From acfb4032058b43553074c2f8a9ed81a6546107ce Mon Sep 17 00:00:00 2001
From: Jukka Lehtosalo <jukka.lehtosalo@iki.fi>
Date: Wed, 19 Apr 2023 16:43:27 +0100
Subject: [PATCH 01/22] Add i16 to test stubs

---
 test-data/unit/lib-stub/mypy_extensions.pyi | 32 ++++++++++++++++++++-
 1 file changed, 31 insertions(+), 1 deletion(-)

diff --git a/test-data/unit/lib-stub/mypy_extensions.pyi b/test-data/unit/lib-stub/mypy_extensions.pyi
index 56fac31e7219..b7ff01064315 100644
--- a/test-data/unit/lib-stub/mypy_extensions.pyi
+++ b/test-data/unit/lib-stub/mypy_extensions.pyi
@@ -50,7 +50,37 @@ class FlexibleAlias(Generic[_T, _U]): ...
 class __SupportsInt(Protocol[T_co]):
     def __int__(self) -> int: pass
 
-_Int = Union[int, i32, i64]
+_Int = Union[int, i16, i32, i64]
+
+class i16:
+    def __init__(self, x: Union[_Int, str, bytes, SupportsInt], base: int = 10) -> None: ...
+    def __add__(self, x: i16) -> i16: ...
+    def __radd__(self, x: i16) -> i16: ...
+    def __sub__(self, x: i16) -> i16: ...
+    def __rsub__(self, x: i16) -> i16: ...
+    def __mul__(self, x: i16) -> i16: ...
+    def __rmul__(self, x: i16) -> i16: ...
+    def __floordiv__(self, x: i16) -> i16: ...
+    def __rfloordiv__(self, x: i16) -> i16: ...
+    def __mod__(self, x: i16) -> i16: ...
+    def __rmod__(self, x: i16) -> i16: ...
+    def __and__(self, x: i16) -> i16: ...
+    def __rand__(self, x: i16) -> i16: ...
+    def __or__(self, x: i16) -> i16: ...
+    def __ror__(self, x: i16) -> i16: ...
+    def __xor__(self, x: i16) -> i16: ...
+    def __rxor__(self, x: i16) -> i16: ...
+    def __lshift__(self, x: i16) -> i16: ...
+    def __rlshift__(self, x: i16) -> i16: ...
+    def __rshift__(self, x: i16) -> i16: ...
+    def __rrshift__(self, x: i16) -> i16: ...
+    def __neg__(self) -> i16: ...
+    def __invert__(self) -> i16: ...
+    def __pos__(self) -> i16: ...
+    def __lt__(self, x: i16) -> bool: ...
+    def __le__(self, x: i16) -> bool: ...
+    def __ge__(self, x: i16) -> bool: ...
+    def __gt__(self, x: i16) -> bool: ...
 
 class i32:
     def __init__(self, x: Union[_Int, str, bytes, SupportsInt], base: int = 10) -> None: ...

From fabfa1a5ebacf7e6bcb1b44ecff1aff6c2d1df5f Mon Sep 17 00:00:00 2001
From: Jukka Lehtosalo <jukka.lehtosalo@iki.fi>
Date: Wed, 19 Apr 2023 16:43:48 +0100
Subject: [PATCH 02/22] Add failing test case

---
 mypyc/test-data/irbuild-i16.test | 21 +++++++++++++++++++++
 mypyc/test/test_irbuild.py       |  1 +
 2 files changed, 22 insertions(+)
 create mode 100644 mypyc/test-data/irbuild-i16.test

diff --git a/mypyc/test-data/irbuild-i16.test b/mypyc/test-data/irbuild-i16.test
new file mode 100644
index 000000000000..b01da23e012b
--- /dev/null
+++ b/mypyc/test-data/irbuild-i16.test
@@ -0,0 +1,21 @@
+# Test cases for i16 native ints. Focus on things that are different from i64; no need to
+# duplicate all i64 test cases here.
+
+[case testI16BinaryOp]
+from mypy_extensions import i16
+
+def add_op(x: i16, y: i16) -> i16:
+    x = y + x
+    y = x + 5
+    y += x
+    y += 7
+    x = 5 + y
+    return x
+def compare(x: i16, y: i16) -> None:
+    a = x == y
+    b = x == -5
+    c = x < y
+    d = x < -5
+    e = -5 == x
+    f = -5 < x
+[out]
diff --git a/mypyc/test/test_irbuild.py b/mypyc/test/test_irbuild.py
index fe347c855661..2b14619a9884 100644
--- a/mypyc/test/test_irbuild.py
+++ b/mypyc/test/test_irbuild.py
@@ -42,6 +42,7 @@
     "irbuild-strip-asserts.test",
     "irbuild-i64.test",
     "irbuild-i32.test",
+    "irbuild-i16.test",
     "irbuild-vectorcall.test",
     "irbuild-unreachable.test",
     "irbuild-isinstance.test",

From 7096d32c77d4758f67550d6462373b1e30b7138c Mon Sep 17 00:00:00 2001
From: Jukka Lehtosalo <jukka.lehtosalo@iki.fi>
Date: Wed, 19 Apr 2023 16:54:10 +0100
Subject: [PATCH 03/22] Some i16 operations work

---
 mypy/types.py                    |  4 ++-
 mypyc/ir/rtypes.py               | 18 ++++++++--
 mypyc/irbuild/ll_builder.py      |  1 +
 mypyc/irbuild/mapper.py          |  3 ++
 mypyc/test-data/irbuild-i16.test | 61 ++++++++++++++++++++++++++++++++
 5 files changed, 84 insertions(+), 3 deletions(-)

diff --git a/mypy/types.py b/mypy/types.py
index 5fbdd385826c..4eff4a82a233 100644
--- a/mypy/types.py
+++ b/mypy/types.py
@@ -150,7 +150,9 @@
 )
 
 # Mypyc fixed-width native int types (compatible with builtins.int)
-MYPYC_NATIVE_INT_NAMES: Final = ("mypy_extensions.i64", "mypy_extensions.i32")
+MYPYC_NATIVE_INT_NAMES: Final = ("mypy_extensions.i64",
+                                 "mypy_extensions.i32",
+                                 "mypy_extensions.i16")
 
 DATACLASS_TRANSFORM_NAMES: Final = (
     "typing.dataclass_transform",
diff --git a/mypyc/ir/rtypes.py b/mypyc/ir/rtypes.py
index 7ff82ac9b297..41456fbd7589 100644
--- a/mypyc/ir/rtypes.py
+++ b/mypyc/ir/rtypes.py
@@ -206,7 +206,7 @@ def __init__(
         self.error_overlap = error_overlap
         if ctype == "CPyTagged":
             self.c_undefined = "CPY_INT_TAG"
-        elif ctype in ("int32_t", "int64_t"):
+        elif ctype in ("int16_t", "int32_t", "int64_t"):
             # This is basically an arbitrary value that is pretty
             # unlikely to overlap with a real value.
             self.c_undefined = "-113"
@@ -290,6 +290,16 @@ def __hash__(self) -> int:
 
 # Low level integer types (correspond to C integer types)
 
+int16_rprimitive: Final = RPrimitive(
+    "int16",
+    is_unboxed=True,
+    is_refcounted=False,
+    is_native_int=True,
+    is_signed=True,
+    ctype="int16_t",
+    size=2,
+    error_overlap=True,
+)
 int32_rprimitive: Final = RPrimitive(
     "int32",
     is_unboxed=True,
@@ -432,6 +442,10 @@ def is_short_int_rprimitive(rtype: RType) -> bool:
     return rtype is short_int_rprimitive
 
 
+def is_int16_rprimitive(rtype: RType) -> bool:
+    return rtype is int16_rprimitive
+
+
 def is_int32_rprimitive(rtype: RType) -> bool:
     return rtype is int32_rprimitive or (
         rtype is c_pyssize_t_rprimitive and rtype._ctype == "int32_t"
@@ -445,7 +459,7 @@ def is_int64_rprimitive(rtype: RType) -> bool:
 
 
 def is_fixed_width_rtype(rtype: RType) -> bool:
-    return is_int32_rprimitive(rtype) or is_int64_rprimitive(rtype)
+    return is_int64_rprimitive(rtype) or is_int32_rprimitive(rtype) or is_int16_rprimitive(rtype)
 
 
 def is_uint32_rprimitive(rtype: RType) -> bool:
diff --git a/mypyc/irbuild/ll_builder.py b/mypyc/irbuild/ll_builder.py
index aa152d32a144..de0e079d87fa 100644
--- a/mypyc/irbuild/ll_builder.py
+++ b/mypyc/irbuild/ll_builder.py
@@ -104,6 +104,7 @@
     is_dict_rprimitive,
     is_fixed_width_rtype,
     is_float_rprimitive,
+    is_int16_rprimitive,
     is_int32_rprimitive,
     is_int64_rprimitive,
     is_int_rprimitive,
diff --git a/mypyc/irbuild/mapper.py b/mypyc/irbuild/mapper.py
index dddb35230fd5..a4712f4af524 100644
--- a/mypyc/irbuild/mapper.py
+++ b/mypyc/irbuild/mapper.py
@@ -32,6 +32,7 @@
     bytes_rprimitive,
     dict_rprimitive,
     float_rprimitive,
+    int16_rprimitive,
     int32_rprimitive,
     int64_rprimitive,
     int_rprimitive,
@@ -102,6 +103,8 @@ def type_to_rtype(self, typ: Type | None) -> RType:
                 return int64_rprimitive
             elif typ.type.fullname == "mypy_extensions.i32":
                 return int32_rprimitive
+            elif typ.type.fullname == "mypy_extensions.i16":
+                return int16_rprimitive
             else:
                 return object_rprimitive
         elif isinstance(typ, TupleType):
diff --git a/mypyc/test-data/irbuild-i16.test b/mypyc/test-data/irbuild-i16.test
index b01da23e012b..d71bbcf3a86f 100644
--- a/mypyc/test-data/irbuild-i16.test
+++ b/mypyc/test-data/irbuild-i16.test
@@ -19,3 +19,64 @@ def compare(x: i16, y: i16) -> None:
     e = -5 == x
     f = -5 < x
 [out]
+def add_op(x, y):
+    x, y, r0, r1, r2, r3, r4 :: int16
+L0:
+    r0 = y + x
+    x = r0
+    r1 = x + 5
+    y = r1
+    r2 = y + x
+    y = r2
+    r3 = y + 7
+    y = r3
+    r4 = 5 + y
+    x = r4
+    return x
+def compare(x, y):
+    x, y :: int16
+    r0 :: bit
+    a :: bool
+    r1 :: bit
+    b :: bool
+    r2 :: bit
+    c :: bool
+    r3 :: bit
+    d :: bool
+    r4 :: bit
+    e :: bool
+    r5 :: bit
+    f :: bool
+L0:
+    r0 = x == y
+    a = r0
+    r1 = x == -5
+    b = r1
+    r2 = x < y :: signed
+    c = r2
+    r3 = x < -5 :: signed
+    d = r3
+    r4 = -5 == x
+    e = r4
+    r5 = -5 < x :: signed
+    f = r5
+    return 1
+
+[case testI16UnaryOp]
+from mypy_extensions import i16
+
+def unary(x: i16) -> i16:
+    y = -x
+    x = ~y
+    y = +x
+    return y
+[out]
+def unary(x):
+    x, r0, y, r1 :: int16
+L0:
+    r0 = 0 - x
+    y = r0
+    r1 = y ^ -1
+    x = r1
+    y = x
+    return y

