fix!: Prefer IntoIterator over &[]

The main breakinge change cases:
- `&[char]`: now requires removing `&`
- All other non-ID `&[_]`: hopefully clap-rs#1041 will make these non-breaking

Fixes clap-rs#2870

Author: epage

Diff for: CHANGELOG.md

@@ -42,6 +42,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
   `Command::disable_version_flag`) and mark the custom flags as `global(true)`.
 - Looking up a group in `ArgMatches` now returns the arg `Id`s, rather than the values.
 - Various `Arg`, `Command`, and `ArgGroup` calls were switched from accepting `&[]` to `[]` via `IntoIterator`
+- `Arg::short_aliases` and other builder functions that took `&[]` need the `&` dropped
 - *(help)* Make `DeriveDisplayOrder` the default and removed the setting.  To sort help, set `next_display_order(None)` (#2808)
 - *(help)* Subcommand display order respects `Command::next_display_order` instead of `DeriveDisplayOrder` and using its own initial display order value (#2808)
 - *(env)* Parse `--help` and `--version` like any `ArgAction::SetTrue` flag (#3776)

Diff for: clap_bench/benches/03_complex.rs

@@ -13,7 +13,7 @@ macro_rules! create_app {
             .arg(arg!(-o --option <opt> ... "tests options").required(false))
             .arg(arg!([positional] "tests positionals"))
             .arg(arg!(-f --flag ... "tests flags").global(true))
-            .args(&[
+            .args([
                 arg!(flag2: -F "tests flags with exclusions")
                     .conflicts_with("flag")
                     .requires("option2"),
@@ -27,10 +27,10 @@ macro_rules! create_app {
                     .value_parser(OPT3_VALS),
                 arg!([positional3] ... "tests positionals with specific values")
                     .value_parser(POS3_VALS),
-                arg!(--multvals <s> "Tests multiple values not mult occs").required(false).value_names(&["one", "two"]),
+                arg!(--multvals <s> "Tests multiple values not mult occs").required(false).value_names(["one", "two"]),
                 arg!(
                     --multvalsmo <s> "Tests multiple values, not mult occs"
-                ).required(false).value_names(&["one", "two"]),
+                ).required(false).value_names(["one", "two"]),
                 arg!(--minvals2 <minvals> ... "Tests 2 min vals").num_args(2..).required(false),
                 arg!(--maxvals3 <maxvals> ... "Tests 3 max vals").num_args(1..=3).required(false),
             ])
@@ -109,14 +109,14 @@ pub fn build_from_builder(c: &mut Criterion) {
                     Arg::new("multvals")
                         .long("multvals")
                         .help("Tests multiple values, not mult occs")
-                        .value_names(&["one", "two"]),
+                        .value_names(["one", "two"]),
                 )
                 .arg(
                     Arg::new("multvalsmo")
                         .long("multvalsmo")
                         .action(ArgAction::Append)
                         .help("Tests multiple values, not mult occs")
-                        .value_names(&["one", "two"]),
+                        .value_names(["one", "two"]),
                 )
                 .arg(
                     Arg::new("minvals")

Diff for: clap_bench/benches/04_new_help.rs

@@ -45,7 +45,7 @@ fn app_example3<'c>() -> Command<'c> {
                 .short('d')
                 .action(ArgAction::SetTrue),
         )
-        .args(&[
+        .args([
             Arg::new("config")
                 .help("sets the config file to use")
                 .action(ArgAction::Set)

Diff for: clap_derive/src/attrs.rs

@@ -561,7 +561,7 @@ impl Attrs {
                                 static DEFAULT_VALUES: clap::__macro_refs::once_cell::sync::Lazy<Vec<&str>> = clap::__macro_refs::once_cell::sync::Lazy::new(|| {
                                     iter_to_vals(#expr)
                                 });
-                                &*DEFAULT_VALUES.as_slice()
+                                DEFAULT_VALUES.iter().copied()
                             }
                         })
                     } else {
@@ -582,7 +582,7 @@ impl Attrs {
                                 static DEFAULT_VALUES: clap::__macro_refs::once_cell::sync::Lazy<Vec<&str>> = clap::__macro_refs::once_cell::sync::Lazy::new(|| {
                                     DEFAULT_STRINGS.iter().map(::std::string::String::as_str).collect()
                                 });
-                                &*DEFAULT_VALUES.as_slice()
+                                DEFAULT_VALUES.iter().copied()
                             }
                         })
                     };
@@ -677,7 +677,7 @@ impl Attrs {
                                 static DEFAULT_VALUES: clap::__macro_refs::once_cell::sync::Lazy<Vec<&::std::ffi::OsStr>> = clap::__macro_refs::once_cell::sync::Lazy::new(|| {
                                     iter_to_vals(#expr)
                                 });
-                                &*DEFAULT_VALUES.as_slice()
+                                DEFAULT_VALUES.iter().copied()
                             }
                         })
                     } else {
@@ -698,7 +698,7 @@ impl Attrs {
                                 static DEFAULT_VALUES: clap::__macro_refs::once_cell::sync::Lazy<Vec<&::std::ffi::OsStr>> = clap::__macro_refs::once_cell::sync::Lazy::new(|| {
                                     DEFAULT_OS_STRINGS.iter().map(::std::ffi::OsString::as_os_str).collect()
                                 });
-                                &*DEFAULT_VALUES.as_slice()
+                                DEFAULT_VALUES.iter().copied()
                             }
                         })
                     };