youknowone · Oct 11, 2026 · Oct 10, 2026 · Oct 10, 2026 · Oct 10, 2026 · Oct 10, 2026
diff --git a/.python-version b/.python-version
@@ -1 +1 @@
-3.14.7
+3.14.8
diff --git a/Lib/test/test_mmap.py b/Lib/test/test_mmap.py
@@ -73,7 +73,7 @@ def test_basic(self):
 
         # Shouldn't crash on boundary (Issue #5292)
         self.assertRaises(IndexError, m.__getitem__, len(m))
-        self.assertRaises(IndexError, m.__setitem__, len(m), b'\0')
+        self.assertRaises(IndexError, m.__setitem__, len(m), 0)
 
         # Modify the file's content
         m[0] = b'3'[0]

diff --git a/crates/stdlib/src/mmap.rs b/crates/stdlib/src/mmap.rs
@@ -1455,17 +1455,15 @@ mod mmap {
             value: &PyObject,
             vm: &VirtualMachine,
         ) -> PyResult<()> {
-            let i: usize = i
-                .wrapped_at(self.__len__())
-                .ok_or_else(|| vm.new_index_error("mmap index out of range"))?;
-
             let b = value_from_object(vm, value)?;
 
             self.try_writable(vm, |mmap| {
+                let i = i
+                    .wrapped_at(mmap.len())
+                    .ok_or_else(|| vm.new_index_error("mmap index out of range"))?;
                 mmap[i] = b;
-            })?;
-
-            Ok(())
+                Ok(())
+            })?
         }
 
         fn setitem_by_slice(
@@ -1474,43 +1472,37 @@ mod mmap {
             value: &PyObject,
             vm: &VirtualMachine,
         ) -> PyResult<()> {
-            let (range, step, slice_len) = slice.adjust_indices(self.__len__());
-
             let bytes = bytes_from_object(vm, value)?;
 
-            if bytes.len() != slice_len {
-                return Err(vm.new_index_error("mmap slice assignment is wrong size"));
-            }
+            self.try_writable(vm, |mmap| {
+                let (range, step, slice_len) = slice.adjust_indices(mmap.len());
 
-            if slice_len == 0 {
-                // do nothing
-                Ok(())
-            } else if step == 1 {
-                self.try_writable(vm, |mmap| {
+                if bytes.len() != slice_len {
+                    return Err(vm.new_index_error("mmap slice assignment is wrong size"));
+                }
+
+                if slice_len == 0 {
+                    // do nothing
+                } else if step == 1 {
                     (&mut mmap[range])
                         .write(&bytes)
                         .map_err(|err| err.to_pyexception(vm))?;
-                    Ok(())
-                })?
-            } else {
-                let mut bi = 0; // bytes index
-                if step.is_negative() {
-                    for i in range.rev().step_by(step.unsigned_abs()) {
-                        self.try_writable(vm, |mmap| {
-                            mmap[i] = bytes[bi];
-                        })?;
-                        bi += 1;
-                    }
                 } else {
-                    for i in range.step_by(step.unsigned_abs()) {
-                        self.try_writable(vm, |mmap| {
+                    let mut bi = 0; // bytes index
+                    if step.is_negative() {
+                        for i in range.rev().step_by(step.unsigned_abs()) {
+                            mmap[i] = bytes[bi];
+                            bi += 1;
+                        }
+                    } else {
+                        for i in range.step_by(step.unsigned_abs()) {
                             mmap[i] = bytes[bi];
-                        })?;
-                        bi += 1;
+                            bi += 1;
+                        }
                     }
                 }
                 Ok(())
-            }
+            })?
         }
     }
 

diff --git a/crates/vm/src/stdlib/_io.rs b/crates/vm/src/stdlib/_io.rs
@@ -3568,6 +3568,17 @@ mod _io {
 
         #[pygetset(setter, name = "_CHUNK_SIZE")]
         fn set_chunksize(&self, value: PySetterValue, vm: &VirtualMachine) -> PyResult<()> {
+            let PySetterValue::Assign(object_value) = value else {
+                let type_name = self.class().slot_name();
+                let mut end = type_name.len().min(100);
+                while !type_name.is_char_boundary(end) {
+                    end -= 1;
+                }
+                return Err(vm.new_attribute_error(format!(
+                    "attribute '_CHUNK_SIZE' of '{}' objects cannot be deleted",
+                    &type_name[..end]
+                )));
+            };
             {
                 let textio = self.lock(vm)?;
                 if self.buffer.deref().is_none() {
@@ -3576,27 +3587,20 @@ mod _io {
                 drop(textio);
             }
 
-            let chunk_size: isize = match value {
-                PySetterValue::Assign(object_value) => {
-                    let integer = object_value.try_index(vm)?;
+            let integer = object_value.try_index(vm)?;
 
-                    integer.try_to_primitive::<isize>(vm).map_err(|_| {
-                        let class = object_value.class();
-                        let type_name = class.name();
-                        let mut end = type_name.len().min(200);
-                        while !type_name.is_char_boundary(end) {
-                            end -= 1;
-                        }
-                        vm.new_value_error(format!(
-                            "cannot fit '{}' into an index-sized integer",
-                            &type_name[..end]
-                        ))
-                    })?
+            let chunk_size = integer.try_to_primitive::<isize>(vm).map_err(|_| {
+                let class = object_value.class();
+                let type_name = class.name();
+                let mut end = type_name.len().min(200);
+                while !type_name.is_char_boundary(end) {
+                    end -= 1;
                 }
-                PySetterValue::Delete => {
-                    return Err(vm.new_attribute_error("cannot delete attribute"));
-                }
-            };
+                vm.new_value_error(format!(
+                    "cannot fit '{}' into an index-sized integer",
+                    &type_name[..end]
+                ))
+            })?;
 
             if chunk_size <= 0 {
                 return Err(vm.new_value_error("a strictly positive integer is required"));

diff --git a/crates/vm/src/stdlib/typevar.rs b/crates/vm/src/stdlib/typevar.rs
@@ -583,10 +583,7 @@ pub(crate) mod typevar {
                 return Err(vm.new_type_error("ParamSpec() takes at most 1 positional argument"));
             };
 
