py: Convert hash API to use MP_UNARY_OP_HASH instead of ad-hoc function.

Hashing is now done using mp_unary_op function with MP_UNARY_OP_HASH as
the operator argument.  Hashing for int, str and bytes still go via
fast-path in mp_unary_op since they are the most common objects which
need to be hashed.

This lead to quite a bit of code cleanup, and should be more efficient
if anything.  It saves 176 bytes code space on Thumb2, and 360 bytes on
x86.

The only loss is that the error message "unhashable type" is now the
more generic "unsupported type for __hash__".

1 files changed, 11 insertions, 1 deletions

diff --git a/tests/basics/builtin_hash.py b/tests/basics/builtin_hash.py
index d7615c3ec0..b6b2ad15cb 100644
--- a/tests/basics/builtin_hash.py
+++ b/tests/basics/builtin_hash.py
@@ -20,11 +20,12 @@ class A:
 print(hash(A()))
 print({A():1})
 
+# all user-classes have default __hash__
 class B:
     pass
 hash(B())
 
-
+# if __eq__ is defined then default __hash__ is not used
 class C:
     def __eq__(self, another):
         return True
@@ -32,3 +33,12 @@ try:
     hash(C())
 except TypeError:
     print("TypeError")
+
+# __hash__ must return an int
+class D:
+    def __hash__(self):
+        return None
+try:
+    hash(D())
+except TypeError:
+    print("TypeError")