Reset errno to zero after calling PyErr_Warn(). It can potentially do

gvanrossum · gvanrossum · commit 3cb8e54da0a3 · 2002-08-11T14:06:15.000Z
a lot of work, including I/O (e.g. to import warnings.py), which might
affect errno.
diff --git a/Python/compile.c b/Python/compile.c
@@ -1162,6 +1162,7 @@ parsenumber(struct compiling *co, char *s)
 				       "will return positive values "
 				       "in Python 2.4 and up") < 0)
 				return NULL;
+			errno = 0; /* Might be changed by PyErr_Warn() */
 		}
 	}
 	else

Original file line number	Diff line number	Diff line change
`@@ -1162,6 +1162,7 @@ parsenumber(struct compiling co, char s)`
`1162`	`1162`	`"will return positive values "`
`1163`	`1163`	`"in Python 2.4 and up") < 0)`
`1164`	`1164`	`return NULL;`
	`1165`	`+ errno = 0; /* Might be changed by PyErr_Warn() */`
`1165`	`1166`	`}`
`1166`	`1167`	`}`
`1167`	`1168`	`else`