Lazy imports grammar / AST changes

Grammar/python.gram

@@ -121,9 +121,9 @@ simple_stmts[asdl_stmt_seq*]:
 simple_stmt[stmt_ty] (memo):
     | assignment
     | &"type" type_alias
+    | &('import' | 'from' | "lazy" ) import_stmt
     | e=star_expressions { _PyAST_Expr(e, EXTRA) }
     | &'return' return_stmt
-    | &('import' | 'from') import_stmt
     | &'raise' raise_stmt
     | &'pass' pass_stmt
     | &'del' del_stmt
@@ -216,7 +216,7 @@ assert_stmt[stmt_ty]:
     | invalid_assert_stmt
     | 'assert' a=expression b=[',' z=expression { z }] { _PyAST_Assert(a, b, EXTRA) }
 
-import_stmt[stmt_ty]:
+import_stmt[stmt_ty](memo):
     | invalid_import
     | import_name
     | import_from
@@ -224,13 +224,16 @@ import_stmt[stmt_ty]:
 # Import statements
 # -----------------
 
-import_name[stmt_ty]: 'import' a=dotted_as_names { _PyAST_Import(a, EXTRA) }
+import_name[stmt_ty]:
+    | 'import' a=dotted_as_names { _PyAST_Import(a, 0, EXTRA) }
+    | "lazy" 'import' a=dotted_as_names { _PyAST_Import(a, 1, EXTRA) }
+
 # note below: the ('.' | '...') is necessary because '...' is tokenized as ELLIPSIS
 import_from[stmt_ty]:
-    | 'from' a=('.' | '...')* b=dotted_name 'import' c=import_from_targets {
+    | lazy="lazy"? 'from' a=('.' | '...')* b=dotted_name 'import' c=import_from_targets {
-        _PyPegen_checked_future_import(p, b->v.Name.id, c, _PyPegen_seq_count_dots(a), EXTRA) }
+        _PyPegen_checked_future_import(p, b->v.Name.id, c, _PyPegen_seq_count_dots(a), lazy ? 1 : 0, EXTRA) }
-    | 'from' a=('.' | '...')+ 'import' b=import_from_targets {
+    | lazy="lazy"? 'from' a=('.' | '...')+ 'import' b=import_from_targets {
-        _PyAST_ImportFrom(NULL, b, _PyPegen_seq_count_dots(a), EXTRA) }
+        _PyAST_ImportFrom(NULL, b, _PyPegen_seq_count_dots(a), lazy ? 1 : 0, EXTRA) }
 import_from_targets[asdl_alias_seq*]:
     | '(' a=import_from_as_names [','] ')' { a }
     | import_from_as_names !','

Include/internal/pycore_ast.h

@@ -329,12 +329,14 @@ struct _stmt {
 
         struct {
             asdl_alias_seq *names;
+            int is_lazy;
         } Import;
 
         struct {
             identifier module;
             asdl_alias_seq *names;
             int level;
+            int is_lazy;
         } ImportFrom;
 
         struct {
@@ -764,11 +766,12 @@ stmt_ty _PyAST_TryStar(asdl_stmt_seq * body, asdl_excepthandler_seq * handlers,
                        end_col_offset, PyArena *arena);
 stmt_ty _PyAST_Assert(expr_ty test, expr_ty msg, int lineno, int col_offset,
                       int end_lineno, int end_col_offset, PyArena *arena);
-stmt_ty _PyAST_Import(asdl_alias_seq * names, int lineno, int col_offset, int
+stmt_ty _PyAST_Import(asdl_alias_seq * names, int is_lazy, int lineno, int
-                      end_lineno, int end_col_offset, PyArena *arena);
+                      col_offset, int end_lineno, int end_col_offset, PyArena
+                      *arena);
 stmt_ty _PyAST_ImportFrom(identifier module, asdl_alias_seq * names, int level,
-                          int lineno, int col_offset, int end_lineno, int
+                          int is_lazy, int lineno, int col_offset, int
-                          end_col_offset, PyArena *arena);
+                          end_lineno, int end_col_offset, PyArena *arena);
 stmt_ty _PyAST_Global(asdl_identifier_seq * names, int lineno, int col_offset,
                       int end_lineno, int end_col_offset, PyArena *arena);
 stmt_ty _PyAST_Nonlocal(asdl_identifier_seq * names, int lineno, int

Include/internal/pycore_ast_state.h

@@ -205,6 +205,7 @@ struct ast_state {
     PyObject *id;
     PyObject *ifs;
     PyObject *is_async;
+    PyObject *is_lazy;
     PyObject *items;
     PyObject *iter;
     PyObject *key;

Include/internal/pycore_ceval.h

@@ -297,7 +297,11 @@ PyAPI_FUNC(void) _PyEval_FormatExcCheckArg(PyThreadState *tstate, PyObject *exc,
 PyAPI_FUNC(void) _PyEval_FormatExcUnbound(PyThreadState *tstate, PyCodeObject *co, int oparg);
 PyAPI_FUNC(void) _PyEval_FormatKwargsError(PyThreadState *tstate, PyObject *func, PyObject *kwargs);
 PyAPI_FUNC(PyObject *) _PyEval_ImportFrom(PyThreadState *, PyObject *, PyObject *);
-PyAPI_FUNC(PyObject *) _PyEval_ImportName(PyThreadState *, _PyInterpreterFrame *, PyObject *, PyObject *, PyObject *);
+PyAPI_FUNC(PyObject *) _PyEval_LazyImportName(PyThreadState *tstate, PyObject *builtins, PyObject *globals, 
+            PyObject *name, PyObject *fromlist, PyObject *level);
+PyAPI_FUNC(PyObject *) _PyEval_LazyImportFrom(PyThreadState *tstate, PyObject *v, PyObject *name);
+PyAPI_FUNC(PyObject *) _PyEval_ImportName(PyThreadState *tstate, PyObject *builtins, PyObject *globals, PyObject *locals,
+            PyObject *name, PyObject *fromlist, PyObject *level);
 PyAPI_FUNC(PyObject *)_PyEval_MatchClass(PyThreadState *tstate, PyObject *subject, PyObject *type, Py_ssize_t nargs, PyObject *kwargs);
 PyAPI_FUNC(PyObject *)_PyEval_MatchKeys(PyThreadState *tstate, PyObject *map, PyObject *keys);
 PyAPI_FUNC(void) _PyEval_MonitorRaise(PyThreadState *tstate, _PyInterpreterFrame *frame, _Py_CODEUNIT *instr);

Include/internal/pycore_import.h

@@ -31,6 +31,12 @@ extern int _PyImport_FixupBuiltin(
     PyObject *modules
     );
 
+extern PyObject *
+_PyImport_ResolveName(PyThreadState *tstate, PyObject *name, PyObject *globals, int level);
+extern PyObject *
+_PyImport_LoadLazyImportTstate(PyThreadState *tstate, PyObject *lazy_import);
+
+
 #ifdef HAVE_DLOPEN
 #  include <dlfcn.h>              // RTLD_NOW, RTLD_LAZY
 #  if HAVE_DECL_RTLD_NOW

Include/internal/pycore_lazyimportobject.h

@@ -0,0 +1,29 @@
+/* Copyright (c) Meta, Inc. and its affiliates. All Rights Reserved */
+/* File added for Lazy Imports */
+
+/* Lazy object interface */
+
+#ifndef Py_LAZYIMPORTOBJECT_H
+#define Py_LAZYIMPORTOBJECT_H
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+PyAPI_DATA(PyTypeObject) PyLazyImport_Type;
+#define PyLazyImport_CheckExact(op) Py_IS_TYPE((op), &PyLazyImport_Type)
+
+typedef struct {
+    PyObject_HEAD
+    PyObject *lz_builtins;
+    PyObject *lz_from;
+    PyObject *lz_attr;
+} PyLazyImportObject;
+
+
+PyAPI_FUNC(PyObject *) _PyLazyImport_GetName(PyObject *lazy_import);
+PyAPI_FUNC(PyObject *) _PyLazyImport_New(PyObject *builtins, PyObject *from, PyObject *attr);
+
+#ifdef __cplusplus
+}
+#endif
+#endif /* !Py_LAZYIMPORTOBJECT_H */

Include/internal/pycore_magic_number.h

@@ -286,6 +286,7 @@ Known values:
     Python 3.15a1 3653 (Fix handling of opcodes that may leave operands on the stack when optimizing LOAD_FAST)
     Python 3.15a1 3654 (Fix missing exception handlers in logical expression)
     Python 3.15a1 3655 (Fix miscompilation of some module-level annotations)
+    Python 3.15a1 3656 Lazy imports IMPORT_NAME opcode changes
 
 
     Python 3.16 will start with 3700
@@ -299,7 +300,7 @@ PC/launcher.c must also be updated.
 
