gh-122245: move checks for writes and shadowing of __debug__ to symtable (#122246)

1 files changed, 85 insertions, 7 deletions

diff --git a/Python/symtable.c b/Python/symtable.c
index c4508cac7f5..a5fa7588785 100644
--- a/Python/symtable.c
+++ b/Python/symtable.c
@@ -1495,8 +1495,57 @@ error:
 }
 
 static int
-symtable_add_def(struct symtable *st, PyObject *name, int flag, _Py_SourceLocation loc)
+check_name(struct symtable *st, PyObject *name, _Py_SourceLocation loc,
+           expr_context_ty ctx)
 {
+    if (ctx == Store && _PyUnicode_EqualToASCIIString(name, "__debug__")) {
+        PyErr_SetString(PyExc_SyntaxError, "cannot assign to __debug__");
+        SET_ERROR_LOCATION(st->st_filename, loc);
+        return 0;
+    }
+    if (ctx == Del && _PyUnicode_EqualToASCIIString(name, "__debug__")) {
+        PyErr_SetString(PyExc_SyntaxError, "cannot delete __debug__");
+        SET_ERROR_LOCATION(st->st_filename, loc);
+        return 0;
+    }
+    return 1;
+}
+
+static int
+check_keywords(struct symtable *st, asdl_keyword_seq *keywords)
+{
+    for (Py_ssize_t i = 0; i < asdl_seq_LEN(keywords); i++) {
+        keyword_ty key = ((keyword_ty)asdl_seq_GET(keywords, i));
+        if (key->arg  && !check_name(st, key->arg, LOCATION(key), Store)) {
+            return 0;
+        }
+    }
+    return 1;
+}
+
+static int
+check_kwd_patterns(struct symtable *st, pattern_ty p)
+{
+    assert(p->kind == MatchClass_kind);
+    asdl_identifier_seq *kwd_attrs = p->v.MatchClass.kwd_attrs;
+    asdl_pattern_seq *kwd_patterns = p->v.MatchClass.kwd_patterns;
+    for (Py_ssize_t i = 0; i < asdl_seq_LEN(kwd_attrs); i++) {
+        _Py_SourceLocation loc = LOCATION(asdl_seq_GET(kwd_patterns, i));
+        if (!check_name(st, asdl_seq_GET(kwd_attrs, i), loc, Store)) {
+            return 0;
+        }
+    }
+    return 1;
+}
+
+static int
+symtable_add_def_ctx(struct symtable *st, PyObject *name, int flag,
+                     _Py_SourceLocation loc, expr_context_ty ctx)
+{
+    int write_mask = DEF_PARAM | DEF_LOCAL | DEF_IMPORT;
+    if ((flag & write_mask) && !check_name(st, name, loc, ctx)) {
+        return 0;
+    }
     if ((flag & DEF_TYPE_PARAM) && st->st_cur->ste_mangled_names != NULL) {
         if(PySet_Add(st->st_cur->ste_mangled_names, name) < 0) {
             return 0;
@@ -1506,6 +1555,14 @@ symtable_add_def(struct symtable *st, PyObject *name, int flag, _Py_SourceLocati
 }
 
