Fix core dump in example from Samuele Pedroni:
from __future__ import nested_scopes
x=7
def f():
x=1
def g():
global x
def i():
def h():
return x
return h()
return i()
return g()
print f()
print x
This kind of code didn't work correctly because x was treated as free
in i, leading to an attempt to load x in g to make a closure for i.
Solution is to make global decl apply to nested scopes unless their is
an assignment. Thus, x in h is global.
diff --git a/Python/compile.c b/Python/compile.c
index bd6a679..efef05b 100644
--- a/Python/compile.c
+++ b/Python/compile.c
@@ -179,6 +179,8 @@
return h;
}
+/* XXX code objects need to participate in GC? */
+
PyTypeObject PyCode_Type = {
PyObject_HEAD_INIT(&PyType_Type)
0,
@@ -2132,8 +2134,13 @@
else /* (reftype == FREE) */
arg = com_lookup_arg(c->c_freevars, name);
if (arg == -1) {
- fprintf(stderr, "lookup %s in %s %d %d\n",
- PyObject_REPR(name), c->c_name, reftype, arg);
+ fprintf(stderr, "lookup %s in %s %d %d\n"
+ "freevars of %s: %s\n",
+ PyObject_REPR(name),
+ c->c_name,
+ reftype, arg,
+ PyString_AS_STRING(co->co_name),
+ PyObject_REPR(co->co_freevars));
Py_FatalError("com_make_closure()");
}
com_addoparg(c, LOAD_CLOSURE, arg);
@@ -4424,8 +4431,8 @@
child = (PySymtableEntryObject *)
PyList_GET_ITEM(ste->ste_children, i);
while (PyDict_Next(child->ste_symbols, &pos, &name, &o)) {
- int v = PyInt_AS_LONG(o);
- if (!(is_free(v)))
+ int flags = PyInt_AS_LONG(o);
+ if (!(is_free(flags)))
continue; /* avoids indentation */
if (list == NULL) {
list = PyList_New(0);
@@ -4438,18 +4445,24 @@
return -1;
}
}
-/*
- if (st->st_nested_scopes == 0
- && list && PyList_GET_SIZE(list) > 0) {
- fprintf(stderr, "function %s has children with "
- "the following free vars:\n%s\n",
- PyString_AS_STRING(ste->ste_name),
- PyObject_REPR(list));
- continue;
- }
-*/
for (j = 0; list && j < PyList_GET_SIZE(list); j++) {
+ PyObject *v;
name = PyList_GET_ITEM(list, j);
+ v = PyDict_GetItem(ste->ste_symbols, name);
+ /* If a name N is declared global in scope A and
+ referenced in scope B contained (perhaps
+ indirectly) in A and there are no scopes
+ with bindings for N between B and A, then N
+ is global in B.
+ */
+ if (v) {
+ int flags = PyInt_AS_LONG(v);
+ if (flags & DEF_GLOBAL) {
+ symtable_undo_free(st, child->ste_id,
+ name);
+ continue;
+ }
+ }
if (ste->ste_nested) {
if (symtable_add_def_o(st, ste->ste_symbols,
name, def) < 0) {
@@ -4481,13 +4494,14 @@
PyObject *o;
int v;
PySymtableEntryObject *ste = st->st_cur;
-
+
if (ste->ste_type == TYPE_CLASS)
return symtable_undo_free(st, child, name);
o = PyDict_GetItem(ste->ste_symbols, name);
if (o == NULL)
return symtable_undo_free(st, child, name);
v = PyInt_AS_LONG(o);
+
if (is_free(v) || (v & DEF_GLOBAL))
return symtable_undo_free(st, child, name);
else
@@ -4506,6 +4520,7 @@
ste = (PySymtableEntryObject *)PyDict_GetItem(st->st_symbols, id);
if (ste == NULL)
return -1;
+
info = PyDict_GetItem(ste->ste_symbols, name);
if (info == NULL)
return 0;
@@ -4938,6 +4953,7 @@
int i;
if (st->st_nscopes == 1) {
+ /* XXX must check that we are compiling file_input */
if (symtable_warn(st,
"global statement has no meaning at module level") < 0)
return;