feat: Support parse string as git/gitoxide features from ENV and Config

- pass 'all' to enable all predefind git/gitoxide features
- stil support parse git/gitoxide as table in Config, but not support parser table in ENV

src/cargo/core/features.rs

@@ -759,7 +759,9 @@ unstable_cli_options!(
     dual_proc_macros: bool = ("Build proc-macros for both the host and the target"),
     features: Option<Vec<String>>,
     gc: bool = ("Track cache usage and \"garbage collect\" unused files"),
+    #[serde(deserialize_with = "deserialize_git_features")]
     git: Option<GitFeatures> = ("Enable support for shallow git fetch operations"),
+    #[serde(deserialize_with = "deserialize_gitoxide_features")]
     gitoxide: Option<GitoxideFeatures> = ("Use gitoxide for the given git interactions, or all of them if no argument is given"),
     host_config: bool = ("Enable the `[host]` section in the .cargo/config.toml file"),
     minimal_versions: bool = ("Resolve minimal dependency versions instead of maximum"),
@@ -866,7 +868,7 @@ where
     ))
 }
 
-#[derive(Debug, Copy, Clone, Default, Deserialize)]
+#[derive(Debug, Copy, Clone, Default, Deserialize, Ord, PartialOrd, Eq, PartialEq)]
 pub struct GitFeatures {
     /// When cloning the index, perform a shallow clone. Maintain shallowness upon subsequent fetches.
     pub shallow_index: bool,
@@ -875,12 +877,59 @@ pub struct GitFeatures {
 }
 
 impl GitFeatures {
-    fn all() -> Self {
+    pub fn all() -> Self {
         GitFeatures {
             shallow_index: true,
             shallow_deps: true,
         }
     }
+
+    fn expecting() -> String {
+        let fields = vec!["'all'", "'shallow-index'", "'shallow-deps'"];
+        format!(
+            "unstable 'git' only takes {} as valid inputs, your can use 'all' to turn out all git features",
+            fields.join(" and ")
+        )
+    }
+}
+
+fn deserialize_git_features<'de, D>(deserializer: D) -> Result<Option<GitFeatures>, D::Error>
+where
+    D: serde::de::Deserializer<'de>,
+{
+    struct GitFeaturesVisitor;
+
+    impl<'de> serde::de::Visitor<'de> for GitFeaturesVisitor {
+        type Value = Option<GitFeatures>;
+
+        fn expecting(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
+            formatter.write_str(&GitFeatures::expecting())
+        }
+
+        fn visit_str<E>(self, s: &str) -> Result<Self::Value, E>
+        where
+            E: serde::de::Error,
+        {
+            Ok(parse_git(s.split(",")).map_err(serde::de::Error::custom)?)
+        }
+
+        fn visit_none<E>(self) -> Result<Self::Value, E>
+        where
+            E: serde::de::Error,
+        {
+            Ok(None)
+        }
+
+        fn visit_map<V>(self, map: V) -> Result<Self::Value, V::Error>
+        where
+            V: serde::de::MapAccess<'de>,
+        {
+            let mvd = serde::de::value::MapAccessDeserializer::new(map);
+            Ok(Some(GitFeatures::deserialize(mvd)?))
+        }
+    }
+
+    deserializer.deserialize_any(GitFeaturesVisitor)
 }
 
 fn parse_git(it: impl Iterator<Item = impl AsRef<str>>) -> CargoResult<Option<GitFeatures>> {
@@ -892,19 +941,18 @@ fn parse_git(it: impl Iterator<Item = impl AsRef<str>>) -> CargoResult<Option<Gi
 
     for e in it {
         match e.as_ref() {
+            "all" => return Ok(Some(GitFeatures::all())),
             "shallow-index" => *shallow_index = true,
             "shallow-deps" => *shallow_deps = true,
             _ => {
-                bail!(
-                    "unstable 'git' only takes 'shallow-index' and 'shallow-deps' as valid inputs"
-                )
+                bail!(GitFeatures::expecting())
             }
         }
     }
     Ok(Some(out))
 }
 
