Issue #9011: Remove buggy and unnecessary ST->AST compilation code
dealing with unary minus applied to a constant. The removed code was
mutating the ST, causing a second compilation to fail. (The peephole
optimizer already takes care of optimizing this case, so there's no
lost optimization opportunity here.)
diff --git a/Lib/test/test_parser.py b/Lib/test/test_parser.py
index a36b544..071d362 100644
--- a/Lib/test/test_parser.py
+++ b/Lib/test/test_parser.py
@@ -484,8 +484,18 @@
st = parser.suite('a = "\\u1"')
self.assertRaises(SyntaxError, parser.compilest, st)
+ def test_issue_9011(self):
+ # Issue 9011: compilation of an unary minus expression changed
+ # the meaning of the ST, so that a second compilation produced
+ # incorrect results.
+ st = parser.expr('-3')
+ code1 = parser.compilest(st)
+ self.assertEqual(eval(code1), -3)
+ code2 = parser.compilest(st)
+ self.assertEqual(eval(code2), -3)
+
class ParserStackLimitTestCase(unittest.TestCase):
- """try to push the parser to/over it's limits.
+ """try to push the parser to/over its limits.
see http://bugs.python.org/issue1881 for a discussion
"""
def _nested_expression(self, level):
diff --git a/Misc/NEWS b/Misc/NEWS
index 0de8581..9c5ea77 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -12,6 +12,11 @@
Core and Builtins
-----------------
+- Issue #9011: Remove buggy and unnecessary (in 3.x) ST->AST
+ compilation code dealing with unary minus applied to a constant.
+ The removed code was mutating the ST, causing a second compilation
+ to fail.
+
- Issue #850997: mbcs encoding (Windows only) handles errors argument: strict
mode raises unicode errors. The encoder only supports "strict" and "replace"
error handlers, the decoder only supports "strict" and "ignore" error
diff --git a/Python/ast.c b/Python/ast.c
index 0703abc..34dc30f 100644
--- a/Python/ast.c
+++ b/Python/ast.c
@@ -1678,34 +1678,8 @@
static expr_ty
ast_for_factor(struct compiling *c, const node *n)
{
- node *pfactor, *ppower, *patom, *pnum;
expr_ty expression;
- /* If the unary - operator is applied to a constant, don't generate
- a UNARY_NEGATIVE opcode. Just store the approriate value as a
- constant. The peephole optimizer already does something like
- this but it doesn't handle the case where the constant is
- (sys.maxint - 1). In that case, we want a PyIntObject, not a
- PyLongObject.
- */
- if (TYPE(CHILD(n, 0)) == MINUS
- && NCH(n) == 2
- && TYPE((pfactor = CHILD(n, 1))) == factor
- && NCH(pfactor) == 1
- && TYPE((ppower = CHILD(pfactor, 0))) == power
- && NCH(ppower) == 1
- && TYPE((patom = CHILD(ppower, 0))) == atom
- && TYPE((pnum = CHILD(patom, 0))) == NUMBER) {
- char *s = PyObject_MALLOC(strlen(STR(pnum)) + 2);
- if (s == NULL)
- return NULL;
- s[0] = '-';
- strcpy(s + 1, STR(pnum));
- PyObject_FREE(STR(pnum));
- STR(pnum) = s;
- return ast_for_atom(c, patom);
- }
-
expression = ast_for_expr(c, CHILD(n, 1));
if (!expression)
return NULL;