Merge branch 'master' into overwrite-union-syntax-1

Author: cdce8p

.github/workflows/test.yml

@@ -95,6 +95,18 @@ jobs:
         #   tox_extra_args: "-n 4 mypyc/test/test_run.py mypyc/test/test_external.py"
         #   debug_build: true
 
+        - name: Parallel tests with py314-ubuntu, interpreted
+          python: '3.14'
+          os: ubuntu-24.04-arm
+          toxenv: py
+          tox_extra_args: "-n 4 --mypy-num-workers=4 mypy/test/testcheck.py"
+        - name: Parallel tests with py314-ubuntu, mypyc-compiled
+          python: '3.14'
+          os: ubuntu-24.04-arm
+          toxenv: py
+          tox_extra_args: "-n 4 --mypy-num-workers=4 mypy/test/testcheck.py"
+          test_mypyc: true
+
         - name: Type check our own code (py310-ubuntu)
           python: '3.10'
           os: ubuntu-latest

docs/source/error_code_list.rst

@@ -1151,6 +1151,25 @@ Warn about cases where a bytes object may be converted to a string in an unexpec
     print(f"The alphabet starts with {b!r}")  # The alphabet starts with b'abc'
     print(f"The alphabet starts with {b.decode('utf-8')}")  # The alphabet starts with abc
 
+.. _code-str-unpack:
+
+Check that ``str`` is not unpacked [str-unpack]
+---------------------------------------------------------
+
+It can sometimes be surprising that ``str`` is iterable, especially when unpacking
+in an assignment.
+
+Example:
+
+.. code-block:: python
+
+    def print_dict(d: dict[str, str]) -> int:
+        # We meant to do d.items(), but instead we're unpacking the str keys of d
+
+        # Error: Unpacking a string is disallowed
+        for k, v in d:
+            print(k, v)
+
 .. _code-overload-overlap:
 
 Check that overloaded functions don't overlap [overload-overlap]