gh-119180: PEP 649 compiler changes (#119361)

Author: JelleZijlstra

Include/internal/pycore_global_objects_fini_generated.h

@@ -45,6 +45,7 @@ struct _Py_global_strings {
         STRUCT_FOR_STR(dot, ".")
         STRUCT_FOR_STR(dot_locals, ".<locals>")
         STRUCT_FOR_STR(empty, "")
+        STRUCT_FOR_STR(format, ".format")
         STRUCT_FOR_STR(generic_base, ".generic_base")
         STRUCT_FOR_STR(json_decoder, "json.decoder")
         STRUCT_FOR_STR(kwdefaults, ".kwdefaults")
@@ -234,7 +235,6 @@ struct _Py_global_strings {
         STRUCT_FOR_ID(_abstract_)
         STRUCT_FOR_ID(_active)
         STRUCT_FOR_ID(_align_)
-        STRUCT_FOR_ID(_annotation)
         STRUCT_FOR_ID(_anonymous_)
         STRUCT_FOR_ID(_argtypes_)
         STRUCT_FOR_ID(_as_parameter_)

Include/internal/pycore_global_strings.h

@@ -57,6 +57,7 @@ extern "C" {
 #define MAKE_FUNCTION_KWDEFAULTS  0x02
 #define MAKE_FUNCTION_ANNOTATIONS 0x04
 #define MAKE_FUNCTION_CLOSURE     0x08
+#define MAKE_FUNCTION_ANNOTATE    0x10
 
 /* Values used as the oparg for LOAD_COMMON_CONSTANT */
 #define CONSTANT_ASSERTIONERROR 0

Include/internal/pycore_opcode_utils.h

@@ -12,8 +12,9 @@ struct _mod;   // Type defined in pycore_ast.h
 
 typedef enum _block_type {
     FunctionBlock, ClassBlock, ModuleBlock,
-    // Used for annotations if 'from __future__ import annotations' is active.
-    // Annotation blocks cannot bind names and are not evaluated.
+    // Used for annotations. If 'from __future__ import annotations' is active,
+    // annotation blocks cannot bind names and are not evaluated. Otherwise, they
+    // are lazily evaluated (see PEP 649).
     AnnotationBlock,
     // Used for generics and type aliases. These work mostly like functions
     // (see PEP 695 for details). The three different blocks function identically;
@@ -89,6 +90,7 @@ typedef struct _symtable_entry {
                                      including free refs to globals */
     unsigned ste_generator : 1;   /* true if namespace is a generator */
     unsigned ste_coroutine : 1;   /* true if namespace is a coroutine */
+    unsigned ste_annotations_used : 1;  /* true if there are any annotations in this scope */
     _Py_comprehension_ty ste_comprehension;  /* Kind of comprehension (if any) */
     unsigned ste_varargs : 1;     /* true if block has varargs */
     unsigned ste_varkeywords : 1; /* true if block has varkeywords */
@@ -110,6 +112,7 @@ typedef struct _symtable_entry {
     int ste_end_col_offset;  /* end offset of first line of block */
     int ste_opt_lineno;      /* lineno of last exec or import * */
     int ste_opt_col_offset;  /* offset of last exec or import * */
+    struct _symtable_entry *ste_annotation_block; /* symbol table entry for this entry's annotations */
     struct symtable *ste_table;
 } PySTEntryObject;
 
@@ -126,6 +129,7 @@ extern struct symtable* _PySymtable_Build(
     PyObject *filename,
     _PyFutureFeatures *future);
 extern PySTEntryObject* _PySymtable_Lookup(struct symtable *, void *);
+extern int _PySymtable_LookupOptional(struct symtable *, void *, PySTEntryObject **);
 
 extern void _PySymtable_Free(struct symtable *);
 

Include/internal/pycore_runtime_init_generated.h

@@ -220,13 +220,7 @@ def get_annotations(obj, *, globals=None, locals=None, eval_str=False):
     """
     if isinstance(obj, type):
         # class
-        obj_dict = getattr(obj, '__dict__', None)
-        if obj_dict and hasattr(obj_dict, 'get'):
-            ann = obj_dict.get('__annotations__', None)
-            if isinstance(ann, types.GetSetDescriptorType):
-                ann = None
-        else:
-            ann = None
+        ann = obj.__annotations__
 
         obj_globals = None
         module_name = getattr(obj, '__module__', None)

Include/internal/pycore_symtable.h

@@ -222,6 +222,8 @@ def get_methods(self):
         if self.__methods is None:
             d = {}
             for st in self._table.children:
+                if st.type == _symtable.TYPE_ANNOTATION:
+                    continue
                 d[st.name] = 1
             self.__methods = tuple(d)
         return self.__methods

Include/internal/pycore_unicodeobject_generated.h

@@ -352,32 +352,21 @@ def wrap_func_w_kwargs():
 dis_annot_stmt_str = """\
   0           RESUME                   0
 
