Providing pattern to dir_ls() silently gives wrong result

[jennybc]

library(fs)

dir_ls()
#> DESCRIPTION                        LICENSE                            
#> LICENSE.md                         NAMESPACE                          
#> NEWS.md                            R                                  
#> README.Rmd                         README.md                          
#> _pkgdown.yml                       codecov.yml                        
#> cran-comments.md                   fs.Rproj                           
#> inst                               man                                
#> man-roxygen                        reprex72c8745a53e2_reprex.R        
#> reprex72c8745a53e2_reprex.spin.R   reprex72c8745a53e2_reprex.spin.Rmd 
#> revdep                             src                                
#> tests                              vignettes

dir_ls(regexp = "[.]yml$")
#> _pkgdown.yml codecov.yml

dir_ls(pattern = "[.]yml$")
#> DESCRIPTION                        LICENSE                            
#> LICENSE.md                         NAMESPACE                          
#> NEWS.md                            R                                  
#> README.Rmd                         README.md                          
#> _pkgdown.yml                       codecov.yml                        
#> cran-comments.md                   fs.Rproj                           
#> inst                               man                                
#> man-roxygen                        reprex72c8745a53e2_reprex.R        
#> reprex72c8745a53e2_reprex.spin.R   reprex72c8745a53e2_reprex.spin.Rmd 
#> revdep                             src                                
#> tests                              vignettes

^{Created on 2021-01-29 by the reprex package (v1.0.0.9000)}

It's very easy for people to provide their filtering regex to dir_ls() via pattern à la list.files(), when what they really mean is regexp. And then pattern gets silently swallowed by ... in dir_ls() and path_filter(), resulting in no filtering at all. The docs say that ... gets passed along to grep(), but that doesn't happen in this case.

Discovered while debugging a puzzling error in usethis (r-lib/usethis#1336).

[gaborcsardi]

fs does pass ... down to grep(), e.g. fixed is passed:

❯ dir_ls(regexp = ".", fixed = TRUE)
LICENSE.md             MAINTENANCE.md         NEWS.md
R-4.1.2-1-1.x86_64.rpm README.Rmd             README.md
_pkgdown.yml           codecov.yml            cran-comments.md
fs.Rproj

❯ dir_ls(regexp = ".")
DESCRIPTION            LICENSE                LICENSE.md
MAINTENANCE.md         NAMESPACE              NEWS.md
R                      R-4.1.2-1-1.x86_64.rpm README.Rmd
README.md              _pkgdown.yml           codecov.yml
cran-comments.md       fs.Rproj               inst
man                    man-roxygen            revdep
src                    tests                  vignettes

But fs also sets the pattern argument of grep() explicitly, in addition to passing it in .... R seems to silently ignore the one in ....

We'll fix this at some point.

[jennybc]

I just puzzled myself with this again today.