Re: [boost] Fwd: Boost.Python build error in 1.58 RC1, 2 and 3 (OK in Beta 1)

On 08/04/15 10:35 AM, Marshall Clow wrote:

---------- Forwarded message ---------- From: Date: Wed, Apr 8, 2015 at 1:29 AM Subject: Boost.Python build error in 1.58 RC1, 2 and 3 (OK in Beta 1) To: mclow.lists@gmail.com

Hi Marshall,

Please excuse the direct mail, but my mailing list posting wasn't picked up on by anyone. I believe I've found a problem in Boost.Python that causes build errors if the user has Python 3.0 or later on their system. This change appears to have been introduced after 1.58 Beta 1.

Using:

bjam address-model=32 runtime-link=shared toolset=msvc-12.0 --stagedir=./stage/x86

C:\Program Files (x86)\Microsoft Visual Studio 12.0\VC\INCLUDE\xtgmath.h(206) : warning C4273: 'round' : inconsistent dll linkage C:\Program Files (x86)\Microsoft Visual Studio 12.0\VC\INCLUDE\math.h(516) : see previous definition of 'round' libs\python\src\exec.cpp(91) : error C2664: 'FILE *_Py_fopen(PyObject *,const char *)' : cannot convert argument 1 from 'char *' to 'PyObject *' Types pointed to are unrelated; conversion requires reinterpret_cast, C-style cast or function-style cast

call "C:\Users\MARK~1.INC\AppData\Local\Temp\b2_msvc_12.0_vcvarsall_x86.cmd" >nul cl /Zm800 -nologo @"bin.v2\libs\python\build\msvc-12.0\debug\link-static\threading-multi\exec.obj.rsp"

...failed compile-c-c++ bin.v2\libs\python\build\msvc-12.0\debug\link-static\threading-multi\exec.obj…

The problem appears to be this Boost.Python code that was changed some time after 1.58 Beta 1 and appears in 1.58 RC1 within boost\libs\python\src\exec.cpp at around line 91:

1.58 beta 1: FILE *fs = fopen(f, "r"); 1.58 RCs: FILE *fs = _Py_fopen(f, "r"); ← f is a char *, hence the error shown above. It expects a PyObject * as the first parameter.

I'm confused. The Python C API provides a "_Py_fopen(const char *, const char *)" function (matching the above call), as well as a "_Py_fopen_obj(PyObject *, const char *)" function. Unfortunately I don't have Windows and thus can't attempt to reproduce the problem. (See https://hg.python.org/cpython/file/0ca028765488/Python/fileutils.c#l1035) What is the exact version of Python you are using ?

This code occurs within a test for #if PY_VERSION_HEX >= 0x03000000 which may explain why no-one else has reported it – I have Python 3.3.0 on my HDD.

I can't reproduce the error on Linux, FWIW, Stefan -- ...ich hab' noch einen Koffer in Berlin...