Speed up stubs suggestions (python#17965)

See python#17948
This is starting to show up on profiles

- 1.01x faster on clean (below noise)
- 1.02x faster on long
- 1.02x faster on openai
- 1.01x faster on openai incremental

I had a dumb bug that was preventing the optimisation for a while, I'll
see if I can make it even faster. Currently it's a small improvement

We could also get rid of the legacy stuff in mypy 2.0

mypy/build.py

@@ -92,7 +92,7 @@
 from mypy.plugins.default import DefaultPlugin
 from mypy.renaming import LimitedVariableRenameVisitor, VariableRenameVisitor
 from mypy.stats import dump_type_stats
-from mypy.stubinfo import legacy_bundled_packages, non_bundled_packages, stub_distribution_name
+from mypy.stubinfo import is_module_from_legacy_bundled_package, stub_distribution_name
 from mypy.types import Type
 from mypy.typestate import reset_global_state, type_state
 from mypy.util import json_dumps, json_loads
@@ -2658,17 +2658,13 @@ def find_module_and_diagnose(
 
         ignore_missing_imports = options.ignore_missing_imports
 
-        id_components = id.split(".")
         # Don't honor a global (not per-module) ignore_missing_imports
         # setting for modules that used to have bundled stubs, as
         # otherwise updating mypy can silently result in new false
         # negatives. (Unless there are stubs but they are incomplete.)
         global_ignore_missing_imports = manager.options.ignore_missing_imports
         if (
-            any(
-                ".".join(id_components[:i]) in legacy_bundled_packages
-                for i in range(len(id_components), 0, -1)
-            )
+            is_module_from_legacy_bundled_package(id)
             and global_ignore_missing_imports
             and not options.ignore_missing_imports_per_module
             and result is ModuleNotFoundReason.APPROVED_STUBS_NOT_INSTALLED
@@ -2789,18 +2785,15 @@ def module_not_found(
             code = codes.IMPORT
         errors.report(line, 0, msg.format(module=target), code=code)
 
-        components = target.split(".")
-        for i in range(len(components), 0, -1):
-            module = ".".join(components[:i])
-            if module in legacy_bundled_packages or module in non_bundled_packages:
-                break
-
+        dist = stub_distribution_name(target)
         for note in notes:
             if "{stub_dist}" in note:
-                note = note.format(stub_dist=stub_distribution_name(module))
+                assert dist is not None
+                note = note.format(stub_dist=dist)
             errors.report(line, 0, note, severity="note", only_once=True, code=code)
         if reason is ModuleNotFoundReason.APPROVED_STUBS_NOT_INSTALLED:
-            manager.missing_stub_packages.add(stub_distribution_name(module))
+            assert dist is not None
+            manager.missing_stub_packages.add(dist)
     errors.set_import_context(save_import_context)
 
 

mypy/modulefinder.py

@@ -331,9 +331,8 @@ def _find_module_non_stub_helper(
             # If this is not a directory then we can't traverse further into it
             if not self.fscache.isdir(dir_path):
                 break
-        for i in range(len(components), 0, -1):
-            if approved_stub_package_exists(".".join(components[:i])):
-                return ModuleNotFoundReason.APPROVED_STUBS_NOT_INSTALLED
+        if approved_stub_package_exists(".".join(components)):
+            return ModuleNotFoundReason.APPROVED_STUBS_NOT_INSTALLED
         if plausible_match:
             return ModuleNotFoundReason.FOUND_WITHOUT_TYPE_HINTS
         else:

mypy/stubinfo.py

@@ -1,22 +1,53 @@
 from __future__ import annotations
 
 
-def is_legacy_bundled_package(prefix: str) -> bool:
-    return prefix in legacy_bundled_packages
+def is_module_from_legacy_bundled_package(module: str) -> bool:
+    top_level = module.split(".", 1)[0]
+    return top_level in legacy_bundled_packages
 
 
-def approved_stub_package_exists(prefix: str) -> bool:
-    return is_legacy_bundled_package(prefix) or prefix in non_bundled_packages
+def approved_stub_package_exists(module: str) -> bool:
+    top_level = module.split(".", 1)[0]
+    if top_level in legacy_bundled_packages:
+        return True
+    if top_level in non_bundled_packages_flat:
+        return True
+    if top_level in non_bundled_packages_namespace:
+        namespace = non_bundled_packages_namespace[top_level]
+        components = module.split(".")
+        for i in range(len(components), 0, -1):
+            module = ".".join(components[:i])
+            if module in namespace:
+                return True
+    return False
 
 
-def stub_distribution_name(prefix: str) -> str:
-    return legacy_bundled_packages.get(prefix) or non_bundled_packages[prefix]
+def stub_distribution_name(module: str) -> str | None:
+    top_level = module.split(".", 1)[0]
+
+    dist = legacy_bundled_packages.get(top_level)
+    if dist:
+        return dist
+    dist = non_bundled_packages_flat.get(top_level)
+    if dist:
+        return dist
+
+    if top_level in non_bundled_packages_namespace:
+        namespace = non_bundled_packages_namespace[top_level]
+        components = module.split(".")
+        for i in range(len(components), 0, -1):
+            module = ".".join(components[:i])
+            dist = namespace.get(module)
+            if dist:
+                return dist
+
+    return None
 
