Feature request: include linter name in warnings

[jameslamb]

Request

Consider the following code:

library(lintr)
f <- tempfile(fileext = ".R")
writeLines("do_thing <- T", f)
lintr::lint(
    filename = f
    , linters = list(
        "tf" = lintr::T_and_F_symbol_linter
    )
    , cache = FALSE
)

On {lintr} 2.0.1 installed from CRAN and on the latest version from GitHub (801fac3, installed with remotes::install_github("r-lib/lintr")), this produces the following output (the (...) is mine, just to make the path a bit more readable):

(...)/T/RtmpIvPGWZ/fileb817b0f6442.R:1:14: style: Use TRUE instead of the symbol T.
do_thing <- T
            ~^

As a user of {lintr}, I'd like to see the linter name printed in the output, like this:

(...)/RtmpIvPGWZ/fileb817b0f6442.R:1:14: style: [T_and_F_symbol_linter] Use TRUE instead of the symbol T.
do_thing <- T
            ~^

Motivation

I learned tonight from @MichaelChirico that as of {lintr} 3.0.0, it'll be possible to use a comment like the following to say "ignore warnings from a specific linter on this line" (microsoft/LightGBM#5249 (comment)).

x <- T  # nolint: T_and_F_symbol_linter`

I totally see the value in being specific there and would like to do that. But since the linter name isn't printed in the warnings from lintr::lint(), figuring out the right value to add in that comment will require some trial-and-error or searching in this package's source code.

References:

As an example, flake8 also supports such targeted comments (https://flake8.pycqa.org/en/3.1.1/user/ignoring-errors.html#in-line-ignoring-errors), and I've found it really helpful that it prints in its output exactly the code that should be added to # noqa comments.

echo "x = (1,2,3,y)" > ./out.py
flake8 ./out.py

./out.py:1:7: E231 missing whitespace after ','
./out.py:1:9: E231 missing whitespace after ','
./out.py:1:11: E231 missing whitespace after ','
./out.py:1:12: F821 undefined name 'y'

Example suppressing one specific warning:

echo "x = (1,2,3,y)  # noqa: E231" > ./out.py
flake8 ./out.py

./out.py:1:12: F821 undefined name 'y'

Thanks for your time and consideration!

[MichaelChirico]

thanks for filing! indeed the though has crossed my mind a few times but I always forgot to file an issue.

v. important to be able to understand at a glance how to suppress each lint now that we have targeted suppression available

[AshesITR]

That's a very reasonable request. So far, I've used as.data.frame(lints) to find the linter name, since the data frame contains a column linter.

We should also think about other output methods, e.g. GHA comments and RStudio Source Markers

[MichaelChirico]

I think for interactive use, as.data.frame() suffices, but not available when running as a plugin or in CI.

easiest to just part of print.lints

[AshesITR]

Yep. Note GHA markers aren't made directly by print.lints IIRC.

[jameslamb]

thanks so much @AshesITR !!

[AshesITR]

Thank you for the suggestion!