 */
 
-#define PYC_MAGIC_NUMBER 3655
+#define PYC_MAGIC_NUMBER 3656
 /* This is equivalent to converting PYC_MAGIC_NUMBER to 2 bytes
    (little-endian) and then appending b'\r\n'. */
 #define PYC_MAGIC_NUMBER_TOKEN \

Lib/dis.py

@@ -35,6 +35,7 @@
 FUNCTION_ATTR_FLAGS = ('defaults', 'kwdefaults', 'annotations', 'closure', 'annotate')
 
 ENTER_EXECUTOR = opmap['ENTER_EXECUTOR']
+IMPORT_NAME = opmap['IMPORT_NAME']
 LOAD_GLOBAL = opmap['LOAD_GLOBAL']
 LOAD_SMALL_INT = opmap['LOAD_SMALL_INT']
 BINARY_OP = opmap['BINARY_OP']
@@ -601,6 +602,12 @@ def get_argval_argrepr(self, op, arg, offset):
                     argval, argrepr = _get_name_info(arg//4, get_name)
                     if (arg & 1) and argrepr:
                         argrepr = f"{argrepr} + NULL|self"
+                elif deop == IMPORT_NAME:
+                    argval, argrepr = _get_name_info(arg//4, get_name)
+                    if (arg & 1) and argrepr:
+                        argrepr = f"{argrepr} + lazy"
+                    elif (arg & 2) and argrepr:
+                        argrepr = f"{argrepr} + eager"
                 else:
                     argval, argrepr = _get_name_info(arg, get_name)
             elif deop in hasjump or deop in hasexc:

Lib/keyword.py

@@ -56,6 +56,7 @@ kwlist = [
 softkwlist = [
     '_',
     'case',
+    'lazy',
     'match',
     'type'
 ]

Lib/test/test_ast/data/ast_repr.txt

@@ -69,10 +69,10 @@ Module(body=[Try(body=[Pass()], handlers=[ExceptHandler(type=Name(...), name='ex
 Module(body=[TryStar(body=[Pass()], handlers=[ExceptHandler(type=Name(...), name='exc', body=[Pass(...)])], orelse=[Pass()], finalbody=[Pass()])], type_ignores=[])
 Module(body=[Assert(test=Name(id='v', ctx=Load(...)), msg=None)], type_ignores=[])
 Module(body=[Assert(test=Name(id='v', ctx=Load(...)), msg=Constant(value='message', kind=None))], type_ignores=[])
-Module(body=[Import(names=[alias(name='sys', asname=None)])], type_ignores=[])
+Module(body=[Import(names=[alias(name='sys', asname=None)], is_lazy=0)], type_ignores=[])
-Module(body=[Import(names=[alias(name='foo', asname='bar')])], type_ignores=[])
+Module(body=[Import(names=[alias(name='foo', asname='bar')], is_lazy=0)], type_ignores=[])
-Module(body=[ImportFrom(module='sys', names=[alias(name='x', asname='y')], level=0)], type_ignores=[])
+Module(body=[ImportFrom(module='sys', names=[alias(name='x', asname='y')], level=0, is_lazy=0)], type_ignores=[])
-Module(body=[ImportFrom(module='sys', names=[alias(name='v', asname=None)], level=0)], type_ignores=[])
+Module(body=[ImportFrom(module='sys', names=[alias(name='v', asname=None)], level=0, is_lazy=0)], type_ignores=[])
 Module(body=[Global(names=['v'])], type_ignores=[])
 Module(body=[Expr(value=Constant(value=1, kind=None))], type_ignores=[])
 Module(body=[Pass()], type_ignores=[])

Lib/test/test_ast/test_ast.py

@@ -1722,8 +1722,8 @@ def check_text(code, empty, full, **kwargs):
 
         check_text(
             "import _ast as ast; from module import sub",
-            empty="Module(body=[Import(names=[alias(name='_ast', asname='ast')]), ImportFrom(module='module', names=[alias(name='sub')], level=0)])",
+            empty="Module(body=[Import(names=[alias(name='_ast', asname='ast')], is_lazy=0), ImportFrom(module='module', names=[alias(name='sub')], level=0, is_lazy=0)])",
-            full="Module(body=[Import(names=[alias(name='_ast', asname='ast')]), ImportFrom(module='module', names=[alias(name='sub')], level=0)], type_ignores=[])",
+            full="Module(body=[Import(names=[alias(name='_ast', asname='ast')], is_lazy=0), ImportFrom(module='module', names=[alias(name='sub')], level=0, is_lazy=0)], type_ignores=[])",
         )
 
     def test_copy_location(self):

Makefile.pre.in

@@ -539,6 +539,7 @@ OBJECT_OBJS=	\
 		Objects/funcobject.o \
 		Objects/interpolationobject.o \
 		Objects/iterobject.o \
+		Objects/lazyimportobject.o \
 		Objects/listobject.o \
 		Objects/longobject.o \
 		Objects/dictobject.o \
@@ -1368,6 +1369,7 @@ PYTHON_HEADERS= \
 		$(srcdir)/Include/internal/pycore_interpolation.h \
 		$(srcdir)/Include/internal/pycore_intrinsics.h \
 		$(srcdir)/Include/internal/pycore_jit.h \
+		$(srcdir)/Include/internal/pycore_lazyimportobject.h \
 		$(srcdir)/Include/internal/pycore_list.h \
 		$(srcdir)/Include/internal/pycore_llist.h \
 		$(srcdir)/Include/internal/pycore_lock.h \

