extract_r_source fails when knitr pattern chunk.end doesn't match any lines

[hstahl]

I have an R source file which causes lintr to throw its hands in the air and fail with an error. The problem is in the extract_r_source function.

To reproduce:

lines <- c("# This single comment `r length(x)` with some inline code is enough.\n")
temp <- tempfile(fileext = '.R')
cat(lines, file = temp)
tryCatch(lint(temp, with_defaults()), finally = unlink(temp))
# Error in rep.int(NA_character_, max(ends - 1)) : invalid 'times' value
# In addition: Warning messages:
#1: In max(ends - 1) : no non-missing arguments to max; returning -Inf
#2: In rep.int(NA_character_, max(ends - 1)) :
#   NAs introduced by coercion to integer range

The error is from https://github.com/jimhester/lintr/blob/master/R/extract.R#L17.

If some knitr patterns are found but the chunk.end pattern doesn't end up matching any lines of code, an error is thrown by rep.int since -Inf gets passed as its times parameter. Leading up to the error:

• pattern is not NULL.
• ends and starts are integer(0) since no matching lines of code were found by grepl
• calling max(integer(0) - 1) returns -Inf
• rep.int(NA_character_, -Inf) throws the error above.

[jsta]

I am having this problem as well. Did you resolve it on your end @hstahl? What patterns do I need to insert in my chunk?

[jsta]

I solved this issue by installing the latest dev version from Github (inspired by #228). I suggest that this issue can be closed.