co_lnotab supports negative line number delta
Issue #26107: The format of the co_lnotab attribute of code objects changes to
support negative line number delta.
Changes:
* assemble_lnotab(): if line number delta is less than -128 or greater than
127, emit multiple (offset_delta, lineno_delta) in co_lnotab
* update functions decoding co_lnotab to use signed 8-bit integers
- dis.findlinestarts()
- PyCode_Addr2Line()
- _PyCode_CheckLineNumber()
- frame_setlineno()
* update lnotab_notes.txt
* increase importlib MAGIC_NUMBER to 3361
* document the change in What's New in Python 3.6
* cleanup also PyCode_Optimize() to use better variable names
diff --git a/Objects/frameobject.c b/Objects/frameobject.c
index 425a9ee..da2d2ed 100644
--- a/Objects/frameobject.c
+++ b/Objects/frameobject.c
@@ -137,7 +137,7 @@
new_lasti = -1;
for (offset = 0; offset < lnotab_len; offset += 2) {
addr += lnotab[offset];
- line += lnotab[offset+1];
+ line += (signed char)lnotab[offset+1];
if (line >= new_lineno) {
new_lasti = addr;
new_lineno = line;