Fail closed on final input bindings and transitive aliases

tools/generate_popular_node_signatures.py

@@ -35,22 +35,25 @@ _MUTATING_METHODS = {
 }
 
 
-def _literal(node, env):
+def _literal(node, env, allow_mutable_env=True):
     if isinstance(node, ast.Constant):
         return node.value
     if isinstance(node, ast.List):
-        return [_literal(item, env) for item in node.elts]
+        return [_literal(item, env, allow_mutable_env=False) for item in node.elts]
     if isinstance(node, ast.Tuple):
-        return tuple(_literal(item, env) for item in node.elts)
+        return tuple(_literal(item, env, allow_mutable_env=False) for item in node.elts)
     if isinstance(node, ast.Dict):
         result = {}
         for key, value in zip(node.keys, node.values):
             if key is None:
                 raise UnsupportedStaticExpression("dict unpacking is not supported")
-            result[_literal(key, env)] = _literal(value, env)
+            result[_literal(key, env, allow_mutable_env=False)] = _literal(value, env, allow_mutable_env=False)
         return result
     if isinstance(node, ast.Name) and node.id in env:
-        return env[node.id]
+        value = env[node.id]
+        if not allow_mutable_env and _is_mutable_static_value(value):
+            raise UnsupportedStaticExpression(f"mutable env reference {node.id!r} is not supported")
+        return value
     raise UnsupportedStaticExpression(type(node).__name__)
 
 
@@ -413,7 +416,7 @@ def _class_attr(cls, name, env):
                 and isinstance(stmt.targets[0], ast.Name)
                 and stmt.targets[0].id != name
                 and isinstance(stmt.value, ast.Name)
-                and stmt.value.id == name
+                and (stmt.value.id == name or stmt.value.id in aliases)
             ):
                 aliases.add(stmt.targets[0].id)
                 continue
@@ -439,7 +442,7 @@ def _class_attr(cls, name, env):
                 isinstance(stmt.target, ast.Name)
                 and stmt.target.id != name
                 and isinstance(stmt.value, ast.Name)
-                and stmt.value.id == name
+                and (stmt.value.id == name or stmt.value.id in aliases)
             ):
                 aliases.add(stmt.target.id)
                 continue
@@ -505,17 +508,47 @@ def _class_attr(cls, name, env):
 
 
 def _input_types(cls, env):
+    value = _MISSING
     for stmt in cls.body:
-        if not isinstance(stmt, ast.FunctionDef) or stmt.name != "INPUT_TYPES":
+        if isinstance(stmt, ast.FunctionDef) and stmt.name == "INPUT_TYPES":
+            if len(stmt.body) != 1 or not isinstance(stmt.body[0], ast.Return):
+                value = _INVALID
+                continue
+            try:
+                candidate = _literal(stmt.body[0].value, env)
+            except UnsupportedStaticExpression:
+                value = _INVALID
+                continue
+            value = candidate if isinstance(candidate, dict) else _INVALID
             continue
-        if len(stmt.body) != 1 or not isinstance(stmt.body[0], ast.Return):
-            return None
-        try:
-            value = _literal(stmt.body[0].value, env)
-        except UnsupportedStaticExpression:
-            return None
-        return value if isinstance(value, dict) else None
-    return None
+        if isinstance(stmt, ast.AsyncFunctionDef) and stmt.name == "INPUT_TYPES":
+            value = _INVALID
+            continue
+        if isinstance(stmt, (ast.Assign, ast.AnnAssign, ast.AugAssign)):
+            if "INPUT_TYPES" in _assignment_target_names(stmt):
+                value = _INVALID
+            continue
+        if isinstance(stmt, ast.Delete):
+            if "INPUT_TYPES" in _delete_target_names(stmt):
+                value = _INVALID
+            continue
+        if isinstance(stmt, ast.Expr):
+            if "INPUT_TYPES" in _mutating_call_target_names(stmt):
+                value = _INVALID
+            if "INPUT_TYPES" in _bound_names(stmt):
+                value = _INVALID
+            continue
+        if isinstance(stmt, (ast.If, ast.For, ast.AsyncFor, ast.While, ast.Try, ast.With, ast.AsyncWith, ast.Match)):
+            if "INPUT_TYPES" in _assigned_names_in_control_flow(stmt):
+                value = _INVALID
+            if _has_wildcard_import_in_control_flow(stmt):
+                value = _INVALID
+            continue
+        if "INPUT_TYPES" in _bound_names(stmt):
+            value = _INVALID
+    if value in (_MISSING, _INVALID):
+        return None
+    return value
 
 
 def _mapping_value_name(value):