Rollup merge of #132754 - Zalathar:opts, r=GuillaumeGomez,jieyouxu

Simplify the internal API for declaring command-line options

The internal APIs for declaring command-line options are old, and intimidatingly complex. This PR replaces them with a single function that takes explicit `stability` and `kind` arguments, making it easier to see how each option is handled, and whether it is treated as stable or unstable.

We also don't appear to have any tests for the output of `rustc --help` and similar, so I've added a run-make test to verify that this PR doesn't change any output. (There is already a similar run-make test for rustdoc's help output.)

---

The librustdoc changes are simply adjusting to updated compiler APIs; no functional change intended.

---

A side-effect of these changes is that rustfmt can once again format the entirety of these option declaration lists, which it was not doing before.

Author: matthiaskrgr

Diff for: compiler/rustc_driver_impl/src/lib.rs

@@ -937,7 +937,7 @@ fn usage(verbose: bool, include_unstable_options: bool, nightly_build: bool) {
     let groups = if verbose { config::rustc_optgroups() } else { config::rustc_short_optgroups() };
     let mut options = getopts::Options::new();
     for option in groups.iter().filter(|x| include_unstable_options || x.is_stable()) {
-        (option.apply)(&mut options);
+        option.apply(&mut options);
     }
     let message = "Usage: rustc [OPTIONS] INPUT";
     let nightly_help = if nightly_build {
@@ -1219,7 +1219,7 @@ pub fn handle_options(early_dcx: &EarlyDiagCtxt, args: &[String]) -> Option<geto
     let mut options = getopts::Options::new();
     let optgroups = config::rustc_optgroups();
     for option in &optgroups {
-        (option.apply)(&mut options);
+        option.apply(&mut options);
     }
     let matches = options.parse(args).unwrap_or_else(|e| {
         let msg: Option<String> = match e {
@@ -1233,7 +1233,7 @@ pub fn handle_options(early_dcx: &EarlyDiagCtxt, args: &[String]) -> Option<geto
                 optgroups.iter().find(|option| option.name == opt).map(|option| {
                     // Print the help just for the option in question.
                     let mut options = getopts::Options::new();
-                    (option.apply)(&mut options);
+                    option.apply(&mut options);
                     // getopt requires us to pass a function for joining an iterator of
                     // strings, even though in this case we expect exactly one string.
                     options.usage_with_format(|it| {

Diff for: compiler/rustc_interface/src/tests.rs

@@ -102,7 +102,7 @@ where
 fn optgroups() -> getopts::Options {
     let mut opts = getopts::Options::new();
     for group in rustc_optgroups() {
-        (group.apply)(&mut opts);
+        group.apply(&mut opts);
     }
     return opts;
 }