef extern from "rocksdb/db.h" namespace "rocksdb":
    cdef cppclass DB:
        const Options& GetOptions() nogil except+


cdef doit(DB* db):
    cdef shared_ptr[Logger] info_log = db.GetOptions().info_log

Cython 0.22 create then following c++ code

rocksdb::Options __pyx_t_1;
std::shared_ptr<rocksdb::Logger>  __pyx_t_2;

  /* "problem.cython":19
 *
 * cdef doit(DB* db):
 *     cdef shared_ptr[Logger] info_log = db.GetOptions().info_log             # <<<<<<<<<<<<<<
 */
  try {
    __pyx_t_1 = __pyx_v_db->GetOptions();
  } catch(...) {/* left out. */}

  /* THIS GOES WRONG, because __pyx_t_1 is not a pointer. */
  __pyx_t_2 = __pyx_t_1->info_log;

As you can see cython does __pyx_t_1->info_log, however this fails during compilation. __pyx_t_1 is not a pointer ......
Cython 0.20 and 0.21 translate it correctly by using __pyx_t_1.info_log

Regards,
 Stephan

[Stephan]

A quick question. Will this be fixed by the cython team, or should I have a look into my code to find a workaround ?

[Robert Bradshaw]

Fixed: https://github.com/cython/cython/commit/b1ef20ad7b850498ca7c1dc516cf99036b6974d2

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