Fix a bug when flattening an enum

Fix #103

CHANGELOG.md

@@ -1,16 +1,23 @@
-# NEXT
+# v0.2.8 (2018-04-28)
 
 * Add `StructOpt::from_iter_safe()`, which returns an `Error` instead of
   killing the program when it fails to parse, or parses one of the
   short-circuiting flags. ([#98](https://github.com/TeXitoi/structopt/pull/98)
   by [@quodlibetor](https://github.com/quodlibetor))
-
-* Allow users to enable `clap` features independently.
+* Allow users to enable `clap` features independently by
+  [@Kerollmops](https://github.com/Kerollmops)
+* Fix a bug when flattening an enum
+  ([#103](https://github.com/TeXitoi/structopt/pull/103) by
+  [@TeXitoi](https://github.com/TeXitoi)
 
 # v0.2.7 (2018-04-12)
 
-* Add flattening, the insertion of options of another StructOpt struct into another ([#92](https://github.com/TeXitoi/structopt/pull/92)) by [@birkenfeld](https://github.com/birkenfeld)
-* Fail compilation when using `default_value` or `required` with `Option` ([#88](https://github.com/TeXitoi/structopt/pull/88)) by [@Kerollmops](https://github.com/Kerollmops)
+* Add flattening, the insertion of options of another StructOpt struct
+  into another ([#92](https://github.com/TeXitoi/structopt/pull/92))
+  by [@birkenfeld](https://github.com/birkenfeld)
+* Fail compilation when using `default_value` or `required` with
+  `Option` ([#88](https://github.com/TeXitoi/structopt/pull/88)) by
+  [@Kerollmops](https://github.com/Kerollmops)
 
 # v0.2.6 (2018-03-31)
 

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "structopt"
-version = "0.2.7"
+version = "0.2.8"
 authors = ["Guillaume Pinot <texitoi@texitoi.eu>"]
 description = "Parse command line argument by defining a struct."
 documentation = "https://docs.rs/structopt"
@@ -27,6 +27,6 @@ travis-ci = { repository = "TeXitoi/structopt" }
 
 [dependencies]
 clap = { version = "2.20", default-features = false }
-structopt-derive = { path = "structopt-derive", version = "0.2.7" }
+structopt-derive = { path = "structopt-derive", version = "0.2.8" }
 
 [workspace]

structopt-derive/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "structopt-derive"
-version = "0.2.7"
+version = "0.2.8"
 authors = ["Guillaume Pinot <texitoi@texitoi.eu>"]
 description = "Parse command line argument by defining a struct, derive crate."
 documentation = "https://docs.rs/structopt-derive"

structopt-derive/src/lib.rs

@@ -90,7 +90,14 @@ fn gen_augmentation(fields: &Punctuated<Field, Comma>, app_var: &Ident) -> quote
                 Kind::Subcommand(_) => None,
                 Kind::FlattenStruct => {
                     let ty = &field.ty;
-                    Some(quote! { let #app_var = <#ty>::augment_clap(#app_var); })
+                    Some(quote! {
+                        let #app_var = <#ty>::augment_clap(#app_var);
+                        let #app_var = if <#ty>::is_subcommand() {
+                            #app_var.setting(::structopt::clap::AppSettings::SubcommandRequiredElseHelp)
+                        } else {
+                            #app_var
+                        };
+                    })
                 }
                 Kind::Arg(ty) => {
                     let convert_type = match ty {

tests/subcommands.rs

@@ -160,3 +160,20 @@ fn enum_in_enum_subsubcommand() {
     let result = Opt::from_iter(&["test", "daemon", "start"]);
     assert_eq!(Opt::Daemon(DaemonCommand::Start), result);
 }
+
+#[test]
+fn flatten_enum() {
+    #[derive(StructOpt, Debug, PartialEq)]
+    struct Opt {
+        #[structopt(flatten)]
+        sub_cmd: SubCmd,
+    }
+    #[derive(StructOpt, Debug, PartialEq)]
+    enum SubCmd {
+        Foo,
+        Bar,
+    }
+
+    assert!(Opt::from_iter_safe(&["test"]).is_err());
+    assert_eq!(Opt::from_iter(&["test", "Foo"]), Opt { sub_cmd: SubCmd::Foo });
+}