* Improve the hash function to increase the chance that distinct sets will
have distinct xor'd hash totals.
* Use PyDict_Merge where possible (it is faster than an equivalent iter/set
pair).
* Don't rebuild dictionaries where the input already has one.
Also SF patch 843455.
This is a critical bugfix.
I'll backport to 2.3 maint, but not beyond that. The bugs this fixes
have been there since weakrefs were introduced.
* Install the unittests, docs, newsitem, include file, and makefile update.
* Exercise the new functions whereever sets.py was being used.
Includes the docs for libfuncs.tex. Separate docs for the types are
forthcoming.
subtype_dealloc(): This left the dying object exposed to gc, so that
if cyclic gc triggered during the weakref callback, gc tried to delete
the dying object a second time. That's a disaster. subtype_dealloc()
had a (I hope!) unique problem here, as every normal dealloc routine
untracks the object (from gc) before fiddling with weakrefs etc. But
subtype_dealloc has obscure technical reasons for re-registering the
dying object with gc (already explained in a large comment block at
the bottom of the function).
The fix amounts to simply refraining from reregistering the dying object
with gc until after the weakref callback (if any) has been called.
This is a critical bug (hard to predict, and causes seemingly random
memory corruption when it occurs). I'll backport it to 2.3 later.
charmaptranslate_makespace() allocated more memory than required for the
next replacement but didn't remember that fact, so memory size was growing
exponentially every time a replacement string is longer that one character.
This fixes SF bug #828737.
key provides C support for the decorate-sort-undecorate pattern.
reverse provide a stable sort of the list with the comparisions reversed.
* Amended the docs to guarantee sort stability.
If a length-1 Unicode string was in the freelist and it was
uninitialized or pointed to a very large (magnitude) negative number,
the check
unicode_latin1[unicode->str[0]] == unicode
could cause a segmentation violation, e.g. unicode->str[0] is 0xcbcbcbcb.
Fix this in two ways:
1. Change guard befor unicode_latin1[] to test against 256U. If I
understand correctly, the unsigned long used to store UCS4 on my
box was getting converted to a signed long to compare with the
signed constant 256.
2. Change _PyUnicode_New() to make sure the first element of str is
always initialized to zero. There are several places in the code
where the caller can exit with an error before initializing any
of str, which would leave junk in str[0].
Also, silence a compiler warning on pointer vs. int arithmetic.
Bug fix candidate.
The unicode_resize() family only returns -1 or 0 so simply checking
for != 0 is sufficient, but somewhat unclear. Many Python API
functions return < 0 on error, reserving the right to return 0 or 1 on
success. Change the call sites for consistency with these calls.
file_truncate(): C doesn't define what fflush(fp) does if fp is open
for update, and the preceding I/O operation on fp was input. On Windows,
fflush() actually changes the current file position then. Because
Windows doesn't support ftruncate() directly, this not only caused
Python's file.truncate() to change the file position (contra our docs),
it also caused the file not to change size.
Repaired by getting the initial file position at the start, restoring
it at the end, and tossing all the complicated micro-efficiency checks
trying to avoid "provably unnecessary" seeks. file.truncate() can't
be a frequent operation, and seeking to the current file position has
got to be cheap anyway.
Bugfix candidate.
