Deprecate several flags in rustdoc

Part of rust-lang#44136

src/librustdoc/lib.rs

@@ -267,6 +267,9 @@ pub fn main_args(args: &[String]) -> isize {
  // Check for unstable options.
  nightly_options::check_nightly_options(&matches, &opts());
 
+ // check for deprecated options
+ check_deprecated_options(&matches);
+
  if matches.opt_present("h") || matches.opt_present("help") {
  usage("rustdoc");
  return 0;
@@ -538,3 +541,16 @@ where R: 'static + Send, F: 'static + Send + FnOnce(Output) -> R {
  });
  rx.recv().unwrap()
 }
+
+/// Prints deprecation warnings for deprecated options
+fn check_deprecated_options(matches: &getopts::Matches) {
+ if matches.opt_present("input-format") ||
+ matches.opt_present("output-format") ||
+ matches.opt_present("plugin-path") ||
+ matches.opt_present("plugins") ||
+ matches.opt_present("no-defaults") ||
+ matches.opt_present("passes") {
+ eprintln!("WARNING: this flag is considered deprecated");
+ eprintln!("WARNING: please see https://github.com/rust-lang/rust/issues/44136");
+ }
+}