The following minor issues may affect the readability of the code implementing symbol tables in Include/symtable.h and Python/symtable.c

    * The comment for st_global in symtable.h says: "borrowed ref to st_top->st_symbols. typo? (st_top->ste_symbols)
    * ste_varnames: the name and the comment after it are misleading, since it actually collects only the function's parameters and not all variables.
    * the st_nblocks and st_future fields of symtable aren't used anywhere - py3k compiles fine when they're removed.
    * in analyze_block a comment says "Recursively call analyze_block()" - untrue, probably meant analyze_child_block. While technically analyze_child_block calls analyze_block, the comment as-is appears misleading.
    * symtable_add_def is also called with the USE flag, not only definitions, hence its name doesn't reflect its purpose accurately
    * There are some indentation artifacts that obscure readability. For example the case Raise_kind of symtable_visit_stmt, where two nested blocks start and end in the same column obscuring the fact they're nested. This could be a result of an automatic tab to space conversion in the past.

I think this needs at least two patches: one to change comments, another to remove two fields. Can you prepare something?

If I recall correctly, st_nblocks and st_future are there for consistency with the corresponding compiler structures.

I believe st_future is also needed whenever a future flag affects the symtable construction (there aren't any at the moment, but a trawl through the version history in the Python 2.x symtable.c may reveal some)

Terry, Nick - is it OK to commit a fix for the comments?

I would say yes (if you are sure changes are correct) unless Nick speaks up to say he wants to review first.

+1 for clarifying the comments. Adding comments for the apparently unused fields (as per my last tracker comment) would be good, too.

New changeset b6fe63c914e4 by Eli Bendersky in branch 'default':
Issue #9904: fix and clarify some comments + fix indentation in symtable code
http://hg.python.org/cpython/rev/b6fe63c914e4

I committed the fixes to 3.3 (see no reason to backport these). So unless there are objections I will close the issue in a few days.

Yep, code cleanup is not done in the stable branches (except as a by-product of a bugfix).

Thanks for the clarification, Éric