Rust: Restore compatibility with Debian Bookworm

Cargo.deps.newer

@@ -2,7 +2,7 @@
 # For the newer-than-Byzantium config
 
 bitflags = "1.3.*"
-clap = { version = "3.2.*", features=["std"], default-features = false }
+clap = { version = "4.*", features=["std"], default-features = false }
 zbus = "1.9.*"
 zvariant = "2.10.*"
 # Newer versions seem to confuse the version of Cargo on Debian Bullseye

Cargo.toml.in

@@ -24,6 +24,7 @@ path = "@path@/examples/find_orphan_layouts.rs"
 [features]
 glib_v0_14 = []
 zbus_v1_5 = []
+clap_v4 = []
 
 # Dependencies which don't change based on build flags
 [dependencies]

meson.build

@@ -99,7 +99,7 @@ cargo_toml_base = configure_file(
 cargo_patch = []
 
 if get_option('newer') == true
-    cargo_build_flags += ['--features', 'glib_v0_14,zbus_v1_5']
+    cargo_build_flags += ['--features', 'glib_v0_14,zbus_v1_5,clap_v4']
     cargo_deps = files('Cargo.deps.newer')
     cargo_lock = files('Cargo.lock.newer')
 else

src/bin/test_layout.rs

@@ -5,12 +5,28 @@ extern crate rs;
 use rs::tests::check_layout_file;
 
 fn main() -> () {
+    #[cfg(feature = "clap_v4")]
+    let matches = clap::Command::new("squeekboard-test-layout")
+        .about("Test keyboard layout for errors. Returns OK or an error message containing further information.")
+        .arg(
+            clap::Arg::new("INPUT")
+                .required(true)
+                .help("Yaml keyboard layout file to test")
+        )
+        .get_matches();
+    #[cfg(feature = "clap_v4")]
+    let m = matches.get_one::<String>("INPUT");
+
+    #[cfg(not(feature = "clap_v4"))]
     let matches = clap_app!(test_layout =>
         (name: "squeekboard-test-layout")
         (about: "Test keyboard layout for errors. Returns OK or an error message containing further information.")
         (@arg INPUT: +required "Yaml keyboard layout file to test")
     ).get_matches();
-    if check_layout_file(matches.value_of("INPUT").unwrap()) == () {
+    #[cfg(not(feature = "clap_v4"))]
+    let m = matches.value_of("INPUT");
+
+    if check_layout_file(m.unwrap()) == () {
         println!("Test result: OK");
     }
 }