Preliminary support for future nested scopes

compile.h: #define NESTED_SCOPES_DEFAULT 0 for Python 2.1
           __future__ feature name: "nested_scopes"

symtable.h: Add st_nested_scopes slot.  Define flags to track exec and
    import star.

Lib/test/test_scope.py: requires nested scopes

compile.c: Fiddle with error messages.

    Reverse the sense of ste_optimized flag on
    PySymtableEntryObjects.  If it is true, there is an optimization
    conflict.

    Modify get_ref_type to respect st_nested_scopes flags.

    Refactor symtable_load_symbols() into several smaller functions,
    which use struct symbol_info to share variables.  In new function
    symtable_update_flags(), raise an error or warning for import * or
    bare exec that conflicts with nested scopes.  Also, modify handle
    for free variables to respect st_nested_scopes flag.

    In symtable_init() assign st_nested_scopes flag to
    NESTED_SCOPES_DEFAULT (defined in compile.h).

    Add preliminary and often incorrect implementation of
    symtable_check_future().

    Add symtable_lookup() helper for future use.

1 files changed, 2 insertions, 0 deletions

diff --git a/Lib/test/test_scope.py b/Lib/test/test_scope.py
index 322431d..d64cead 100644
--- a/Lib/test/test_scope.py
+++ b/Lib/test/test_scope.py
@@ -1,3 +1,5 @@
+from __future__ import nested_scopes
+
 from test.test_support import verify, TestFailed, check_syntax
 
 print "1. simple nesting"