Merge pull request #666 from r-lib/sysreqs-platforms

List known platforms in `pkg_sysreqs()` documentation

DESCRIPTION

@@ -87,5 +87,5 @@ Config/Needs/deploy:
     processx
 Config/testthat/edition: 3
 Encoding: UTF-8
-RoxygenNote: 7.2.3.9000
+RoxygenNote: 7.3.2
 Biarch: true

R/sysreqs.R

@@ -68,10 +68,16 @@ sysreqs_fix_installed <- function(packages = NULL,
 #' Calculate system requirements of one of more packages
 #'
 #' @inheritParams pkg_install
-#' @param sysreqs_platform System requirements platform. If `NULL`, then the
-#'   `sysreqs_platform` \eval{man_config_link("configuration option")}
-#'   is used, which defaults to the current platform. Set this option if
-#'   \eval{.packageName} does not detect your platform correctly.
+#' @param sysreqs_platform System requirements platform. 
+#' 
+#'   If `NULL`, then the `sysreqs_platform` 
+#'   \eval{man_config_link("configuration option")} is used, which defaults to 
+#'   the current platform. 
+#' 
+#'   Set this option if to one of \eval{platforms()} if \eval{.packageName} 
+#'   fails to correctly detect your platform or if you want to see the system 
+#'   requirements for a different platform.
+#'   
 #' @return List with entries:
 #'   * `os`: character string. Operating system.
 #'   * `distribution`: character string. Linux distribution, `NA` if the
@@ -197,3 +203,8 @@ print.pak_sysreqs <- function(x, ...) {
   class(x) <- setdiff(class(x), "pak_sysreqs")
   NextMethod("[")
 }
+
+
+platforms <- function() {
+  paste0('\\code{"', sort(sysreqs_platforms()$distribution), '"}', collapse = ", ")
+}