Check the exact full import name for eager imports

Summary: We used to check parent import and `fromlist` separately for eagerness. This makes it so we check for the exact full import name on the container instead. This works well with the strategy files introduced in D65434680 and D65555319.

Reviewed By: brittanyrey

Differential Revision: D65775372

fbshipit-source-id: 322e6fa44cf8adcc7533d6b41b834a244a0f81b1

Lib/test/lazyimports/set_lazy_imports_eager.py

@@ -8,19 +8,18 @@
 import importlib
 
 importlib.set_lazy_imports(eager=[
-    "test.lazyimports.data.metasyntactic.foo",
-    "test.lazyimports.data.metasyntactic.waldo",
+    "test.lazyimports.data.metasyntactic.foo.bar",
     "test.lazyimports.data.metasyntactic.plugh.Plugh",
 ])
 
 import test.lazyimports.data.metasyntactic.foo as foo
-self.assertFalse(importlib.is_lazy_import(globals(), "foo"))  # should be eager
+self.assertTrue(importlib.is_lazy_import(globals(), "foo"))  # should be lazy
 
 from test.lazyimports.data.metasyntactic.foo import bar
-self.assertFalse(importlib.is_lazy_import(globals(), "bar"))  # maybe this should have been lazy?
+self.assertFalse(importlib.is_lazy_import(globals(), "bar"))  # listed in the eager list, so should not be lazy
 
-from test.lazyimports.data.metasyntactic.waldo import Waldo
-self.assertFalse(importlib.is_lazy_import(globals(), "Waldo"))  # maybe this should have been lazy?
+from test.lazyimports.data.metasyntactic.foo.bar import Bar
+self.assertTrue(importlib.is_lazy_import(globals(), "Bar"))  # should be lazy
 
 import test.lazyimports.data.metasyntactic.waldo.fred as fred
 self.assertTrue(importlib.is_lazy_import(globals(), "fred"))  # this should be lazy
@@ -29,7 +28,7 @@
 self.assertTrue(importlib.is_lazy_import(globals(), "Fred"))  # this should be lazy
 
 from test.lazyimports.data.metasyntactic.waldo import fred
-self.assertFalse(importlib.is_lazy_import(globals(), "fred"))  # maybe this should have been lazy?
+self.assertTrue(importlib.is_lazy_import(globals(), "fred"))  # this should be lazy
 
 import test.lazyimports.data.metasyntactic.plugh as plugh
 self.assertTrue(importlib.is_lazy_import(globals(), "plugh"))  # this should be lazy

Python/import.c

@@ -2886,25 +2886,18 @@ add_lazy_modules(PyThreadState *tstate, PyObject *builtins, PyObject *name, PyOb
     PyObject *lazy_submodules;
 
     if (tstate->interp->eager_imports != NULL) {
-        int found = PySequence_Contains(tstate->interp->eager_imports, name);
-        if (found < 0) {
-            goto error;
-        }
-        if (found) {
-            ret = 0; /* If the module is flagged as eager import, load eagerly */
-            goto end;
-        }
+        Py_ssize_t size = 0;
         if (fromlist != NULL && fromlist != Py_None) {
             assert(PyTuple_CheckExact(fromlist));
-            Py_ssize_t size = PyTuple_GET_SIZE(fromlist);
+            size = PyTuple_GET_SIZE(fromlist);
             for (Py_ssize_t i = 0; i < size; ++i) {
                 PyObject* item = PyTuple_GET_ITEM(fromlist, i);
                 assert(PyUnicode_Check(item));
                 PyObject *from_name = PyUnicode_FromFormat("%U.%U", name, item);
                 if (from_name == NULL) {
                     goto error;
                 }
-                found = PySequence_Contains(tstate->interp->eager_imports, from_name);
+                int found = PySequence_Contains(tstate->interp->eager_imports, from_name);
                 Py_DECREF(from_name);
                 if (found < 0) {
                     goto error;
@@ -2915,6 +2908,16 @@ add_lazy_modules(PyThreadState *tstate, PyObject *builtins, PyObject *name, PyOb
                 }
             }
         }
+        if (size == 0) {
+            int found = PySequence_Contains(tstate->interp->eager_imports, name);
+            if (found < 0) {
+                goto error;
+            }
+            if (found) {
+                ret = 0; /* If the module is flagged as eager import, load eagerly */
+                goto end;
+            }
+        }
     }
 
     lazy_submodules = PyDict_GetItemWithError(lazy_modules, name);