chore: checkpoint before Python removal

vendor/clap/examples/cargo-example-derive.rs

@@ -0,0 +1,31 @@
+use clap::Parser;
+
+#[derive(Parser)] // requires `derive` feature
+#[command(name = "cargo")]
+#[command(bin_name = "cargo")]
+#[command(styles = CLAP_STYLING)]
+enum CargoCli {
+    ExampleDerive(ExampleDeriveArgs),
+}
+
+// See also `clap_cargo::style::CLAP_STYLING`
+pub const CLAP_STYLING: clap::builder::styling::Styles = clap::builder::styling::Styles::styled()
+    .header(clap_cargo::style::HEADER)
+    .usage(clap_cargo::style::USAGE)
+    .literal(clap_cargo::style::LITERAL)
+    .placeholder(clap_cargo::style::PLACEHOLDER)
+    .error(clap_cargo::style::ERROR)
+    .valid(clap_cargo::style::VALID)
+    .invalid(clap_cargo::style::INVALID);
+
+#[derive(clap::Args)]
+#[command(version, about, long_about = None)]
+struct ExampleDeriveArgs {
+    #[arg(long)]
+    manifest_path: Option<std::path::PathBuf>,
+}
+
+fn main() {
+    let CargoCli::ExampleDerive(args) = CargoCli::parse();
+    println!("{:?}", args.manifest_path);
+}