From 91fd5333b1721542b5f95cd7e7155883768bfe95 Mon Sep 17 00:00:00 2001
From: Jukka Lehtosalo <jukka.lehtosalo@iki.fi>
Date: Wed, 19 Apr 2023 16:55:46 +0100
Subject: [PATCH 04/22] Add test case

---
 mypyc/test-data/irbuild-i16.test | 51 ++++++++++++++++++++++++++++++++
 1 file changed, 51 insertions(+)

diff --git a/mypyc/test-data/irbuild-i16.test b/mypyc/test-data/irbuild-i16.test
index d71bbcf3a86f..3c06f657d880 100644
--- a/mypyc/test-data/irbuild-i16.test
+++ b/mypyc/test-data/irbuild-i16.test
@@ -80,3 +80,54 @@ L0:
     x = r1
     y = x
     return y
+
+[case testI16DivisionByConstant]
+from mypy_extensions import i16
+
+def div_by_constant(x: i16) -> i16:
+    x = x // 5
+    x //= 17
+    return x
+[out]
+def div_by_constant(x):
+    x, r0, r1 :: int16
+    r2, r3, r4 :: bit
+    r5 :: int16
+    r6 :: bit
+    r7, r8, r9 :: int16
+    r10, r11, r12 :: bit
+    r13 :: int16
+    r14 :: bit
+    r15 :: int16
+L0:
+    r0 = x / 5
+    r1 = r0
+    r2 = x < 0 :: signed
+    r3 = 5 < 0 :: signed
+    r4 = r2 == r3
+    if r4 goto L3 else goto L1 :: bool
+L1:
+    r5 = r1 * 5
+    r6 = r5 == x
+    if r6 goto L3 else goto L2 :: bool
+L2:
+    r7 = r1 - 1
+    r1 = r7
+L3:
+    x = r1
+    r8 = x / 17
+    r9 = r8
+    r10 = x < 0 :: signed
+    r11 = 17 < 0 :: signed
+    r12 = r10 == r11
+    if r12 goto L6 else goto L4 :: bool
+L4:
+    r13 = r9 * 17
+    r14 = r13 == x
+    if r14 goto L6 else goto L5 :: bool
+L5:
+    r15 = r9 - 1
+    r9 = r15
+L6:
+    x = r9
+    return x

From e03d00660bc6105c10c171f9ed76d415d4d0f32c Mon Sep 17 00:00:00 2001
From: Jukka Lehtosalo <jukka.lehtosalo@iki.fi>
Date: Wed, 19 Apr 2023 17:00:33 +0100
Subject: [PATCH 05/22] Partial support for // and %

---
 mypyc/irbuild/ll_builder.py      |  6 ++++
 mypyc/primitives/int_ops.py      | 15 ++++++++
 mypyc/test-data/irbuild-i16.test | 60 ++++++++++++++++++++++++++++++++
 3 files changed, 81 insertions(+)

diff --git a/mypyc/irbuild/ll_builder.py b/mypyc/irbuild/ll_builder.py
index de0e079d87fa..9dccec107c41 100644
--- a/mypyc/irbuild/ll_builder.py
+++ b/mypyc/irbuild/ll_builder.py
@@ -147,6 +147,8 @@
     py_vectorcall_op,
 )
 from mypyc.primitives.int_ops import (
+    int16_divide_op,
+    int16_mod_op,
     int32_divide_op,
     int32_mod_op,
     int32_overflow,
@@ -2039,6 +2041,8 @@ def fixed_width_int_op(self, type: RType, lhs: Value, rhs: Value, op: int, line:
                 prim = int64_divide_op
             elif is_int32_rprimitive(type):
                 prim = int32_divide_op
+            elif is_int16_rprimitive(type):
+                prim = int16_divide_op
             else:
                 assert False, type
             return self.call_c(prim, [lhs, rhs], line)
@@ -2051,6 +2055,8 @@ def fixed_width_int_op(self, type: RType, lhs: Value, rhs: Value, op: int, line:
                 prim = int64_mod_op
             elif is_int32_rprimitive(type):
                 prim = int32_mod_op
+            elif is_int16_rprimitive(type):
+                prim = int16_mod_op
             else:
                 assert False, type
             return self.call_c(prim, [lhs, rhs], line)
diff --git a/mypyc/primitives/int_ops.py b/mypyc/primitives/int_ops.py
index eff4b4ffd8ab..dc6fb40300dc 100644
--- a/mypyc/primitives/int_ops.py
+++ b/mypyc/primitives/int_ops.py
@@ -19,6 +19,7 @@
     bool_rprimitive,
     c_pyssize_t_rprimitive,
     float_rprimitive,
+    int16_rprimitive,
     int32_rprimitive,
     int64_rprimitive,
     int_rprimitive,
@@ -231,6 +232,20 @@ class IntComparisonOpDescription(NamedTuple):
     error_kind=ERR_MAGIC_OVERLAPPING,
 )
 
+int16_divide_op = custom_op(
+    arg_types=[int16_rprimitive, int16_rprimitive],
+    return_type=int16_rprimitive,
+    c_function_name="CPyInt16_Divide",
+    error_kind=ERR_MAGIC_OVERLAPPING,
+)
+
+int16_mod_op = custom_op(
+    arg_types=[int16_rprimitive, int16_rprimitive],
+    return_type=int16_rprimitive,
+    c_function_name="CPyInt16_Remainder",
+    error_kind=ERR_MAGIC_OVERLAPPING,
+)
+
 # Convert tagged int (as PyObject *) to i64
 int_to_int64_op = custom_op(
     arg_types=[object_rprimitive],
diff --git a/mypyc/test-data/irbuild-i16.test b/mypyc/test-data/irbuild-i16.test
index 3c06f657d880..07272e80ad89 100644
--- a/mypyc/test-data/irbuild-i16.test
+++ b/mypyc/test-data/irbuild-i16.test
@@ -131,3 +131,63 @@ L5:
 L6:
     x = r9
     return x
+
+[case testI16ModByConstant]
+from mypy_extensions import i16
+
+def mod_by_constant(x: i16) -> i16:
+    x = x % 5
+    x %= 17
+    return x
+[out]
+def mod_by_constant(x):
+    x, r0, r1 :: int16
+    r2, r3, r4, r5 :: bit
+    r6, r7, r8 :: int16
+    r9, r10, r11, r12 :: bit
+    r13 :: int16
+L0:
+    r0 = x % 5
+    r1 = r0
+    r2 = x < 0 :: signed
+    r3 = 5 < 0 :: signed
+    r4 = r2 == r3
+    if r4 goto L3 else goto L1 :: bool
+L1:
+    r5 = r1 == 0
+    if r5 goto L3 else goto L2 :: bool
+L2:
+    r6 = r1 + 5
+    r1 = r6
+L3:
+    x = r1
+    r7 = x % 17
+    r8 = r7
+    r9 = x < 0 :: signed
+    r10 = 17 < 0 :: signed
+    r11 = r9 == r10
+    if r11 goto L6 else goto L4 :: bool
+L4:
+    r12 = r8 == 0
+    if r12 goto L6 else goto L5 :: bool
+L5:
+    r13 = r8 + 17
+    r8 = r13
+L6:
+    x = r8
+    return x
+
+[case testI16DivModByVariable]
+from mypy_extensions import i16
+
+def divmod(x: i16, y: i16) -> i16:
+    a = x // y
+    return a % y
+[out]
+def divmod(x, y):
+    x, y, r0, a, r1 :: int16
+L0:
+    r0 = CPyInt16_Divide(x, y)
+    a = r0
+    r1 = CPyInt16_Remainder(a, y)
+    return r1

From 22cefd393aad7cd3d070474de767a5d61f96d4f4 Mon Sep 17 00:00:00 2001
From: Jukka Lehtosalo <jukka.lehtosalo@iki.fi>
Date: Wed, 19 Apr 2023 17:02:05 +0100
Subject: [PATCH 06/22] Add irbuild test case

---
 mypyc/test-data/irbuild-i16.test | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/mypyc/test-data/irbuild-i16.test b/mypyc/test-data/irbuild-i16.test
index 07272e80ad89..4e17fa3a8d3f 100644
--- a/mypyc/test-data/irbuild-i16.test
+++ b/mypyc/test-data/irbuild-i16.test
@@ -191,3 +191,21 @@ L0:
     a = r0
     r1 = CPyInt16_Remainder(a, y)
     return r1
+
+[case testI16BoxAndUnbox]
+from typing import Any
+from mypy_extensions import i16
+
+def f(x: Any) -> Any:
+    y: i16 = x
+    return y
+[out]
+def f(x):
+    x :: object
+    r0, y :: int16
+    r1 :: object
+L0:
+    r0 = unbox(int16, x)
+    y = r0
+    r1 = box(int16, y)
+    return r1

From 50845587232095d9c8d02d3d014b2868cecddfa2 Mon Sep 17 00:00:00 2001
From: Jukka Lehtosalo <jukka.lehtosalo@iki.fi>
Date: Wed, 19 Apr 2023 17:06:46 +0100
Subject: [PATCH 07/22] Add irbuild support for int -> i16 coercions