-            let bound = kwargs
-                .swap_remove("bound")
-                .map(|b| type_check(b, "Bound must be a type.", vm))
-                .transpose()?;
+            let bound = kwargs.swap_remove("bound");
             let covariant = kwargs
                 .swap_remove("covariant")
                 .map(|v| v.try_to_bool(vm))

diff --git a/extra_tests/snippets/stdlib_io.py b/extra_tests/snippets/stdlib_io.py
@@ -166,10 +166,24 @@ def __index__(self):
     "underlying buffer has been detached",
     lambda: setattr(detached_textio, "_CHUNK_SIZE", 16),
 )
-expect_value_error(
-    "underlying buffer has been detached",
-    lambda: delattr(detached_textio, "_CHUNK_SIZE"),
-)
+for wrapper in (textio, uninitialized_textio, detached_textio):
+    with assert_raises(AttributeError) as error:
+        del wrapper._CHUNK_SIZE
+    assert str(error.exception) == (
+        "attribute '_CHUNK_SIZE' of '_io.TextIOWrapper' objects cannot be deleted"
+    )
+
+
+for wrapper_name in ("ChunkWrapper", "€" * 34):
+    wrapper_type = type(wrapper_name, (TextIOWrapper,), {})
+    wrapper = wrapper_type(BytesIO())
+    with assert_raises(AttributeError) as error:
+        del wrapper._CHUNK_SIZE
+    displayed_name = wrapper_name.encode("utf-8")[:100].decode("utf-8", "ignore")
+    assert str(error.exception) == (
+        f"attribute '_CHUNK_SIZE' of '{displayed_name}' objects cannot be deleted"
+    )
+    wrapper.close()
 
 
 long_type_name = "X" * 250

diff --git a/extra_tests/snippets/stdlib_mmap.py b/extra_tests/snippets/stdlib_mmap.py
@@ -77,3 +77,41 @@
     with assert_raises(ValueError):
         mapped.resize(4)
     assert mapped.closed
+
+
+# Assignment validates current storage after argument conversion, even if empty.
+with mmap.mmap(-1, 4) as mapped:
+    with assert_raises(ValueError):
+        mapped[4] = 256
+    mapped[0:0] = b""
+with assert_raises(ValueError):
+    mapped[0:0] = b""
+
+with mmap.mmap(-1, 4, access=mmap.ACCESS_READ) as mapped:
+    with assert_raises(TypeError):
+        mapped[0:0] = b""
+
+
+class CloseOnIndex:
+    def __init__(self, mapped):
+        self.mapped = mapped
+
+    def __index__(self):
+        self.mapped.close()
+        return 0
+
+
+for close_from in ("key", "value", "slice"):
+    mapped = mmap.mmap(-1, 4)
+    closer = CloseOnIndex(mapped)
+    try:
+        with assert_raises(ValueError):
+            if close_from == "key":
+                mapped[closer] = 0
+            elif close_from == "value":
+                mapped[0] = closer
+            else:
+                mapped[closer:0] = b""
+        assert mapped.closed
+    finally:
+        mapped.close()
diff --git a/extra_tests/snippets/stdlib_typing.py b/extra_tests/snippets/stdlib_typing.py
@@ -65,6 +65,11 @@ def method(self, value: Union[int, float]) -> Union[str, bytes]:
     pass
 
 
+# Python 3.14.8 retains ParamSpec bounds without converting or validating them.
+assert ParamSpec("Unbounded").__bound__ is None
+for bound in (None, "int", "not valid Python!", (int, str), object()):
+    assert ParamSpec("BoundSpec", bound=bound).__bound__ is bound
+
 # Eager aliases without a caller module never inspect their aliased value.
 alias_module_lookups = []
Original file line number	Diff line number	Diff line change
		@@ -1 +1 @@
		3.14.7
		3.14.8
chatgpt-codex-connector Bot Oct 10, 2026 Copy link Copy Markdown Choose a reason for hiding this comment The reason will be displayed to describe this comment to others. Learn more. Add the mandatory AI-assistance trailer The reviewed commit is authored by `Codex`, but its commit message has no `Assisted-by: AGENT_NAME:MODEL_VERSION` trailer. `AGENTS.md` makes that disclosure mandatory for every AI-assisted contribution, so add the required trailer before merge. AGENTS.md reference: AGENTS.md:L20-L23 Useful? React with 👍 / 👎. chatgpt-codex-connector Bot Oct 10, 2026 Copy link Copy Markdown Choose a reason for hiding this comment The reason will be displayed to describe this comment to others. Learn more. Update the library-upgrade workflow to 3.14.8 Changing the repository target here leaves `.github/workflows/upgrade-pylib.md:55` pinned to `PYTHON_VERSION: "v3.14.7"`, and line 71 clones that branch. Every manually dispatched library-upgrade run will therefore copy 3.14.7 sources even though the status and CI workflows now derive 3.14.8 from this file, producing stale upgrade PRs; update that workflow pin with the target bump. Useful? React with 👍 / 👎.