Gregory (Grisha) Trubetskoy wrote:
OK, here is the flex scoop - as the the docs point out, anything before
2.5.31 is not reentrant and I think even uses a slightly different
interface so older flex won't even process the psp_parser.l file correctly.
Looking at Fedora Core 4, it still has flex 2.5.4a. (Note that 2.5.31 >
2.5.4 because 31 > 4 - I for a while had trouble seeing that for some
reason), so the new flex is still not commonplace.
This is true. I took a quick survey when I was adding the --with-flex
option, and 2.5.4 was the most common. Oh, and the version numbering
confused me for a while as well, but the configure script does take it
into account when deciding if it has the correct flex.
So until reentrant flex becomes commonplace, the solution was to include
a pre-parsed psp_parser.c so that you woudln't need flex at all to
compile mod_python. Looks like this still should be the case.
The ./configure should just print a warning that if flex is not found or
too old, should you need to rebuild psp_parser.c you will need to get
the right version of flex.
When I added the flex detection I had not considered the case where
there was *no* flex on the system... just tested for the correct
version. :-(
Also, I wasn't sure how verbose to make the configure message. I just
figured that people would see the WARNING and then go to the README to
see what the deal was, which would have been the perfect plan... if I
had actually updated the README accordingly.
I'll make the fixes to configure and the README. Is the explanation in
doc-html/inst-configure.html clear or does it need to be revised as well?
Jim
See doc-html/inst-configure.html:
""" Attempts to locate flex and determine its version. If flex
cannot be found in your PATH configure will fail. If the wrong
version is found configure will generate a warning. You can generally
ignore this warning unless you need to re-create src/psp_parser.c.
The parser used by psp (See 4.9) is written in C generated using flex.
This requires a reentrant version of flex which at this time is
2.5.31. Most platforms however ship with version 2.5.4 which is not
suitable, so a pre-generated copy of psp_parser.c is included with the
source. If you do need to compile src/psp_parser.c you must get the
correct flex version.
If the first flex binary in the path is not suitable or not the one
desired you can specify an alternative location with the --with-flex
option, e.g:
$ ./configure --with-flex=/usr/local/bin/flex
"""
I'll copy this into the README as well.
In 3.1.x the path to flex was hard coded to /usr/local/bin, which
caused compilation to fail and required the user to edit the Makefile
manually. Other than the detection of the flex path, the behaviour is
the same as 3.1.x. The previous warning about needing the correct flex
version was just a comment in the Makefile. Any suggestions on how to
make this clearer are welcome.
