make-API-more-complex.diff

From afb9cfba2854c48e1995e1c4940d679469febd94 Mon Sep 17 00:00:00 2001
From: Alexey Spiridonov <XXX@gmail.com>
Date: Sun, 5 Aug 2018 15:36:06 -0700
Subject: [PATCH] Switch to a more complex plugin invocation API

---
 mypy/plugin.py  | 11 ++++++-----
 mypy/semanal.py |  7 ++++++-
 2 files changed, 12 insertions(+), 6 deletions(-)

diff --git a/mypy/plugin.py b/mypy/plugin.py
index 4392e55..6f59c57 100644
--- a/mypy/plugin.py
+++ b/mypy/plugin.py
@@ -210,8 +210,9 @@ class Plugin:
                             ) -> Optional[Callable[[ClassDefContext], None]]:
         return None
 
-    def customize_class_mro(self, ctx: ClassDefContext) -> None:
-        pass
+    def get_customize_class_mro_hook(self, fullname: str
+                                     ) -> Optional[Callable[[ClassDefContext], None]]:
+        return None
 
 
 T = TypeVar('T')
@@ -269,9 +270,9 @@ class ChainedPlugin(Plugin):
                             ) -> Optional[Callable[[ClassDefContext], None]]:
         return self._find_hook(lambda plugin: plugin.get_base_class_hook(fullname))
 
-    def customize_class_mro(self, ctx: ClassDefContext) -> None:
-        for plugin in self._plugins:
-            plugin.customize_class_mro(ctx)
+    def get_customize_class_mro_hook(self, fullname: str
+                                     ) -> Optional[Callable[[ClassDefContext], None]]:
+        return self._find_hook(lambda plugin: plugin.get_customize_class_mro_hook(fullname))
 
     def _find_hook(self, lookup: Callable[[Plugin], T]) -> Optional[T]:
         for plugin in self._plugins:
diff --git a/mypy/semanal.py b/mypy/semanal.py
index 635bb94..daf0fa5 100644
--- a/mypy/semanal.py
+++ b/mypy/semanal.py
@@ -1145,7 +1145,12 @@ class SemanticAnalyzerPass2(NodeVisitor[None],
             self.fail_blocker('Cannot determine consistent method resolution '
                               'order (MRO) for "%s"' % defn.name, defn)
             defn.info.mro = []
-        self.plugin.customize_class_mro(ClassDefContext(defn, Expression(), self))
+        # Allow plugins to alter the MRO to handle the fact that `def mro()`
+        # on metaclasses permits MRO rewriting.
+        if defn.fullname:
+            hook = self.plugin.get_customize_class_mro_hook(defn.fullname)
+            if hook:
+                hook(ClassDefContext(defn, Expression(), self))
 
     def update_metaclass(self, defn: ClassDef) -> None:
         """Lookup for special metaclass declarations, and update defn fields accordingly.
-- 
1.9.1