[ty] infer type for enum members

astral-sh/ty#876

Author: thejchap

crates/ty_python_semantic/resources/mdtest/enums.md

@@ -4,6 +4,7 @@
 
 ```py
 from enum import Enum
+from typing import Literal
 
 class Color(Enum):
     RED = 1
@@ -13,6 +14,12 @@ class Color(Enum):
 reveal_type(Color.RED)  # revealed: Literal[Color.RED]
 # TODO: This could be `Literal[1]`
 reveal_type(Color.RED.value)  # revealed: Any
+# TODO: This could be `Literal[1]`
+reveal_type(Color.RED._value_)  # revealed: Any
+
+reveal_type(Color.RED.name)  # revealed: Literal["RED"]
+
+reveal_type(Color.RED._name_)  # revealed: Literal["RED"]
 
 # TODO: Should be `Color` or `Literal[Color.RED]`
 reveal_type(Color["RED"])  # revealed: Unknown
@@ -21,6 +28,13 @@ reveal_type(Color["RED"])  # revealed: Unknown
 reveal_type(Color(1))  # revealed: Color
 
 reveal_type(Color.RED in Color)  # revealed: bool
+
+def func1(red_or_blue: Literal[Color.RED, Color.BLUE]):
+    reveal_type(red_or_blue.name)  # revealed: Literal["RED", "BLUE"]
+
+def func2(any_color: Color):
+    # TODO: Literal["RED", "GREEN", "BLUE"]
+    reveal_type(any_color.name)  # revealed: Any
 ```
 
 ## Enum members

crates/ty_python_semantic/src/types.rs

@@ -3465,6 +3465,14 @@ impl<'db> Type<'db> {
                 .value_type(db)
                 .member_lookup_with_policy(db, name, policy),
 
+            Type::EnumLiteral(enum_literal) if matches!(name_str, "name" | "_name_") => {
+                Place::bound(Type::StringLiteral(StringLiteralType::new(
+                    db,
+                    enum_literal.name(db).as_str(),
+                )))
+                .into()
+            }
+
             Type::NominalInstance(..)
             | Type::ProtocolInstance(..)
             | Type::BooleanLiteral(..)

crates/ty_python_semantic/src/types/builder.rs

@@ -429,6 +429,9 @@ impl<'db> UnionBuilder<'db> {
 
                 let all_members_are_in_union = metadata
                     .members
+                    .keys()
+                    .cloned()
+                    .collect::<FxOrderSet<_>>()
                     .difference(&enum_members_in_union)
                     .next()
                     .is_none();

crates/ty_python_semantic/src/types/call/bind.rs

@@ -711,7 +711,7 @@ impl<'db> Bindings<'db> {
                                                 db,
                                                 metadata
                                                     .members
-                                                    .iter()
+                                                    .keys()
                                                     .map(|member| Type::string_literal(db, member)),
                                             )
                                         } else {

crates/ty_python_semantic/src/types/enums.rs

@@ -2,7 +2,7 @@ use ruff_python_ast::name::Name;
 use rustc_hash::FxHashMap;
 
 use crate::{
-    Db, FxOrderSet,
+    Db, FxOrderMap,
     place::{Place, PlaceAndQualifiers, place_from_bindings, place_from_declarations},
     semantic_index::{place_table, use_def_map},
     types::{
@@ -13,7 +13,7 @@ use crate::{
 
 #[derive(Debug, PartialEq, Eq)]
 pub(crate) struct EnumMetadata {
-    pub(crate) members: FxOrderSet<Name>,
+    pub(crate) members: FxOrderMap<Name, Name>,
     pub(crate) aliases: FxHashMap<Name, Name>,
 }
 
@@ -22,13 +22,13 @@ impl get_size2::GetSize for EnumMetadata {}
 impl EnumMetadata {
     fn empty() -> Self {
         EnumMetadata {
-            members: FxOrderSet::default(),
+            members: FxOrderMap::default(),
             aliases: FxHashMap::default(),
         }
     }
 
     pub(crate) fn resolve_member<'a>(&'a self, name: &'a Name) -> Option<&'a Name> {
-        if self.members.contains(name) {
+        if self.members.contains_key(name) {
             Some(name)
         } else {
             self.aliases.get(name)
@@ -217,9 +217,9 @@ pub(crate) fn enum_metadata<'db>(
                 }
             }
 
-            Some(name.clone())
+            Some((name.clone(), name.clone()))
         })
-        .collect::<FxOrderSet<_>>();
+        .collect::<FxOrderMap<_, _>>();
 
     if members.is_empty() {
         // Enum subclasses without members are not considered enums.
@@ -237,7 +237,7 @@ pub(crate) fn enum_member_literals<'a, 'db: 'a>(
     enum_metadata(db, class).map(|metadata| {
         metadata
             .members
-            .iter()
+            .keys()
             .filter(move |name| Some(*name) != exclude_member)
             .map(move |name| Type::EnumLiteral(EnumLiteralType::new(db, class, name.clone())))
     })