Fix #2232: Trace chunk location in progress bar

[zeehio]

On #2232 we discussed a minor inconsistency in chunk names between RStudio and knitr. @yihui suggested to change the progress bar when knitting, so it shows the chunk name and the line number.

Here I do that and I add as well the file name, so we know precisely the location of the chunk even when having child documents. This is how the progress bar now looks with this pull request. Notice that the label in the progress bar includes chunk name @ file name : line -range.

Download if you like the parent and child Rmd used to create the screenshot: test-rmd-with-child.zip

• We avoid breaking cache because it's just a display change (not a change in chunk labels or counting)
• It handles child documents correctly
• Most compilers use the colon (:) to separate file name from the line number when reporting errors, I thought that would be a good design pattern to copy.

[zeehio]

Are you okay with making this feature optional? e.g., show the line numbers only when options(knitr.progress.linenums = TRUE). Thanks!

Sure, I guess you would like the default to be FALSE, right?

[yihui]

Right (getOption('knitr.progress.linenums', FALSE)).

[zeehio]

Hi :-)

options(knitr.progress.linenums = TRUE) is implemented and all conflicts due to NEWS entries have been resolved

Feel free to tell me if there is any other suggestion.

Thanks!