Where would I look to find the current expected status of python3 on
MacOsX Lion?
The distributed binaries aren't capable of allowing extensions that use gcc.
I can build the source naked, but then it lacks some libraries, notably,
readline.
Attempting to build the full Mac packages fails, even with the few tiny
patches I used for 2.7.2.
Is anyone working on this? Are there pre-release patches available?
The short answer is: yes, it is being worked on but it has been taking
longer than it should.
The 64-bit/32-bit installers from python.org for Python 2.7.x and Python
3.2.x have been being built on 10.6 with gcc-4.2. OSX 10.7 (Lion) was
initially released with Xcode 4.1 which still included a version of
gcc-4.2 similar to what has been available all along in 10.6 (Snow
Leopard). However, more recently, Apple has released Xcode 4.2 which
finally removed gcc-4.2 and now only includes updated versions of
llvm-gcc-4.2 (gcc front-end with an llvm code generator backend) and
clang (clang front-end with an llvm backend). Apple has made it clear
that they want developers and other users to move eventually to clang
and that llvm-gcc is an interim step towards the migration to clang.
While there are other reasons for that move (like the change in gcc
licensing), I believe Apple believes that clang will provide an
all-around better build experience (better code, better checking, better
diagnostics, more flexibility). But, as with any major change to a
build compiler and environment, lots of nitty and often knotty problems
are to be expected. (For an idea of the breadth of them, peruse the
MacPorts project mailing lists for all the issues they've been
discovering in the many open source packages they support since they've
moved to using clang by default.) Python is no exception. There are
already a couple of fixes that have been applied for upcoming Python
releases to deal with either llvm-gcc or clang issues.
To further complicate things, prior to the release of Lion, Apple made a
preliminary version of Xcode 4 available for Snow Leopard through the
Mac App Store but appears to have removed it for new purchases after
Lion was released although it seems that previous purchasers and paying
members of the Mac Developer program can get updates for it. So, now
some 10.6 users also no longer have gcc-4.2, although they do have the
supported option of reverting to the most recent Xcode 3 release for
10.6 which is free and still available through the Apple Developer
Connection website.
The PSF (via python.org) also supplies 32-bit-only installer variants
for OS X 10.3+ which were great for building applications to run on
multiple versions of OS X. But since Xcode 4 doesn't ship the necessary
SDK (10.4u) and gcc-4.0, that installer version is also problematic on
10.7. We need to be careful in developing any fixes that we don't
inadvertently break anything for older OS X releases like 10.5. So,
it's all a bit of mess at the moment with *a lot* of variables.
I had hoped to complete a comprehensive set of tests of the most
important combinations of build environments with the three current
active branches of python development (2.7.x, 3.2.x, and the future 3.3)
for 10.7, 10.6, as well as baselines on 10.5 and 10.4 several weeks ago
but, unfortunately, other events intervened. Such is the downside of
all-volunteer projects. But I will be working on completing this over
the next couple of weeks and, after review by the other core developers,
will summarize the known issues and suggested fixes on the python.org
website (with pointers posted here). I expect that we will then need to
push maintenance releases of 2.7.x and 3.2.x. In the meantime, the
safest approach is to continue to build on OS X 10.6 with Xcode 3
installed.
