Perf: avoid unnecessary allocations when transforming Expr
#8591
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Which issue does this PR close?
N/A. Addresses a
TODO
item intree_node/expr.rs
Rationale for this change
Inspired by #7942: currently, the
Expr
transformer'stransform_box
andtransform_vec
methods allocate a newBox
andVec
, respectively, with potentially harmful performance implications. We can usestd::mem::replace
to avoid this allocation by reusing the existingBox
/Vec
.What changes are included in this PR?
Switch to in-place mutations in the
transform_box
andtransform_vec
methods onExpr
s.Are these changes tested?
Yes, existing tests.
Are there any user-facing changes?
No.