#23378 Pants 2.31.0 regression: 'FrozenDict' object has no attribute 'replace' with --changed-since X --changed-dependents=transitive Issue created by ablassejr Pants version: 2.31.0 (and 2.31.1rc1 — unfixed there as well) OS: reproduced on both macOS 15 (darwin-arm64) and ubuntu-latest GHA runners Symptom

$ pants --changed-since=HEAD~1 --changed-dependents=transitive lint
…
File ".../pants/init/specs_calculator.py", line 105, in calculate_specs
    (changed_addresses,) = session.product_request(
File ".../pants/engine/internals/scheduler.py", line 523, in _raise_on_error
    raise ExecutionError(

Exception message: 1 Exception encountered:

AttributeError: 'FrozenDict' object has no attribute 'replace'

NoneType: None

The same invocation without

--changed-dependents=transitive

succeeds. Plain

pants lint ::

succeeds. Suspected cause PR #22501 ("perf: Port

frozendict

to rust") replaced the Python

FrozenDict

with a Rust-backed implementation. Some rule on the

ChangedAddresses

→

find_dependents

codepath still calls

.replace(...)

on a

FrozenDict

instance, which no longer exists on the Rust port. Engine stack trace is suppressed (

NoneType: None

), so the exact callsite is opaque from a user repo. Reproduction Any non-trivial workspace with at least one transitive dependent:

pants --changed-since=HEAD~1 --changed-dependents=transitive lint

Workaround Drop

--changed-dependents=transitive

and run lint/test over

::

instead. Costs a full-tree run per CI invocation; viable with a remote cache (BuildBuddy / Buildfarm) but expensive on a cold runner. Notes • 2.31.1rc1 changelog only carries: jar-tool DEFLATED ZIP fix, sandboxer stdin/stdout fd fix, Trivy 0.69.2 bump. No frozendict change. • No existing issue or PR mentioning

FrozenDict.replace

in repo search. pantsbuild/pants