[New-bugs-announce] [issue6848] curses module build failure (ncurses 5.7)

[Mark Dickinson]

New submission from Mark Dickinson <dickinsm at gmail.com>:

There seems to be a problem building the curses module on systems with 
ncurses 5.7.  The following output was produced on OS X 10.6, on a trunk 
build;  I'm not sure whether this problem is Mac-specific (or 64-bit 
specific).

building '_curses' extension
gcc -fno-strict-aliasing -g -Wall -Wstrict-prototypes -
I/Users/dickinsm/python/svn/trunk/Mac/Include -I. -I./Include -IInclude 
-I/Users/dickinsm/python/svn/trunk -c 
/Users/dickinsm/python/svn/trunk/Modules/_cursesmodule.c -o 
build/temp.macosx-10.4-i386-2.7-
pydebug/Users/dickinsm/python/svn/trunk/Modules/_cursesmodule.o
/Users/dickinsm/python/svn/trunk/Modules/_cursesmodule.c: In function 
‘PyCursesWindow_EchoChar’:
/Users/dickinsm/python/svn/trunk/Modules/_cursesmodule.c:805: error: 
dereferencing pointer to incomplete type
/Users/dickinsm/python/svn/trunk/Modules/_cursesmodule.c:812: warning: 
control reaches end of non-void function
/Users/dickinsm/python/svn/trunk/Modules/_cursesmodule.c: In function 
‘PyCursesWindow_NoOutRefresh’:
/Users/dickinsm/python/svn/trunk/Modules/_cursesmodule.c:1230: error: 
dereferencing pointer to incomplete type
/Users/dickinsm/python/svn/trunk/Modules/_cursesmodule.c:1261: warning: 
control reaches end of non-void function
/Users/dickinsm/python/svn/trunk/Modules/_cursesmodule.c: In function 
‘PyCursesWindow_Refresh’:
/Users/dickinsm/python/svn/trunk/Modules/_cursesmodule.c:1372: error: 
dereferencing pointer to incomplete type
/Users/dickinsm/python/svn/trunk/Modules/_cursesmodule.c:1402: warning: 
control reaches end of non-void function
/Users/dickinsm/python/svn/trunk/Modules/_cursesmodule.c: In function 
‘PyCursesWindow_SubWin’:
/Users/dickinsm/python/svn/trunk/Modules/_cursesmodule.c:1438: error: 
dereferencing pointer to incomplete type

Here's a relevant excerpt from _cursesmodule.c (lines 804--811)

#ifdef WINDOW_HAS_FLAGS
  if (self->win->_flags & _ISPAD)
    return PyCursesCheckERR(pechochar(self->win, ch | attr),
                            "echochar");
  else
#endif
    return PyCursesCheckERR(wechochar(self->win, ch | attr),
                            "echochar");

Here self->win has type WINDOW;  the problem is that as of ncurses 5.7, the internals of the WINDOW type (and much else besides) are deliberately hidden (by default) from users of the library;  there's a 
preprocessor constant NCURSES_OPAQUE that controls this.

So an obvious workaround is to set NCURSES_OPAQUE=0 somewhere in the 
Python build process;  however, that may be the wrong thing to do if the ncurses developers are planning to mess with the ncurses internals in 
the near future (which would explain the NCURSES_OPAQUE business).  I 
don't know whether there's some alternative 'official' way to 
distinguish between ncurses windows and pads.

----------
components: Build
messages: 92312
nosy: marketdickinson
severity: normal
status: open
title: curses module build failure (ncurses 5.7)
versions: Python 2.7

_______________________________________
Python tracker <report at bugs.python.org>
<http://bugs.python.org/issue6848>
_______________________________________