libprelude: python bindings fail to build on OSX 10.12 and earlier, due to lack of 'fmemopen'

[ctreleaven (Craig Treleaven)]

Relevant portion of the log seems to be:

gnumake[3]: Entering directory `/opt/local/var/macports/build/_opt_bblocal_var_buildworker_ports_build_ports_security_libprelude/libprelude/work/libprelude-5.2.0/bindings/python'
CC="/usr/bin/clang++" /opt/local/bin/python3.8 setup.py build
running build
running build_py
creating build
creating build/lib.macosx-10.12-x86_64-3.8
copying prelude.py -> build/lib.macosx-10.12-x86_64-3.8
running build_ext
building '_prelude' extension
creating build/temp.macosx-10.12-x86_64-3.8
/usr/bin/clang++ -Wno-unused-result -Wsign-compare -Wunreachable-code -fno-common -dynamic -DNDEBUG -g -fwrapv -O3 -Wall -pipe -Os -I/opt/local/Library/Frameworks/Python.framework/Versions/3.8/include/python3.8 -c _prelude.cxx -o build/temp.macosx-10.12-x86_64-3.8/_prelude.o -I../.. -I../../src/include -I../../src/include -I../../src/libprelude-error -I../../bindings/c++/include
In file included from _prelude.cxx:188:
In file included from /opt/local/Library/Frameworks/Python.framework/Versions/3.8/include/python3.8/Python.h:85:
In file included from /opt/local/Library/Frameworks/Python.framework/Versions/3.8/include/python3.8/pytime.h:6:
In file included from /opt/local/Library/Frameworks/Python.framework/Versions/3.8/include/python3.8/object.h:746:
/opt/local/Library/Frameworks/Python.framework/Versions/3.8/include/python3.8/cpython/object.h:177:16: warning: 'tp_print' is deprecated [-Wdeprecated-declarations]
typedef struct _typeobject {
               ^
/opt/local/Library/Frameworks/Python.framework/Versions/3.8/include/python3.8/cpython/object.h:260:5: note: 'tp_print' has been explicitly marked deprecated here
    Py_DEPRECATED(3.8) int (*tp_print)(PyObject *, FILE *, int);
    ^
/opt/local/Library/Frameworks/Python.framework/Versions/3.8/include/python3.8/pyport.h:515:54: note: expanded from macro 'Py_DEPRECATED'
#define Py_DEPRECATED(VERSION_UNUSED) __attribute__((__deprecated__))
                                                     ^
In file included from _prelude.cxx:188:
In file included from /opt/local/Library/Frameworks/Python.framework/Versions/3.8/include/python3.8/Python.h:85:
In file included from /opt/local/Library/Frameworks/Python.framework/Versions/3.8/include/python3.8/pytime.h:6:
In file included from /opt/local/Library/Frameworks/Python.framework/Versions/3.8/include/python3.8/object.h:746:
/opt/local/Library/Frameworks/Python.framework/Versions/3.8/include/python3.8/cpython/object.h:177:16: warning: 'tp_print' is deprecated [-Wdeprecated-declarations]
typedef struct _typeobject {
               ^
/opt/local/Library/Frameworks/Python.framework/Versions/3.8/include/python3.8/cpython/object.h:260:5: note: 'tp_print' has been explicitly marked deprecated here
    Py_DEPRECATED(3.8) int (*tp_print)(PyObject *, FILE *, int);
    ^
/opt/local/Library/Frameworks/Python.framework/Versions/3.8/include/python3.8/pyport.h:515:54: note: expanded from macro 'Py_DEPRECATED'
#define Py_DEPRECATED(VERSION_UNUSED) __attribute__((__deprecated__))
                                                     ^
_prelude.cxx:6388:22: error: use of undeclared identifier 'fmemopen'; did you mean 'freopen'?
                fd = fmemopen(buf, len, "r");
                     ^~~~~~~~
                     freopen
/usr/include/stdio.h:248:7: note: 'freopen' declared here
FILE    *freopen(const char * __restrict, const char * __restrict,
         ^
_prelude.cxx:6388:36: error: cannot initialize a parameter of type 'const char *' with an lvalue of type 'ssize_t' (aka 'long')
                fd = fmemopen(buf, len, "r");
                                   ^~~
/usr/include/stdio.h:248:63: note: passing argument to parameter here
FILE    *freopen(const char * __restrict, const char * __restrict,
                                                                 ^
2 warnings and 2 errors generated.
error: command '/usr/bin/clang++' failed with exit status 1
gnumake[3]: *** [python-build] Error 1

I suspect this is obvious to some but not me.

[ctreleaven (Craig Treleaven)]

Buildbot log file 10.12

[jmroot (Joshua Root)]

I think you'll find that fmemopen was not implemented in macOS until 10.13.

[ctreleaven (Craig Treleaven)]

In c90c9c9458f2d727d240718f9d84857fcfa529da/macports-ports (master):

libprelude: fix build failures

• blacklist clang before Xcode 9.4.1, OSX 10.13

Fixes: #64805

[jmroot (Joshua Root)]

Changing compilers won't help; fmemopen is a libc function and doesn't exist at all on the older OSes. You would have to either provide an implementation of the function, or modify the code to do whatever it's doing without using that function.

[ctreleaven (Craig Treleaven)]

Thanks Josh, I'm starting to get a glimmer now. (I'm not a C/C++ guy.)

AIUI, I would need to use an SDK from 10.13 or newer to get the appropriate version of stdio.h. For example:

$ bbfind fmemopen /Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include
/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/stdio.h:356: FILE *fmemopen(void * __restrict __buf, size_t __size, const char * __restrict __mode) __API_AVAILABLE(macos(10.13), ios(11.0), tvos(11.0), watchos(4.0));

I believe Ryan has an uncommitted port that is supposed to address this kind of problem? I'll see if I can locate a ticket.

In the meantime, I can disable the Python bindings in this port on older OS versions which should get around the problem. I appreciate your help.

[ctreleaven (Craig Treleaven)]

Not finding a ticket but the WIP is at:

​https://github.com/ryandesign/macports-ports/blob/master/devel/MacOSX.sdk/Portfile

[ctreleaven (Craig Treleaven)]

In aab08b023e83e528a2656f65f025099e2e7e6cb9/macports-ports (master):

libprelude: avoid build errors on older OS

• prevent +python38 on OSX 10.12 and older
• set default +python38 on OSX 10.13 and newer

See #64805

[jmroot (Joshua Root)]

Replying to ctreleaven:

AIUI, I would need to use an SDK from 10.13 or newer to get the appropriate version of stdio.h.

Using a newer SDK would allow the code to compile, but it would then fail at runtime on < 10.13. You can check for the function's availability at runtime too, but you still need some alternative code that does the same thing but without using fmemopen.

[barracuda156]

Has any replacement for fmemopen been found ever since?

Maybe this? ​https://github.com/NimbusKit/memorymapping

[mascguy (Christopher Nielsen)]

Replying to barracuda156:

Has any replacement for fmemopen been found ever since?

Maybe this? ​https://github.com/NimbusKit/memorymapping

fmemopen() will be available via legacy-support within a few days. (But it's currently testable via legacy-support-devel as of this writing.)