Implement enum config options deserialization

Author: GabrielMajeri

src/cargo/util/config/de.rs

@@ -195,11 +195,31 @@ impl<'de, 'config> de::Deserializer<'de> for Deserializer<'config> {
         }
     }
 
+    fn deserialize_enum<V>(
+        self,
+        _name: &'static str,
+        _variants: &'static [&'static str],
+        visitor: V,
+    ) -> Result<V::Value, Self::Error>
+    where
+        V: de::Visitor<'de>,
+    {
+        let value = self
+            .config
+            .get_string_priv(&self.key)?
+            .ok_or_else(|| ConfigError::missing(&self.key))?;
+
+        let Value { val, definition } = value;
+        visitor
+            .visit_enum(val.into_deserializer())
+            .map_err(|e: ConfigError| e.with_key_context(&self.key, definition))
+    }
+
     // These aren't really supported, yet.
     serde::forward_to_deserialize_any! {
         f32 f64 char str bytes
         byte_buf unit unit_struct
-        enum identifier ignored_any
+        identifier ignored_any
     }
 }
 

tests/testsuite/config.rs

@@ -1276,3 +1276,26 @@ strip = 'debuginfo'
     let strip = p.strip.unwrap();
     assert_eq!(strip, Strip::DebugInfo);
 }
+
+#[cargo_test]
+fn parse_enum_fail() {
+    write_config(
+        "\
+[profile.release]
+strip = 'invalid'
+",
+    );
+
+    let config = new_config();
+
+    assert_error(
+        config
+            .get::<toml::TomlProfile>("profile.release")
+            .unwrap_err(),
+        "\
+error in [..]/.cargo/config: could not load config key `profile.release.strip`
+
+Caused by:
+  unknown variant `invalid`, expected one of `debuginfo`, `none`, `symbols`",
+    );
+}