Condense lint_dir(patterns=) default (#2174)

* use literal regex for pattern= argument

* TODO

---------

Co-authored-by: AshesITR <alexander.rosenstock@web.de>

R/lint.R

@@ -130,8 +130,8 @@ lint <- function(filename, linters = NULL, ..., cache = FALSE, parse_settings =
 lint_dir <- function(path = ".", ...,
                      relative_path = TRUE,
                      exclusions = list("renv", "packrat"),
-                     pattern = rex(".", or(group(one_of("Rr"), or("", "html", "md", "nw", "rst", "tex", "txt")),
-                                           group(one_of("Qq"), "md")), end),
+                     # TODO(r-lib/rex#85): Re-write in case-sensitive rex()
+                     pattern = "(?i)[.](r|rmd|qmd|rnw|rhtml|rrst|rtex|rtxt)$",
                      parse_settings = TRUE,
                      show_progress = NULL) {
   if (has_positional_logical(list(...))) {