Wrapping warning messages in knitr is not consistent with R output

[helske]

There seems to be slight issue of inconsistency in how knitr wraps lines in warning messages (and error messages) compared to usual R output:

warning_fun <- function(){
  long_function_name <- function(){
    warning("this is a relatively long warning message which should be on new line.")
  }
  long_function_name()
}

On knitted PDF:

warning_fun()
## Warning in long_function_name(): this is a relatively long warning message
## which should be on new line.

On R console:

warning_fun()
# Warning message:
# In long_function_name() :
#   this is a relatively long warning message which should be on new line.

It seems that if I set options(warn = 1) then I get similar warning in R console (but warning itself is still on a new line):

options(warn = 1)
warning_fun()
# Warning in long_function_name() :
#   this is a relatively long warning message which should be on new line.

This seems minor issue itself, but I suspect this relates to the issue that some warnings and errors to become truncated in PDFs due to long function call:

sqrt("aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa")
## Error in sqrt("aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"): non-numeric argu

On R console:

sqrt("aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa")
# Error in sqrt("aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa") : 
#   non-numeric argument to mathematical function

[yihui]

The inconsistency looks minor, and I tend not to change it at this point. If the main issue here is to solve the truncation of text in PDF, you can customize the error/warning hook function to wrap the error/warning message, e.g.

library(knitr)
local({
  hook_error = knit_hooks$get('error')
  knit_hooks$set(error = function(x, options) {
    # process the error message here; you may print(x)/gsub()/strwrap(x)/...
    hook_error(x, options)
  })
})

There is endless pain like this with PDFs due to the constraint of page sizes. I don't think it completely solves the problem even if I move the message to a new line. For example, your function name may be so wide that it may have already exceeded the page margin. I may be able to treat the symptom you had there, but it definitely does not treat the disease.

[github-actions]

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