[ferdingler]

Description

Inside $(...), a brace group, subshell, if, loop, or case always came back as success, whatever its last command did. So X=$( { false; } && echo yes) set X to yes, where bash leaves it empty, and the || side never ran. $? read 0 right after one of these too, and even after a plain false.

Now each of those carries the real status of the last command it ran, and $? inside the substitution follows along. This only touches the command substitution path.

I checked every new expectation against bash 5.2 first. Without the fix, 22 of the new tests failed; with it, they all pass, along with the success cases and the rest of the suite. There's some overlap in the same file with #169, #173, #174 and #176, but not on the same lines. A few related problems are still open and I left them for separate changes: the status of the substitution itself (X=$(exit 3); echo $? prints 0), a group with an input redirect inside $(...) still reports success, and ! in front of a group or other compound gets dropped. Inside $(...), that last one now behaves the same as it does outside, so ! { false; } is wrong in both places. Before, it happened to be right inside a substitution.

Related Issues

None.

Documentation PR

None.

Type of Change

Bug fix

Testing

How have you tested the change? Verify that the changes do not break functionality or introduce new warnings.

• I ran the relevant test suites for the bindings I touched (cargo test --workspace --all-targets, pytest tests/python, npm test)
• If I touched Rust, I ran cargo fmt and cargo clippy

Checklist

• I have read the CONTRIBUTING document
• I have reviewed and understand every line of code in this PR, including any generated by AI tools, and I can explain why it works
• My change is focused and reasonably small; I have split unrelated work into separate PRs
• I have added any necessary tests that prove my fix is effective or my feature works
• I have updated the documentation accordingly
• I have added an appropriate example to the documentation to outline the feature, or no new docs are needed
• My changes generate no new warnings
• Any dependent changes have been merged and published

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