Untagged and internally tagged enums

test_suite/tests/compile-fail/enum-representation/internal-tuple-variant.rs

@@ -0,0 +1,10 @@
+#[macro_use]
+extern crate serde_derive;
+
+#[derive(Serialize)] //~ ERROR: custom derive attribute panicked
+#[serde(tag = "type")] //~^ HELP: #[serde(tag = "...")] cannot be used with tuple variants
+enum E {
+    Tuple(u8, u8),
+}
+
+fn main() {}

test_suite/tests/compile-fail/enum-representation/internally-tagged-struct.rs

@@ -0,0 +1,8 @@
+#[macro_use]
+extern crate serde_derive;
+
+#[derive(Serialize)] //~ ERROR: custom derive attribute panicked
+#[serde(tag = "type")] //~^ HELP: #[serde(tag = "...")] can only be used on enums
+struct S;
+
+fn main() {}

test_suite/tests/compile-fail/enum-representation/untagged-and-internal.rs

@@ -0,0 +1,12 @@
+#[macro_use]
+extern crate serde_derive;
+
+#[derive(Serialize)] //~ ERROR: custom derive attribute panicked
+#[serde(untagged)]
+#[serde(tag = "type")] //~^^ HELP: enum cannot be both untagged and internally tagged
+enum E {
+    A(u8),
+    B(String),
+}
+
+fn main() {}

test_suite/tests/compile-fail/enum-representation/untagged-struct.rs

@@ -0,0 +1,8 @@
+#[macro_use]
+extern crate serde_derive;
+
+#[derive(Serialize)] //~ ERROR: custom derive attribute panicked
+#[serde(untagged)] //~^ HELP: #[serde(untagged)] can only be used on enums
+struct S;
+
+fn main() {}