-  2           SETUP_ANNOTATIONS
-              LOAD_CONST               0 (1)
+  2           LOAD_CONST               0 (1)
               STORE_NAME               0 (x)
-              LOAD_NAME                1 (int)
-              LOAD_NAME                2 (__annotations__)
-              LOAD_CONST               1 ('x')
-              STORE_SUBSCR
-
-  3           LOAD_NAME                3 (fun)
-              PUSH_NULL
-              LOAD_CONST               0 (1)
-              CALL                     1
-              LOAD_NAME                2 (__annotations__)
-              LOAD_CONST               2 ('y')
-              STORE_SUBSCR
 
   4           LOAD_CONST               0 (1)
-              LOAD_NAME                4 (lst)
-              LOAD_NAME                3 (fun)
+              LOAD_NAME                1 (lst)
+              LOAD_NAME                2 (fun)
               PUSH_NULL
-              LOAD_CONST               3 (0)
+              LOAD_CONST               1 (0)
               CALL                     1
               STORE_SUBSCR
-              LOAD_NAME                1 (int)
-              POP_TOP
-              RETURN_CONST             4 (None)
+
+  2           LOAD_CONST               2 (<code object __annotate__ at 0x..., file "<dis>", line 2>)
+              MAKE_FUNCTION
+              STORE_NAME               3 (__annotate__)
+              RETURN_CONST             3 (None)
 """
 
 compound_stmt_str = """\

Lib/inspect.py

@@ -306,16 +306,6 @@ def test_eof_error(self):
 
 var_annot_global: int # a global annotated is necessary for test_var_annot
 
-# custom namespace for testing __annotations__
-
-class CNS:
-    def __init__(self):
-        self._dct = {}
-    def __setitem__(self, item, value):
-        self._dct[item.lower()] = value
-    def __getitem__(self, item):
-        return self._dct[item]
-
 
 class GrammarTests(unittest.TestCase):
 
@@ -446,22 +436,12 @@ class F(C, A):
         self.assertEqual(E.__annotations__, {})
         self.assertEqual(F.__annotations__, {})
 
-
-    def test_var_annot_metaclass_semantics(self):
-        class CMeta(type):
-            @classmethod
-            def __prepare__(metacls, name, bases, **kwds):
-                return {'__annotations__': CNS()}
-        class CC(metaclass=CMeta):
-            XX: 'ANNOT'
-        self.assertEqual(CC.__annotations__['xx'], 'ANNOT')
-
     def test_var_annot_module_semantics(self):
         self.assertEqual(test.__annotations__, {})
         self.assertEqual(ann_module.__annotations__,
-                     {1: 2, 'x': int, 'y': str, 'f': typing.Tuple[int, int], 'u': int | float})
+                         {'x': int, 'y': str, 'f': typing.Tuple[int, int], 'u': int | float})
         self.assertEqual(ann_module.M.__annotations__,
-                              {'123': 123, 'o': type})
+                         {'o': type})
         self.assertEqual(ann_module2.__annotations__, {})
 
     def test_var_annot_in_module(self):
@@ -476,51 +456,12 @@ def test_var_annot_in_module(self):
             ann_module3.D_bad_ann(5)
 
     def test_var_annot_simple_exec(self):
-        gns = {}; lns= {}
+        gns = {}; lns = {}
         exec("'docstring'\n"
-             "__annotations__[1] = 2\n"
              "x: int = 5\n", gns, lns)
-        self.assertEqual(lns["__annotations__"], {1: 2, 'x': int})
-        with self.assertRaises(KeyError):
-            gns['__annotations__']
-
-    def test_var_annot_custom_maps(self):
-        # tests with custom locals() and __annotations__
-        ns = {'__annotations__': CNS()}
-        exec('X: int; Z: str = "Z"; (w): complex = 1j', ns)
-        self.assertEqual(ns['__annotations__']['x'], int)
-        self.assertEqual(ns['__annotations__']['z'], str)
+        self.assertEqual(lns["__annotate__"](1), {'x': int})
         with self.assertRaises(KeyError):
-            ns['__annotations__']['w']
-        nonloc_ns = {}
-        class CNS2:
-            def __init__(self):
-                self._dct = {}
-            def __setitem__(self, item, value):
-                nonlocal nonloc_ns
-                self._dct[item] = value
-                nonloc_ns[item] = value
-            def __getitem__(self, item):
-                return self._dct[item]
-        exec('x: int = 1', {}, CNS2())
-        self.assertEqual(nonloc_ns['__annotations__']['x'], int)
-
-    def test_var_annot_refleak(self):
-        # complex case: custom locals plus custom __annotations__
-        # this was causing refleak
-        cns = CNS()
-        nonloc_ns = {'__annotations__': cns}
-        class CNS2:
-            def __init__(self):
-                self._dct = {'__annotations__': cns}
-            def __setitem__(self, item, value):
-                nonlocal nonloc_ns
-                self._dct[item] = value
-                nonloc_ns[item] = value
-            def __getitem__(self, item):
-                return self._dct[item]
-        exec('X: str', {}, CNS2())
-        self.assertEqual(nonloc_ns['__annotations__']['x'], str)
+            gns['__annotate__']
 
     def test_var_annot_rhs(self):
         ns = {}

Lib/symtable.py

@@ -360,6 +360,8 @@ def test_annotations_are_created_correctly(self):
         ann_module4 = import_helper.import_fresh_module(
             'test.typinganndata.ann_module4',
         )
+        self.assertFalse("__annotations__" in ann_module4.__dict__)
+        self.assertEqual(ann_module4.__annotations__, {"a": int, "b": str})
         self.assertTrue("__annotations__" in ann_module4.__dict__)
         del ann_module4.__annotations__
         self.assertFalse("__annotations__" in ann_module4.__dict__)

