1 files changed, 99 insertions, 32 deletions

diff --git a/crates/assists/src/handlers/generate_from_impl_for_enum.rs b/crates/assists/src/handlers/generate_from_impl_for_enum.rs
index d9af6ab11..d9388a737 100644
--- a/crates/assists/src/handlers/generate_from_impl_for_enum.rs
+++ b/crates/assists/src/handlers/generate_from_impl_for_enum.rs
@@ -3,7 +3,7 @@ use ide_db::RootDatabase;
 use syntax::ast::{self, AstNode, NameOwner};
 use test_utils::mark;
 
-use crate::{AssistContext, AssistId, AssistKind, Assists};
+use crate::{utils::generate_trait_impl_text, AssistContext, AssistId, AssistKind, Assists};
 
 // Assist: generate_from_impl_for_enum
 //
@@ -18,25 +18,29 @@ use crate::{AssistContext, AssistId, AssistKind, Assists};
 //
 // impl From<u32> for A {
 //     fn from(v: u32) -> Self {
-//         A::One(v)
+//         Self::One(v)
 //     }
 // }
 // ```
 pub(crate) fn generate_from_impl_for_enum(acc: &mut Assists, ctx: &AssistContext) -> Option<()> {
     let variant = ctx.find_node_at_offset::<ast::Variant>()?;
     let variant_name = variant.name()?;
-    let enum_name = variant.parent_enum().name()?;
-    let field_list = match variant.kind() {
-        ast::StructKind::Tuple(field_list) => field_list,
-        _ => return None,
-    };
-    if field_list.fields().count() != 1 {
-        return None;
-    }
-    let field_type = field_list.fields().next()?.ty()?;
-    let path = match field_type {
-        ast::Type::PathType(it) => it,
-        _ => return None,
+    let enum_ = ast::Adt::Enum(variant.parent_enum());
+    let (field_name, field_type) = match variant.kind() {
+        ast::StructKind::Tuple(field_list) => {
+            if field_list.fields().count() != 1 {
+                return None;
+            }
+            (None, field_list.fields().next()?.ty()?)
+        }
+        ast::StructKind::Record(field_list) => {
+            if field_list.fields().count() != 1 {
+                return None;
+            }
+            let field = field_list.fields().next()?;
+            (Some(field.name()?), field.ty()?)
+        }
+        ast::StructKind::Unit => return None,
     };
 
     if existing_from_impl(&ctx.sema, &variant).is_some() {
@@ -51,19 +55,27 @@ pub(crate) fn generate_from_impl_for_enum(acc: &mut Assists, ctx: &AssistContext
         target,
         |edit| {
             let start_offset = variant.parent_enum().syntax().text_range().end();
-            let buf = format!(
-                r#"
-
-impl From<{0}> for {1} {{
-    fn from(v: {0}) -> Self {{
-        {1}::{2}(v)
-    }}
-}}"#,
-                path.syntax(),
-                enum_name,
-                variant_name
-            );
-            edit.insert(start_offset, buf);
+            let from_trait = format!("From<{}>", field_type.syntax());
+            let impl_code = if let Some(name) = field_name {
+                format!(
+                    r#"    fn from({0}: {1}) -> Self {{
+        Self::{2} {{ {0} }}
+    }}"#,
+                    name.text(),
+                    field_type.syntax(),
+                    variant_name,
+                )
+            } else {
+                format!(
+                    r#"    fn from(v: {}) -> Self {{
+        Self::{}(v)
+    }}"#,
+                    field_type.syntax(),
+                    variant_name,
+                )
+            };
+            let from_impl = generate_trait_impl_text(&enum_, &from_trait, &impl_code);
+            edit.insert(start_offset, from_impl);
         },
     )
 }
@@ -106,7 +118,7 @@ mod tests {
 
 impl From<u32> for A {
     fn from(v: u32) -> Self {
-        A::One(v)
+        Self::One(v)
     }
 }"#,
         );
@@ -121,7 +133,7 @@ impl From<u32> for A {
 
 impl From<foo::bar::baz::Boo> for A {
     fn from(v: foo::bar::baz::Boo) -> Self {
-        A::One(v)
+        Self::One(v)
     }
 }"#,
         );
@@ -145,7 +157,17 @@ impl From<foo::bar::baz::Boo> for A {
 
     #[test]
     fn test_add_from_impl_struct_variant() {
-        check_not_applicable("enum A { $0One { x: u32 } }");
+        check_assist(
+            generate_from_impl_for_enum,
+            "enum A { $0One { x: u32 } }",
+            r#"enum A { One { x: u32 } }
+
+impl From<u32> for A {
+    fn from(x: u32) -> Self {
+        Self::One { x }
+    }
+}"#,
+        );
     }
 
     #[test]
@@ -157,7 +179,7 @@ enum A { $0One(u32), }
 
 impl From<u32> for A {
     fn from(v: u32) -> Self {
-        A::One(v)
+        Self::One(v)
     }
 }
 "#,
@@ -183,7 +205,7 @@ pub trait From<T> {
 
 impl From<u32> for A {
     fn from(v: u32) -> Self {
-        A::One(v)
+        Self::One(v)
     }
 }
 
@@ -198,4 +220,49 @@ pub trait From<T> {
 }"#,
         );
     }
+
+    #[test]
+    fn test_add_from_impl_static_str() {
+        check_assist(
+            generate_from_impl_for_enum,
+            "enum A { $0One(&'static str) }",
+            r#"enum A { One(&'static str) }
+
+impl From<&'static str> for A {
+    fn from(v: &'static str) -> Self {
+        Self::One(v)
+    }
+}"#,
+        );
+    }
+
+    #[test]
+    fn test_add_from_impl_generic_enum() {
+        check_assist(
+            generate_from_impl_for_enum,
+            "enum Generic<T, U: Clone> { $0One(T), Two(U) }",
+            r#"enum Generic<T, U: Clone> { One(T), Two(U) }
+
+impl<T, U: Clone> From<T> for Generic<T, U> {
+    fn from(v: T) -> Self {
+        Self::One(v)
+    }
+}"#,
+        );
+    }
+
+    #[test]
+    fn test_add_from_impl_with_lifetime() {
+        check_assist(
+            generate_from_impl_for_enum,
+            "enum Generic<'a> { $0One(&'a i32) }",
+            r#"enum Generic<'a> { One(&'a i32) }
+
+impl<'a> From<&'a i32> for Generic<'a> {
+    fn from(v: &'a i32) -> Self {
+        Self::One(v)
+    }
+}"#,
+        );
+    }
 }