Objects/lazyimportobject.c

@@ -0,0 +1,137 @@
+/* Copyright (c) Meta, Inc. and its affiliates. All Rights Reserved */
+/* File added for Lazy Imports */
+
+/* Lazy object implementation */
+
+#include "Python.h"
+#include "pycore_lazyimportobject.h"
+
+PyObject *
+_PyLazyImport_New(PyObject *builtins, PyObject *from, PyObject *attr)
+{
+    PyLazyImportObject *m;
+    if (!from || !PyUnicode_Check(from)) {
+        PyErr_BadArgument();
+        return NULL;
+    }
+    if (attr == Py_None) {
+        attr = NULL;
+    }
+    assert(!attr || PyObject_IsTrue(attr));
+    m = PyObject_GC_New(PyLazyImportObject, &PyLazyImport_Type);
+    if (m == NULL) {
+        return NULL;
+    }
+    Py_XINCREF(builtins);
+    m->lz_builtins = builtins;
+    Py_INCREF(from);
+    m->lz_from = from;
+    Py_XINCREF(attr);
+    m->lz_attr = attr;
+    PyObject_GC_Track(m);
+    return (PyObject *)m;
+}
+
+static void
+lazy_import_dealloc(PyLazyImportObject *m)
+{
+    PyObject_GC_UnTrack(m);
+    Py_XDECREF(m->lz_builtins);
+    Py_XDECREF(m->lz_from);
+    Py_XDECREF(m->lz_attr);
+    Py_TYPE(m)->tp_free((PyObject *)m);
+}
+
+static PyObject *
+lazy_import_name(PyLazyImportObject *m)
+{
+    if (m->lz_attr != NULL) {
+        if (PyUnicode_Check(m->lz_attr)) {
+            return PyUnicode_FromFormat("%U.%U", m->lz_from, m->lz_attr);
+        } else {
+            return PyUnicode_FromFormat("%U...", m->lz_from);
+        }
+    }
+    Py_INCREF(m->lz_from);
+    return m->lz_from;
+}
+
+static PyObject *
+lazy_import_repr(PyLazyImportObject *m)
+{
+    PyObject *name = lazy_import_name(m);
+    if (name == NULL) {
+        return NULL;
+    }
+    PyObject *res = PyUnicode_FromFormat("<lazy_import '%U'>", name);
+    Py_DECREF(name);
+    return res;
+}
+
+static int
+lazy_import_traverse(PyLazyImportObject *m, visitproc visit, void *arg)
+{
+    Py_VISIT(m->lz_builtins);
+    Py_VISIT(m->lz_from);
+    Py_VISIT(m->lz_attr);
+    return 0;
+}
+
+static int
+lazy_import_clear(PyLazyImportObject *m)
+{
+    Py_CLEAR(m->lz_builtins);
+    Py_CLEAR(m->lz_from);
+    Py_CLEAR(m->lz_attr);
+    return 0;
+}
+
+PyObject *
+_PyLazyImport_GetName(PyObject *lazy_import)
+{
+    assert(PyLazyImport_CheckExact(lazy_import));
+    return lazy_import_name((PyLazyImportObject *)lazy_import);
+}
+
+PyTypeObject PyLazyImport_Type = {
+    PyVarObject_HEAD_INIT(&PyType_Type, 0)
+    "lazy_import",                              /* tp_name */
+    sizeof(PyLazyImportObject),                       /* tp_basicsize */
+    0,                                          /* tp_itemsize */
+    (destructor)lazy_import_dealloc,            /* tp_dealloc */
+    0,                                          /* tp_print */
+    0,                                          /* tp_getattr */
+    0,                                          /* tp_setattr */
+    0,                                          /* tp_reserved */
+    (reprfunc)lazy_import_repr,                 /* tp_repr */
+    0,                                          /* tp_as_number */
+    0,                                          /* tp_as_sequence */
+    0,                                          /* tp_as_mapping */
+    0,                                          /* tp_hash */
+    0,                                          /* tp_call */
+    0,                                          /* tp_str */
+    0,                                          /* tp_getattro */
+    0,                                          /* tp_setattro */
+    0,                                          /* tp_as_buffer */
+    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC |
+        Py_TPFLAGS_BASETYPE,                    /* tp_flags */
+    0,                                          /* tp_doc */
+    (traverseproc)lazy_import_traverse,         /* tp_traverse */
+    (inquiry)lazy_import_clear,                 /* tp_clear */
+    0,                                          /* tp_richcompare */
+    0,                                          /* tp_weaklistoffset */
+    0,                                          /* tp_iter */
+    0,                                          /* tp_iternext */
+    0,                                          /* tp_methods */
+    0,                                          /* tp_members */
+    0,                                          /* tp_getset */
+    0,                                          /* tp_base */
+    0,                                          /* tp_dict */
+    0,                                          /* tp_descr_get */
+    0,                                          /* tp_descr_set */
+    0,                                          /* tp_dictoffset */
+    0,                                          /* tp_init */
+    PyType_GenericAlloc,                        /* tp_alloc */
+    PyType_GenericNew,                          /* tp_new */
+    PyObject_GC_Del,                            /* tp_free */
+};

Parser/Python.asdl

@@ -45,8 +45,8 @@ module Python
           | TryStar(stmt* body, excepthandler* handlers, stmt* orelse, stmt* finalbody)
           | Assert(expr test, expr? msg)
 
-          | Import(alias* names)
+          | Import(alias* names, int? is_lazy)
-          | ImportFrom(identifier? module, alias* names, int? level)
+          | ImportFrom(identifier? module, alias* names, int? level, int? is_lazy)
 
           | Global(identifier* names)
           | Nonlocal(identifier* names)

Parser/action_helpers.c

@@ -1916,7 +1916,7 @@ _PyPegen_concatenate_strings(Parser *p, asdl_expr_seq *strings,
 
 stmt_ty
 _PyPegen_checked_future_import(Parser *p, identifier module, asdl_alias_seq * names, int level,
-                  			   int lineno, int col_offset, int end_lineno, int end_col_offset,
+                               int is_lazy, int lineno, int col_offset, int end_lineno, int end_col_offset,
                       		   PyArena *arena) {
     if (level == 0 && PyUnicode_CompareWithASCIIString(module, "__future__") == 0) {
         for (Py_ssize_t i = 0; i < asdl_seq_LEN(names); i++) {
@@ -1926,7 +1926,7 @@ _PyPegen_checked_future_import(Parser *p, identifier module, asdl_alias_seq * na
             }
         }
     }
-    return _PyAST_ImportFrom(module, names, level, lineno, col_offset, end_lineno, end_col_offset, arena);
+    return _PyAST_ImportFrom(module, names, level, is_lazy, lineno, col_offset, end_lineno, end_col_offset, arena);
 }
 
 asdl_stmt_seq*

Parser/pegen.h

@@ -366,7 +366,7 @@ void *_PyPegen_arguments_parsing_error(Parser *, expr_ty);
 expr_ty _PyPegen_get_last_comprehension_item(comprehension_ty comprehension);
 void *_PyPegen_nonparen_genexp_in_call(Parser *p, expr_ty args, asdl_comprehension_seq *comprehensions);
 stmt_ty _PyPegen_checked_future_import(Parser *p, identifier module, asdl_alias_seq *,
-                                       int , int, int , int , int , PyArena *);
+                                       int , int, int , int , int , int, PyArena *);
 asdl_stmt_seq* _PyPegen_register_stmts(Parser *p, asdl_stmt_seq* stmts);
 stmt_ty _PyPegen_register_stmt(Parser *p, stmt_ty s);
 

Programs/test_frozenmain.h

@@ -2,7 +2,7 @@
 unsigned char M_test_frozenmain[] = {
     227,0,0,0,0,0,0,0,0,0,0,0,0,9,0,0,
     0,0,0,0,0,243,184,0,0,0,128,0,94,0,82,1,
-    73,0,116,0,94,0,82,1,73,1,116,1,93,2,33,0,
+    73,0,116,0,94,0,82,1,73,4,116,1,93,2,33,0,
     82,2,52,1,0,0,0,0,0,0,31,0,93,2,33,0,
     82,3,93,0,80,6,0,0,0,0,0,0,0,0,0,0,
     0,0,0,0,0,0,0,0,52,2,0,0,0,0,0,0,

