Then I have found the right list to post on, for my problem is a bug in the 
Python 3.5.1 distribution.  Albeit one which will only manifest in certain 
situations.

The presence of numerous `-isysroot /Developer/SDKs/MacOSX10.6.sdk` directives 
in the following file

/Library/Frameworks/Python.framework/Versions/3.5/lib/python3.5/_sysconfigdata.py

Will cause errors for people who have kept around the old /Developer directory 
tree, and old SDKs like 10.6, for building backwards compatible old code.  
Newer versions of the SDKs are now kept inside the Xcode application itself.  
And then they will only have a problem when trying to install a package with C 
extensions, which in my case was Persistence, a dependency of ZODB.  And even 
more so, ONLY when trying to pip install said package into a virtual 
environment created by 3.5’s pyvenv command, if installing the package into the 
system wide Python there will be no error.

Such is this corner-case hell I have found myself, until I decided to dump my 
older /Developer directory tree and SDKs, as those were for a project long 
defunct.  You see the -isysroot flag has the unusual behavior where instead of 
reporting an error when it cannot find the newly specified system root it 
simply has no effect.  So if you don’t have the SDK specified in the location 
specified then the flag does nothing, as I assume is the case for 99% of 
people. 

I understand the need to make Python 3.5 backwards compatible, but doing it 
this way would appear to have the side effect of breaking the ability to 
install packages using C extensions in virtual environments, or at least it did 
for me.

Joseph Nunn
josephn...@gmail.com
joseph.n...@uci.edu


> On May 06 , 2016, at 4:20 AM, Ned Deily <n...@python.org> wrote:
> 
> 
> On May 6, 2016, at 05:42, Joseph Nunn <josephn...@gmail.com> wrote:
>> Hello Everyone, my first post.  I would also like to subscribe but 
>> haven't seen how yet.  
>> 
>> So I've an issue with how the 3.5.1 OSX 
>> package installs on OSX.  The problem was first made apparent 
>> when trying to create a virtual environment and `pip install ZODB`, 
>> which failed as clang and the linker could not find either the 
>> include or lib directories for a dependency.  By adding a -v option
>> to the compiler options I was able to see in the  compiler flags 
>> the following:
>> 
>> -isysroot /Developer/SDKs/MacOSX10.6.sdk
>> 
>> Which was not present in the compiler flags of other people 
>> who I was talking with. [...]
> 
> Hi Joseph!
> 
> Welcome!  Note this list is for the development of Python itself, not for 
> usage or installation issues.  The Python Developer's Guide 
> (https://docs.python.org/devguide/) including its FAQ gives information about 
> mailing lists and other support forums to get help with general Python 
> issues.  That said, without more information, it would be difficult to know 
> exactly what problem you are running into but, since you mention missing 
> headers, my guess is that you need to install Apple's Command Line Tools as 
> described here:
> 
> https://docs.python.org/devguide/setup.html#build-dependencies
> 
> Installing Xcode by itself is not sufficient.  The sysroot and flag values 
> you note in _sysconfigdata.py are normal and there for compatibility with 
> installing on older versions of OS X; they should not cause a problem on 
> newer releases.  For what it's worth, I was able to install ZODB with the 
> current python.org 3.5.1 on OS X 10.11.4 using either venv or virtualenv.
> 
> Good luck!
> 
> --Ned
> 
> P.S. Mailing list info is available here: https://mail.python.org.  The bug 
> tracker is here: https://bugs.python.org
> 
> --
>  Ned Deily
>  n...@python.org -- []
> 

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