Backport Jeremy's checkin 2.198:

Fix 2.1 nested scopes crash reported by Evan Simpson

The new test case demonstrates the bug.  Be more careful in
symtable_resolve_free() to add a var to cells or frees only if it
won't be added under some other rule.

XXX Add new assertion that will catch this bug.

diff --git a/Python/compile.c b/Python/compile.c
index 0939f059c40ff1bb2e5a377a3b3d91cad12e8580..86147cf9454d3cb71ed67a277eff5e7201fd21ac 100644 (file)
--- a/Python/compile.c
+++ b/Python/compile.c
@@ -4069,7 +4069,7 @@ symtable_init_info(struct symbol_info *si)
 }
 
 static int
-symtable_resolve_free(struct compiling *c, PyObject *name, 
+symtable_resolve_free(struct compiling *c, PyObject *name, int flags,
                      struct symbol_info *si)
 {
        PyObject *dict, *v;
@@ -4079,11 +4079,19 @@ symtable_resolve_free(struct compiling *c, PyObject *name,
           cell var).  If it occurs in a class, then the class has a
           method and a free variable with the same name.
        */
-
        if (c->c_symtable->st_cur->ste_type == TYPE_FUNCTION) {
+               /* If it isn't declared locally, it can't be a cell. */
+               if (!(flags & (DEF_LOCAL | DEF_PARAM)))
+                       return 0;
                v = PyInt_FromLong(si->si_ncells++);
                dict = c->c_cellvars;
        } else {
+               /* If it is free anyway, then there is no need to do
+                  anything here.
+               */
+               if (is_free(flags ^ DEF_FREE_CLASS) 
+                   || flags == DEF_FREE_CLASS)
+                       return 0;
                v = PyInt_FromLong(si->si_nfrees++);
                dict = c->c_freevars;
        }
@@ -4369,10 +4377,7 @@ symtable_load_symbols(struct compiling *c)
                   variables or declared global.
                */
                if (flags & (DEF_FREE | DEF_FREE_CLASS)) {
-                   if ((ste->ste_type == TYPE_CLASS 
-                        && flags != DEF_FREE_CLASS)
-                       || (flags & (DEF_LOCAL | DEF_PARAM)))
-                       symtable_resolve_free(c, name, &si);
+                       symtable_resolve_free(c, name, flags, &si);
                }
 
                if (flags & DEF_STAR) {
@@ -4432,6 +4437,15 @@ symtable_load_symbols(struct compiling *c)
                }
        }
 
+       /*
+       fprintf(stderr, 
+               "cells %d: %s\n"
+               "frees %d: %s\n",
+               si.si_ncells, PyObject_REPR(c->c_cellvars),
+               si.si_nfrees, PyObject_REPR(c->c_freevars));
+       */
+       assert(PyDict_Size(c->c_freevars) == si.si_nfrees);
+
        if (si.si_ncells > 1) { /* one cell is always in order */
                if (symtable_cellvar_offsets(&c->c_cellvars, c->c_argcount,
                                             c->c_varnames, c->c_flags) < 0)