gh-152298: Fix LazyImportType.resolve reification

Doc/library/types.rst

@@ -350,6 +350,16 @@ Standard names are defined for the following types:
    actually accessed. This type can be used to detect lazy imports
    programmatically.
 
+   .. method:: resolve()
+
+      Resolve the lazy import and return the imported object. Successful
+      resolutions are cached.
+
+      For a module-level lazy import, ``resolve()`` also updates the original
+      module global if that name still refers to this proxy. If the name was
+      deleted or rebound, it is left unchanged; later ``resolve()`` calls return
+      the cached object without updating that name.
+
    .. versionadded:: 3.15
 
    .. seealso:: :pep:`810`

Include/internal/pycore_lazyimportobject.h

@@ -19,15 +19,44 @@ typedef struct {
     PyObject *lz_builtins;
     PyObject *lz_from;
     PyObject *lz_attr;
+    // Protected by the import lock. lz_owner_* records the first module
+    // global that resolve() may replace. Pending owners are being stored;
+    // finalized owners cannot be claimed again.
+    PyObject *lz_owner_globals;
+    PyObject *lz_owner_key;
+    PyObject *lz_resolved;
     // Frame information for the original import location.
     PyCodeObject *lz_code;     // Code object where the lazy import was created.
+    int lz_owner_pending;
+    int lz_owner_finalized;
     int lz_instr_offset;       // Instruction offset where the lazy import was created.
 } PyLazyImportObject;
 
 
 PyAPI_FUNC(PyObject *) _PyLazyImport_GetName(PyObject *lazy_import);
 PyAPI_FUNC(PyObject *) _PyLazyImport_New(
     struct _PyInterpreterFrame *frame, PyObject *import_func, PyObject *from, PyObject *attr);
+PyAPI_FUNC(int) _PyLazyImport_BindGlobal(
+    PyThreadState *tstate,
+    PyObject *lazy_import,
+    PyObject *globals,
+    PyObject *name);
+PyAPI_FUNC(void) _PyLazyImport_FinishGlobalBinding(
+    PyThreadState *tstate,
+    PyObject *lazy_import,
+    PyObject *globals,
+    PyObject *name,
+    int stored);
+PyAPI_FUNC(int) _PyLazyImport_CommitIfCurrent(
+    PyThreadState *tstate,
+    PyObject *lazy_import,
+    PyObject *globals,
+    PyObject *name,
+    PyObject *resolved);
+PyAPI_FUNC(int) _PyLazyImport_CommitStoredIfCurrent(
+    PyThreadState *tstate,
+    PyObject *lazy_import,
+    PyObject *resolved);
 
 #ifdef __cplusplus
 }