 static int
+symtable_add_def(struct symtable *st, PyObject *name, int flag,
+                 _Py_SourceLocation loc)
+{
+    return symtable_add_def_ctx(st, name, flag, loc,
+                                flag == USE ? Load : Store);
+}
+
+static int
 symtable_enter_type_param_block(struct symtable *st, identifier name,
                                void *ast, int has_defaults, int has_kwdefaults,
                                enum _stmt_kind kind, _Py_SourceLocation loc)
@@ -1757,6 +1814,9 @@ symtable_visit_stmt(struct symtable *st, stmt_ty s)
             VISIT_SEQ(st, type_param, s->v.ClassDef.type_params);
         }
         VISIT_SEQ(st, expr, s->v.ClassDef.bases);
+        if (!check_keywords(st, s->v.ClassDef.keywords)) {
+            VISIT_QUIT(st, 0);
+        }
         VISIT_SEQ(st, keyword, s->v.ClassDef.keywords);
         if (!symtable_enter_block(st, s->v.ClassDef.name, ClassBlock,
                                   (void *)s, LOCATION(s))) {
@@ -1871,10 +1931,11 @@ symtable_visit_stmt(struct symtable *st, stmt_ty s)
             VISIT(st, expr, s->v.AnnAssign.value);
         }
         break;
-    case AugAssign_kind:
+    case AugAssign_kind: {
         VISIT(st, expr, s->v.AugAssign.target);
         VISIT(st, expr, s->v.AugAssign.value);
         break;
+    }
     case For_kind:
         VISIT(st, expr, s->v.For.target);
         VISIT(st, expr, s->v.For.iter);
@@ -2311,6 +2372,9 @@ symtable_visit_expr(struct symtable *st, expr_ty e)
     case Call_kind:
         VISIT(st, expr, e->v.Call.func);
         VISIT_SEQ(st, expr, e->v.Call.args);
+        if (!check_keywords(st, e->v.Call.keywords)) {
+            VISIT_QUIT(st, 0);
+        }
         VISIT_SEQ_WITH_NULL(st, keyword, e->v.Call.keywords);
         break;
     case FormattedValue_kind:
@@ -2326,6 +2390,9 @@ symtable_visit_expr(struct symtable *st, expr_ty e)
         break;
     /* The following exprs can be assignment targets. */
     case Attribute_kind:
+        if (!check_name(st, e->v.Attribute.attr, LOCATION(e), e->v.Attribute.ctx)) {
+            VISIT_QUIT(st, 0);
+        }
         VISIT(st, expr, e->v.Attribute.value);
         break;
     case Subscript_kind:
@@ -2344,9 +2411,11 @@ symtable_visit_expr(struct symtable *st, expr_ty e)
             VISIT(st, expr, e->v.Slice.step);
         break;
     case Name_kind:
-        if (!symtable_add_def(st, e->v.Name.id,
-                              e->v.Name.ctx == Load ? USE : DEF_LOCAL, LOCATION(e)))
+        if (!symtable_add_def_ctx(st, e->v.Name.id,
+                                  e->v.Name.ctx == Load ? USE : DEF_LOCAL,
+                                  LOCATION(e), e->v.Name.ctx)) {
             VISIT_QUIT(st, 0);
+        }
         /* Special-case super: it counts as a use of __class__ */
         if (e->v.Name.ctx == Load &&
             _PyST_IsFunctionLike(st->st_cur) &&
@@ -2472,19 +2541,26 @@ symtable_visit_pattern(struct symtable *st, pattern_ty p)
         break;
     case MatchStar_kind:
         if (p->v.MatchStar.name) {
-            symtable_add_def(st, p->v.MatchStar.name, DEF_LOCAL, LOCATION(p));
+            if (!symtable_add_def(st, p->v.MatchStar.name, DEF_LOCAL, LOCATION(p))) {
+                VISIT_QUIT(st, 0);
+            }
         }
         break;
     case MatchMapping_kind:
         VISIT_SEQ(st, expr, p->v.MatchMapping.keys);
         VISIT_SEQ(st, pattern, p->v.MatchMapping.patterns);
         if (p->v.MatchMapping.rest) {
-            symtable_add_def(st, p->v.MatchMapping.rest, DEF_LOCAL, LOCATION(p));
+            if (!symtable_add_def(st, p->v.MatchMapping.rest, DEF_LOCAL, LOCATION(p))) {
+                VISIT_QUIT(st, 0);
+            }
         }
         break;
     case MatchClass_kind:
         VISIT(st, expr, p->v.MatchClass.cls);
         VISIT_SEQ(st, pattern, p->v.MatchClass.patterns);
+        if (!check_kwd_patterns(st, p)) {
+            VISIT_QUIT(st, 0);
+        }
         VISIT_SEQ(st, pattern, p->v.MatchClass.kwd_patterns);
         break;
     case MatchAs_kind:
@@ -2492,7 +2568,9 @@ symtable_visit_pattern(struct symtable *st, pattern_ty p)
             VISIT(st, pattern, p->v.MatchAs.pattern);
         }
         if (p->v.MatchAs.name) {
-            symtable_add_def(st, p->v.MatchAs.name, DEF_LOCAL, LOCATION(p));
+            if (!symtable_add_def(st, p->v.MatchAs.name, DEF_LOCAL, LOCATION(p))) {
+                VISIT_QUIT(st, 0);
+            }
         }
         break;
     case MatchOr_kind: