COUNT_REGEXP_INSTANCES vs. empty files

[4Luke4]

According to the documentation, this command is supposed to return the number of times regexp appears in the current file.

However, if the current file is empty, it returns -1 instead of 0.

Steps to reproduce

OUTER_PATCH ~a~ BEGIN
    COUNT_REGEXP_INSTANCES CASE_INSENSITIVE EVALUATE_REGEXP "\bwhatever\b" "count"
END
PRINT ~%count%~ // will print 0 (OK)

OUTER_PATCH ~~ BEGIN
    COUNT_REGEXP_INSTANCES CASE_INSENSITIVE EVALUATE_REGEXP "\bwhatever\b" "count"
END
PRINT ~%count%~ // will print -1 (OK...?)

Is it intended...?

[FredrikLindgren]

I would say undefined behaviour. It's returning -1 on an empty file and 0 on a file with no matches due to an implementation detail. What's desired behaviour?

[4Luke4]

I would say undefined behaviour. It's returning -1 on an empty file and 0 on a file with no matches due to an implementation detail. What's desired behaviour?

Up to you I guess... I mean, it is easy to workaround, so you might want to keep things as they are... If that is the case, then you might want to clarify the undefined behaviour in the docs...