Check for integer overflow in Bytes.extend

[yallop]

Current behaviour:

# Bytes.extend "abc" max_int max_int;;
- : bytes = "\000"

With this fix:

# Bytes.extend "abc" max_int max_int;;
Exception: Invalid_argument "Bytes.extend".

[gasche]

Sorting entries by MPR first, GPR second, this should go as the very last item of the category.

[gasche]

I find the shadowing used here not very readable. You could name the first variable len_left, or declare let (++) a b = (* check for overflow *) let c = a + b in if c < 0 then invalid_arg "Bytes.extend" else c and let len = length s ++ left ++ right.

[yallop]

Thanks for the comments, @gasche. I've updated the patch.

I think this may need a bit more care before merging, though, since it rejects

Bytes.extend "abc" (-4) 4

which was previously accepted, and had reasonable behaviour. I'll come back to this shortly.

[yallop]

Thanks for the comments, @gasche. I've updated the patch.

I think this may need a bit more care before merging, though, since it rejects

Bytes.extend "abc" (-4) 4

which was previously accepted, and had reasonable behaviour. I'll come back to this shortly.

[yallop]

I've updated the overflow check to take care with negative inputs (31f8776) and added a testsuite for Bytes.extend that includes tests both for existing behaviour and for the overflow check (5de7108).

[yallop]

I've updated the overflow check to take care with negative inputs (31f8776) and added a testsuite for Bytes.extend that includes tests both for existing behaviour and for the overflow check (5de7108).

[gasche]

I'm partial to patches that come with testsuite support. Merged.

[gasche]

I'm partial to patches that come with testsuite support. Merged.