fix(parser): SetFalse should also not allow self-override

Author: epage

src/builder/action.rs

@@ -169,7 +169,7 @@ pub enum ArgAction {
     ///             .action(clap::ArgAction::SetFalse)
     ///     );
     ///
-    /// let matches = cmd.clone().try_get_matches_from(["mycmd", "--flag", "--flag"]).unwrap();
+    /// let matches = cmd.clone().try_get_matches_from(["mycmd", "--flag"]).unwrap();
     /// assert!(matches.contains_id("flag"));
     /// assert_eq!(
     ///     matches.get_one::<bool>("flag").copied(),

src/parser/parser.rs

@@ -1240,7 +1240,7 @@ impl<'cmd> Parser<'cmd> {
                     raw_vals
                 };
 
-                if matcher.remove(&arg.id) && self.cmd.is_args_override_self() {
+                if matcher.remove(&arg.id) && !self.cmd.is_args_override_self() {
                     return Err(ClapError::argument_conflict(
                         self.cmd,
                         arg.to_string(),

tests/builder/action.rs

@@ -240,8 +240,15 @@ fn set_false() {
     assert_eq!(matches.contains_id("mammal"), true);
     assert_eq!(matches.index_of("mammal"), Some(1));
 
+    let result = cmd
+        .clone()
+        .try_get_matches_from(["test", "--mammal", "--mammal"]);
+    let err = result.err().unwrap();
+    assert_eq!(err.kind(), ErrorKind::ArgumentConflict);
+
     let matches = cmd
         .clone()
+        .args_override_self(true)
         .try_get_matches_from(["test", "--mammal", "--mammal"])
         .unwrap();
     assert_eq!(*matches.get_one::<bool>("mammal").unwrap(), false);