cdbed919ec
This PR fixes spurious unused variable warnings for variables used in non-atomic match discriminants in `do` notation. For example, in `match Json.parse s >>= fromJson? with`, the variable `s` would be reported as unused. The root cause is that `expandNonAtomicDiscrs?` eagerly elaborates the discriminant via `Term.elabTerm`, which creates TermInfo for variable references. The result is then passed to `elabDoElem` for further elaboration. When the match elaboration is postponed (e.g. because the discriminant type contains an mvar from `fromJson?`), the result is a postponed synthetic mvar. The `withTermInfoContext'` wrapper in `elabDoElemFns` checks `isTacticOrPostponedHole?` on this result, detects a postponed mvar, and replaces the info subtree with a `hole` node — discarding all the TermInfo that was accumulated during discriminant elaboration. The fix applies `mkSaveInfoAnnotation` to the result, which prevents `isTacticOrPostponedHole?` from recognizing it as a hole. This is the same mechanism that `elabLetMVar` uses to preserve info trees when the body is a metavariable. 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com> |
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