currencies in client never drifts from the server from now on

common/src/money.rs

@@ -18,6 +18,24 @@ pub fn require_iso_currency_code(currency_code: &str) -> Result<&'static iso::Cu
     iso::find(currency_code).ok_or_else(|| format!("Unknown ISO-4217 currency: {currency_code}"))
 }
 
+/// Returns every currency accepted by [`require_iso_currency_code`], ordered by
+/// its canonical alphabetic code.
+pub fn iso_currency_codes() -> Vec<&'static str> {
+    let mut currencies = Vec::new();
+    for first in b'A'..=b'Z' {
+        for second in b'A'..=b'Z' {
+            for third in b'A'..=b'Z' {
+                let bytes = [first, second, third];
+                let code = std::str::from_utf8(&bytes).expect("uppercase ASCII currency code");
+                if let Some(currency) = iso::find(code) {
+                    currencies.push(currency.iso_alpha_code);
+                }
+            }
+        }
+    }
+    currencies
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;