 
 # Stubs for these third-party packages used to be shipped with mypy.
 #
 # Map package name to PyPI stub distribution name.
-legacy_bundled_packages = {
+legacy_bundled_packages: dict[str, str] = {
     "aiofiles": "types-aiofiles",
     "bleach": "types-bleach",
     "boto": "types-boto",
@@ -32,7 +63,6 @@ def stub_distribution_name(prefix: str) -> str:
     "docutils": "types-docutils",
     "first": "types-first",
     "gflags": "types-python-gflags",
-    "google.protobuf": "types-protobuf",
     "markdown": "types-Markdown",
     "mock": "types-mock",
     "OpenSSL": "types-pyOpenSSL",
@@ -66,20 +96,17 @@ def stub_distribution_name(prefix: str) -> str:
 # include packages that have a release that includes PEP 561 type
 # information.
 #
-# Package name can have one or two components ('a' or 'a.b').
-#
 # Note that these packages are omitted for now:
 #   pika:       typeshed's stubs are on PyPI as types-pika-ts.
 #               types-pika already exists on PyPI, and is more complete in many ways,
 #               but is a non-typeshed stubs package.
-non_bundled_packages = {
+non_bundled_packages_flat: dict[str, str] = {
     "MySQLdb": "types-mysqlclient",
     "PIL": "types-Pillow",
     "PyInstaller": "types-pyinstaller",
     "Xlib": "types-python-xlib",
     "aws_xray_sdk": "types-aws-xray-sdk",
     "babel": "types-babel",
-    "backports.ssl_match_hostname": "types-backports.ssl_match_hostname",
     "braintree": "types-braintree",
     "bs4": "types-beautifulsoup4",
     "bugbear": "types-flake8-bugbear",
@@ -107,7 +134,6 @@ def stub_distribution_name(prefix: str) -> str:
     "flask_migrate": "types-Flask-Migrate",
     "fpdf": "types-fpdf2",
     "gdb": "types-gdb",
-    "google.cloud.ndb": "types-google-cloud-ndb",
     "hdbcli": "types-hdbcli",
     "html5lib": "types-html5lib",
     "httplib2": "types-httplib2",
@@ -123,7 +149,6 @@ def stub_distribution_name(prefix: str) -> str:
     "oauthlib": "types-oauthlib",
     "openpyxl": "types-openpyxl",
     "opentracing": "types-opentracing",
-    "paho.mqtt": "types-paho-mqtt",
     "parsimonious": "types-parsimonious",
     "passlib": "types-passlib",
     "passpy": "types-passpy",
@@ -171,3 +196,10 @@ def stub_distribution_name(prefix: str) -> str:
     "pandas": "pandas-stubs",  # https://github.com/pandas-dev/pandas-stubs
     "lxml": "lxml-stubs",  # https://github.com/lxml/lxml-stubs
 }
+
+
+non_bundled_packages_namespace: dict[str, dict[str, str]] = {
+    "backports": {"backports.ssl_match_hostname": "types-backports.ssl_match_hostname"},
+    "google": {"google.cloud.ndb": "types-google-cloud-ndb", "google.protobuf": "types-protobuf"},
+    "paho": {"paho.mqtt": "types-paho-mqtt"},
+}

mypy/test/teststubinfo.py

@@ -2,11 +2,45 @@
 
 import unittest
 
-from mypy.stubinfo import is_legacy_bundled_package
+from mypy.stubinfo import (
+    approved_stub_package_exists,
+    is_module_from_legacy_bundled_package,
+    legacy_bundled_packages,
+    non_bundled_packages_flat,
+    stub_distribution_name,
+)
 
 
 class TestStubInfo(unittest.TestCase):
     def test_is_legacy_bundled_packages(self) -> None:
-        assert not is_legacy_bundled_package("foobar_asdf")
-        assert is_legacy_bundled_package("pycurl")
-        assert is_legacy_bundled_package("dataclasses")
+        assert not is_module_from_legacy_bundled_package("foobar_asdf")
+        assert not is_module_from_legacy_bundled_package("PIL")
+        assert is_module_from_legacy_bundled_package("pycurl")
+        assert is_module_from_legacy_bundled_package("dataclasses")
+
+    def test_approved_stub_package_exists(self) -> None:
+        assert not approved_stub_package_exists("foobar_asdf")
+        assert approved_stub_package_exists("pycurl")
+        assert approved_stub_package_exists("babel")
+        assert approved_stub_package_exists("google.cloud.ndb")
+        assert approved_stub_package_exists("google.cloud.ndb.submodule")
+        assert not approved_stub_package_exists("google.cloud.unknown")
+        assert approved_stub_package_exists("google.protobuf")
+        assert approved_stub_package_exists("google.protobuf.submodule")
+        assert not approved_stub_package_exists("google")
+
+    def test_stub_distribution_name(self) -> None:
+        assert stub_distribution_name("foobar_asdf") is None
+        assert stub_distribution_name("pycurl") == "types-pycurl"
+        assert stub_distribution_name("babel") == "types-babel"
+        assert stub_distribution_name("google.cloud.ndb") == "types-google-cloud-ndb"
+        assert stub_distribution_name("google.cloud.ndb.submodule") == "types-google-cloud-ndb"
+        assert stub_distribution_name("google.cloud.unknown") is None
+        assert stub_distribution_name("google.protobuf") == "types-protobuf"
+        assert stub_distribution_name("google.protobuf.submodule") == "types-protobuf"
+        assert stub_distribution_name("google") is None
+
+    def test_period_in_top_level(self) -> None:
+        for packages in (non_bundled_packages_flat, legacy_bundled_packages):
+            for top_level_module in packages:
+                assert "." not in top_level_module