1 files changed, 32 insertions, 0 deletions
diff --git a/third_party/rust/clap/examples/derive_ref/custom-bool.rs b/third_party/rust/clap/examples/derive_ref/custom-bool.rs
new file mode 100644
index 0000000000..10f93f40ac
--- /dev/null
+++ b/third_party/rust/clap/examples/derive_ref/custom-bool.rs
@@ -0,0 +1,32 @@
+use clap::Parser;
+
+#[derive(Parser, Debug, PartialEq)]
+#[clap(author, version, about, long_about = None)]
+struct Opt {
+    // Default parser for `try_from_str` is FromStr::from_str.
+    // `impl FromStr for bool` parses `true` or `false` so this
+    // works as expected.
+    #[clap(long, parse(try_from_str))]
+    foo: bool,
+
+    // Of course, this could be done with an explicit parser function.
+    #[clap(long, parse(try_from_str = true_or_false), default_value_t)]
+    bar: bool,
+
+    // `bool` can be positional only with explicit `parse(...)` annotation
+    #[clap(parse(try_from_str))]
+    boom: bool,
+}
+
+fn true_or_false(s: &str) -> Result<bool, &'static str> {
+    match s {
+        "true" => Ok(true),
+        "false" => Ok(false),
+        _ => Err("expected `true` or `false`"),
+    }
+}
+
+fn main() {
+    let opt = Opt::parse();
+    dbg!(opt);
+}