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PR #28676 ecosystem summary

The PR adds four redundant-condition-strict warnings. Three identify redundant membership conditions under the projects' existing annotations. The fourth, in dd-trace-py, is a runtime false positive caused by an existing limitation in modeling dynamically replaced configuration attributes. The same limitation already produces equality warnings on the merge base; the PR exposes it in inline list membership as well.

Affected projects

1. dd-trace-py: dynamically replaced configuration attributes

Report entry: ddtrace/internal/settings/errortracking.py:43

The PR adds warning[redundant-condition-strict] Condition config._report_handled_errors in ["all", "user", "third_party"] is always false. At runtime, envier replaces the configuration marker with a parsed string through setattr, so this condition can be true. Both revisions infer the attribute as EnvVariable[str], following the factory's return annotation. Envier supplies a mypy plugin to model this transformation; ordinary annotations do not express it.

The merge base already reports the subsequent equalities with "user", "third_party", and "all" as always false. Equivalent tuple membership also warns on the merge base. The new warning therefore extends existing comparison reasoning to the inline list; it does not demonstrate a new error in how list membership compares the inferred types. We accept this existing dynamic-inference limitation, consistent with the current treatment of equality and tuple membership.

Related ty issue: ty#2016 discusses limitations of dynamic setattr effects; it is not an envier-specific issue.

class EnvVariable:
    pass

class ErrorTrackingConfig:
    _report_handled_errors = EnvVariable()

config = ErrorTrackingConfig()
setattr(config, "_report_handled_errors", "all")
# Merge base: no diagnostic
# PR: warning[redundant-condition-strict] Condition `config._report_handled_errors in ["all"]` is always false
if config._report_handled_errors in ["all"]:
    pass

The minimized condition evaluates to True at runtime.

2. paasta: a tuple parameter checked against strings

Report entry: paasta_tools/paastaapi/api_client.py:211

The parameter is annotated as Optional[Tuple[Any]], but the condition tests response_type not in ["file", "bytes"]. The merge base reports no diagnostic at this condition; the PR correctly reports that it is always true under the existing non-strict equality policy. An ordinary tuple or None cannot match either string. This exposes an ineffective check under the annotation. Strict equality semantics continue to leave the result uncertain because a tuple subclass can override equality.

def check(response_type: tuple[object]):
    # Merge base: no diagnostic
    # PR: warning[redundant-condition-strict] Condition `response_type not in ["file"]` is always true
    if response_type not in ["file"]:
        pass

3. SciPy: a literal union cannot match either excluded method

Report entry: scipy/optimize/tests/test__root.py:25

The loop iterates over seven method names, excluding both linearmixing and excitingmixing. The PR correctly identifies method in ('linearmixing', 'excitingmixing') as always false. This also improves tuple membership: the shared equality evaluator now recognizes that every member of a union of builtin literals has reflexive equality.

for method in ["hybr", "lm"]:
    # Merge base: no diagnostic
    # PR: warning[redundant-condition-strict] Condition `method in ("linearmixing",)` is always false
    if method in ("linearmixing",):
        pass

4. steam.py: excluding an absent slot name

Report entry: steam/chat.py:172

Both revisions infer _BaseMember.__slots__ as tuple[Literal["_user"], Literal["_cs_channel"]]. The generator excludes "_state", which is absent from those slots. The PR correctly reports slot not in {"_state"} as always true. The source reduces to a constant set membership condition without imports or class definitions.

# Merge base: no diagnostic
# PR: warning[redundant-condition-strict] Condition `"_user" not in {"_state"}` is always true
if "_user" not in {"_state"}:
    pass

Reproduction

• Detailed report: ecosystem-analyzer report
• Actions run: run 35281371799, attempt 1
• Ruff comparison: eb3751b19c to 91cfc6f349, the merge of PR head ab0586463e
• ecosystem-analyzer: a31ef389f3
• mypy-primer: 3058720299
• Dependency cutoff: 2026-09-17T22:18:41Z
• Project Python: dd-trace-py, paasta, SciPy, and steam.py use Python 3.11.
• Project analysis mode: all four projects use non-strict settings.
• Comparison method: run both exact-revision profiling binaries with the PR ecosystem configuration installed as user-level configuration and each pinned project environment. Use ty check for SciPy; ty check paasta_tools for paasta; ty check steam for steam.py; and ty check --exclude tests/appsec/iast/fixtures/aspects/str/non_utf8_content.py --exclude tests/appsec/iast/fixtures/ast/str/non_utf8_content.py for dd-trace-py. Each command includes --python <project-venv> --output-format concise, with TY_CONFIG_FILE unset and no strict-analysis overrides. The standalone minimized examples need only ty check <file> --python-version 3.11 with the same user-level configuration.