WIP

src/builder/app_settings.rs

@@ -31,6 +31,7 @@ pub(crate) enum AppSettings {
     IgnoreErrors,
     AllowHyphenValues,
     AllowNegativeNumbers,
+    AllArgsOverrideSelf,
     AllowMissingPositional,
     TrailingVarArg,
     DontDelimitTrailingValues,
@@ -93,6 +94,7 @@ bitflags! {
         const VALID_ARG_FOUND                = 1 << 35;
         const INFER_SUBCOMMANDS              = 1 << 36;
         const CONTAINS_LAST                  = 1 << 37;
+        const ARGS_OVERRIDE_SELF             = 1 << 38;
         const HELP_REQUIRED                  = 1 << 39;
         const SUBCOMMAND_PRECEDENCE_OVER_ARG = 1 << 40;
         const DISABLE_HELP_FLAG              = 1 << 41;
@@ -163,6 +165,8 @@ impl_settings! { AppSettings, AppFlags,
         => Flags::BIN_NAME_BUILT,
     InferSubcommands
         => Flags::INFER_SUBCOMMANDS,
+    AllArgsOverrideSelf
+        => Flags::ARGS_OVERRIDE_SELF,
     InferLongArgs
         => Flags::INFER_LONG_ARGS
 }

src/builder/command.rs

@@ -978,6 +978,23 @@ impl Command {
         }
     }
 
+    /// Specifies that all arguments override themselves.
+    ///
+    /// This is the equivalent to saying the `foo` arg using [`Arg::overrides_with("foo")`] for all
+    /// defined arguments.
+    ///
+    /// **NOTE:** This choice is propagated to all child subcommands.
+    ///
+    /// [`Arg::overrides_with("foo")`]: crate::Arg::overrides_with()
+    #[inline]
+    pub fn args_override_self(self, yes: bool) -> Self {
+        if yes {
+            self.global_setting(AppSettings::AllArgsOverrideSelf)
+        } else {
+            self.unset_global_setting(AppSettings::AllArgsOverrideSelf)
+        }
+    }
+
     /// Disables the automatic delimiting of values after `--` or when [`Command::trailing_var_arg`]
     /// was used.
     ///
@@ -3671,6 +3688,11 @@ impl Command {
         self.is_set(AppSettings::ArgsNegateSubcommands)
     }
 
+    #[doc(hidden)]
+    pub fn is_args_override_self(&self) -> bool {
+        self.is_set(AppSettings::AllArgsOverrideSelf)
+    }
+
     /// Report whether [`Command::subcommand_precedence_over_arg`] is set
     pub fn is_subcommand_precedence_over_arg_set(&self) -> bool {
         self.is_set(AppSettings::SubcommandPrecedenceOverArg)

src/parser/arg_matcher.rs

@@ -101,8 +101,8 @@ impl ArgMatcher {
         self.matches.args.get_mut(arg)
     }
 
-    pub(crate) fn remove(&mut self, arg: &Id) {
-        self.matches.args.remove(arg);
+    pub(crate) fn remove(&mut self, arg: &Id) -> bool {
+        self.matches.args.remove(arg).is_some()
     }
 
     pub(crate) fn contains(&self, arg: &Id) -> bool {

src/parser/parser.rs

@@ -1179,7 +1179,14 @@ impl<'cmd> Parser<'cmd> {
                     self.cur_idx.set(self.cur_idx.get() + 1);
                     debug!("Parser::react: cur_idx:={}", self.cur_idx.get());
                 }
-                matcher.remove(&arg.id);
+                if matcher.remove(&arg.id) && !self.cmd.is_args_override_self() {
+                    return Err(ClapError::argument_conflict(
+                        self.cmd,
+                        arg.to_string(),
+                        vec![arg.to_string()],
+                        Usage::new(self.cmd).create_usage_with_title(&[]),
+                    ));
+                }
                 self.start_custom_arg(matcher, arg, source);
                 self.push_arg_values(arg, raw_vals, matcher)?;
                 if cfg!(debug_assertions) && matcher.needs_more_vals(arg) {
@@ -1213,7 +1220,14 @@ impl<'cmd> Parser<'cmd> {
                     raw_vals
                 };
 
-                matcher.remove(&arg.id);
+                if matcher.remove(&arg.id) && !self.cmd.is_args_override_self() {
+                    return Err(ClapError::argument_conflict(
+                        self.cmd,
+                        arg.to_string(),
+                        vec![arg.to_string()],
+                        Usage::new(self.cmd).create_usage_with_title(&[]),
+                    ));
+                }
                 self.start_custom_arg(matcher, arg, source);
                 self.push_arg_values(arg, raw_vals, matcher)?;
                 Ok(ParseResult::ValuesDone)
@@ -1225,7 +1239,14 @@ impl<'cmd> Parser<'cmd> {
                     raw_vals
                 };
 
-                matcher.remove(&arg.id);
+                if matcher.remove(&arg.id) && self.cmd.is_args_conflicts_with_self() {
+                    return Err(ClapError::argument_conflict(
+                        self.cmd,
+                        arg.to_string(),
+                        vec![arg.to_string()],
+                        Usage::new(self.cmd).create_usage_with_title(&[]),
+                    ));
+                }
                 self.start_custom_arg(matcher, arg, source);
                 self.push_arg_values(arg, raw_vals, matcher)?;
                 Ok(ParseResult::ValuesDone)