Python/Python-ast.c

@@ -222,6 +222,7 @@ void _PyAST_Fini(PyInterpreterState *interp)
     Py_CLEAR(state->id);
     Py_CLEAR(state->ifs);
     Py_CLEAR(state->is_async);
+    Py_CLEAR(state->is_lazy);
     Py_CLEAR(state->items);
     Py_CLEAR(state->iter);
     Py_CLEAR(state->key);
@@ -327,6 +328,7 @@ static int init_identifiers(struct ast_state *state)
     if ((state->id = PyUnicode_InternFromString("id")) == NULL) return -1;
     if ((state->ifs = PyUnicode_InternFromString("ifs")) == NULL) return -1;
     if ((state->is_async = PyUnicode_InternFromString("is_async")) == NULL) return -1;
+    if ((state->is_lazy = PyUnicode_InternFromString("is_lazy")) == NULL) return -1;
     if ((state->items = PyUnicode_InternFromString("items")) == NULL) return -1;
     if ((state->iter = PyUnicode_InternFromString("iter")) == NULL) return -1;
     if ((state->key = PyUnicode_InternFromString("key")) == NULL) return -1;
@@ -527,11 +529,13 @@ static const char * const Assert_fields[]={
 };
 static const char * const Import_fields[]={
     "names",
+    "is_lazy",
 };
 static const char * const ImportFrom_fields[]={
     "module",
     "names",
     "level",
+    "is_lazy",
 };
 static const char * const Global_fields[]={
     "names",
@@ -2254,6 +2258,21 @@ add_ast_annotations(struct ast_state *state)
             return 0;
         }
     }
+    {
+        PyObject *type = (PyObject *)&PyLong_Type;
+        type = _Py_union_type_or(type, Py_None);
+        cond = type != NULL;
+        if (!cond) {
+            Py_DECREF(Import_annotations);
+            return 0;
+        }
+        cond = PyDict_SetItemString(Import_annotations, "is_lazy", type) == 0;
+        Py_DECREF(type);
+        if (!cond) {
+            Py_DECREF(Import_annotations);
+            return 0;
+        }
+    }
     cond = PyObject_SetAttrString(state->Import_type, "_field_types",
                                   Import_annotations) == 0;
     if (!cond) {
@@ -2315,6 +2334,22 @@ add_ast_annotations(struct ast_state *state)
             return 0;
         }
     }
+    {
+        PyObject *type = (PyObject *)&PyLong_Type;
+        type = _Py_union_type_or(type, Py_None);
+        cond = type != NULL;
+        if (!cond) {
+            Py_DECREF(ImportFrom_annotations);
+            return 0;
+        }
+        cond = PyDict_SetItemString(ImportFrom_annotations, "is_lazy", type) ==
+                                    0;
+        Py_DECREF(type);
+        if (!cond) {
+            Py_DECREF(ImportFrom_annotations);
+            return 0;
+        }
+    }
     cond = PyObject_SetAttrString(state->ImportFrom_type, "_field_types",
                                   ImportFrom_annotations) == 0;
     if (!cond) {
@@ -6218,8 +6253,8 @@ init_types(void *arg)
         "     | Try(stmt* body, excepthandler* handlers, stmt* orelse, stmt* finalbody)\n"
         "     | TryStar(stmt* body, excepthandler* handlers, stmt* orelse, stmt* finalbody)\n"
         "     | Assert(expr test, expr? msg)\n"
-        "     | Import(alias* names)\n"
+        "     | Import(alias* names, int? is_lazy)\n"
-        "     | ImportFrom(identifier? module, alias* names, int? level)\n"
+        "     | ImportFrom(identifier? module, alias* names, int? level, int? is_lazy)\n"
         "     | Global(identifier* names)\n"
         "     | Nonlocal(identifier* names)\n"
         "     | Expr(expr value)\n"
@@ -6348,17 +6383,21 @@ init_types(void *arg)
     if (PyObject_SetAttr(state->Assert_type, state->msg, Py_None) == -1)
         return -1;
     state->Import_type = make_type(state, "Import", state->stmt_type,
-                                   Import_fields, 1,
+                                   Import_fields, 2,
-        "Import(alias* names)");
+        "Import(alias* names, int? is_lazy)");
     if (!state->Import_type) return -1;
+    if (PyObject_SetAttr(state->Import_type, state->is_lazy, Py_None) == -1)
+        return -1;
     state->ImportFrom_type = make_type(state, "ImportFrom", state->stmt_type,
-                                       ImportFrom_fields, 3,
+                                       ImportFrom_fields, 4,
-        "ImportFrom(identifier? module, alias* names, int? level)");
+        "ImportFrom(identifier? module, alias* names, int? level, int? is_lazy)");
     if (!state->ImportFrom_type) return -1;
     if (PyObject_SetAttr(state->ImportFrom_type, state->module, Py_None) == -1)
         return -1;
     if (PyObject_SetAttr(state->ImportFrom_type, state->level, Py_None) == -1)
         return -1;
+    if (PyObject_SetAttr(state->ImportFrom_type, state->is_lazy, Py_None) == -1)
+        return -1;
     state->Global_type = make_type(state, "Global", state->stmt_type,
                                    Global_fields, 1,
         "Global(identifier* names)");
@@ -7598,8 +7637,8 @@ _PyAST_Assert(expr_ty test, expr_ty msg, int lineno, int col_offset, int
 }
 
 stmt_ty
-_PyAST_Import(asdl_alias_seq * names, int lineno, int col_offset, int
+_PyAST_Import(asdl_alias_seq * names, int is_lazy, int lineno, int col_offset,
-              end_lineno, int end_col_offset, PyArena *arena)
+              int end_lineno, int end_col_offset, PyArena *arena)
 {
     stmt_ty p;
     p = (stmt_ty)_PyArena_Malloc(arena, sizeof(*p));
@@ -7607,6 +7646,7 @@ _PyAST_Import(asdl_alias_seq * names, int lineno, int col_offset, int
         return NULL;
     p->kind = Import_kind;
     p->v.Import.names = names;
+    p->v.Import.is_lazy = is_lazy;
     p->lineno = lineno;
     p->col_offset = col_offset;
     p->end_lineno = end_lineno;
@@ -7616,8 +7656,8 @@ _PyAST_Import(asdl_alias_seq * names, int lineno, int col_offset, int
 
 stmt_ty
 _PyAST_ImportFrom(identifier module, asdl_alias_seq * names, int level, int
-                  lineno, int col_offset, int end_lineno, int end_col_offset,
+                  is_lazy, int lineno, int col_offset, int end_lineno, int
-                  PyArena *arena)
+                  end_col_offset, PyArena *arena)
 {
     stmt_ty p;
     p = (stmt_ty)_PyArena_Malloc(arena, sizeof(*p));
@@ -7627,6 +7667,7 @@ _PyAST_ImportFrom(identifier module, asdl_alias_seq * names, int level, int
     p->v.ImportFrom.module = module;
     p->v.ImportFrom.names = names;
     p->v.ImportFrom.level = level;
+    p->v.ImportFrom.is_lazy = is_lazy;
     p->lineno = lineno;
     p->col_offset = col_offset;
     p->end_lineno = end_lineno;
@@ -9465,6 +9506,11 @@ ast2obj_stmt(struct ast_state *state, void* _o)
         if (PyObject_SetAttr(result, state->names, value) == -1)
             goto failed;
         Py_DECREF(value);
+        value = ast2obj_int(state, o->v.Import.is_lazy);
+        if (!value) goto failed;
+        if (PyObject_SetAttr(result, state->is_lazy, value) == -1)
+            goto failed;
+        Py_DECREF(value);
         break;
     case ImportFrom_kind:
         tp = (PyTypeObject *)state->ImportFrom_type;
@@ -9486,6 +9532,11 @@ ast2obj_stmt(struct ast_state *state, void* _o)
         if (PyObject_SetAttr(result, state->level, value) == -1)
             goto failed;
         Py_DECREF(value);
+        value = ast2obj_int(state, o->v.ImportFrom.is_lazy);
+        if (!value) goto failed;
+        if (PyObject_SetAttr(result, state->is_lazy, value) == -1)
+            goto failed;
+        Py_DECREF(value);
         break;
     case Global_kind:
         tp = (PyTypeObject *)state->Global_type;
@@ -13481,6 +13532,7 @@ obj2ast_stmt(struct ast_state *state, PyObject* obj, stmt_ty* out, PyArena*
     }
     if (isinstance) {
         asdl_alias_seq* names;
+        int is_lazy;
 
         if (PyObject_GetOptionalAttr(obj, state->names, &tmp) < 0) {
             return -1;
@@ -13520,7 +13572,24 @@ obj2ast_stmt(struct ast_state *state, PyObject* obj, stmt_ty* out, PyArena*
             }
             Py_CLEAR(tmp);
         }
-        *out = _PyAST_Import(names, lineno, col_offset, end_lineno,
+        if (PyObject_GetOptionalAttr(obj, state->is_lazy, &tmp) < 0) {
+            return -1;
+        }
+        if (tmp == NULL || tmp == Py_None) {
+            Py_CLEAR(tmp);
+            is_lazy = 0;
+        }
+        else {
+            int res;
+            if (_Py_EnterRecursiveCall(" while traversing 'Import' node")) {
+                goto failed;
+            }
+            res = obj2ast_int(state, tmp, &is_lazy, arena);
+            _Py_LeaveRecursiveCall();
+            if (res != 0) goto failed;
+            Py_CLEAR(tmp);
+        }
+        *out = _PyAST_Import(names, is_lazy, lineno, col_offset, end_lineno,
                              end_col_offset, arena);
         if (*out == NULL) goto failed;
         return 0;
@@ -13534,6 +13603,7 @@ obj2ast_stmt(struct ast_state *state, PyObject* obj, stmt_ty* out, PyArena*
         identifier module;
         asdl_alias_seq* names;
         int level;
+        int is_lazy;
 
         if (PyObject_GetOptionalAttr(obj, state->module, &tmp) < 0) {
             return -1;
@@ -13607,8 +13677,25 @@ obj2ast_stmt(struct ast_state *state, PyObject* obj, stmt_ty* out, PyArena*
             if (res != 0) goto failed;
             Py_CLEAR(tmp);
         }
-        *out = _PyAST_ImportFrom(module, names, level, lineno, col_offset,
+        if (PyObject_GetOptionalAttr(obj, state->is_lazy, &tmp) < 0) {
-                                 end_lineno, end_col_offset, arena);
+            return -1;
+        }
+        if (tmp == NULL || tmp == Py_None) {
+            Py_CLEAR(tmp);
+            is_lazy = 0;
+        }
+        else {
+            int res;
+            if (_Py_EnterRecursiveCall(" while traversing 'ImportFrom' node")) {
+                goto failed;
+            }
+            res = obj2ast_int(state, tmp, &is_lazy, arena);
+            _Py_LeaveRecursiveCall();
+            if (res != 0) goto failed;
+            Py_CLEAR(tmp);
+        }
+        *out = _PyAST_ImportFrom(module, names, level, is_lazy, lineno,
+                                 col_offset, end_lineno, end_col_offset, arena);
         if (*out == NULL) goto failed;
         return 0;
     }

Python/bytecodes.c

@@ -1758,6 +1758,13 @@ dummy_func(
                         }
                         ERROR_NO_POP();
                     }
+
+                    if (PyLazyImport_CheckExact(v_o)) {
+                        PyObject *l_v = _PyImport_LoadLazyImportTstate(tstate, v_o);
+                        Py_DECREF(v_o);
+                        v_o = l_v;
+                        ERROR_IF(v_o == NULL);
+                    }
                 }
                 else {
                     /* Slow-path if globals or builtins is not a dict */
@@ -1775,6 +1782,12 @@ dummy_func(
                             ERROR_IF(true);
                         }
                     }
+                    if (PyLazyImport_CheckExact(v_o)) {
+                        PyObject *l_v = _PyImport_LoadLazyImportTstate(tstate, v_o);
+                        Py_DECREF(v_o);
+                        v_o = l_v;
+                        ERROR_IF(v_o == NULL);
+                    }
                 }
             }
             v = PyStackRef_FromPyObjectSteal(v_o);
@@ -1784,6 +1797,13 @@ dummy_func(
             PyObject *name = GETITEM(FRAME_CO_NAMES, oparg);
             PyObject *v_o = _PyEval_LoadName(tstate, frame, name);
             ERROR_IF(v_o == NULL);
+            if (PyLazyImport_CheckExact(v_o)) {
+                PyObject *l_v = _PyImport_LoadLazyImportTstate(tstate, v_o);
+                Py_DECREF(v_o);
+                v_o = l_v;
+                ERROR_IF(v_o == NULL);
+            }
+
             v = PyStackRef_FromPyObjectSteal(v_o);
         }
 
@@ -1809,7 +1829,18 @@ dummy_func(
         op(_LOAD_GLOBAL, ( -- res[1])) {
             PyObject *name = GETITEM(FRAME_CO_NAMES, oparg>>1);
             _PyEval_LoadGlobalStackRef(GLOBALS(), BUILTINS(), name, res);
+
             ERROR_IF(PyStackRef_IsNull(*res));
+
+            PyObject *res_o = PyStackRef_AsPyObjectBorrow(*res);
+            if (PyLazyImport_CheckExact(res_o)) {
+                PyObject *l_v = _PyImport_LoadLazyImportTstate(tstate, res_o);
+                Py_DECREF(res_o);
+                res_o = l_v;
+                PyStackRef_CLOSE(res[0]);
+                ERROR_IF(res_o == NULL);
+                *res = PyStackRef_FromPyObjectSteal(res_o);
+            }
         }
 
         op(_PUSH_NULL_CONDITIONAL, ( -- null[oparg & 1])) {
@@ -2914,10 +2945,18 @@ dummy_func(
         }
 
          inst(IMPORT_NAME, (level, fromlist -- res)) {
-            PyObject *name = GETITEM(FRAME_CO_NAMES, oparg);
+            PyObject *name = GETITEM(FRAME_CO_NAMES, oparg >> 2);
-            PyObject *res_o = _PyEval_ImportName(tstate, frame, name,
+            PyObject *res_o;
-                              PyStackRef_AsPyObjectBorrow(fromlist),
+            if (oparg & 0x01) {
-                              PyStackRef_AsPyObjectBorrow(level));
+                res_o = _PyEval_LazyImportName(tstate, BUILTINS(), GLOBALS(),  name, 
+                                PyStackRef_AsPyObjectBorrow(fromlist),
+                                PyStackRef_AsPyObjectBorrow(level));
+
+            } else {
+                res_o = _PyEval_ImportName(tstate, BUILTINS(), GLOBALS(), LOCALS(), name,
+                                PyStackRef_AsPyObjectBorrow(fromlist),
+                                PyStackRef_AsPyObjectBorrow(level));
+            }
             DECREF_INPUTS();
             ERROR_IF(res_o == NULL);
             res = PyStackRef_FromPyObjectSteal(res_o);
@@ -2925,7 +2964,13 @@ dummy_func(
 
         inst(IMPORT_FROM, (from -- from, res)) {
             PyObject *name = GETITEM(FRAME_CO_NAMES, oparg);
-            PyObject *res_o = _PyEval_ImportFrom(tstate, PyStackRef_AsPyObjectBorrow(from), name);
+            PyObject *res_o;
+            if (PyLazyImport_CheckExact(PyStackRef_AsPyObjectBorrow(from))) {
+                res_o = _PyEval_LazyImportFrom(tstate, PyStackRef_AsPyObjectBorrow(from), name);
+            } else {
+                res_o = _PyEval_ImportFrom(tstate, PyStackRef_AsPyObjectBorrow(from), name);
+            }
+
             ERROR_IF(res_o == NULL);
             res = PyStackRef_FromPyObjectSteal(res_o);
         }

Python/ceval.c

@@ -22,6 +22,7 @@
 #include "pycore_interpolation.h" // _PyInterpolation_Build()
 #include "pycore_intrinsics.h"
 #include "pycore_jit.h"
+#include "pycore_lazyimportobject.h"
 #include "pycore_list.h"          // _PyList_GetItemRef()
 #include "pycore_long.h"          // _PyLong_GetZero()
 #include "pycore_moduleobject.h"  // PyModuleObject
@@ -2986,11 +2987,11 @@ _PyEval_SliceIndexNotNone(PyObject *v, Py_ssize_t *pi)
 }
 
