WISH: Make grep(pattern, ...) produce an error if length(pattern) > 1 - not just a warning

[HenrikBengtsson]

Issue

The grep() family of functions will produce a warning if pattern specified more than one regular expression, e.g.

> pattern <- c("Volvo", "Fiat")
> grep(pattern, rownames(mtcars))
[1] 32
Warning message:
In grep(pattern, rownames(mtcars)) :
  argument 'pattern' has length > 1 and only the first element will be used

I don't think that is ever anything other than a coding mistake, i.e. a bug.

Suggestion

Instead of a warning, produce an error:

Error in grep(pattern, rownames(mtcars)) : 
  argument 'pattern' has length != 1

This applies to functions:

• [ ] agrep()
• [ ] agrepl()
• [ ] grep()
• [ ] grepl()
• [ ] grepRaw()
• [ ] regexpr()
• [ ] gregexpr()
• [ ] regexec()
• [ ] gsub()
• [ ] sub()
• [ ] ...?

The above was verified on R 4.0.4.

[HenrikBengtsson]

Feature request PR#18577 was filed to BugZilla on 2023-08-09.