---
 mypyc/irbuild/ll_builder.py      |  5 +++
 mypyc/primitives/int_ops.py      |  7 ++++
 mypyc/test-data/irbuild-i16.test | 70 ++++++++++++++++++++++++++++++++
 3 files changed, 82 insertions(+)

diff --git a/mypyc/irbuild/ll_builder.py b/mypyc/irbuild/ll_builder.py
index 9dccec107c41..feddfd6238e8 100644
--- a/mypyc/irbuild/ll_builder.py
+++ b/mypyc/irbuild/ll_builder.py
@@ -149,6 +149,7 @@
 from mypyc.primitives.int_ops import (
     int16_divide_op,
     int16_mod_op,
+    int16_overflow,
     int32_divide_op,
     int32_mod_op,
     int32_overflow,
@@ -459,6 +460,10 @@ def coerce_int_to_fixed_width(self, src: Value, target_type: RType, line: int) -
             # Slow path just always generates an OverflowError
             self.call_c(int32_overflow, [], line)
             self.add(Unreachable())
+        elif is_int16_rprimitive(target_type):
+            # Slow path just always generates an OverflowError
+            self.call_c(int16_overflow, [], line)
+            self.add(Unreachable())
         else:
             assert False, target_type
 
diff --git a/mypyc/primitives/int_ops.py b/mypyc/primitives/int_ops.py
index dc6fb40300dc..c847f9a7a414 100644
--- a/mypyc/primitives/int_ops.py
+++ b/mypyc/primitives/int_ops.py
@@ -282,3 +282,10 @@ class IntComparisonOpDescription(NamedTuple):
     c_function_name="CPyInt32_Overflow",
     error_kind=ERR_ALWAYS,
 )
+
+int16_overflow = custom_op(
+    arg_types=[],
+    return_type=void_rtype,
+    c_function_name="CPyInt16_Overflow",
+    error_kind=ERR_ALWAYS,
+)
diff --git a/mypyc/test-data/irbuild-i16.test b/mypyc/test-data/irbuild-i16.test
index 4e17fa3a8d3f..d778f87e66f7 100644
--- a/mypyc/test-data/irbuild-i16.test
+++ b/mypyc/test-data/irbuild-i16.test
@@ -209,3 +209,73 @@ L0:
     y = r0
     r1 = box(int16, y)
     return r1
+
+[case testI16MixedCompare1]
+from mypy_extensions import i16
+def f(x: int, y: i16) -> bool:
+    return x == y
+[out]
+def f(x, y):
+    x :: int
+    y :: int16
+    r0 :: native_int
+    r1, r2, r3 :: bit
+    r4 :: native_int
+    r5, r6 :: int16
+    r7 :: bit
+L0:
+    r0 = x & 1
+    r1 = r0 == 0
+    if r1 goto L1 else goto L4 :: bool
+L1:
+    r2 = x < 65536 :: signed
+    if r2 goto L2 else goto L4 :: bool
+L2:
+    r3 = x >= -65536 :: signed
+    if r3 goto L3 else goto L4 :: bool
+L3:
+    r4 = x >> 1
+    r5 = truncate r4: native_int to int16
+    r6 = r5
+    goto L5
+L4:
+    CPyInt16_Overflow()
+    unreachable
+L5:
+    r7 = r6 == y
+    return r7
+
+[case testI16MixedCompare2]
+from mypy_extensions import i16
+def f(x: i16, y: int) -> bool:
+    return x == y
+[out]
+def f(x, y):
+    x :: int16
+    y :: int
+    r0 :: native_int
+    r1, r2, r3 :: bit
+    r4 :: native_int
+    r5, r6 :: int16
+    r7 :: bit
+L0:
+    r0 = y & 1
+    r1 = r0 == 0
+    if r1 goto L1 else goto L4 :: bool
+L1:
+    r2 = y < 65536 :: signed
+    if r2 goto L2 else goto L4 :: bool
+L2:
+    r3 = y >= -65536 :: signed
+    if r3 goto L3 else goto L4 :: bool
+L3:
+    r4 = y >> 1
+    r5 = truncate r4: native_int to int16
+    r6 = r5
+    goto L5
+L4:
+    CPyInt16_Overflow()
+    unreachable
+L5:
+    r7 = x == r6
+    return r7

From 1e456c9970f577fe5ea9c923accfb4fd4737d496 Mon Sep 17 00:00:00 2001
From: Jukka Lehtosalo <jukka.lehtosalo@iki.fi>
Date: Wed, 19 Apr 2023 17:10:34 +0100
Subject: [PATCH 08/22] Support i16 -> int coercion

---
 mypyc/irbuild/ll_builder.py      |  2 +-
 mypyc/test-data/irbuild-i16.test | 15 +++++++++++++++
 2 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/mypyc/irbuild/ll_builder.py b/mypyc/irbuild/ll_builder.py
index feddfd6238e8..a37bcc0dbb86 100644
--- a/mypyc/irbuild/ll_builder.py
+++ b/mypyc/irbuild/ll_builder.py
@@ -477,7 +477,7 @@ def coerce_short_int_to_fixed_width(self, src: Value, target_type: RType, line:
         assert False, (src.type, target_type)
 
     def coerce_fixed_width_to_int(self, src: Value, line: int) -> Value:
-        if is_int32_rprimitive(src.type) and PLATFORM_SIZE == 8:
+        if (is_int32_rprimitive(src.type) and PLATFORM_SIZE == 8) or is_int16_rprimitive(src.type):
             # Simple case -- just sign extend and shift.
             extended = self.add(Extend(src, c_pyssize_t_rprimitive, signed=True))
             return self.int_op(
diff --git a/mypyc/test-data/irbuild-i16.test b/mypyc/test-data/irbuild-i16.test
index d778f87e66f7..8953f97e53e3 100644
--- a/mypyc/test-data/irbuild-i16.test
+++ b/mypyc/test-data/irbuild-i16.test
@@ -279,3 +279,18 @@ L4:
 L5:
     r7 = x == r6
     return r7
+
+[case testI16ConvertToInt]
+from mypy_extensions import i16
+
+def i16_to_int(a: i16) -> int:
+    return a
+[out]
+def i16_to_int(a):
+    a :: int16
+    r0 :: native_int
+    r1 :: int
+L0:
+    r0 = extend signed a: int16 to native_int
+    r1 = r0 << 1
+    return r1

From 8618333721652f41ff1dbaf4b56ec112d2a664a2 Mon Sep 17 00:00:00 2001
From: Jukka Lehtosalo <jukka.lehtosalo@iki.fi>
Date: Wed, 19 Apr 2023 17:13:07 +0100
Subject: [PATCH 09/22] Add test case

---
 mypyc/test-data/irbuild-i16.test | 42 ++++++++++++++++++++++++++++++++
 1 file changed, 42 insertions(+)

diff --git a/mypyc/test-data/irbuild-i16.test b/mypyc/test-data/irbuild-i16.test
index 8953f97e53e3..defdae168cfe 100644
--- a/mypyc/test-data/irbuild-i16.test
+++ b/mypyc/test-data/irbuild-i16.test
@@ -294,3 +294,45 @@ L0:
     r0 = extend signed a: int16 to native_int
     r1 = r0 << 1
     return r1
+
+[case testI16OperatorAssignmentMixed]
+from mypy_extensions import i16
+
+def f(a: i16) -> None:
+    x = 0
+    x += a
+[out]
+def f(a):
+    a :: int16
+    x :: int
+    r0 :: native_int
+    r1, r2, r3 :: bit
+    r4 :: native_int
+    r5, r6, r7 :: int16
+    r8 :: native_int
+    r9 :: int
+L0:
+    x = 0
+    r0 = x & 1
+    r1 = r0 == 0
+    if r1 goto L1 else goto L4 :: bool
+L1:
+    r2 = x < 65536 :: signed
+    if r2 goto L2 else goto L4 :: bool
+L2:
+    r3 = x >= -65536 :: signed
+    if r3 goto L3 else goto L4 :: bool
+L3:
+    r4 = x >> 1
+    r5 = truncate r4: native_int to int16
+    r6 = r5
+    goto L5
+L4:
+    CPyInt16_Overflow()
+    unreachable
+L5:
+    r7 = r6 + a
+    r8 = extend signed r7: int16 to native_int
+    r9 = r8 << 1
+    x = r9
+    return 1

From 531cca280a959a01e1714ba2e13521433ec12afb Mon Sep 17 00:00:00 2001
From: Jukka Lehtosalo <jukka.lehtosalo@iki.fi>
Date: Wed, 19 Apr 2023 17:33:04 +0100
Subject: [PATCH 10/22] Add and update unit tests

---
 mypyc/test/test_typeops.py | 23 +++++++++++++++++++----
 1 file changed, 19 insertions(+), 4 deletions(-)

diff --git a/mypyc/test/test_typeops.py b/mypyc/test/test_typeops.py
index 0d9860d88ffe..8bf238ef7733 100644
--- a/mypyc/test/test_typeops.py
+++ b/mypyc/test/test_typeops.py
@@ -8,6 +8,7 @@
     RUnion,
     bit_rprimitive,
     bool_rprimitive,
+    int16_rprimitive,
     int32_rprimitive,
     int64_rprimitive,
     int_rprimitive,
@@ -19,30 +20,44 @@
 from mypyc.subtype import is_subtype
 
 
+native_int_types = [int64_rprimitive, int32_rprimitive, int16_rprimitive]
+
+
 class TestSubtype(unittest.TestCase):
     def test_bit(self) -> None:
         assert is_subtype(bit_rprimitive, bool_rprimitive)
         assert is_subtype(bit_rprimitive, int_rprimitive)
         assert is_subtype(bit_rprimitive, short_int_rprimitive)
-        assert is_subtype(bit_rprimitive, int64_rprimitive)
-        assert is_subtype(bit_rprimitive, int32_rprimitive)
+        for rt in native_int_types:
+            assert is_subtype(bit_rprimitive, rt)
 
     def test_bool(self) -> None:
         assert not is_subtype(bool_rprimitive, bit_rprimitive)
         assert is_subtype(bool_rprimitive, int_rprimitive)
         assert is_subtype(bool_rprimitive, short_int_rprimitive)
-        assert is_subtype(bool_rprimitive, int64_rprimitive)
-        assert is_subtype(bool_rprimitive, int32_rprimitive)
+        for rt in native_int_types:
+            assert is_subtype(bool_rprimitive, rt)
 
     def test_int64(self) -> None:
+        assert is_subtype(int64_rprimitive, int64_rprimitive)
         assert is_subtype(int64_rprimitive, int_rprimitive)
         assert not is_subtype(int64_rprimitive, short_int_rprimitive)
         assert not is_subtype(int64_rprimitive, int32_rprimitive)
+        assert not is_subtype(int64_rprimitive, int16_rprimitive)
 
     def test_int32(self) -> None:
+        assert is_subtype(int32_rprimitive, int32_rprimitive)
         assert is_subtype(int32_rprimitive, int_rprimitive)
         assert not is_subtype(int32_rprimitive, short_int_rprimitive)
         assert not is_subtype(int32_rprimitive, int64_rprimitive)
+        assert not is_subtype(int32_rprimitive, int16_rprimitive)
+
+    def test_int16(self) -> None:
+        assert is_subtype(int16_rprimitive, int16_rprimitive)
+        assert is_subtype(int16_rprimitive, int_rprimitive)
+        assert not is_subtype(int16_rprimitive, short_int_rprimitive)
+        assert not is_subtype(int16_rprimitive, int64_rprimitive)
+        assert not is_subtype(int16_rprimitive, int32_rprimitive)
 
 
 class TestRuntimeSubtype(unittest.TestCase):

