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The slices.Insert function should panic if i is out of range, but it does not panic if there are no values to insert:
s := []string{"a", "b", "c"}
s = slices.Insert(s, -1) // does not panic
s = slices.Insert(s, 5) // does not panic
fmt.Println(s)Metadata
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[-]slices: Insert function does not panic if i is out of range and there are not values to insert[/-][+]slices: Insert function does not panic if i is out of range and there are no values to insert[/+]bcmills commentedon Nov 2, 2023
The documentation does indeed claim that it will panic:
“Insert panics if i is out of range.”
(attn @ianlancetaylor @eliben)
eliben commentedon Nov 2, 2023
Interesting edge case. I looked back at the original implementation of
slices.Insertwhen it was just moved into the stdlib, and that one panics for the test cases specified here. However, following the optimizations in https://go-review.googlesource.com/c/go/+/494817 it no longer panics for these cases. @randall77 @cuonglm WDYT?randall77 commentedon Nov 3, 2023
Making it panic in these cases is fine.
gopherbot commentedon Nov 6, 2023
Change https://go.dev/cl/540155 mentions this issue:
slices: make Insert panic if index is out of range and there are no valuesgopherbot commentedon Nov 15, 2023
Change https://go.dev/cl/542455 mentions this issue:
slices: imporve Insert panic message for index out of rangeslices: improve Insert panic message for index out of range