From d1273051fcdf3cd19b20f0d4a4ba64872eeed334 Mon Sep 17 00:00:00 2001
From: Ed Page <eopage@gmail.com>
Date: Fri, 11 Feb 2022 15:10:38 -0600
Subject: [PATCH] fix(derive): Give more meaningful error on missing subcommand

Showing help on `$ cmd` makes sense but when an arg is present but not
subcommand, that suggests the user missed something, so we should show a
more specific error message.

Compatibility note: Settings we apply for subcommands have changed.

Fixes #3280
---
 clap_derive/src/derives/args.rs       | 6 +++---
 clap_derive/src/derives/into_app.rs   | 3 ++-
 clap_derive/src/derives/subcommand.rs | 4 +++-
 3 files changed, 8 insertions(+), 5 deletions(-)

diff --git a/clap_derive/src/derives/args.rs b/clap_derive/src/derives/args.rs
index 291b6287d24..2e8aa4e2983 100644
--- a/clap_derive/src/derives/args.rs
+++ b/clap_derive/src/derives/args.rs
@@ -168,9 +168,9 @@ pub fn gen_augment(
                 quote!()
             } else {
                 quote_spanned! { kind.span()=>
-                    let #app_var = #app_var.setting(
-                        clap::AppSettings::SubcommandRequiredElseHelp
-                    );
+                    let #app_var = #app_var
+                        .subcommand_required(true)
+                        .arg_required_else_help(true);
                 }
             };
 
diff --git a/clap_derive/src/derives/into_app.rs b/clap_derive/src/derives/into_app.rs
index a7842707a93..9573504c0c4 100644
--- a/clap_derive/src/derives/into_app.rs
+++ b/clap_derive/src/derives/into_app.rs
@@ -104,7 +104,8 @@ pub fn gen_for_enum(enum_name: &Ident, generics: &Generics, attrs: &[Attribute])
         impl #impl_generics clap::IntoApp for #enum_name #ty_generics #where_clause {
             fn into_app<'b>() -> clap::App<'b> {
                 let #app_var = clap::App::new(#name)
-                    .setting(clap::AppSettings::SubcommandRequiredElseHelp);
+                    .subcommand_required(true)
+                    .arg_required_else_help(true);
                 <Self as clap::Subcommand>::augment_subcommands(#app_var)
             }
 
diff --git a/clap_derive/src/derives/subcommand.rs b/clap_derive/src/derives/subcommand.rs
index 1e53375fb9a..3301bdda76f 100644
--- a/clap_derive/src/derives/subcommand.rs
+++ b/clap_derive/src/derives/subcommand.rs
@@ -248,7 +248,9 @@ fn gen_augment(
                             let #subcommand_var = clap::App::new(#name);
                             let #subcommand_var = #subcommand_var #initial_app_methods;
                             let #subcommand_var = #arg_block;
-                            let #subcommand_var = #subcommand_var.setting(clap::AppSettings::SubcommandRequiredElseHelp);
+                            let #subcommand_var = #subcommand_var
+                                .subcommand_required(true)
+                                .arg_required_else_help(true);
                             #subcommand_var #final_from_attrs
                         });
                     };