From fcdd7e164aa8dcf7b7d89f504747ac19378ce1fd Mon Sep 17 00:00:00 2001
From: Jukka Lehtosalo <jukka.lehtosalo@iki.fi>
Date: Wed, 19 Apr 2023 17:39:36 +0100
Subject: [PATCH 11/22] Fix conversions

---
 mypyc/irbuild/specialize.py      |  22 +++-
 mypyc/primitives/int_ops.py      |   2 +-
 mypyc/test-data/irbuild-i16.test | 166 +++++++++++++++++++++++++++++++
 3 files changed, 188 insertions(+), 2 deletions(-)

diff --git a/mypyc/irbuild/specialize.py b/mypyc/irbuild/specialize.py
index ff9df0cd597b..c96e3a896b23 100644
--- a/mypyc/irbuild/specialize.py
+++ b/mypyc/irbuild/specialize.py
@@ -49,6 +49,7 @@
     bool_rprimitive,
     c_int_rprimitive,
     dict_rprimitive,
+    int16_rprimitive,
     int32_rprimitive,
     int64_rprimitive,
     int_rprimitive,
@@ -56,6 +57,7 @@
     is_dict_rprimitive,
     is_fixed_width_rtype,
     is_float_rprimitive,
+    is_int16_rprimitive,
     is_int32_rprimitive,
     is_int64_rprimitive,
     is_int_rprimitive,
@@ -163,6 +165,7 @@ def translate_globals(builder: IRBuilder, expr: CallExpr, callee: RefExpr) -> Va
 @specialize_function("builtins.complex")
 @specialize_function("mypy_extensions.i64")
 @specialize_function("mypy_extensions.i32")
+@specialize_function("mypy_extensions.i16")
 def translate_builtins_with_unary_dunder(
     builder: IRBuilder, expr: CallExpr, callee: RefExpr
 ) -> Value | None:
@@ -171,7 +174,7 @@ def translate_builtins_with_unary_dunder(
         arg = expr.args[0]
         arg_typ = builder.node_type(arg)
         shortname = callee.fullname.split(".")[1]
-        if shortname in ("i64", "i32"):
+        if shortname in ("i64", "i32", "i16"):
             method = "__int__"
         else:
             method = f"__{shortname}__"
@@ -706,6 +709,23 @@ def translate_i32(builder: IRBuilder, expr: CallExpr, callee: RefExpr) -> Value
     return None
 
 
+@specialize_function("mypy_extensions.i16")
+def translate_i16(builder: IRBuilder, expr: CallExpr, callee: RefExpr) -> Value | None:
+    if len(expr.args) != 1 or expr.arg_kinds[0] != ARG_POS:
+        return None
+    arg = expr.args[0]
+    arg_type = builder.node_type(arg)
+    if is_int16_rprimitive(arg_type):
+        return builder.accept(arg)
+    elif is_int32_rprimitive(arg_type) or is_int64_rprimitive(arg_type):
+        val = builder.accept(arg)
+        return builder.add(Truncate(val, int16_rprimitive, line=expr.line))
+    elif is_int_rprimitive(arg_type) or is_bool_rprimitive(arg_type):
+        val = builder.accept(arg)
+        return builder.coerce(val, int16_rprimitive, expr.line)
+    return None
+
+
 @specialize_function("builtins.int")
 def translate_int(builder: IRBuilder, expr: CallExpr, callee: RefExpr) -> Value | None:
     if len(expr.args) != 1 or expr.arg_kinds[0] != ARG_POS:
diff --git a/mypyc/primitives/int_ops.py b/mypyc/primitives/int_ops.py
index c847f9a7a414..64c6d7bdc859 100644
--- a/mypyc/primitives/int_ops.py
+++ b/mypyc/primitives/int_ops.py
@@ -38,7 +38,7 @@
 
 # Constructors for builtins.int and native int types have the same behavior. In
 # interpreted mode, native int types are just aliases to 'int'.
-for int_name in ("builtins.int", "mypy_extensions.i64", "mypy_extensions.i32"):
+for int_name in ("builtins.int", "mypy_extensions.i64", "mypy_extensions.i32", "mypy_extensions.i16"):
     # These int constructors produce object_rprimitives that then need to be unboxed
     # I guess unboxing ourselves would save a check and branch though?
 
diff --git a/mypyc/test-data/irbuild-i16.test b/mypyc/test-data/irbuild-i16.test
index defdae168cfe..0f34ea53818d 100644
--- a/mypyc/test-data/irbuild-i16.test
+++ b/mypyc/test-data/irbuild-i16.test
@@ -336,3 +336,169 @@ L5:
     r9 = r8 << 1
     x = r9
     return 1
+
+[case testI16InitializeFromLiteral]
+from mypy_extensions import i16, i64
+
+def f() -> None:
+    x: i16 = 0
+    y: i16 = -127
+    z: i16 = 5 + 7
+[out]
+def f():
+    x, y, z :: int16
+L0:
+    x = 0
+    y = -127
+    z = 12
+    return 1
+
+[case testI16ExplicitConversionFromNativeInt]
+from mypy_extensions import i64, i32, i16
+
+def from_i16(x: i16) -> i16:
+    return i16(x)
+
+def from_i32(x: i32) -> i16:
+    return i16(x)
+
+def from_i64(x: i64) -> i16:
+    return i16(x)
+[out]
+def from_i16(x):
+    x :: int16
+L0:
+    return x
+def from_i32(x):
+    x :: int32
+    r0 :: int16
+L0:
+    r0 = truncate x: int32 to int16
+    return r0
+def from_i64(x):
+    x :: int64
+    r0 :: int16
+L0:
+    r0 = truncate x: int64 to int16
+    return r0
+
+[case testI16ExplicitConversionFromInt]
+from mypy_extensions import i16
+
+def f(x: int) -> i16:
+    return i16(x)
+[out]
+def f(x):
+    x :: int
+    r0 :: native_int
+    r1, r2, r3 :: bit
+    r4 :: native_int
+    r5, r6 :: int16
+L0:
+    r0 = x & 1
+    r1 = r0 == 0
+    if r1 goto L1 else goto L4 :: bool
+L1:
+    r2 = x < 65536 :: signed
+    if r2 goto L2 else goto L4 :: bool
+L2:
+    r3 = x >= -65536 :: signed
+    if r3 goto L3 else goto L4 :: bool
+L3:
+    r4 = x >> 1
+    r5 = truncate r4: native_int to int16
+    r6 = r5
+    goto L5
+L4:
+    CPyInt16_Overflow()
+    unreachable
+L5:
+    return r6
+
+[case testI16ExplicitConversionFromLiteral]
+from mypy_extensions import i16
+
+def f() -> None:
+    x = i16(0)
+    y = i16(11)
+    z = i16(-3)
+[out]
+def f():
+    x, y, z :: int16
+L0:
+    x = 0
+    y = 11
+    z = -3
+    return 1
+
+[case testI16ExplicitConversionFromVariousTypes]
+from mypy_extensions import i16
+
+def bool_to_i16(b: bool) -> i16:
+    return i16(b)
+
+def str_to_i16(s: str) -> i16:
+    return i16(s)
+
+class C:
+    def __int__(self) -> i16:
+        return 5
+
+def instance_to_i16(c: C) -> i16:
+    return i16(c)
+
+def float_to_i16(x: float) -> i16:
+    return i16(x)
+[out]
+def bool_to_i16(b):
+    b :: bool
+    r0 :: int16
+L0:
+    r0 = extend b: builtins.bool to int16
+    return r0
+def str_to_i16(s):
+    s :: str
+    r0 :: object
+    r1 :: int16
+L0:
+    r0 = CPyLong_FromStr(s)
+    r1 = unbox(int16, r0)
+    return r1
+def C.__int__(self):
+    self :: __main__.C
+L0:
+    return 5
+def instance_to_i16(c):
+    c :: __main__.C
+    r0 :: int16
+L0:
+    r0 = c.__int__()
+    return r0
+def float_to_i16(x):
+    x :: float
+    r0 :: int
+    r1 :: native_int
+    r2, r3, r4 :: bit
+    r5 :: native_int
+    r6, r7 :: int16
+L0:
+    r0 = CPyTagged_FromFloat(x)
+    r1 = r0 & 1
+    r2 = r1 == 0
+    if r2 goto L1 else goto L4 :: bool
+L1:
+    r3 = r0 < 65536 :: signed
+    if r3 goto L2 else goto L4 :: bool
+L2:
+    r4 = r0 >= -65536 :: signed
+    if r4 goto L3 else goto L4 :: bool
+L3:
+    r5 = r0 >> 1
+    r6 = truncate r5: native_int to int16
+    r7 = r6
+    goto L5
+L4:
+    CPyInt16_Overflow()
+    unreachable
+L5:
+    return r7

From de7b9a58a4cf7a991c984e567ea8897451e9852c Mon Sep 17 00:00:00 2001
From: Jukka Lehtosalo <jukka.lehtosalo@iki.fi>
Date: Wed, 19 Apr 2023 17:51:12 +0100
Subject: [PATCH 12/22] Document i16

---
 mypyc/doc/float_operations.rst       |  6 ++++--
 mypyc/doc/int_operations.rst         | 25 ++++++++++++++++++++-----
 mypyc/doc/using_type_annotations.rst | 16 +++++++++-------
 3 files changed, 33 insertions(+), 14 deletions(-)

diff --git a/mypyc/doc/float_operations.rst b/mypyc/doc/float_operations.rst
index 915c184ae8e7..1705b7672409 100644
--- a/mypyc/doc/float_operations.rst
+++ b/mypyc/doc/float_operations.rst
@@ -14,6 +14,7 @@ Construction
 * ``float(x: int)``
 * ``float(x: i64)``
 * ``float(x: i32)``
+* ``float(x: i16)``
 * ``float(x: str)``
 * ``float(x: float)`` (no-op)
 
@@ -28,8 +29,9 @@ Functions
 ---------
 
 * ``int(f)``
-* ``i32(f)`` (convert to ``i32``)
-* ``i64(f)`` (convert to ``i64``)
+* ``i64(f)`` (convert to 64-bit signed integer)
+* ``i32(f)`` (convert to 32-bit signed integer)
+* ``i16(f)`` (convert to 16-bit signed integer)
 * ``abs(f)``
 * ``math.sin(f)``
 * ``math.cos(f)``
diff --git a/mypyc/doc/int_operations.rst b/mypyc/doc/int_operations.rst
index 058fdbd511dd..88a4a9d778a1 100644
--- a/mypyc/doc/int_operations.rst
+++ b/mypyc/doc/int_operations.rst
@@ -8,14 +8,16 @@ Mypyc supports these integer types:
 * ``int`` (arbitrary-precision integer)
 * ``i64`` (64-bit signed integer)
 * ``i32`` (32-bit signed integer)
+* ``i16`` (16-bit signed integer)
 
-``i64`` and ``i32`` are *native integer types* and must be imported
+``i64``, ``i32`` and ``i16`` are *native integer types* and must be imported
 from the ``mypy_extensions`` module. ``int`` corresponds to the Python
 ``int`` type, but uses a more efficient runtime representation (tagged
-pointer). Native integer types are value types. All integer types have
-optimized primitive operations, but the native integer types are more
-efficient than ``int``, since they don't require range or bounds
-checks.
+pointer). Native integer types are value types.
+
+All integer types have optimized primitive operations, but the native
+integer types are more efficient than ``int``, since they don't
+require range or bounds checks.
 