Lib/test/test_dis.py

@@ -39,16 +39,19 @@ class C: pass
     def test_use_existing_annotations(self):
         ns = {'__annotations__': {1: 2}}
         exec('x: int', ns)
-        self.assertEqual(ns['__annotations__'], {'x': int, 1: 2})
+        self.assertEqual(ns['__annotations__'], {1: 2})
 
     def test_do_not_recreate_annotations(self):
         # Don't rely on the existence of the '__annotations__' global.
         with support.swap_item(globals(), '__annotations__', {}):
-            del globals()['__annotations__']
+            globals().pop('__annotations__', None)
             class C:
-                del __annotations__
-                with self.assertRaises(NameError):
-                    x: int
+                try:
+                    del __annotations__
+                except NameError:
+                    pass
+                x: int
+            self.assertEqual(C.__annotations__, {"x": int})
 
     def test_raise_class_exceptions(self):
 

Lib/test/test_grammar.py

@@ -2,6 +2,7 @@
 
 import dis
 import pickle
+import types
 import unittest
 
 from test.support import check_syntax_error
@@ -440,7 +441,9 @@ def f(x: not (int is int), /): ...
         # without constant folding we end up with
         # COMPARE_OP(is), IS_OP (0)
         # with constant folding we should expect a IS_OP (1)
-        codes = [(i.opname, i.argval) for i in dis.get_instructions(g)]
+        code_obj = next(const for const in g.__code__.co_consts
+                        if isinstance(const, types.CodeType) and const.co_name == "__annotate__")
+        codes = [(i.opname, i.argval) for i in dis.get_instructions(code_obj)]
         self.assertNotIn(('UNARY_NOT', None), codes)
         self.assertIn(('IS_OP', 1), codes)
 

Lib/test/test_module/__init__.py

@@ -109,6 +109,8 @@ def ismethod(oclass, obj, name):
 
                 actualMethods = []
                 for m in py_item.__dict__.keys():
+                    if m == "__annotate__":
+                        continue
                     if ismethod(py_item, getattr(py_item, m), m):
                         actualMethods.append(m)
                 foundMethods = []

Lib/test/test_opcodes.py

@@ -77,6 +77,11 @@ class A(builtins.object)
      |  __weakref__%s
 
     class B(builtins.object)
+     |  Methods defined here:
+     |
+     |  __annotate__(...)
+     |
+     |  ----------------------------------------------------------------------
      |  Data descriptors defined here:
      |
      |  __dict__%s
@@ -87,8 +92,6 @@ class B(builtins.object)
      |  Data and other attributes defined here:
      |
      |  NO_MEANING = 'eggs'
-     |
-     |  __annotations__ = {'NO_MEANING': <class 'str'>}
 
     class C(builtins.object)
      |  Methods defined here:
@@ -176,6 +179,9 @@ class A(builtins.object)
             list of weak references to the object
 
 class B(builtins.object)
+    Methods defined here:
+        __annotate__(...)
+    ----------------------------------------------------------------------
     Data descriptors defined here:
         __dict__
             dictionary for instance variables
@@ -184,7 +190,6 @@ class B(builtins.object)
     ----------------------------------------------------------------------
     Data and other attributes defined here:
         NO_MEANING = 'eggs'
-        __annotations__ = {'NO_MEANING': <class 'str'>}
 
 
 class C(builtins.object)

Lib/test/test_positional_only_arg.py

@@ -105,7 +105,7 @@ def test_runsource_shows_syntax_error_for_failed_compilation(self):
 
     def test_no_active_future(self):
         console = InteractiveColoredConsole()
-        source = "x: int = 1; print(__annotations__)"
+        source = "x: int = 1; print(__annotate__(1))"
         f = io.StringIO()
         with contextlib.redirect_stdout(f):
             result = console.runsource(source)

Lib/test/test_pyclbr.py

@@ -205,12 +205,14 @@ def test_assigned(self):
 
     def test_annotated(self):
         st1 = symtable.symtable('def f():\n    x: int\n', 'test', 'exec')
-        st2 = st1.get_children()[0]
+        st2 = st1.get_children()[1]
+        self.assertEqual(st2.get_type(), "function")
         self.assertTrue(st2.lookup('x').is_local())
         self.assertTrue(st2.lookup('x').is_annotated())
         self.assertFalse(st2.lookup('x').is_global())
         st3 = symtable.symtable('def f():\n    x = 1\n', 'test', 'exec')
-        st4 = st3.get_children()[0]
+        st4 = st3.get_children()[1]
+        self.assertEqual(st4.get_type(), "function")
         self.assertTrue(st4.lookup('x').is_local())
         self.assertFalse(st4.lookup('x').is_annotated())