fix(builder): Don't double-has arg id in default_value_ifs_os (#3815)

src/builder/arg.rs

@@ -3307,7 +3307,7 @@ impl<'help> Arg<'help> {
         ifs: &[(T, Option<&'help OsStr>, Option<&'help OsStr>)],
     ) -> Self {
         for (arg, val, default) in ifs {
-            self = self.default_value_if_os(arg.key(), *val, *default);
+            self = self.default_value_if_os(arg, *val, *default);
         }
         self
     }

tests/builder/arg_settings.rs

@@ -1,5 +1,7 @@
 #![allow(deprecated)]
-use clap::{Arg, ArgSettings};
+
+use clap::{Arg, ArgSettings, Command};
+use std::ffi::OsStr;
 
 #[test]
 fn setting() {
@@ -42,3 +44,42 @@ fn unset_setting_bitor() {
     assert!(!m.is_hide_set(), "{:#?}", m);
     assert!(!m.is_last_set(), "{:#?}", m);
 }
+
+#[test]
+fn default_value_ifs_os() {
+    let cmd = Command::new("my_cargo")
+        .arg(
+            Arg::new("flag")
+                .long("flag")
+                .allow_invalid_utf8(true)
+                .takes_value(true),
+        )
+        .arg(
+            Arg::new("other")
+                .long("other")
+                .allow_invalid_utf8(true)
+                .default_value_ifs_os(&[(
+                    "flag",
+                    Some("标记2").map(OsStr::new),
+                    Some("flag=标记2").map(OsStr::new),
+                )]),
+        );
+    let result = cmd.try_get_matches_from([
+        OsStr::new("my_cargo"),
+        OsStr::new("--flag"),
+        OsStr::new("标记2"),
+    ]);
+    assert!(result.is_ok());
+    match result {
+        Ok(arg_matches) => {
+            assert_eq!(arg_matches.value_of_os("flag"), Some(OsStr::new("标记2")));
+            assert_eq!(
+                arg_matches.value_of_os("other"),
+                Some(OsStr::new("flag=标记2")),
+            );
+        }
+        Err(e) => {
+            println!("{}", e.to_string());
+        }
+    }
+}