Error when parsing FromMeta containing NestedMeta::Lit

core/src/codegen/variant_data.rs

@@ -58,11 +58,17 @@ impl<'a> FieldsGen<'a> {
 
         quote!(
             for __item in __items {
-                if let ::syn::NestedMeta::Meta(ref __inner) = *__item {
-                    let __name = ::darling::util::path_to_string(__inner.path());
-                    match __name.as_str() {
-                        #(#arms)*
-                        __other => { #handle_unknown }
+                match *__item {
+                    ::syn::NestedMeta::Meta(ref __inner) => {
+                        let __name = ::darling::util::path_to_string(__inner.path());
+                        match __name.as_str() {
+                            #(#arms)*
+                            __other => { #handle_unknown }
+                        }
+                    }
+                    ::syn::NestedMeta::Lit(ref __inner) => {
+                        __errors.push(::darling::Error::unsupported_format("literal")
+                            .with_span(__inner));
                     }
                 }
             }

tests/from_meta.rs

@@ -0,0 +1,66 @@
+use darling::{Error, FromMeta};
+use syn::parse_quote;
+
+#[derive(Debug, FromMeta)]
+struct Meta {
+    #[darling(default)]
+    meta1: Option<String>,
+    #[darling(default)]
+    meta2: bool,
+}
+
+#[test]
+fn nested_meta_meta_value() {
+    let meta = Meta::from_list(&vec![parse_quote! {
+        meta1 = "thefeature"
+    }])
+    .unwrap();
+    assert_eq!(meta.meta1, Some("thefeature".to_string()));
+    assert_eq!(meta.meta2, false);
+}
+
+#[test]
+fn nested_meta_meta_bool() {
+    let meta = Meta::from_list(&vec![parse_quote! {
+        meta2
+    }])
+    .unwrap();
+    assert_eq!(meta.meta1, None);
+    assert_eq!(meta.meta2, true);
+}
+
+#[test]
+fn nested_meta_lit_string_errors() {
+    let err = Meta::from_list(&vec![parse_quote! {
+        "meta2"
+    }])
+    .unwrap_err();
+    assert_eq!(
+        err.to_string(),
+        Error::unsupported_format("literal").to_string()
+    );
+}
+
+#[test]
+fn nested_meta_lit_integer_errors() {
+    let err = Meta::from_list(&vec![parse_quote! {
+        2
+    }])
+    .unwrap_err();
+    assert_eq!(
+        err.to_string(),
+        Error::unsupported_format("literal").to_string()
+    );
+}
+
+#[test]
+fn nested_meta_lit_bool_errors() {
+    let err = Meta::from_list(&vec![parse_quote! {
+        true
+    }])
+    .unwrap_err();
+    assert_eq!(
+        err.to_string(),
+        Error::unsupported_format("literal").to_string()
+    );
+}