-#[derive(Debug, Copy, Clone, Default, Deserialize)]
+#[derive(Debug, Copy, Clone, Default, Deserialize, Ord, PartialOrd, Eq, PartialEq)]
 pub struct GitoxideFeatures {
     /// All fetches are done with `gitoxide`, which includes git dependencies as well as the crates index.
     pub fetch: bool,
@@ -918,7 +966,7 @@ pub struct GitoxideFeatures {
 }
 
 impl GitoxideFeatures {
-    fn all() -> Self {
+    pub fn all() -> Self {
         GitoxideFeatures {
             fetch: true,
             checkout: true,
@@ -935,6 +983,55 @@ impl GitoxideFeatures {
             internal_use_git2: false,
         }
     }
+
+    fn expecting() -> String {
+        let fields = vec!["'all'", "'fetch'", "'checkout'", "'internal-use-git2'"];
+        format!(
+            "unstable 'gitoxide' only takes {} as valid inputs, your can use 'all' to turn out all gitoxide features, for shallow fetches see `shallow-index,shallow-deps`",
+            fields.join(" and ")
+        )
+    }
+}
+
+fn deserialize_gitoxide_features<'de, D>(
+    deserializer: D,
+) -> Result<Option<GitoxideFeatures>, D::Error>
+where
+    D: serde::de::Deserializer<'de>,
+{
+    struct GitoxideFeaturesVisitor;
+
+    impl<'de> serde::de::Visitor<'de> for GitoxideFeaturesVisitor {
+        type Value = Option<GitoxideFeatures>;
+
+        fn expecting(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
+            formatter.write_str(&GitoxideFeatures::expecting())
+        }
+
+        fn visit_str<E>(self, s: &str) -> Result<Self::Value, E>
+        where
+            E: serde::de::Error,
+        {
+            Ok(parse_gitoxide(s.split(",")).map_err(serde::de::Error::custom)?)
+        }
+
+        fn visit_none<E>(self) -> Result<Self::Value, E>
+        where
+            E: serde::de::Error,
+        {
+            Ok(None)
+        }
+
+        fn visit_map<V>(self, map: V) -> Result<Self::Value, V::Error>
+        where
+            V: serde::de::MapAccess<'de>,
+        {
+            let mvd = serde::de::value::MapAccessDeserializer::new(map);
+            Ok(Some(GitoxideFeatures::deserialize(mvd)?))
+        }
+    }
+
+    deserializer.deserialize_any(GitoxideFeaturesVisitor)
 }
 
 fn parse_gitoxide(
@@ -949,11 +1046,12 @@ fn parse_gitoxide(
 
     for e in it {
         match e.as_ref() {
+            "all" => return Ok(Some(GitoxideFeatures::all())),
             "fetch" => *fetch = true,
             "checkout" => *checkout = true,
             "internal-use-git2" => *internal_use_git2 = true,
             _ => {
-                bail!("unstable 'gitoxide' only takes `fetch` and 'checkout' as valid input, for shallow fetches see `-Zgit=shallow-index,shallow-deps`")
+                bail!(GitoxideFeatures::expecting())
             }
         }
     }

src/cargo/util/context/de.rs

@@ -62,7 +62,12 @@ impl<'de, 'gctx> de::Deserializer<'de> for Deserializer<'gctx> {
             let (res, def) = res;
             return res.map_err(|e| e.with_key_context(&self.key, def));
         }
-        Err(ConfigError::missing(&self.key))
+
+        // Let's assume that `unstable.git` had defined its `deserialize_any`` method,
+        // then run `CARGO_UNSTABLE_GIT_SHALLOW_INDEX cargo fetch`, here will return `missing config key unstable.git`.
+        // It seems that anything that starts with CARGO_UNSTABLE_GIT, even like CARGO_UNSTABLE_GITOXIDE can trigger this.
+        // This is a workaround for now, but should be fixed in the future.
+        visitor.visit_none()
     }
 
     deserialize_method!(deserialize_bool, visit_bool, get_bool);