 PyObject *
-_PyEval_ImportName(PyThreadState *tstate, _PyInterpreterFrame *frame,
+_PyEval_ImportName(PyThreadState *tstate, PyObject *builtins, PyObject *globals, PyObject *locals,
             PyObject *name, PyObject *fromlist, PyObject *level)
 {
     PyObject *import_func;
-    if (PyMapping_GetOptionalItem(frame->f_builtins, &_Py_ID(__import__), &import_func) < 0) {
+    if (PyMapping_GetOptionalItem(builtins, &_Py_ID(__import__), &import_func) < 0) {
         return NULL;
     }
     if (import_func == NULL) {
@@ -2998,7 +2999,6 @@ _PyEval_ImportName(PyThreadState *tstate, _PyInterpreterFrame *frame,
         return NULL;
     }
 
-    PyObject *locals = frame->f_locals;
     if (locals == NULL) {
         locals = Py_None;
     }
@@ -3012,18 +3012,50 @@ _PyEval_ImportName(PyThreadState *tstate, _PyInterpreterFrame *frame,
         }
         return PyImport_ImportModuleLevelObject(
                         name,
-                        frame->f_globals,
+                        globals,
                         locals,
                         fromlist,
                         ilevel);
     }
 
-    PyObject* args[5] = {name, frame->f_globals, locals, fromlist, level};
+    PyObject* args[5] = {name, globals, locals, fromlist, level};
     PyObject *res = PyObject_Vectorcall(import_func, args, 5, NULL);
     Py_DECREF(import_func);
     return res;
 }
 
+
+PyObject *
+_PyEval_LazyImportName(PyThreadState *tstate, PyObject *builtins, PyObject *globals,
+            PyObject *name, PyObject *fromlist, PyObject *level)
+{
+    PyObject *res = NULL;
+    PyObject *abs_name = NULL;
+    int ilevel = PyLong_AsInt(level);
+    if (ilevel == -1 && PyErr_Occurred()) {
+        goto error;
+    }
+    if (ilevel > 0) {
+        abs_name = _PyImport_ResolveName(tstate, name, globals, ilevel);
+        if (abs_name == NULL) {
+            goto error;
+        }
+    } else {  /* ilevel == 0 */
+        if (PyUnicode_GET_LENGTH(name) == 0) {
+            PyErr_SetString(PyExc_ValueError, "Empty module name");
+            goto error;
+        }
+        abs_name = name;
+        Py_INCREF(abs_name);
+    }
+
+    // TODO: check sys.modules for module
+    res = _PyLazyImport_New(builtins, abs_name, fromlist);
+error:
+    Py_XDECREF(abs_name);
+    return res;
+}
+
 PyObject *
 _PyEval_ImportFrom(PyThreadState *tstate, PyObject *v, PyObject *name)
 {
@@ -3192,6 +3224,33 @@ _PyEval_ImportFrom(PyThreadState *tstate, PyObject *v, PyObject *name)
     return NULL;
 }
 
+PyObject *
+_PyEval_LazyImportFrom(PyThreadState *tstate, PyObject *v, PyObject *name)
+{
+    assert(PyLazyImport_CheckExact(v));
+    assert(name && PyUnicode_Check(name));
+    PyObject *ret;
+    PyLazyImportObject *d = (PyLazyImportObject *)v;
+    if (d->lz_attr != NULL) {
+        if (PyUnicode_Check(d->lz_attr)) {
+            PyObject *from = PyUnicode_FromFormat("%U.%U", d->lz_from, d->lz_attr);
+            ret = _PyLazyImport_New(d->lz_builtins, from, name);
+            Py_DECREF(from);
+            return ret;
+        }
+    } else {
+        Py_ssize_t dot = PyUnicode_FindChar(d->lz_from, '.', 0, PyUnicode_GET_LENGTH(d->lz_from), 1);
+        if (dot >= 0) {
+            PyObject *from = PyUnicode_Substring(d->lz_from, 0, dot);
+            ret = _PyLazyImport_New(d->lz_builtins, from, name);
+            Py_DECREF(from);
+            return ret;
+        }
+    }
+    ret = _PyLazyImport_New(d->lz_builtins, d->lz_from, name);
+    return ret;
+}
+
 #define CANNOT_CATCH_MSG "catching classes that do not inherit from "\
                          "BaseException is not allowed"
 

Python/codegen.c

@@ -351,8 +351,8 @@ codegen_addop_o(compiler *c, location loc,
 #define LOAD_ZERO_SUPER_METHOD -4
 
 static int
-codegen_addop_name(compiler *c, location loc,
+codegen_addop_name_custom(compiler *c, location loc,
-                   int opcode, PyObject *dict, PyObject *o)
+                   int opcode, PyObject *dict, PyObject *o, int shift, int low)
 {
     PyObject *mangled = _PyCompile_MaybeMangle(c, o);
     if (!mangled) {
@@ -363,40 +363,51 @@ codegen_addop_name(compiler *c, location loc,
     if (arg < 0) {
         return ERROR;
     }
+    ADDOP_I(c, loc, opcode, (arg << shift) | low);
+    return SUCCESS;
+}
+
+static int
+codegen_addop_name(compiler *c, location loc,
+                   int opcode, PyObject *dict, PyObject *o)
+{
+    int shift = 0, low = 0;
     if (opcode == LOAD_ATTR) {
-        arg <<= 1;
+        shift = 1;
     }
     if (opcode == LOAD_METHOD) {
         opcode = LOAD_ATTR;
-        arg <<= 1;
+        shift = 1;
-        arg |= 1;
+        low = 1;
     }
     if (opcode == LOAD_SUPER_ATTR) {
-        arg <<= 2;
+        shift = 2;
-        arg |= 2;
+        low = 2;
     }
     if (opcode == LOAD_SUPER_METHOD) {
         opcode = LOAD_SUPER_ATTR;
-        arg <<= 2;
+        shift = 2;
-        arg |= 3;
+        low = 3;
     }
     if (opcode == LOAD_ZERO_SUPER_ATTR) {
         opcode = LOAD_SUPER_ATTR;
-        arg <<= 2;
+        shift = 2;
     }
     if (opcode == LOAD_ZERO_SUPER_METHOD) {
         opcode = LOAD_SUPER_ATTR;
-        arg <<= 2;
+        shift = 2;
-        arg |= 1;
+        low = 1;
     }
-    ADDOP_I(c, loc, opcode, arg);
+    return codegen_addop_name_custom(c, loc, opcode, dict, o, shift, low);
-    return SUCCESS;
 }
 
 #define ADDOP_NAME(C, LOC, OP, O, TYPE) \
     RETURN_IF_ERROR(codegen_addop_name((C), (LOC), (OP), METADATA(C)->u_ ## TYPE, (O)))
 
-static int
+#define ADDOP_NAME_CUSTOM(C, LOC, OP, O, TYPE, SHIFT, LOW) \
+    RETURN_IF_ERROR(codegen_addop_name_custom((C), (LOC), (OP), METADATA(C)->u_ ## TYPE, (O), SHIFT, LOW))
+
+    static int
 codegen_addop_j(instr_sequence *seq, location loc,
                 int opcode, jump_target_label target)
 {
@@ -2861,7 +2872,13 @@ codegen_import(compiler *c, stmt_ty s)
 
         ADDOP_LOAD_CONST(c, loc, zero);
         ADDOP_LOAD_CONST(c, loc, Py_None);
-        ADDOP_NAME(c, loc, IMPORT_NAME, alias->name, names);
+        if (s->v.Import.is_lazy) {
+            // TODO: SyntaxError when not in module scope
+            ADDOP_NAME_CUSTOM(c, loc, IMPORT_NAME, alias->name, names, 2, 1);
+        } else {
+            // TODO: If in try/except, set 2nd bit
+            ADDOP_NAME_CUSTOM(c, loc, IMPORT_NAME, alias->name, names, 2, 0);
+        }
 
         if (alias->asname) {
             r = codegen_import_as(c, loc, alias->name, alias->asname);
@@ -2907,12 +2924,15 @@ codegen_from_import(compiler *c, stmt_ty s)
 
