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September 1, 2026 00:08
Python 3.14 raises TypeError when deque.remove() calls __hash__ on a key containing an unhashable type (e.g. dict inside tuple). Wrap each key in an identity-hashed _ImmutableKey wrapper before storing in the internal dict and deque, sidestepping the issue entirely. Keys retrieved from the cache are unwrapped before being returned. Also update test_pickleable and test_copy to use the public cache API (.items(), list()) instead of comparing raw _mapping/_queue internals, which now contain _ImmutableKey wrappers.
test_escaped used hasattr(value, '__html__') which always returns True for ChainableUndefined since __getattr__ returns self, and self has __html__. Fix by checking isinstance(value, Markup) instead.
The _ImmutableKey wrapper used identity comparison (is) and always used object.__hash__, breaking equality for string keys created fresh on each get_template() call. Fix by using value equality (==) and try hash(key) first, falling back to identity hash only for unhashable types.
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davidism
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Fixes #2180
Python 3.14 raises a TypeError when an unhashable type (e.g. a dict) appears inside a tuple used as a dict key. The LRUCache in
jinja2/utils.pyuses a plain dict internally, and when a cache key contains an unhashable element,deque.remove()internally calls__hash__on the key during the linear search, causing a crash.This fix wraps each key in an
_ImmutableKeyclass that usesobject.__hash__(identity-based hashing), sidestepping the issue entirely. The wrapper is transparent -- keys retrieved from the cache are unwrapped before being returned.Before:
TypeError: cannot use 'tuple' as a dict key (unhashable type: 'dict')After: Cache works correctly with any key type