Bugs item #1186195, was opened at 2005-04-19 12:02
Message generated for change (Tracker Item Submitted) made by Item Submitter
You can respond by visiting:
https://sourceforge.net/tracker/?func=detail&atid=105470&aid=1186195&group_id=5470
Category: Parser/Compiler
Group: AST
Status: Open
Resolution: None
Priority: 5
Submitted By: Brett Cannon (bcannon)
Assigned to: Nick Coghlan (ncoghlan)
Summary: [AST] genexps get scoping wrong
Initial Comment:
test_genexps is failing because it is unable to find a
global defined in a genexp that is returned. Here is
the problem simplified:
def f(n): return (i for i in xrange(n))
list(f(10))
Leads to ``SystemError: no locals when loading 'xrange'``.
Comparing Python 2.4 bytecode:
1 0 LOAD_CONST 1 (<code
object <generator expression> at 0x3931e0, file
"<stdin>", line 1>)
3 MAKE_FUNCTION 0
6 LOAD_GLOBAL 0 (xrange)
9 LOAD_FAST 0 (n)
12 CALL_FUNCTION 1
15 GET_ITER
16 CALL_FUNCTION 1
19 RETURN_VALUE
20 LOAD_CONST 0 (None)
23 RETURN_VALUE
to AST bytecode:
1 0 LOAD_CLOSURE 0 (n)
3 BUILD_TUPLE 1
6 LOAD_CONST 1 (<code
object <generator expression> at 0x5212e8, file
"<stdin>", line 1>)
9 MAKE_CLOSURE 0
12 LOAD_NAME 0 (xrange)
15 LOAD_DEREF 0 (n)
18 CALL_FUNCTION 1
21 GET_ITER
22 CALL_FUNCTION 1
25 RETURN_VALUE
26 LOAD_CONST 0 (None)
29 RETURN_VALUE
makes it obvious something is off (no peepholer; turned
it off in my build of 2.4).
Looks like extraneous work is being done in making a
closure. Seems like it will still work, though.
Plus the usage of LOAD_NAME is wrong in the AST;
LOAD_NAME gets an object from the local namespace based
on its name instead of offset.
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https://sourceforge.net/tracker/?func=detail&atid=105470&aid=1186195&group_id=5470
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