Without this change, test_unicode.UnicodeTest.test_codecs_utf7 crashes in
debug mode. What happens is the unicode string u'\U000abcde' with a length
of 1 encodes to the string '+2m/c3g-' of length 8. Since only 5 bytes is
reserved in the buffer, a buffer overrun occurs.
lnotab-based tracing is very complicated and isn't documented very well. There
were at least 3 comment blocks purporting to document co_lnotab, and none did a
very good job. This patch unifies them into Objects/lnotab_notes.txt which
tries to completely capture the current state of affairs.
I also discovered that we've attached 2 layers of patches to the basic tracing
scheme. The first layer avoids jumping to instructions that don't start a line,
to avoid problems in if statements and while loops. The second layer
discovered that jumps backward do need to trace at instructions that don't
start a line, so it added extra lnotab entries for 'while' and 'for' loops, and
added a special case for backward jumps within the same line. I replaced these
patches by just treating forward and backward jumps differently.
made it try to set the line number from the trace callback for a 'call' event.
This patch makes the error message a little more helpful in that case, and
makes it a little less likely that a future editor will make the same mistake
in test_trace.
Most uses of PyCode_Addr2Line
(http://www.google.com/codesearch?q=PyCode_Addr2Line) are just trying to get
the line number of a specified frame, but there's no way to do that directly.
Forcing people to go through the code object makes them know more about the
guts of the interpreter than they should need.
The remaining uses of PyCode_Addr2Line seem to be getting the line from a
traceback (for example,
http://www.google.com/codesearch/p?hl=en#u_9_nDrchrw/pygame-1.7.1release/src/base.c&q=PyCode_Addr2Line),
which is replaced by the tb_lineno field. So we may be able to deprecate
PyCode_Addr2Line entirely for external use.
Mark Dickinson
Benjamin Peterson
Eric Smith
Raymond Hettinger
Georg Brandl
Alexandre Vassalotti
Hirokazu Yamamoto
Amaury Forgeot d'Arc
Antoine Pitrou
Jeffrey Yasskin