2026-07-18 05:19:31 -07:00
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# nash ↔ bash divergence log
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Live record of behavioral divergences found by the replay harness
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(`replay.py`, corpus in `corpus.jsonl`). Per docs/NASH.md §10.3/§11, each entry
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stays open until fixed in the fork (or upstream) and re-verified by the corpus.
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## Open
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(none)
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## Closed
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### D1 — IFS word-splitting applied to literal words (fixed in fork)
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- **Found**: M0 corpus run (`ifs-split`), brush-shell-v0.4.0.
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- **Repro**: `IFS=,; set -- a,b,c; echo $1` → bash `a b c`, nash `a`.
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- **Root cause**: brush applied IFS splitting to *literal* words, not just
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expansion results: under `IFS=,`, `echo a,b,c` printed `a b c` (bash:
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`a,b,c`) and `set -- a,b,c` received 3 args (bash: 1). POSIX/bash split only
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the results of parameter/command/arithmetic expansion. Mechanically,
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`brush-core/src/expansion.rs` had a two-state `ExpansionPiece`
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(`Splittable`/`Unsplittable`) conflating "field-splittable" with
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"glob-active", and literal text was marked `Splittable`.
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- **Fix**: added a third piece state `LiteralText` (never field-split, glob
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chars active) and produce it for unquoted literal text, the no-expansion-chars
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fast path, and retained-backslash escapes (`// nash:` markers in
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`expansion.rs`). Corpus back to 100% (94/94); candidate for upstreaming.
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- **Regression tests**: corpus `ifs-split` (+ `glob-all`, `glob-txt`,
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`cond-pattern`, `case` guard the glob/pattern side); brush compat suite.
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2026-07-18 12:23:09 -07:00
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- **Fix fallout (caught by the brush compat suite, both fixed)**: (a) text
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substituted by `${v:-word}`/`${v:+word}`/`${v:=word}` *is* an expansion result
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and must split — restored via a boundary conversion in the
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`ParameterExpansion` arm; (b) `compgen -W` splits its word-list string as
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data — restored via `ExpanderOptions.field_split_literal_text`. Final suite:
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1684 succeeded / 6 failed, failure set identical to the pristine-brush
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baseline in this container (environmental only); 3 upstream known-fail IFS
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tests now pass (markers flipped in `ifs.yaml`).
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