 Operations on integers that are listed here have fast, optimized
 implementations. Other integer operations use generic implementations
@@ -31,6 +33,7 @@ Construction
 * ``int(x: float)``
 * ``int(x: i64)``
 * ``int(x: i32)``
+* ``int(x: i16)``
 * ``int(x: str)``
 * ``int(x: str, base: int)``
 * ``int(x: int)`` (no-op)
@@ -40,6 +43,7 @@ Construction
 * ``i64(x: int)``
 * ``i64(x: float)``
 * ``i64(x: i32)``
+* ``i64(x: i16)``
 * ``i64(x: str)``
 * ``i64(x: str, base: int)``
 * ``i64(x: i64)`` (no-op)
@@ -49,10 +53,21 @@ Construction
 * ``i32(x: int)``
 * ``i32(x: float)``
 * ``i32(x: i64)`` (truncate)
+* ``i32(x: i16)``
 * ``i32(x: str)``
 * ``i32(x: str, base: int)``
 * ``i32(x: i32)`` (no-op)
 
+``i16`` type:
+
+* ``i16(x: int)``
+* ``i16(x: float)``
+* ``i16(x: i64)`` (truncate)
+* ``i16(x: i32)`` (truncate)
+* ``i16(x: str)``
+* ``i16(x: str, base: int)``
+* ``i16(x: i16)`` (no-op)
+
 Conversions from ``int`` to a native integer type raise
 ``OverflowError`` if the value is too large or small. Conversions from
 a wider native integer type to a narrower one truncate the value and never
diff --git a/mypyc/doc/using_type_annotations.rst b/mypyc/doc/using_type_annotations.rst
index 6c9277786751..f095a6717271 100644
--- a/mypyc/doc/using_type_annotations.rst
+++ b/mypyc/doc/using_type_annotations.rst
@@ -32,6 +32,7 @@ implementations:
 * ``int`` (:ref:`native operations <int-ops>`)
 * ``i64`` (:ref:`documentation <native-ints>`, :ref:`native operations <int-ops>`)
 * ``i32`` (:ref:`documentation <native-ints>`, :ref:`native operations <int-ops>`)
+* ``i16`` (:ref:`documentation <native-ints>`, :ref:`native operations <int-ops>`)
 * ``float`` (:ref:`native operations <float-ops>`)
 * ``bool`` (:ref:`native operations <bool-ops>`)
 * ``str`` (:ref:`native operations <str-ops>`)
@@ -342,13 +343,14 @@ Examples::
 Native integer types
 --------------------
 
-You can use the native integer types ``i64`` (64-bit signed integer)
-and ``i32`` (32-bit signed integer) if you know that integer values
-will always fit within fixed bounds. These types are faster than the
-arbitrary-precision ``int`` type, since they don't require overflow
-checks on operations. ``i32`` may also use less memory than ``int``
-values. The types are imported from the ``mypy_extensions`` module
-(installed via ``pip install mypy_extensions``).
+You can use the native integer types ``i64`` (64-bit signed integer),
+``i32`` (32-bit signed integer), and ``i16`` (16-bit signed integer)
+if you know that integer values will always fit within fixed
+bounds. These types are faster than the arbitrary-precision ``int``
+type, since they don't require overflow checks on operations. ``i32``
+and ``i16`` may also use less memory than ``int`` values. The types
+are imported from the ``mypy_extensions`` module (installed via ``pip
+install mypy_extensions``).
 
 Example::
 

From c5e67bb3d6870670127c9cce5867c4ca53494b44 Mon Sep 17 00:00:00 2001
From: Jukka Lehtosalo <jukka.lehtosalo@iki.fi>
Date: Wed, 19 Apr 2023 18:04:36 +0100
Subject: [PATCH 13/22] Support explicit conversion from i16 to i32/i64
 (extend)

---
 mypyc/irbuild/specialize.py      |  5 ++++-
 mypyc/test-data/irbuild-i32.test | 11 ++++++++++-
 mypyc/test-data/irbuild-i64.test | 11 ++++++++++-
 3 files changed, 24 insertions(+), 3 deletions(-)

diff --git a/mypyc/irbuild/specialize.py b/mypyc/irbuild/specialize.py
index c96e3a896b23..e6e7baea9c29 100644
--- a/mypyc/irbuild/specialize.py
+++ b/mypyc/irbuild/specialize.py
@@ -683,7 +683,7 @@ def translate_i64(builder: IRBuilder, expr: CallExpr, callee: RefExpr) -> Value
     arg_type = builder.node_type(arg)
     if is_int64_rprimitive(arg_type):
         return builder.accept(arg)
-    elif is_int32_rprimitive(arg_type):
+    elif is_int32_rprimitive(arg_type) or is_int16_rprimitive(arg_type):
         val = builder.accept(arg)
         return builder.add(Extend(val, int64_rprimitive, signed=True, line=expr.line))
     elif is_int_rprimitive(arg_type) or is_bool_rprimitive(arg_type):
@@ -703,6 +703,9 @@ def translate_i32(builder: IRBuilder, expr: CallExpr, callee: RefExpr) -> Value
     elif is_int64_rprimitive(arg_type):
         val = builder.accept(arg)
         return builder.add(Truncate(val, int32_rprimitive, line=expr.line))
+    elif is_int16_rprimitive(arg_type):
+        val = builder.accept(arg)
+        return builder.add(Extend(val, int32_rprimitive, signed=True, line=expr.line))
     elif is_int_rprimitive(arg_type) or is_bool_rprimitive(arg_type):
         val = builder.accept(arg)
         return builder.coerce(val, int32_rprimitive, expr.line)
diff --git a/mypyc/test-data/irbuild-i32.test b/mypyc/test-data/irbuild-i32.test
index 725e183657b1..4b69fa3a6bbb 100644
--- a/mypyc/test-data/irbuild-i32.test
+++ b/mypyc/test-data/irbuild-i32.test
@@ -413,7 +413,10 @@ L0:
     return 1
 
 [case testI32ExplicitConversionFromNativeInt]
-from mypy_extensions import i64, i32
+from mypy_extensions import i64, i32, i16
+
+def from_i16(x: i16) -> i32:
+    return i32(x)
 
 def from_i32(x: i32) -> i32:
     return i32(x)
@@ -421,6 +424,12 @@ def from_i32(x: i32) -> i32:
 def from_i64(x: i64) -> i32:
     return i32(x)
 [out]
+def from_i16(x):
+    x :: int16
+    r0 :: int32
+L0:
+    r0 = extend signed x: int16 to int32
+    return r0
 def from_i32(x):
     x :: int32
 L0:
diff --git a/mypyc/test-data/irbuild-i64.test b/mypyc/test-data/irbuild-i64.test
index a18171c41d57..38561178ddd0 100644
--- a/mypyc/test-data/irbuild-i64.test
+++ b/mypyc/test-data/irbuild-i64.test
@@ -1506,7 +1506,10 @@ L0:
     return 1
 
 [case testI64ExplicitConversionFromNativeInt]
-from mypy_extensions import i64, i32
+from mypy_extensions import i64, i32, i16
+
+def from_i16(x: i16) -> i64:
+    return i64(x)
 
 def from_i32(x: i32) -> i64:
     return i64(x)
@@ -1514,6 +1517,12 @@ def from_i32(x: i32) -> i64:
 def from_i64(x: i64) -> i64:
     return i64(x)
 [out]
+def from_i16(x):
+    x :: int16
+    r0 :: int64
+L0:
+    r0 = extend signed x: int16 to int64
+    return r0
 def from_i32(x):
     x :: int32
     r0 :: int64

From 09992a5efaf24b677525bccc5c9e6612154ef933 Mon Sep 17 00:00:00 2001
From: Jukka Lehtosalo <jukka.lehtosalo@iki.fi>
Date: Wed, 19 Apr 2023 18:36:41 +0100
Subject: [PATCH 14/22] Support i16 at runtime

---
 mypyc/codegen/emit.py        |  10 +-
 mypyc/ir/rtypes.py           |   2 +
 mypyc/lib-rt/int_ops.c       |  69 ++++++++
 mypyc/test-data/run-i16.test | 332 +++++++++++++++++++++++++++++++++++
 mypyc/test/test_run.py       |   1 +
 5 files changed, 413 insertions(+), 1 deletion(-)
 create mode 100644 mypyc/test-data/run-i16.test

diff --git a/mypyc/codegen/emit.py b/mypyc/codegen/emit.py
index 8114e0517219..39ceb45eb2b4 100644
--- a/mypyc/codegen/emit.py
+++ b/mypyc/codegen/emit.py
@@ -35,6 +35,7 @@
     is_dict_rprimitive,
     is_fixed_width_rtype,
     is_float_rprimitive,
+    is_int16_rprimitive,
     is_int32_rprimitive,
     is_int64_rprimitive,
     is_int_rprimitive,
@@ -912,6 +913,13 @@ def emit_unbox(
             self.emit_line(f"{dest} = CPyLong_AsInt32({src});")
             # TODO: Handle 'optional'
             # TODO: Handle 'failure'
+        elif is_int16_rprimitive(typ):
+            # Whether we are borrowing or not makes no difference.
+            if declare_dest:
+                self.emit_line(f"int16_t {dest};")
+            self.emit_line(f"{dest} = CPyLong_AsInt16({src});")
+            # TODO: Handle 'optional'
+            # TODO: Handle 'failure'
         elif is_float_rprimitive(typ):
             if declare_dest:
                 self.emit_line("double {};".format(dest))
@@ -1006,7 +1014,7 @@ def emit_box(
             self.emit_lines(f"{declaration}{dest} = Py_None;")
             if not can_borrow:
                 self.emit_inc_ref(dest, object_rprimitive)
-        elif is_int32_rprimitive(typ):
+        elif is_int32_rprimitive(typ) or is_int16_rprimitive(typ):
             self.emit_line(f"{declaration}{dest} = PyLong_FromLong({src});")
         elif is_int64_rprimitive(typ):
             self.emit_line(f"{declaration}{dest} = PyLong_FromLongLong({src});")
diff --git a/mypyc/ir/rtypes.py b/mypyc/ir/rtypes.py
index 41456fbd7589..61f83c9c041e 100644
--- a/mypyc/ir/rtypes.py
+++ b/mypyc/ir/rtypes.py
@@ -550,6 +550,8 @@ def visit_rprimitive(self, t: RPrimitive) -> str:
             return "8"  # "8 byte integer"
         elif t._ctype == "int32_t":
             return "4"  # "4 byte integer"
+        elif t._ctype == "int16_t":
+            return "2"  # "2 byte integer"
         elif t._ctype == "double":
             return "F"
         assert not t.is_unboxed, f"{t} unexpected unboxed type"
diff --git a/mypyc/lib-rt/int_ops.c b/mypyc/lib-rt/int_ops.c
index 843d9b0d2230..56720d1992e8 100644
--- a/mypyc/lib-rt/int_ops.c
+++ b/mypyc/lib-rt/int_ops.c
@@ -641,6 +641,75 @@ void CPyInt32_Overflow() {
     PyErr_SetString(PyExc_OverflowError, "int too large to convert to i32");
 }
 
