From a27b68b1b8a7fac2ef0d0fda3fedc76f6f72d37d Mon Sep 17 00:00:00 2001
From: Ed Page <eopage@gmail.com>
Date: Mon, 28 Aug 2023 15:53:14 -0500
Subject: [PATCH] refactor: Use more serde_untagged

---
 src/cargo/util/toml/mod.rs                    | 197 ++++--------------
 .../testsuite/inheritable_workspace_fields.rs |   6 +-
 2 files changed, 47 insertions(+), 156 deletions(-)

diff --git a/src/cargo/util/toml/mod.rs b/src/cargo/util/toml/mod.rs
index 12529102a637..4b9585cb614d 100644
--- a/src/cargo/util/toml/mod.rs
+++ b/src/cargo/util/toml/mod.rs
@@ -1171,195 +1171,84 @@ type MaybeWorkspaceSemverVersion = MaybeWorkspace<semver::Version, TomlWorkspace
 
 type MaybeWorkspaceString = MaybeWorkspace<String, TomlWorkspaceField>;
 impl<'de> de::Deserialize<'de> for MaybeWorkspaceString {
-    fn deserialize<D>(d: D) -> Result<Self, D::Error>
+    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
     where
         D: de::Deserializer<'de>,
     {
-        struct Visitor;
-
-        impl<'de> de::Visitor<'de> for Visitor {
-            type Value = MaybeWorkspaceString;
-
-            fn expecting(&self, f: &mut fmt::Formatter<'_>) -> Result<(), std::fmt::Error> {
-                f.write_str("a string or workspace")
-            }
-
-            fn visit_string<E>(self, value: String) -> Result<Self::Value, E>
-            where
-                E: de::Error,
-            {
-                Ok(MaybeWorkspaceString::Defined(value))
-            }
-
-            fn visit_map<V>(self, map: V) -> Result<Self::Value, V::Error>
-            where
-                V: de::MapAccess<'de>,
-            {
-                let mvd = de::value::MapAccessDeserializer::new(map);
-                TomlWorkspaceField::deserialize(mvd).map(MaybeWorkspace::Workspace)
-            }
-        }
-
-        d.deserialize_any(Visitor)
+        UntaggedEnumVisitor::new()
+            .expecting("a string or workspace")
+            .string(|value| Ok(MaybeWorkspace::Defined(value.to_owned())))
+            .map(|value| value.deserialize().map(MaybeWorkspace::Workspace))
+            .deserialize(deserializer)
     }
 }
 
 type MaybeWorkspacePartialVersion = MaybeWorkspace<PartialVersion, TomlWorkspaceField>;
 impl<'de> de::Deserialize<'de> for MaybeWorkspacePartialVersion {
-    fn deserialize<D>(d: D) -> Result<Self, D::Error>
+    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
     where
         D: de::Deserializer<'de>,
     {
-        struct Visitor;
-
-        impl<'de> de::Visitor<'de> for Visitor {
-            type Value = MaybeWorkspacePartialVersion;
-
-            fn expecting(&self, f: &mut fmt::Formatter<'_>) -> Result<(), std::fmt::Error> {
-                f.write_str("a semver or workspace")
-            }
-
-            fn visit_string<E>(self, value: String) -> Result<Self::Value, E>
-            where
-                E: de::Error,
-            {
-                let value = value.parse::<PartialVersion>().map_err(|e| E::custom(e))?;
-                Ok(MaybeWorkspacePartialVersion::Defined(value))
-            }
-
-            fn visit_map<V>(self, map: V) -> Result<Self::Value, V::Error>
-            where
-                V: de::MapAccess<'de>,
-            {
-                let mvd = de::value::MapAccessDeserializer::new(map);
-                TomlWorkspaceField::deserialize(mvd).map(MaybeWorkspace::Workspace)
-            }
-        }
-
-        d.deserialize_any(Visitor)
+        use serde::de::Error as _;
+        UntaggedEnumVisitor::new()
+            .expecting("a SemVer version or workspace")
+            .string(|value| {
+                let value = value
+                    .parse::<PartialVersion>()
+                    .map_err(|e| serde_untagged::de::Error::custom(e))?;
+                Ok(MaybeWorkspace::Defined(value))
+            })
+            .map(|value| value.deserialize().map(MaybeWorkspace::Workspace))
+            .deserialize(deserializer)
     }
 }
 
 type MaybeWorkspaceVecString = MaybeWorkspace<Vec<String>, TomlWorkspaceField>;
 impl<'de> de::Deserialize<'de> for MaybeWorkspaceVecString {
-    fn deserialize<D>(d: D) -> Result<Self, D::Error>
+    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
     where
         D: de::Deserializer<'de>,
     {
-        struct Visitor;
-
-        impl<'de> de::Visitor<'de> for Visitor {
-            type Value = MaybeWorkspaceVecString;
-
-            fn expecting(&self, f: &mut fmt::Formatter<'_>) -> Result<(), fmt::Error> {
-                f.write_str("a vector of strings or workspace")
-            }
-            fn visit_seq<A>(self, v: A) -> Result<Self::Value, A::Error>
-            where
-                A: de::SeqAccess<'de>,
-            {
-                let seq = de::value::SeqAccessDeserializer::new(v);
-                Vec::deserialize(seq).map(MaybeWorkspace::Defined)
-            }
-
-            fn visit_map<V>(self, map: V) -> Result<Self::Value, V::Error>
-            where
-                V: de::MapAccess<'de>,
-            {
-                let mvd = de::value::MapAccessDeserializer::new(map);
-                TomlWorkspaceField::deserialize(mvd).map(MaybeWorkspace::Workspace)
-            }
-        }
-
-        d.deserialize_any(Visitor)
+        UntaggedEnumVisitor::new()
+            .expecting("a vector of strings or workspace")
+            .seq(|value| value.deserialize().map(MaybeWorkspace::Defined))
+            .map(|value| value.deserialize().map(MaybeWorkspace::Workspace))
+            .deserialize(deserializer)
     }
 }
 
