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Gustavo2622
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Apr 13, 2026
Gustavo2622
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Allow rewrite patterns to designate a subterm inside a larger context with the [x in pattern] syntax. This lets rewrite target exactly the occurrence named by the surrounding context, and adds regression coverage for that form. The context variable must appear exactly once in the pattern (linearity check). Delta expansion and conversion are disabled during contextual pattern matching to ensure position computation remains sound.
Split the `Some (prw, subl)` match arm into two separate cases — plain r-pattern and contextual r-pattern — so that the strict no-conv/no-delta matching constraint is structurally scoped to the contextual branch. The permissive `modes` from the outer scope is no longer reachable from the contextual code.
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Allow rewrite patterns to designate a subterm inside a
larger context with the [x in pattern] syntax.
This lets rewrite target exactly the occurrence named by
the surrounding context, and adds regression coverage for
that form.
The context variable must appear exactly once in the pattern
(linearity check). Delta expansion and conversion are disabled
during contextual pattern matching to ensure position computation
remains sound.