+int16_t CPyLong_AsInt16(PyObject *o) {
+    if (likely(PyLong_Check(o))) {
+        PyLongObject *lobj = (PyLongObject *)o;
+        Py_ssize_t size = lobj->ob_base.ob_size;
+        if (likely(size == 1)) {
+            // Fast path
+            digit x = lobj->ob_digit[0];
+            if (x < 0x8000)
+                return x;
+        } else if (likely(size == 0)) {
+            return 0;
+        }
+    }
+    // Slow path
+    int overflow;
+    long result = PyLong_AsLongAndOverflow(o, &overflow);
+    if (result > 0x7fff || result < -0x8000) {
+        overflow = 1;
+        result = -1;
+    }
+    if (result == -1) {
+        if (PyErr_Occurred()) {
+            return CPY_LL_INT_ERROR;
+        } else if (overflow) {
+            PyErr_SetString(PyExc_OverflowError, "int too large to convert to i16");
+            return CPY_LL_INT_ERROR;
+        }
+    }
+    return result;
+}
+
+int16_t CPyInt16_Divide(int16_t x, int16_t y) {
+    if (y == 0) {
+        PyErr_SetString(PyExc_ZeroDivisionError, "integer division or modulo by zero");
+        return CPY_LL_INT_ERROR;
+    }
+    if (y == -1 && x == INT16_MIN) {
+        PyErr_SetString(PyExc_OverflowError, "integer division overflow");
+        return CPY_LL_INT_ERROR;
+    }
+    int16_t d = x / y;
+    // Adjust for Python semantics
+    if (((x < 0) != (y < 0)) && d * y != x) {
+        d--;
+    }
+    return d;
+}
+
+int16_t CPyInt16_Remainder(int16_t x, int16_t y) {
+    if (y == 0) {
+        PyErr_SetString(PyExc_ZeroDivisionError, "integer division or modulo by zero");
+        return CPY_LL_INT_ERROR;
+    }
+    // Edge case: avoid core dump
+    if (y == -1 && x == INT16_MIN) {
+        return 0;
+    }
+    int16_t d = x % y;
+    // Adjust for Python semantics
+    if (((x < 0) != (y < 0)) && d != 0) {
+        d += y;
+    }
+    return d;
+}
+
+void CPyInt16_Overflow() {
+    PyErr_SetString(PyExc_OverflowError, "int too large to convert to i16");
+}
+
 double CPyTagged_TrueDivide(CPyTagged x, CPyTagged y) {
     if (unlikely(y == 0)) {
         PyErr_SetString(PyExc_ZeroDivisionError, "division by zero");
diff --git a/mypyc/test-data/run-i16.test b/mypyc/test-data/run-i16.test
new file mode 100644
index 000000000000..39406801fbf3
--- /dev/null
+++ b/mypyc/test-data/run-i16.test
@@ -0,0 +1,332 @@
+[case testI16BasicOps]
+from typing import Any, Tuple
+
+from mypy_extensions import i16, i32, i64
+
+from testutil import assertRaises
+
+def test_box_and_unbox() -> None:
+    values = (list(range(-2**15, -2**15 + 100)) +
+              list(range(-1000, 1000)) +
+              list(range(2**15 - 100, 2**15)))
+    for i in values:
+        o: Any = i
+        x: i16 = o
+        o2: Any = x
+        assert o == o2
+        assert x == i
+    with assertRaises(OverflowError, "int too large to convert to i16"):
+        o = 2**15
+        x2: i16 = o
+    with assertRaises(OverflowError, "int too large to convert to i16"):
+        o = -2**15 - 1
+        x3: i16 = o
+
+def div_by_7(x: i16) -> i16:
+    return x // 7
+def div_by_neg_7(x: i16) -> i16:
+    return x // -7
+
+def div(x: i16, y: i16) -> i16:
+    return x // y
+
+def test_divide_by_constant() -> None:
+    for i in range(-1000, 1000):
+        assert div_by_7(i) == i // 7
+    for i in range(-2**15, -2**15 + 1000):
+        assert div_by_7(i) == i // 7
+    for i in range(2**15 - 1000, 2**15):
+        assert div_by_7(i) == i // 7
+
+def test_divide_by_negative_constant() -> None:
+    for i in range(-1000, 1000):
+        assert div_by_neg_7(i) == i // -7
+    for i in range(-2**15, -2**15 + 1000):
+        assert div_by_neg_7(i) == i // -7
+    for i in range(2**15 - 1000, 2**15):
+        assert div_by_neg_7(i) == i // -7
+
+def test_divide_by_variable() -> None:
+    values = (list(range(-50, 50)) +
+              list(range(-2**15, -2**15 + 10)) +
+              list(range(2**15 - 10, 2**15)))
+    for x in values:
+        for y in values:
+            if y != 0:
+                if x // y == 2**15:
+                    with assertRaises(OverflowError, "integer division overflow"):
+                        div(x, y)
+                else:
+                    assert div(x, y) == x // y
+            else:
+                with assertRaises(ZeroDivisionError, "integer division or modulo by zero"):
+                    div(x, y)
+
+def mod_by_7(x: i16) -> i16:
+    return x % 7
+
+def mod_by_neg_7(x: i16) -> i16:
+    return x // -7
+
+def mod(x: i16, y: i16) -> i16:
+    return x % y
+
+def test_mod_by_constant() -> None:
+    for i in range(-1000, 1000):
+        assert mod_by_7(i) == i % 7
+    for i in range(-2**15, -2**15 + 1000):
+        assert mod_by_7(i) == i % 7
+    for i in range(2**15 - 1000, 2**15):
+        assert mod_by_7(i) == i % 7
+
+def test_mod_by_negative_constant() -> None:
+    for i in range(-1000, 1000):
+        assert mod_by_neg_7(i) == i // -7
+    for i in range(-2**15, -2**15 + 1000):
+        assert mod_by_neg_7(i) == i // -7
+    for i in range(2**15 - 1000, 2**15):
+        assert mod_by_neg_7(i) == i // -7
+
+def test_mod_by_variable() -> None:
+    values = (list(range(-50, 50)) +
+              list(range(-2**15, -2**15 + 10)) +
+              list(range(2**15 - 10, 2**15)))
+    for x in values:
+        for y in values:
+            if y != 0:
+                assert mod(x, y) == x % y
+            else:
+                with assertRaises(ZeroDivisionError, "integer division or modulo by zero"):
+                    mod(x, y)
+
+def test_simple_arithmetic_ops() -> None:
+    zero: i16 = int()
+    one: i16 = zero + 1
+    two: i16 = one + 1
+    neg_one: i16 = -one
+    assert one + one == 2
+    assert one + two == 3
+    assert one + neg_one == 0
+    assert one - one == 0
+    assert one - two == -1
+    assert one * one == 1
+    assert one * two == 2
+    assert two * two == 4
+    assert two * neg_one == -2
+    assert neg_one * one == -1
+    assert neg_one * neg_one == 1
+    assert two * 0 == 0
+    assert 0 * two == 0
+    assert -one == -1
+    assert -two == -2
+    assert -neg_one == 1
+    assert -zero == 0
+
+def test_bitwise_ops() -> None:
+    x: i16 = 13855 + int()
+    y: i16 = 367 + int()
+    z: i16 = -11091 + int()
+    zero: i16 = int()
+    one: i16 = zero + 1
+    two: i16 = zero + 2
+    neg_one: i16 = -one
+
+    assert x & y == 15
+    assert x & z == 5133
+    assert z & z == z
+    assert x & zero == 0
+
+    assert x | y == 14207
+    assert x | z == -2369
+    assert z | z == z
+    assert x | 0 == x
+
+    assert x ^ y == 14192
+    assert x ^ z == -7502
+    assert z ^ z == 0
+    assert z ^ 0 == z
+
+    assert x << one == 27710
+    assert x << two == -10116
+    assert z << two == 21172
+    assert z << 0 == z
+
+    assert x >> one == 6927
+    assert x >> two == 3463
+    assert z >> two == -2773
+    assert z >> 0 == z
+
+    assert ~x == -13856
+    assert ~z == 11090
+    assert ~zero == -1
+    assert ~neg_one == 0
+
+def eq(x: i16, y: i16) -> bool:
+    return x == y
+
+def test_eq() -> None:
+    assert eq(int(), int())
+    assert eq(5 + int(), 5 + int())
+    assert eq(-5 + int(), -5 + int())
+    assert not eq(int(), 1 + int())
+    assert not eq(5 + int(), 6 + int())
+    assert not eq(-5 + int(), -6 + int())
+    assert not eq(-5 + int(), 5 + int())
+
+def test_comparisons() -> None:
+    one: i16 = 1 + int()
+    one2: i16 = 1 + int()
+    two: i16 = 2 + int()
+    assert one < two
+    assert not (one < one2)
+    assert not (two < one)
+    assert two > one
+    assert not (one > one2)
+    assert not (one > two)
+    assert one <= two
+    assert one <= one2
+    assert not (two <= one)
+    assert two >= one
+    assert one >= one2
+    assert not (one >= two)
+    assert one == one2
+    assert not (one == two)
+    assert one != two
+    assert not (one != one2)
+
+def test_mixed_comparisons() -> None:
+    i16_3: i16 = int() + 3
+    int_5 = int() + 5
+    assert i16_3 < int_5
+    assert int_5 > i16_3
+    b = i16_3 > int_5
+    assert not b
+
+    int_largest = int() + (1 << 15) - 1
+    assert int_largest > i16_3
+    int_smallest = int() - (1 << 15)
+    assert i16_3 > int_smallest
+
+    int_too_big = int() + (1 << 15)
+    int_too_small = int() - (1 << 15) - 1
+    with assertRaises(OverflowError):
+        assert i16_3 < int_too_big
+    with assertRaises(OverflowError):
+        assert int_too_big < i16_3
+    with assertRaises(OverflowError):
+        assert i16_3 > int_too_small
+    with assertRaises(OverflowError):
+        assert int_too_small < i16_3
+
+def test_mixed_arithmetic_and_bitwise_ops() -> None:
+    i16_3: i16 = int() + 3
+    int_5 = int() + 5
+    assert i16_3 + int_5 == 8
+    assert int_5 - i16_3 == 2
+    assert i16_3 << int_5 == 96
+    assert int_5 << i16_3  == 40
+    assert i16_3 ^ int_5 == 6
+    assert int_5 | i16_3  == 7
+
+    int_largest = int() + (1 << 15) - 1
+    assert int_largest - i16_3 == 32764
+    int_smallest = int() - (1 << 15)
+    assert int_smallest + i16_3 == -32765
+
+    int_too_big = int() + (1 << 15)
+    int_too_small = int() - (1 << 15) - 1
+    with assertRaises(OverflowError):
+        assert i16_3 & int_too_big
+    with assertRaises(OverflowError):
+        assert int_too_small & i16_3
+
+def test_coerce_to_and_from_int() -> None:
+    for shift in range(0, 16):
+        for sign in 1, -1:
+            for delta in range(-5, 5):
+                n = sign * (1 << shift) + delta
+                if -(1 << 15) <= n < (1 << 15):
+                    x: i16 = n
+                    m: int = x
+                    assert m == n
+
+def test_explicit_conversion_to_i16() -> None:
+    x = i16(5)
+    assert x == 5
+    y = int() - 113
+    x = i16(y)
+    assert x == -113
+    n64: i64 = 1733
+    x = i16(n64)
+    assert x == 1733
+    n32 = -1733
+    x = i16(n32)
+    assert x == -1733
+    z = i16(x)
+    assert z == -1733
+
+def test_explicit_conversion_overflow() -> None:
+    max_i16 = int() + 2**15 - 1
+    x = i16(max_i16)
+    assert x == 2**15 - 1
+    assert int(x) == max_i16
+
+    min_i16 = int() - 2**15
+    y = i16(min_i16)
+    assert y == -2**15
+    assert int(y) == min_i16
+
+    too_big = int() + 2**15
+    with assertRaises(OverflowError):
+        x = i16(too_big)
+
+    too_small = int() - 2**15 - 1
+    with assertRaises(OverflowError):
+        x = i16(too_small)
+
+def test_i16_from_large_small_literal() -> None:
+    x = i16(2**15 - 1)
+    assert x == 2**15 - 1
+    x = i16(-2**15)
+    assert x == -2**15
+
+def test_i16_truncate_from_i64() -> None:
+    large = i64(2**32 + 65536 + 157 + int())
+    x = i16(large)
+    assert x == 157
+    small = i64(-2**32 - 65536 - 157 + int())
+    x = i16(small)
+    assert x == -157
+    large2 = i64(2**15 + int())
+    x = i16(large2)
+    assert x == -2**15
+    small2 = i64(-2**15 - 1 - int())
+    x = i16(small2)
+    assert x == 2**15 - 1
+
+def from_float(x: float) -> i16:
+    return i16(x)
+
+def test_explicit_conversion_from_float() -> None:
+    assert from_float(0.0) == 0
+    assert from_float(1.456) == 1
+    assert from_float(-1234.567) == -1234
+    assert from_float(2**15 - 1) == 2**15 - 1
+    assert from_float(-2**15) == -2**15
+    # The error message could be better, but this is acceptable
+    with assertRaises(OverflowError, "int too large to convert to i16"):
+        assert from_float(float(2**15))
+    with assertRaises(OverflowError, "int too large to convert to i16"):
+        # One ulp below the lowest valid i64 value
+        from_float(float(-2**15 - 1))
+
+def test_tuple_i16() -> None:
+    a: i16 = 1
+    b: i16 = 2
+    t = (a, b)
+    a, b = t
+    assert a == 1
+    assert b == 2
+    x: Any = t
+    tt: Tuple[i16, i16] = x
+    assert tt == (1, 2)
diff --git a/mypyc/test/test_run.py b/mypyc/test/test_run.py
index dc054ac9002f..a4071b9c3de5 100644
--- a/mypyc/test/test_run.py
+++ b/mypyc/test/test_run.py
@@ -41,6 +41,7 @@
     "run-integers.test",
     "run-i64.test",
     "run-i32.test",
+    "run-i16.test",
     "run-floats.test",
     "run-math.test",
     "run-bools.test",

