lean4

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Kim Morrison 9e241a4087 fix: revert "split ngen on async elab" (#12148 )

This PR reverts #12000, which introduced a regression where `simp`
incorrectly rejects valid rewrites for perm lemmas.

The issue is that `NameGenerator.mkChild` creates names that don't
maintain the ordering assumption used by `acLt` for perm lemma
decisions. For example, after the change:
- Child generator creates names like `_uniq.102.2`
- Parent continues with `_uniq.7`
- But `Name.lt (.num (.num `_uniq 102) 2) (.num `_uniq 7)` is true

This causes fvars created later (in async tasks) to compare as smaller
than fvars created earlier, breaking the assumption that later fvars
compare greater according to `Name.lt`.

Fixes #12136.

🤖 Prepared with [Claude Code](https://claude.com/claude-code)

Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com>

2026-01-25 03:18:24 +00:00