From 98a0e3fb28f9f5dea6242ecd3b1062abc49914af Mon Sep 17 00:00:00 2001
From: Mike Bayer <mike_mp@zzzcomputing.com>
Date: Sat, 5 Dec 2015 15:02:20 -0500
Subject: [PATCH] - Added a type-level comparator that distinguishes
 :class:`.Integer`, :class:`.BigInteger`, and :class:`.SmallInteger` types and
 dialect-specific types; these all have "Integer" affinity so previously all
 compared as the same. fixes #341

---
 alembic/ddl/impl.py         | 16 +++++++++++-
 docs/build/changelog.rst    |  9 +++++++
 tests/test_autogen_diffs.py | 50 ++++++++++++++++++++++++++++++++++++-
 3 files changed, 73 insertions(+), 2 deletions(-)

diff --git a/alembic/ddl/impl.py b/alembic/ddl/impl.py
index ac3493bc..d87a2fcb 100644
--- a/alembic/ddl/impl.py
+++ b/alembic/ddl/impl.py
@@ -337,7 +337,21 @@ def _numeric_compare(t1, t2):
             t1.scale is not None and
             t1.scale != t2.scale
         )
+
+
+def _integer_compare(t1, t2):
+    t1_small_or_big = (
+        'S' if isinstance(t1, sqltypes.SmallInteger)
+        else 'B' if isinstance(t1, sqltypes.BigInteger) else 'I'
+    )
+    t2_small_or_big = (
+        'S' if isinstance(t2, sqltypes.SmallInteger)
+        else 'B' if isinstance(t2, sqltypes.BigInteger) else 'I'
+    )
+    return t1_small_or_big != t2_small_or_big
+
 _type_comparators = {
     sqltypes.String: _string_compare,
-    sqltypes.Numeric: _numeric_compare
+    sqltypes.Numeric: _numeric_compare,
+    sqltypes.Integer: _integer_compare
 }
diff --git a/docs/build/changelog.rst b/docs/build/changelog.rst
index 15c5f0cc..d9b8de5b 100644
--- a/docs/build/changelog.rst
+++ b/docs/build/changelog.rst
@@ -6,6 +6,15 @@ Changelog
 .. changelog::
     :version: 0.8.4
 
+    .. change::
+      :tags: bug, autogenerate
+      :tickets: 341
+
+      Added a type-level comparator that distinguishes :class:`.Integer`,
+      :class:`.BigInteger`, and :class:`.SmallInteger` types and
+      dialect-specific types; these all have "Integer" affinity so previously
+      all compared as the same.
+
     .. change::
       :tags: bug, batch
       :tickets: 338
diff --git a/tests/test_autogen_diffs.py b/tests/test_autogen_diffs.py
index 690f4773..6887058f 100644
--- a/tests/test_autogen_diffs.py
+++ b/tests/test_autogen_diffs.py
@@ -3,7 +3,8 @@ import sys
 from sqlalchemy import MetaData, Column, Table, Integer, String, Text, \
     Numeric, CHAR, ForeignKey, INTEGER, Index, UniqueConstraint, \
     TypeDecorator, CheckConstraint, text, PrimaryKeyConstraint, \
-    ForeignKeyConstraint
+    ForeignKeyConstraint, VARCHAR, DECIMAL, DateTime, BigInteger, BIGINT, \
+    SmallInteger
 from sqlalchemy.types import NULLTYPE
 from sqlalchemy.engine.reflection import Inspector
 
@@ -554,6 +555,53 @@ class AutogenerateDiffTestWSchema(ModelOne, AutogenTest, TestBase):
         eq_(diffs[10][3].name, 'pw')
 
 
+class CompareTypeSpecificityTest(TestBase):
+    def _fixture(self):
+        from alembic.ddl import impl
+        from sqlalchemy.engine import default
+
+        return impl.DefaultImpl(
+            default.DefaultDialect(), None, False, True, None, {})
+
+    def test_string(self):
+        t1 = String(30)
+        t2 = String(40)
+        t3 = VARCHAR(30)
+        t4 = Integer
+
+        impl = self._fixture()
+        is_(impl.compare_type(Column('x', t3), Column('x', t1)), False)
+        is_(impl.compare_type(Column('x', t3), Column('x', t2)), True)
+        is_(impl.compare_type(Column('x', t3), Column('x', t4)), True)
+
+    def test_numeric(self):
+        t1 = Numeric(10, 5)
+        t2 = Numeric(12, 5)
+        t3 = DECIMAL(10, 5)
+        t4 = DateTime
+
+        impl = self._fixture()
+        is_(impl.compare_type(Column('x', t3), Column('x', t1)), False)
+        is_(impl.compare_type(Column('x', t3), Column('x', t2)), True)
+        is_(impl.compare_type(Column('x', t3), Column('x', t4)), True)
+
+    def test_integer(self):
+        t1 = Integer()
+        t2 = SmallInteger()
+        t3 = BIGINT()
+        t4 = String()
+        t5 = INTEGER()
+        t6 = BigInteger()
+
+        impl = self._fixture()
+        is_(impl.compare_type(Column('x', t5), Column('x', t1)), False)
+        is_(impl.compare_type(Column('x', t3), Column('x', t1)), True)
+        is_(impl.compare_type(Column('x', t3), Column('x', t6)), False)
+        is_(impl.compare_type(Column('x', t3), Column('x', t2)), True)
+        is_(impl.compare_type(Column('x', t5), Column('x', t2)), True)
+        is_(impl.compare_type(Column('x', t1), Column('x', t4)), True)
+
+
 class AutogenerateCustomCompareTypeTest(AutogenTest, TestBase):
     __only_on__ = 'sqlite'
 
-- 
2.47.2