From d8259117248896e1646f629976ee37765c90285c Mon Sep 17 00:00:00 2001
From: Jukka Lehtosalo <jukka.lehtosalo@iki.fi>
Date: Wed, 19 Apr 2023 18:48:36 +0100
Subject: [PATCH 15/22] More runtime tests

---
 mypyc/test-data/run-i32.test | 6 +++++-
 mypyc/test-data/run-i64.test | 6 +++++-
 2 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/mypyc/test-data/run-i32.test b/mypyc/test-data/run-i32.test
index af99fb79d35e..5f43a5ba4c6f 100644
--- a/mypyc/test-data/run-i32.test
+++ b/mypyc/test-data/run-i32.test
@@ -1,7 +1,7 @@
 [case testI32BasicOps]
 from typing import Any, Tuple
 
-from mypy_extensions import i32, i64
+from mypy_extensions import i16, i32, i64
 
 from testutil import assertRaises
 
@@ -264,6 +264,10 @@ def test_explicit_conversion_to_i32() -> None:
     assert x == -1733
     z = i32(x)
     assert z == -1733
+    a: i16 = int() + 19764
+    assert i32(a) == 19764
+    a = int() - 1
+    assert i32(a) == -1
 
 def test_explicit_conversion_overflow() -> None:
     max_i32 = int() + 2**31 - 1
diff --git a/mypyc/test-data/run-i64.test b/mypyc/test-data/run-i64.test
index bcde39fed5ff..e0941a2f76be 100644
--- a/mypyc/test-data/run-i64.test
+++ b/mypyc/test-data/run-i64.test
@@ -1,7 +1,7 @@
 [case testI64BasicOps]
 from typing import List, Any, Tuple, Union
 
-from mypy_extensions import i64, i32
+from mypy_extensions import i64, i32, i16
 
 from testutil import assertRaises
 
@@ -282,6 +282,10 @@ def test_explicit_conversion_to_i64() -> None:
     assert x == -1733
     z = i64(x)
     assert z == -1733
+    a: i16 = int() + 19764
+    assert i64(a) == 19764
+    a = int() - 1
+    assert i64(a) == -1
 
 def test_explicit_conversion_overflow() -> None:
     max_i64 = int() + 2**63 - 1

From 80f39320531ca1badafc923406ed837222bb28f4 Mon Sep 17 00:00:00 2001
From: Jukka Lehtosalo <jukka.lehtosalo@iki.fi>
Date: Wed, 19 Apr 2023 18:53:59 +0100
Subject: [PATCH 16/22] Some test updates

---
 mypyc/test-data/run-i16.test | 8 +++++++-
 mypyc/test-data/run-i32.test | 2 +-
 2 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/mypyc/test-data/run-i16.test b/mypyc/test-data/run-i16.test
index 39406801fbf3..fbb0c15220bc 100644
--- a/mypyc/test-data/run-i16.test
+++ b/mypyc/test-data/run-i16.test
@@ -259,7 +259,7 @@ def test_explicit_conversion_to_i16() -> None:
     n64: i64 = 1733
     x = i16(n64)
     assert x == 1733
-    n32 = -1733
+    n32: i32 = -1733
     x = i16(n32)
     assert x == -1733
     z = i16(x)
@@ -304,6 +304,12 @@ def test_i16_truncate_from_i64() -> None:
     x = i16(small2)
     assert x == 2**15 - 1
 
+def test_i16_truncate_from_i32() -> None:
+    large = i32(2**16 + 2**30 + 5 + int())
+    assert i16(large) == 5
+    small = i32(-2**16 - 2**30 - 1 + int())
+    assert i16(small) == -1
+
 def from_float(x: float) -> i16:
     return i16(x)
 
diff --git a/mypyc/test-data/run-i32.test b/mypyc/test-data/run-i32.test
index 5f43a5ba4c6f..bb1fa43bb9fd 100644
--- a/mypyc/test-data/run-i32.test
+++ b/mypyc/test-data/run-i32.test
@@ -259,7 +259,7 @@ def test_explicit_conversion_to_i32() -> None:
     n64: i64 = 1733
     x = i32(n64)
     assert x == 1733
-    n32 = -1733
+    n32: i32 = -1733
     x = i32(n32)
     assert x == -1733
     z = i32(x)

From e470524e48108a0ca7b36108eec9245f4e665257 Mon Sep 17 00:00:00 2001
From: Jukka Lehtosalo <jukka.lehtosalo@iki.fi>
Date: Wed, 19 Apr 2023 18:56:49 +0100
Subject: [PATCH 17/22] Add missing header declarations

---
 mypyc/lib-rt/CPy.h | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/mypyc/lib-rt/CPy.h b/mypyc/lib-rt/CPy.h
index 30d93be60989..689526e0e826 100644
--- a/mypyc/lib-rt/CPy.h
+++ b/mypyc/lib-rt/CPy.h
@@ -155,6 +155,10 @@ int32_t CPyLong_AsInt32(PyObject *o);
 int32_t CPyInt32_Divide(int32_t x, int32_t y);
 int32_t CPyInt32_Remainder(int32_t x, int32_t y);
 void CPyInt32_Overflow(void);
+int16_t CPyLong_AsInt16(PyObject *o);
+int16_t CPyInt16_Divide(int16_t x, int16_t y);
+int16_t CPyInt16_Remainder(int16_t x, int16_t y);
+void CPyInt16_Overflow(void);
 double CPyTagged_TrueDivide(CPyTagged x, CPyTagged y);
 
 static inline int CPyTagged_CheckLong(CPyTagged x) {

From 9ac00f05fef91934273e48e6700b145f90a07545 Mon Sep 17 00:00:00 2001
From: Jukka Lehtosalo <jukka.lehtosalo@iki.fi>
Date: Wed, 19 Apr 2023 18:57:26 +0100
Subject: [PATCH 18/22] Black

---
 mypyc/primitives/int_ops.py | 7 ++++++-
 mypyc/test/test_typeops.py  | 1 -
 2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/mypyc/primitives/int_ops.py b/mypyc/primitives/int_ops.py
index 64c6d7bdc859..ef79bbc51ce6 100644
--- a/mypyc/primitives/int_ops.py
+++ b/mypyc/primitives/int_ops.py
@@ -38,7 +38,12 @@
 
