py-lxml fails with default gcc compiler

[rmottola (Riccardo)]

on 10.5 compilation fails:

In file included from src/lxml/etree.c:265443:
/opt/local/Library/Frameworks/Python.framework/Versions/3.12/include/python3.12/internal/pycore_frame.h: In function ‘_PyFrame_Initialize’:
/opt/local/Library/Frameworks/Python.framework/Versions/3.12/include/python3.12/internal/pycore_frame.h:134: error: ‘for’ loop initial declaration used outside C99 mode
Compile failed: command '/usr/bin/gcc-4.2' failed with exit code 1

I tried using: apple gcc 4.2: fails macports gcc 4.8: fails macports gcc 6 : works!

so I propose blacklisting gcc 4.x versions

[kencu (Ken)]

that works, but macports will usually want you to try setting the C standard first, if you can.

That can be tricky sometimes with python ports, but something like

configure.cflags-append -std=c99

is usually what works.

[kencu (Ken)]

(the reason using gcc6+ works is that those newer gcc versions default to a newer C standard).

[reneeotten (Renee Otten)]

see [40490a9e8cd54eeeb332af15b38fb7b5f4c92e08/macports-ports], so please do a self-update first.

[reneeotten (Renee Otten)]

oh, are you suggesting Ken that that wasn't the correct fix and setting the C standard would also work? Then that's probably a better solution than the one that I merged... so perhaps this ticket shouldn't be closed?

[barracuda156]

Replying to kencu:

that works, but macports will usually want you to try setting the C standard first, if you can.

That can be tricky sometimes with python ports, but something like

configure.cflags-append -std=c99

is usually what works.

I might have tried that, if the error was suggestive, and perhaps it did not work in a way I tried. (I am pretty sure I did not go with any hacking of the source itself to pass needed flags though.)

Unfortunately, I have no way to test anything for older systems at the moment and I will be back to my normal hardware in about 2–3 weeks. If you or someone could test it, it would be helpful.

[jmroot (Joshua Root)]

Yes, adding a -std to the CFLAGS is a better fix. However it's likely that most if not all extension modules built against the Python 3.12 headers with these old compilers will hit this...

[jmroot (Joshua Root)]

Hm, looking again, it appears that lxml is directly including an internal header, which is hopefully rare.

[jmroot (Joshua Root)]

In ae323eaa5c528bd0730981fd4912e8ad2f803bf2/macports-ports (master):

py-lxml: enable C99 mode with old compilers

Fixes: #69386