Merge #3169

3169: Show record field names in Enum completion r=flodiebold a=adamrk

Adresses https://github.com/rust-analyzer/rust-analyzer/issues/2947.
Previously the details shown when autocompleting an Enum variant would look like the variant was a tuple even if it was a record:
![2020-02-16-15:59:32_crop](https://user-images.githubusercontent.com/16367467/74607233-64f21980-50d7-11ea-99db-e973e29c71d7.png)

This change will show the names of the fields for a record and use curly braces instead of parentheses:
![2020-02-16-15:33:00_crop](https://user-images.githubusercontent.com/16367467/74607251-8ce17d00-50d7-11ea-9d4d-38d198a4aec0.png)

This required exposing the type `adt::StructKind` from `ra_hir` and adding a function 
```
kind(self, db: &impl HirDatabase) -> StructKind
```
in the `impl` of `EnumVariant`. 

There was also a previously existing function `is_unit(self, db: &impl HirDatabase) -> bool` for `EnumVariant` which I removed because it seemed redundant after adding `kind`.

Co-authored-by: adamrk <[email protected]>

1 files changed, 95 insertions, 6 deletions

diff --git a/crates/ra_ide/src/completion/presentation.rs b/crates/ra_ide/src/completion/presentation.rs
index 97475fc0b..1a3bcffae 100644
--- a/crates/ra_ide/src/completion/presentation.rs
+++ b/crates/ra_ide/src/completion/presentation.rs
@@ -1,6 +1,6 @@
 //! This modules takes care of rendering various definitions as completion items.
 
-use hir::{db::HirDatabase, Docs, HasAttrs, HasSource, HirDisplay, ScopeDef, Type};
+use hir::{db::HirDatabase, Docs, HasAttrs, HasSource, HirDisplay, ScopeDef, StructKind, Type};
 use join_to_string::join;
 use ra_syntax::ast::NameOwner;
 use test_utils::tested_by;
@@ -268,11 +268,22 @@ impl Completions {
     pub(crate) fn add_enum_variant(&mut self, ctx: &CompletionContext, variant: hir::EnumVariant) {
         let is_deprecated = is_deprecated(variant, ctx.db);
         let name = variant.name(ctx.db);
-        let detail_types = variant.fields(ctx.db).into_iter().map(|field| field.ty(ctx.db));
-        let detail = join(detail_types.map(|t| t.display(ctx.db).to_string()))
-            .separator(", ")
-            .surround_with("(", ")")
-            .to_string();
+        let detail_types =
+            variant.fields(ctx.db).into_iter().map(|field| (field.name(ctx.db), field.ty(ctx.db)));
+        let detail = match variant.kind(ctx.db) {
+            StructKind::Tuple | StructKind::Unit => {
+                join(detail_types.map(|(_, t)| t.display(ctx.db).to_string()))
+                    .separator(", ")
+                    .surround_with("(", ")")
+                    .to_string()
+            }
+            StructKind::Record => {
+                join(detail_types.map(|(n, t)| format!("{}: {}", n, t.display(ctx.db).to_string())))
+                    .separator(", ")
+                    .surround_with("{ ", " }")
+                    .to_string()
+            }
+        };
         CompletionItem::new(CompletionKind::Reference, ctx.source_range(), name.to_string())
             .kind(CompletionItemKind::EnumVariant)
             .set_documentation(variant.docs(ctx.db))
@@ -298,6 +309,84 @@ mod tests {
     }
 
     #[test]
+    fn enum_detail_includes_names_for_record() {
+        assert_debug_snapshot!(
+        do_reference_completion(
+            r#"
+                enum Foo {
+                    Foo {x: i32, y: i32}
+                }
+
+                fn main() { Foo::Fo<|> }
+                "#,
+        ),
+        @r###"
+        [
+            CompletionItem {
+                label: "Foo",
+                source_range: [121; 123),
+                delete: [121; 123),
+                insert: "Foo",
+                kind: EnumVariant,
+                detail: "{ x: i32, y: i32 }",
+            },
+        ]"###
+        );
+    }
+
+    #[test]
+    fn enum_detail_doesnt_include_names_for_tuple() {
+        assert_debug_snapshot!(
+        do_reference_completion(
+            r#"
+                enum Foo {
+                    Foo (i32, i32)
+                }
+
+                fn main() { Foo::Fo<|> }
+                "#,
+        ),
+        @r###"
+        [
+            CompletionItem {
+                label: "Foo",
+                source_range: [115; 117),
+                delete: [115; 117),
+                insert: "Foo",
+                kind: EnumVariant,
+                detail: "(i32, i32)",
+            },
+        ]"###
+        );
+    }
+
+    #[test]
+    fn enum_detail_just_parentheses_for_unit() {
+        assert_debug_snapshot!(
+        do_reference_completion(
+            r#"
+                enum Foo {
+                    Foo
+                }
+
+                fn main() { Foo::Fo<|> }
+                "#,
+        ),
+        @r###"
+        [
+            CompletionItem {
+                label: "Foo",
+                source_range: [104; 106),
+                delete: [104; 106),
+                insert: "Foo",
+                kind: EnumVariant,
+                detail: "()",
+            },
+        ]"###
+        );
+    }
+
+    #[test]
     fn sets_deprecated_flag_in_completion_items() {
         assert_debug_snapshot!(
             do_reference_completion(