fix: Add test for flattening struct in enum

clap_derive/tests/ui/flatten_on_subcommand.stderr → clap_derive/tests/ui/flatten_enum_in_struct.stderr

@@ -1,5 +1,5 @@
 error[E0277]: the trait bound `SubCmd: clap::Args` is not satisfied
- --> $DIR/flatten_on_subcommand.rs:3:12
+ --> $DIR/flatten_enum_in_struct.rs:3:12
   |
 3 |     #[clap(flatten)]
   |            ^^^^^^^ the trait `clap::Args` is not implemented for `SubCmd`

clap_derive/tests/ui/flatten_struct_in_enum.rs

@@ -0,0 +1,10 @@
+#[derive(clap::Parser)]
+enum Opt {
+    #[clap(flatten)]
+    Sub(SubCmd),
+}
+
+#[derive(clap::Parser)]
+struct SubCmd {}
+
+fn main() {}

clap_derive/tests/ui/flatten_struct_in_enum.stderr

@@ -0,0 +1,26 @@
+error[E0277]: the trait bound `SubCmd: Subcommand` is not satisfied
+ --> $DIR/flatten_struct_in_enum.rs:1:10
+  |
+1 | #[derive(clap::Parser)]
+  |          ^^^^^^^^^^^^ the trait `Subcommand` is not implemented for `SubCmd`
+  |
+  = note: required by `has_subcommand`
+  = note: this error originates in the derive macro `clap::Parser` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+error[E0277]: the trait bound `SubCmd: Subcommand` is not satisfied
+ --> $DIR/flatten_struct_in_enum.rs:1:10
+  |
+1 | #[derive(clap::Parser)]
+  |          ^^^^^^^^^^^^ the trait `Subcommand` is not implemented for `SubCmd`
+  |
+  = note: required by `augment_subcommands`
+  = note: this error originates in the derive macro `clap::Parser` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+error[E0277]: the trait bound `SubCmd: Subcommand` is not satisfied
+ --> $DIR/flatten_struct_in_enum.rs:1:10
+  |
+1 | #[derive(clap::Parser)]
+  |          ^^^^^^^^^^^^ the trait `Subcommand` is not implemented for `SubCmd`
+  |
+  = note: required by `augment_subcommands_for_update`
+  = note: this error originates in the derive macro `clap::Parser` (in Nightly builds, run with -Z macro-backtrace for more info)