     ADDOP_LOAD_CONST_NEW(c, LOC(s), names);
 
+    identifier from = &_Py_STR(empty);
     if (s->v.ImportFrom.module) {
-        ADDOP_NAME(c, LOC(s), IMPORT_NAME, s->v.ImportFrom.module, names);
+        from = s->v.ImportFrom.module;
     }
-    else {
+    if (s->v.ImportFrom.is_lazy) {
-        _Py_DECLARE_STR(empty, "");
+        // TODO: SyntaxError when not in module scope
-        ADDOP_NAME(c, LOC(s), IMPORT_NAME, &_Py_STR(empty), names);
+        ADDOP_NAME_CUSTOM(c, LOC(s), IMPORT_NAME, from, names, 2, 1);
+    } else {
+        ADDOP_NAME_CUSTOM(c, LOC(s), IMPORT_NAME, from, names, 2, 0);
     }
     for (Py_ssize_t i = 0; i < n; i++) {
         alias_ty alias = (alias_ty)asdl_seq_GET(s->v.ImportFrom.names, i);

Python/executor_cases.c.h

@@ -2458,6 +2458,16 @@
             if (v_o == NULL) {
                 JUMP_TO_ERROR();
             }
+            if (PyLazyImport_CheckExact(v_o)) {
+                _PyFrame_SetStackPointer(frame, stack_pointer);
+                PyObject *l_v = _PyImport_LoadLazyImportTstate(tstate, v_o);
+                Py_DECREF(v_o);
+                stack_pointer = _PyFrame_GetStackPointer(frame);
+                v_o = l_v;
+                if (v_o == NULL) {
+                    JUMP_TO_ERROR();
+                }
+            }
             v = PyStackRef_FromPyObjectSteal(v_o);
             stack_pointer[0] = v;
             stack_pointer += 1;
@@ -2476,6 +2486,21 @@
             if (PyStackRef_IsNull(*res)) {
                 JUMP_TO_ERROR();
             }
+            PyObject *res_o = PyStackRef_AsPyObjectBorrow(*res);
+            if (PyLazyImport_CheckExact(res_o)) {
+                _PyFrame_SetStackPointer(frame, stack_pointer);
+                PyObject *l_v = _PyImport_LoadLazyImportTstate(tstate, res_o);
+                Py_DECREF(res_o);
+                stack_pointer = _PyFrame_GetStackPointer(frame);
+                res_o = l_v;
+                _PyFrame_SetStackPointer(frame, stack_pointer);
+                PyStackRef_CLOSE(res[0]);
+                stack_pointer = _PyFrame_GetStackPointer(frame);
+                if (res_o == NULL) {
+                    JUMP_TO_ERROR();
+                }
+                *res = PyStackRef_FromPyObjectSteal(res_o);
+            }
             stack_pointer += 1;
             assert(WITHIN_STACK_BOUNDS());
             break;
@@ -4120,11 +4145,22 @@
             oparg = CURRENT_OPARG();
             fromlist = stack_pointer[-1];
             level = stack_pointer[-2];
-            PyObject *name = GETITEM(FRAME_CO_NAMES, oparg);
+            PyObject *name = GETITEM(FRAME_CO_NAMES, oparg >> 2);
+            PyObject *res_o;
+            if (oparg & 0x01) {
+                _PyFrame_SetStackPointer(frame, stack_pointer);
+                res_o = _PyEval_LazyImportName(tstate, BUILTINS(), GLOBALS(),  name,
+                    PyStackRef_AsPyObjectBorrow(fromlist),
+                    PyStackRef_AsPyObjectBorrow(level));
+                stack_pointer = _PyFrame_GetStackPointer(frame);
+            } else {
+                _PyFrame_SetStackPointer(frame, stack_pointer);
+                res_o = _PyEval_ImportName(tstate, BUILTINS(), GLOBALS(), LOCALS(), name,
+                    PyStackRef_AsPyObjectBorrow(fromlist),
+                    PyStackRef_AsPyObjectBorrow(level));
+                stack_pointer = _PyFrame_GetStackPointer(frame);
+            }
             _PyFrame_SetStackPointer(frame, stack_pointer);
-            PyObject *res_o = _PyEval_ImportName(tstate, frame, name,
-                PyStackRef_AsPyObjectBorrow(fromlist),
-                PyStackRef_AsPyObjectBorrow(level));
             _PyStackRef tmp = fromlist;
             fromlist = PyStackRef_NULL;
             stack_pointer[-1] = fromlist;
@@ -4152,9 +4188,16 @@
             oparg = CURRENT_OPARG();
             from = stack_pointer[-1];
             PyObject *name = GETITEM(FRAME_CO_NAMES, oparg);
-            _PyFrame_SetStackPointer(frame, stack_pointer);
+            PyObject *res_o;
-            PyObject *res_o = _PyEval_ImportFrom(tstate, PyStackRef_AsPyObjectBorrow(from), name);
+            if (PyLazyImport_CheckExact(PyStackRef_AsPyObjectBorrow(from))) {
-            stack_pointer = _PyFrame_GetStackPointer(frame);
+                _PyFrame_SetStackPointer(frame, stack_pointer);
+                res_o = _PyEval_LazyImportFrom(tstate, PyStackRef_AsPyObjectBorrow(from), name);
+                stack_pointer = _PyFrame_GetStackPointer(frame);
+            } else {
+                _PyFrame_SetStackPointer(frame, stack_pointer);
+                res_o = _PyEval_ImportFrom(tstate, PyStackRef_AsPyObjectBorrow(from), name);
+                stack_pointer = _PyFrame_GetStackPointer(frame);
+            }
             if (res_o == NULL) {
                 JUMP_TO_ERROR();
             }

