From d1e0bf67578f2d0b19bcc171838395c500458ada Mon Sep 17 00:00:00 2001
From: Jukka Lehtosalo <jukka.lehtosalo@iki.fi>
Date: Thu, 8 Jan 2026 17:03:54 +0000
Subject: [PATCH 1/3] [mypyc] Remove bytearray code paths from bytes primitives

These are now unreachable, since bytearray isn't compatible with
bytes. We can add bytearray-specific primitives later.
---
 mypyc/lib-rt/bytes_ops.c | 38 +++++++++++---------------------------
 1 file changed, 11 insertions(+), 27 deletions(-)

diff --git a/mypyc/lib-rt/bytes_ops.c b/mypyc/lib-rt/bytes_ops.c
index a9b694116866..2a03e32a013a 100644
--- a/mypyc/lib-rt/bytes_ops.c
+++ b/mypyc/lib-rt/bytes_ops.c
@@ -50,21 +50,14 @@ CPyTagged CPyBytes_GetItem(PyObject *o, CPyTagged index) {
 }
 
 PyObject *CPyBytes_Concat(PyObject *a, PyObject *b) {
-    if (PyBytes_Check(a) && PyBytes_Check(b)) {
-        Py_ssize_t a_len = ((PyVarObject *)a)->ob_size;
-        Py_ssize_t b_len = ((PyVarObject *)b)->ob_size;
-        PyBytesObject *ret = (PyBytesObject *)PyBytes_FromStringAndSize(NULL, a_len + b_len);
-        if (ret != NULL) {
-            memcpy(ret->ob_sval, ((PyBytesObject *)a)->ob_sval, a_len);
-            memcpy(ret->ob_sval + a_len, ((PyBytesObject *)b)->ob_sval, b_len);
-        }
-        return (PyObject *)ret;
-    } else if (PyByteArray_Check(a)) {
-        return PyByteArray_Concat(a, b);
-    } else {
-        PyBytes_Concat(&a, b);
-        return a;
+    Py_ssize_t a_len = ((PyVarObject *)a)->ob_size;
+    Py_ssize_t b_len = ((PyVarObject *)b)->ob_size;
+    PyBytesObject *ret = (PyBytesObject *)PyBytes_FromStringAndSize(NULL, a_len + b_len);
+    if (ret != NULL) {
+        memcpy(ret->ob_sval, ((PyBytesObject *)a)->ob_sval, a_len);
+        memcpy(ret->ob_sval + a_len, ((PyBytesObject *)b)->ob_sval, b_len);
     }
+    return (PyObject *)ret;
 }
 
 static inline Py_ssize_t Clamp(Py_ssize_t a, Py_ssize_t b, Py_ssize_t c) {
@@ -72,8 +65,7 @@ static inline Py_ssize_t Clamp(Py_ssize_t a, Py_ssize_t b, Py_ssize_t c) {
 }
 
 PyObject *CPyBytes_GetSlice(PyObject *obj, CPyTagged start, CPyTagged end) {
-    if ((PyBytes_Check(obj) || PyByteArray_Check(obj))
-            && CPyTagged_CheckShort(start) && CPyTagged_CheckShort(end)) {
+    if (CPyTagged_CheckShort(start) && CPyTagged_CheckShort(end)) {
         Py_ssize_t startn = CPyTagged_ShortAsSsize_t(start);
         Py_ssize_t endn = CPyTagged_ShortAsSsize_t(end);
         Py_ssize_t len = ((PyVarObject *)obj)->ob_size;
@@ -141,18 +133,10 @@ PyObject *CPyBytes_Build(Py_ssize_t len, ...) {
     return (PyObject *)ret;
 }
 
-
 CPyTagged CPyBytes_Ord(PyObject *obj) {
-    if (PyBytes_Check(obj)) {
-        Py_ssize_t s = PyBytes_GET_SIZE(obj);
-        if (s == 1) {
-            return (unsigned char)(PyBytes_AS_STRING(obj)[0]) << 1;
-        }
-    } else if (PyByteArray_Check(obj)) {
-        Py_ssize_t s = PyByteArray_GET_SIZE(obj);
-        if (s == 1) {
-            return (unsigned char)(PyByteArray_AS_STRING(obj)[0]) << 1;
-        }
+    Py_ssize_t s = PyBytes_GET_SIZE(obj);
+    if (s == 1) {
+        return (unsigned char)(PyBytes_AS_STRING(obj)[0]) << 1;
     }
     PyErr_SetString(PyExc_TypeError, "ord() expects a character");
     return CPY_INT_TAG;

From 343eb2da2d4f3297975bef61cd05a5bfc9adb641 Mon Sep 17 00:00:00 2001
From: Jukka Lehtosalo <jukka.lehtosalo@iki.fi>
Date: Thu, 8 Jan 2026 17:09:56 +0000
Subject: [PATCH 2/3] Fix builtins.bytearray primitive

---
 mypyc/primitives/bytes_ops.py | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/mypyc/primitives/bytes_ops.py b/mypyc/primitives/bytes_ops.py
index 728da4181135..2268acd80aa5 100644
--- a/mypyc/primitives/bytes_ops.py
+++ b/mypyc/primitives/bytes_ops.py
@@ -51,7 +51,7 @@
 function_op(
     name="builtins.bytearray",
     arg_types=[object_rprimitive],
-    return_type=bytes_rprimitive,
+    return_type=object_rprimitive,
     c_function_name="PyByteArray_FromObject",
     error_kind=ERR_MAGIC,
 )
@@ -74,7 +74,6 @@
 )
 
 # bytes + bytes
-# bytearray + bytearray
 binary_op(
     name="+",
     arg_types=[bytes_rprimitive, bytes_rprimitive],

From 5728ef64e00d39377912c4896478e78bd30f86c3 Mon Sep 17 00:00:00 2001
From: Jukka Lehtosalo <jukka.lehtosalo@iki.fi>
Date: Thu, 8 Jan 2026 17:11:23 +0000
Subject: [PATCH 3/3] Update test case

---
 mypyc/test-data/irbuild-bytes.test | 6 +-----
 1 file changed, 1 insertion(+), 5 deletions(-)

diff --git a/mypyc/test-data/irbuild-bytes.test b/mypyc/test-data/irbuild-bytes.test
index 0c77c4bfbb69..613ba4e46eee 100644
--- a/mypyc/test-data/irbuild-bytes.test
+++ b/mypyc/test-data/irbuild-bytes.test
@@ -50,11 +50,7 @@ def f(s, num):
     num :: int
     r0 :: object
     r1 :: str
-    r2, r3, a :: object
-    r4 :: bytes
-    b, r5 :: object
-    r6 :: bytes
-    c :: object
+    r2, r3, a, r4, b, r5, r6, c :: object
 L0:
     r0 = builtins :: module
     r1 = 'bytearray'