 type MaybeWorkspaceStringOrBool = MaybeWorkspace<StringOrBool, TomlWorkspaceField>;
 impl<'de> de::Deserialize<'de> for MaybeWorkspaceStringOrBool {
-    fn deserialize<D>(d: D) -> Result<Self, D::Error>
+    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
     where
         D: de::Deserializer<'de>,
     {
-        struct Visitor;
-
-        impl<'de> de::Visitor<'de> for Visitor {
-            type Value = MaybeWorkspaceStringOrBool;
-
-            fn expecting(&self, f: &mut fmt::Formatter<'_>) -> Result<(), fmt::Error> {
-                f.write_str("a string, a bool, or workspace")
-            }
-
-            fn visit_bool<E>(self, v: bool) -> Result<Self::Value, E>
-            where
-                E: de::Error,
-            {
-                let b = de::value::BoolDeserializer::new(v);
-                StringOrBool::deserialize(b).map(MaybeWorkspace::Defined)
-            }
-
-            fn visit_string<E>(self, v: String) -> Result<Self::Value, E>
-            where
-                E: de::Error,
-            {
-                let string = de::value::StringDeserializer::new(v);
-                StringOrBool::deserialize(string).map(MaybeWorkspace::Defined)
-            }
-
-            fn visit_map<V>(self, map: V) -> Result<Self::Value, V::Error>
-            where
-                V: de::MapAccess<'de>,
-            {
-                let mvd = de::value::MapAccessDeserializer::new(map);
-                TomlWorkspaceField::deserialize(mvd).map(MaybeWorkspace::Workspace)
-            }
-        }
-
-        d.deserialize_any(Visitor)
+        UntaggedEnumVisitor::new()
+            .expecting("a string, a bool, or workspace")
+            .bool(|b| Ok(StringOrBool::Bool(b)).map(MaybeWorkspace::Defined))
+            .string(|s| Ok(StringOrBool::String(s.to_owned())).map(MaybeWorkspace::Defined))
+            .map(|value| value.deserialize().map(MaybeWorkspace::Workspace))
+            .deserialize(deserializer)
     }
 }
 
 type MaybeWorkspaceVecStringOrBool = MaybeWorkspace<VecStringOrBool, TomlWorkspaceField>;
 impl<'de> de::Deserialize<'de> for MaybeWorkspaceVecStringOrBool {
-    fn deserialize<D>(d: D) -> Result<Self, D::Error>
+    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
     where
         D: de::Deserializer<'de>,
     {
-        struct Visitor;
-
-        impl<'de> de::Visitor<'de> for Visitor {
-            type Value = MaybeWorkspaceVecStringOrBool;
-
-            fn expecting(&self, f: &mut fmt::Formatter<'_>) -> Result<(), fmt::Error> {
-                f.write_str("a boolean, a vector of strings, or workspace")
-            }
-
-            fn visit_bool<E>(self, v: bool) -> Result<Self::Value, E>
-            where
-                E: de::Error,
-            {
-                let b = de::value::BoolDeserializer::new(v);
-                VecStringOrBool::deserialize(b).map(MaybeWorkspace::Defined)
-            }
-
-            fn visit_seq<A>(self, v: A) -> Result<Self::Value, A::Error>
-            where
-                A: de::SeqAccess<'de>,
-            {
-                let seq = de::value::SeqAccessDeserializer::new(v);
-                VecStringOrBool::deserialize(seq).map(MaybeWorkspace::Defined)
-            }
-
-            fn visit_map<V>(self, map: V) -> Result<Self::Value, V::Error>
-            where
-                V: de::MapAccess<'de>,
-            {
-                let mvd = de::value::MapAccessDeserializer::new(map);
-                TomlWorkspaceField::deserialize(mvd).map(MaybeWorkspace::Workspace)
-            }
-        }
-
-        d.deserialize_any(Visitor)
+        UntaggedEnumVisitor::new()
+            .expecting("a boolean, a vector of strings, or workspace")
+            .bool(|value| Ok(VecStringOrBool::Bool(value)).map(MaybeWorkspace::Defined))
+            .seq(|value| {
+                value
+                    .deserialize()
+                    .map(VecStringOrBool::VecString)
+                    .map(MaybeWorkspace::Defined)
+            })
+            .map(|value| value.deserialize().map(MaybeWorkspace::Workspace))
+            .deserialize(deserializer)
     }
 }
 
diff --git a/tests/testsuite/inheritable_workspace_fields.rs b/tests/testsuite/inheritable_workspace_fields.rs
index 47437102a596..6a200af3556f 100644
--- a/tests/testsuite/inheritable_workspace_fields.rs
+++ b/tests/testsuite/inheritable_workspace_fields.rs
@@ -1234,11 +1234,13 @@ fn error_workspace_false() {
 [ERROR] failed to parse manifest at `[CWD]/Cargo.toml`
 
 Caused by:
-  TOML parse error at line 7, column 41
+  TOML parse error at line 7, column 27
     |
   7 |             description = { workspace = false }
-    |                                         ^^^^^
+    |                           ^^^^^^^^^^^^^^^^^^^^^
   `workspace` cannot be false
+  in `workspace`
+
 ",
         )
         .run();