Python/generated_cases.c.h

@@ -6188,9 +6188,16 @@
             _PyStackRef res;
             from = stack_pointer[-1];
             PyObject *name = GETITEM(FRAME_CO_NAMES, oparg);
-            _PyFrame_SetStackPointer(frame, stack_pointer);
+            PyObject *res_o;
-            PyObject *res_o = _PyEval_ImportFrom(tstate, PyStackRef_AsPyObjectBorrow(from), name);
+            if (PyLazyImport_CheckExact(PyStackRef_AsPyObjectBorrow(from))) {
-            stack_pointer = _PyFrame_GetStackPointer(frame);
+                _PyFrame_SetStackPointer(frame, stack_pointer);
+                res_o = _PyEval_LazyImportFrom(tstate, PyStackRef_AsPyObjectBorrow(from), name);
+                stack_pointer = _PyFrame_GetStackPointer(frame);
+            } else {
+                _PyFrame_SetStackPointer(frame, stack_pointer);
+                res_o = _PyEval_ImportFrom(tstate, PyStackRef_AsPyObjectBorrow(from), name);
+                stack_pointer = _PyFrame_GetStackPointer(frame);
+            }
             if (res_o == NULL) {
                 JUMP_TO_LABEL(error);
             }
@@ -6214,11 +6221,22 @@
             _PyStackRef res;
             fromlist = stack_pointer[-1];
             level = stack_pointer[-2];
-            PyObject *name = GETITEM(FRAME_CO_NAMES, oparg);
+            PyObject *name = GETITEM(FRAME_CO_NAMES, oparg >> 2);
+            PyObject *res_o;
+            if (oparg & 0x01) {
+                _PyFrame_SetStackPointer(frame, stack_pointer);
+                res_o = _PyEval_LazyImportName(tstate, BUILTINS(), GLOBALS(),  name,
+                    PyStackRef_AsPyObjectBorrow(fromlist),
+                    PyStackRef_AsPyObjectBorrow(level));
+                stack_pointer = _PyFrame_GetStackPointer(frame);
+            } else {
+                _PyFrame_SetStackPointer(frame, stack_pointer);
+                res_o = _PyEval_ImportName(tstate, BUILTINS(), GLOBALS(), LOCALS(), name,
+                    PyStackRef_AsPyObjectBorrow(fromlist),
+                    PyStackRef_AsPyObjectBorrow(level));
+                stack_pointer = _PyFrame_GetStackPointer(frame);
+            }
             _PyFrame_SetStackPointer(frame, stack_pointer);
-            PyObject *res_o = _PyEval_ImportName(tstate, frame, name,
-                PyStackRef_AsPyObjectBorrow(fromlist),
-                PyStackRef_AsPyObjectBorrow(level));
             _PyStackRef tmp = fromlist;
             fromlist = PyStackRef_NULL;
             stack_pointer[-1] = fromlist;
@@ -9074,6 +9092,16 @@
                         }
                         JUMP_TO_LABEL(error);
                     }
+                    if (PyLazyImport_CheckExact(v_o)) {
+                        _PyFrame_SetStackPointer(frame, stack_pointer);
+                        PyObject *l_v = _PyImport_LoadLazyImportTstate(tstate, v_o);
+                        Py_DECREF(v_o);
+                        stack_pointer = _PyFrame_GetStackPointer(frame);
+                        v_o = l_v;
+                        if (v_o == NULL) {
+                            JUMP_TO_LABEL(error);
+                        }
+                    }
                 }
                 else {
                     _PyFrame_SetStackPointer(frame, stack_pointer);
@@ -9098,6 +9126,16 @@
                             JUMP_TO_LABEL(error);
                         }
                     }
+                    if (PyLazyImport_CheckExact(v_o)) {
+                        _PyFrame_SetStackPointer(frame, stack_pointer);
+                        PyObject *l_v = _PyImport_LoadLazyImportTstate(tstate, v_o);
+                        Py_DECREF(v_o);
+                        stack_pointer = _PyFrame_GetStackPointer(frame);
+                        v_o = l_v;
+                        if (v_o == NULL) {
+                            JUMP_TO_LABEL(error);
+                        }
+                    }
                 }
             }
             v = PyStackRef_FromPyObjectSteal(v_o);
@@ -9150,6 +9188,21 @@
                 if (PyStackRef_IsNull(*res)) {
                     JUMP_TO_LABEL(error);
                 }
+                PyObject *res_o = PyStackRef_AsPyObjectBorrow(*res);
+                if (PyLazyImport_CheckExact(res_o)) {
+                    _PyFrame_SetStackPointer(frame, stack_pointer);
+                    PyObject *l_v = _PyImport_LoadLazyImportTstate(tstate, res_o);
+                    Py_DECREF(res_o);
+                    stack_pointer = _PyFrame_GetStackPointer(frame);
+                    res_o = l_v;
+                    _PyFrame_SetStackPointer(frame, stack_pointer);
+                    PyStackRef_CLOSE(res[0]);
+                    stack_pointer = _PyFrame_GetStackPointer(frame);
+                    if (res_o == NULL) {
+                        JUMP_TO_LABEL(error);
+                    }
+                    *res = PyStackRef_FromPyObjectSteal(res_o);
+                }
             }
             // _PUSH_NULL_CONDITIONAL
             {
@@ -9350,6 +9403,16 @@
             if (v_o == NULL) {
                 JUMP_TO_LABEL(error);
             }
+            if (PyLazyImport_CheckExact(v_o)) {
+                _PyFrame_SetStackPointer(frame, stack_pointer);
+                PyObject *l_v = _PyImport_LoadLazyImportTstate(tstate, v_o);
+                Py_DECREF(v_o);
+                stack_pointer = _PyFrame_GetStackPointer(frame);
+                v_o = l_v;
+                if (v_o == NULL) {
+                    JUMP_TO_LABEL(error);
+                }
+            }
             v = PyStackRef_FromPyObjectSteal(v_o);
             stack_pointer[0] = v;
             stack_pointer += 1;

Python/import.c

@@ -7,6 +7,8 @@
 #include "pycore_import.h"        // _PyImport_BootstrapImp()
 #include "pycore_initconfig.h"    // _PyStatus_OK()
 #include "pycore_interp.h"        // struct _import_runtime_state
+#include "pycore_long.h"          // _PyLong_GetZero
+#include "pycore_lazyimportobject.h"
 #include "pycore_magic_number.h"  // PYC_MAGIC_NUMBER_TOKEN
 #include "pycore_moduleobject.h"  // _PyModule_GetDef()
 #include "pycore_namespace.h"     // _PyNamespace_Type
@@ -3670,6 +3672,101 @@ resolve_name(PyThreadState *tstate, PyObject *name, PyObject *globals, int level
     return NULL;
 }
 
+PyObject *
+_PyImport_ResolveName(PyThreadState *tstate, PyObject *name, PyObject *globals, int level)
+{
+  return resolve_name(tstate, name, globals, level);  
+}
+
+PyObject *
+_PyImport_LoadLazyImportTstate(PyThreadState *tstate, PyObject *lazy_import)
+{
+    PyObject *obj = NULL;
+    PyObject *fromlist = NULL;
+    assert(lazy_import != NULL);
+    assert(PyLazyImport_CheckExact(lazy_import));
+    PyObject *state_dict = _PyThreadState_GetDict(tstate);
+    assert(state_dict != NULL);
+
+    PyLazyImportObject *lz = (PyLazyImportObject *)lazy_import;
+
+    Py_ssize_t dot = -1;
+    int full = 0;
+    if (lz->lz_attr != NULL) {
+        full = 1;
+    }
+    if (!full) {
+        dot = PyUnicode_FindChar(lz->lz_from, '.', 0, PyUnicode_GET_LENGTH(lz->lz_from), 1);
+    }
+    if (dot < 0) {
+        full = 1;
+    }
+
+    if (lz->lz_attr != NULL) {
+        if (PyUnicode_Check(lz->lz_attr)) {
+            fromlist = PyTuple_New(1);
+            if (fromlist == NULL) {
+                goto error;
+            }
+            Py_INCREF(lz->lz_attr);
+            PyTuple_SET_ITEM(fromlist, 0, lz->lz_attr);
+        } else {
+            Py_INCREF(lz->lz_attr);
+            fromlist = lz->lz_attr;
+        }
+    }
+
+    PyObject *globals = PyEval_GetGlobals();
+
+    if (full) {
+        obj = _PyEval_ImportName(tstate,
+                                   lz->lz_builtins,
+                                   globals,
+                                   globals,
+                                   lz->lz_from,
+                                   fromlist,
+                                   _PyLong_GetZero());
+    } else {
+        PyObject *name = PyUnicode_Substring(lz->lz_from, 0, dot);
+        if (name == NULL) {
+            goto error;
+        }
+        obj = _PyEval_ImportName(tstate,
+                                   lz->lz_builtins,
+                                   globals,
+                                   globals,
+                                   name,
+                                   fromlist,
+                                   _PyLong_GetZero());
+        Py_DECREF(name);
+    }
+
+    if (obj == NULL) {
+        goto error;
+    }
+
+    if (lz->lz_attr != NULL && PyUnicode_Check(lz->lz_attr)) {
+        PyObject *from = obj;
+        obj = _PyEval_ImportFrom(tstate, from, lz->lz_attr);
+        Py_DECREF(from);
+        if (obj == NULL) {
+            goto error;
+        }
+    }
+
+    assert(!PyLazyImport_CheckExact(obj));
+
+    goto ok;
+
+error:
+    Py_XDECREF(obj);
+    obj = NULL;
+
+ok:
+    Py_XDECREF(fromlist);
+    return obj;
+}
+
 static PyObject *
 import_find_and_load(PyThreadState *tstate, PyObject *abs_name)
 {