 # Constructors for builtins.int and native int types have the same behavior. In
 # interpreted mode, native int types are just aliases to 'int'.
-for int_name in ("builtins.int", "mypy_extensions.i64", "mypy_extensions.i32", "mypy_extensions.i16"):
+for int_name in (
+    "builtins.int",
+    "mypy_extensions.i64",
+    "mypy_extensions.i32",
+    "mypy_extensions.i16",
+):
     # These int constructors produce object_rprimitives that then need to be unboxed
     # I guess unboxing ourselves would save a check and branch though?
 
diff --git a/mypyc/test/test_typeops.py b/mypyc/test/test_typeops.py
index 8bf238ef7733..ff2c05ad983e 100644
--- a/mypyc/test/test_typeops.py
+++ b/mypyc/test/test_typeops.py
@@ -19,7 +19,6 @@
 from mypyc.rt_subtype import is_runtime_subtype
 from mypyc.subtype import is_subtype
 
-
 native_int_types = [int64_rprimitive, int32_rprimitive, int16_rprimitive]
 
 

From e1446799280bdd9339620e0e2cf2adc3514e86b4 Mon Sep 17 00:00:00 2001
From: Jukka Lehtosalo <jukka.lehtosalo@iki.fi>
Date: Sun, 18 Jun 2023 18:29:06 +0100
Subject: [PATCH 19/22] We can't handle optional cases in unbox for types with
 overlapping error values

---
 mypyc/codegen/emit.py | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/mypyc/codegen/emit.py b/mypyc/codegen/emit.py
index 39ceb45eb2b4..e5ade32a3745 100644
--- a/mypyc/codegen/emit.py
+++ b/mypyc/codegen/emit.py
@@ -901,26 +901,27 @@ def emit_unbox(
             self.emit_line(f"    {dest} = 1;")
         elif is_int64_rprimitive(typ):
             # Whether we are borrowing or not makes no difference.
+            assert not optional  # Not supported for overlapping error values
             if declare_dest:
                 self.emit_line(f"int64_t {dest};")
             self.emit_line(f"{dest} = CPyLong_AsInt64({src});")
-            # TODO: Handle 'optional'
             # TODO: Handle 'failure'
         elif is_int32_rprimitive(typ):
             # Whether we are borrowing or not makes no difference.
+            assert not optional  # Not supported for overlapping error values
             if declare_dest:
                 self.emit_line(f"int32_t {dest};")
             self.emit_line(f"{dest} = CPyLong_AsInt32({src});")
-            # TODO: Handle 'optional'
             # TODO: Handle 'failure'
         elif is_int16_rprimitive(typ):
             # Whether we are borrowing or not makes no difference.
+            assert not optional  # Not supported for overlapping error values
             if declare_dest:
                 self.emit_line(f"int16_t {dest};")
             self.emit_line(f"{dest} = CPyLong_AsInt16({src});")
-            # TODO: Handle 'optional'
             # TODO: Handle 'failure'
         elif is_float_rprimitive(typ):
+            assert not optional  # Not supported for overlapping error values
             if declare_dest:
                 self.emit_line("double {};".format(dest))
             # TODO: Don't use __float__ and __index__
@@ -928,7 +929,6 @@ def emit_unbox(
             self.emit_lines(
                 f"if ({dest} == -1.0 && PyErr_Occurred()) {{", f"{dest} = -113.0;", "}"
             )
-            # TODO: Handle 'optional'
             # TODO: Handle 'failure'
         elif isinstance(typ, RTuple):
             self.declare_tuple_struct(typ)

From 8cf1a9289edda9e6b15f90f2ae024a205966d909 Mon Sep 17 00:00:00 2001
From: Jukka Lehtosalo <jukka.lehtosalo@iki.fi>
Date: Sun, 18 Jun 2023 19:13:28 +0100
Subject: [PATCH 20/22] Fix unbox failure handling for all types with
 overlapping error values

---
 mypyc/codegen/emit.py        | 20 +++++++++++++++-----
 mypyc/test-data/run-i64.test | 13 +++++++++++++
 2 files changed, 28 insertions(+), 5 deletions(-)

diff --git a/mypyc/codegen/emit.py b/mypyc/codegen/emit.py
index e5ade32a3745..cc6e7586e104 100644
--- a/mypyc/codegen/emit.py
+++ b/mypyc/codegen/emit.py
@@ -905,21 +905,24 @@ def emit_unbox(
             if declare_dest:
                 self.emit_line(f"int64_t {dest};")
             self.emit_line(f"{dest} = CPyLong_AsInt64({src});")
-            # TODO: Handle 'failure'
+            if not isinstance(error, AssignHandler):
+                self.emit_unbox_failure_with_overlapping_error_value(dest, typ, failure)
         elif is_int32_rprimitive(typ):
             # Whether we are borrowing or not makes no difference.
             assert not optional  # Not supported for overlapping error values
             if declare_dest:
                 self.emit_line(f"int32_t {dest};")
             self.emit_line(f"{dest} = CPyLong_AsInt32({src});")
-            # TODO: Handle 'failure'
+            if not isinstance(error, AssignHandler):
+                self.emit_unbox_failure_with_overlapping_error_value(dest, typ, failure)
         elif is_int16_rprimitive(typ):
             # Whether we are borrowing or not makes no difference.
             assert not optional  # Not supported for overlapping error values
             if declare_dest:
                 self.emit_line(f"int16_t {dest};")
             self.emit_line(f"{dest} = CPyLong_AsInt16({src});")
-            # TODO: Handle 'failure'
+            if not isinstance(error, AssignHandler):
+                self.emit_unbox_failure_with_overlapping_error_value(dest, typ, failure)
         elif is_float_rprimitive(typ):
             assert not optional  # Not supported for overlapping error values
             if declare_dest:
@@ -927,9 +930,10 @@ def emit_unbox(
             # TODO: Don't use __float__ and __index__
             self.emit_line(f"{dest} = PyFloat_AsDouble({src});")
             self.emit_lines(
-                f"if ({dest} == -1.0 && PyErr_Occurred()) {{", f"{dest} = -113.0;", "}"
+                f"if ({dest} == -1.0 && PyErr_Occurred()) {{",
+                failure,
+                "}"
             )
-            # TODO: Handle 'failure'
         elif isinstance(typ, RTuple):
             self.declare_tuple_struct(typ)
             if declare_dest:
@@ -1145,6 +1149,12 @@ def _emit_traceback(
         if DEBUG_ERRORS:
             self.emit_line('assert(PyErr_Occurred() != NULL && "failure w/o err!");')
 
+    def emit_unbox_failure_with_overlapping_error_value(
+            self, dest: str, typ: RType, failure: str) -> None:
+        self.emit_line(f"if ({dest} == {self.c_error_value(typ)} && PyErr_Occurred()) {{")
+        self.emit_line(failure)
+        self.emit_line("}")
+
 
 def c_array_initializer(components: list[str], *, indented: bool = False) -> str:
     """Construct an initializer for a C array variable.
diff --git a/mypyc/test-data/run-i64.test b/mypyc/test-data/run-i64.test
index e0941a2f76be..1a82ac3e2dd1 100644
--- a/mypyc/test-data/run-i64.test
+++ b/mypyc/test-data/run-i64.test
@@ -1504,3 +1504,16 @@ def test_implement_trait_attribute() -> None:
     a.y = 8
     assert a.x == 7
     assert a.y == 8
+
+class DunderErr:
+    def __contains__(self, i: i64) -> bool:
+        raise IndexError()
+
+def test_dunder_arg_check() -> None:
+    o: Any = DunderErr()
+    with assertRaises(TypeError):
+        'x' in o
+    with assertRaises(TypeError):
+        2**63 in o
+    with assertRaises(IndexError):
+        1 in o

From 90cc72ac31b004b4eb251f8f8fff89534505a711 Mon Sep 17 00:00:00 2001
From: Jukka Lehtosalo <jukka.lehtosalo@iki.fi>
Date: Sun, 18 Jun 2023 19:15:04 +0100
Subject: [PATCH 21/22] Black

---
 mypyc/codegen/emit.py | 9 +++------
 1 file changed, 3 insertions(+), 6 deletions(-)

diff --git a/mypyc/codegen/emit.py b/mypyc/codegen/emit.py
index cc6e7586e104..8f0e0bc65edc 100644
--- a/mypyc/codegen/emit.py
+++ b/mypyc/codegen/emit.py
@@ -929,11 +929,7 @@ def emit_unbox(
                 self.emit_line("double {};".format(dest))
             # TODO: Don't use __float__ and __index__
             self.emit_line(f"{dest} = PyFloat_AsDouble({src});")
-            self.emit_lines(
-                f"if ({dest} == -1.0 && PyErr_Occurred()) {{",
-                failure,
-                "}"
-            )
+            self.emit_lines(f"if ({dest} == -1.0 && PyErr_Occurred()) {{", failure, "}")
         elif isinstance(typ, RTuple):
             self.declare_tuple_struct(typ)
             if declare_dest:
@@ -1150,7 +1146,8 @@ def _emit_traceback(
             self.emit_line('assert(PyErr_Occurred() != NULL && "failure w/o err!");')
 
     def emit_unbox_failure_with_overlapping_error_value(
-            self, dest: str, typ: RType, failure: str) -> None:
+        self, dest: str, typ: RType, failure: str
+    ) -> None:
         self.emit_line(f"if ({dest} == {self.c_error_value(typ)} && PyErr_Occurred()) {{")
         self.emit_line(failure)
         self.emit_line("}")

From 05c459eee95c29be21ecdbb6d52177f114798d18 Mon Sep 17 00:00:00 2001
From: "pre-commit-ci[bot]"
 <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Date: Mon, 19 Jun 2023 09:36:30 +0000
Subject: [PATCH 22/22] [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci
---
 mypy/types.py | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/mypy/types.py b/mypy/types.py
index 4eff4a82a233..6fe6fbada52e 100644
--- a/mypy/types.py
+++ b/mypy/types.py
@@ -150,9 +150,11 @@
 )
 
 # Mypyc fixed-width native int types (compatible with builtins.int)
-MYPYC_NATIVE_INT_NAMES: Final = ("mypy_extensions.i64",
-                                 "mypy_extensions.i32",
-                                 "mypy_extensions.i16")
+MYPYC_NATIVE_INT_NAMES: Final = (
+    "mypy_extensions.i64",
+    "mypy_extensions.i32",
+    "mypy_extensions.i16",
+)
 
 DATACLASS_TRANSFORM_NAMES: Final = (
     "typing.dataclass_transform",