[mypyc] fix name generation for modules with similar full names (#18001)

Fixes mypyc/mypyc#1071
Adds a test to cover this case

Building certain package layouts now succeeds instead of failing. The
behavior for all package layouts not affected by the error is unchanged.

In `namegen.make_module_translation_map(names)`, if argument `names`
have `"foo"` and `"foo.foo"`, all suffixes found for `"foo"` are also
found for `"foo.foo"`. This means that module `foo` has no unique
suffixes, which currently causes an `AssertionError`.
The fix forces a module to take the last, fullest suffix if none are
unique. It is guaranteed that no other module will also take the same
suffix because they either will have a unique suffix to take, or they
will take the fullest suffix for their name which is always going to be
different.

mypyc/namegen.py

@@ -100,10 +100,9 @@ def make_module_translation_map(names: list[str]) -> dict[str, str]:
     for name in names:
         for suffix in candidate_suffixes(name):
             if num_instances[suffix] == 1:
-                result[name] = suffix
                 break
-        else:
-            assert False, names
+        # Takes the last suffix if none are unique
+        result[name] = suffix
     return result
 
 

mypyc/test/test_namegen.py

@@ -35,6 +35,12 @@ def test_make_module_translation_map(self) -> None:
             "fu.bar": "fu.bar.",
             "foo.baz": "baz.",
         }
+        assert make_module_translation_map(["foo", "foo.foo", "bar.foo", "bar.foo.bar.foo"]) == {
+            "foo": "foo.",
+            "foo.foo": "foo.foo.",
+            "bar.foo": "bar.foo.",
+            "bar.foo.bar.foo": "foo.bar.foo.",
+        }
 
     def test_name_generator(self) -> None:
         g = NameGenerator([["foo", "foo.zar"]])