Merge #475

475: Show types of fields in completion r=matklad a=matklad

![image](https://user-images.githubusercontent.com/1711539/50910524-0f146200-143f-11e9-84d6-0ba80761cd89.png)

r? @flodiebold 


Co-authored-by: Aleksey Kladov <aleksey.kladov@gmail.com>

crates/ra_hir/src/adt.rs

@@ -4,7 +4,7 @@ use ra_db::Cancelable;
 use ra_syntax::ast::{self, NameOwner, StructFlavor, AstNode};
 
 use crate::{
-    DefId, Name, AsName, Struct, Enum, VariantData, StructField, HirDatabase, DefKind,
+    DefId, Name, AsName, Struct, Enum, HirDatabase, DefKind,
     type_ref::TypeRef,
 };
 
@@ -12,6 +12,10 @@ impl Struct {
     pub(crate) fn new(def_id: DefId) -> Self {
         Struct { def_id }
     }
+
+    pub(crate) fn variant_data(&self, db: &impl HirDatabase) -> Cancelable<Arc<VariantData>> {
+        Ok(db.struct_data(self.def_id)?.variant_data.clone())
+    }
 }
 
 #[derive(Debug, Clone, PartialEq, Eq)]
@@ -83,6 +87,51 @@ impl EnumData {
     }
 }
 
+/// A single field of an enum variant or struct
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct StructField {
+    pub(crate) name: Name,
+    pub(crate) type_ref: TypeRef,
+}
+
+/// Fields of an enum variant or struct
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub enum VariantData {
+    Struct(Vec<StructField>),
+    Tuple(Vec<StructField>),
+    Unit,
+}
+
+impl VariantData {
+    pub fn fields(&self) -> &[StructField] {
+        match self {
+            VariantData::Struct(fields) | VariantData::Tuple(fields) => fields,
+            _ => &[],
+        }
+    }
+
+    pub fn is_struct(&self) -> bool {
+        match self {
+            VariantData::Struct(..) => true,
+            _ => false,
+        }
+    }
+
+    pub fn is_tuple(&self) -> bool {
+        match self {
+            VariantData::Tuple(..) => true,
+            _ => false,
+        }
+    }
+
+    pub fn is_unit(&self) -> bool {
+        match self {
+            VariantData::Unit => true,
+            _ => false,
+        }
+    }
+}
+
 impl VariantData {
     fn new(flavor: StructFlavor) -> Self {
         match flavor {
@@ -114,7 +163,7 @@ impl VariantData {
     pub(crate) fn get_field_type_ref(&self, field_name: &Name) -> Option<&TypeRef> {
         self.fields()
             .iter()
-            .find(|f| f.name() == field_name)
-            .map(|f| f.type_ref())
+            .find(|f| f.name == *field_name)
+            .map(|f| &f.type_ref)
     }
 }

crates/ra_hir/src/code_model_api.rs

@@ -5,12 +5,13 @@ use ra_db::{CrateId, Cancelable, FileId};
 use ra_syntax::{ast, TreePtr, SyntaxNode};
 
 use crate::{
-    Name, DefId, Path, PerNs, ScopesWithSyntaxMapping,
+    Name, DefId, Path, PerNs, ScopesWithSyntaxMapping, Ty,
     type_ref::TypeRef,
     nameres::ModuleScope,
     db::HirDatabase,
     expr::BodySyntaxMapping,
     ty::InferenceResult,
+    adt::VariantData,
 };
 
 /// hir::Crate describes a single crate. It's the main interface with which
@@ -137,58 +138,18 @@ impl Module {
     }
 }
 
-/// A single field of an enum variant or struct
-#[derive(Debug, Clone, PartialEq, Eq)]
+#[derive(Debug, Clone, PartialEq, Eq, Hash)]
 pub struct StructField {
-    pub(crate) name: Name,
-    pub(crate) type_ref: TypeRef,
+    struct_: Struct,
+    name: Name,
 }
 
 impl StructField {
     pub fn name(&self) -> &Name {
         &self.name
     }
-
-    pub fn type_ref(&self) -> &TypeRef {
-        &self.type_ref
-    }
-}
-
-/// Fields of an enum variant or struct
-#[derive(Debug, Clone, PartialEq, Eq)]
-pub enum VariantData {
-    Struct(Vec<StructField>),
-    Tuple(Vec<StructField>),
-    Unit,
-}
-
-impl VariantData {
-    pub fn fields(&self) -> &[StructField] {
-        match self {
-            VariantData::Struct(fields) | VariantData::Tuple(fields) => fields,
-            _ => &[],
-        }
-    }
-
-    pub fn is_struct(&self) -> bool {
-        match self {
-            VariantData::Struct(..) => true,
-            _ => false,
-        }
-    }
-
-    pub fn is_tuple(&self) -> bool {
-        match self {
-            VariantData::Tuple(..) => true,
-            _ => false,
-        }
-    }
-
-    pub fn is_unit(&self) -> bool {
-        match self {
-            VariantData::Unit => true,
-            _ => false,
-        }
+    pub fn ty(&self, db: &impl HirDatabase) -> Cancelable<Option<Ty>> {
+        db.type_for_field(self.struct_.def_id, self.name.clone())
     }
 }
 
@@ -206,8 +167,18 @@ impl Struct {
         Ok(db.struct_data(self.def_id)?.name.clone())
     }
 
-    pub fn variant_data(&self, db: &impl HirDatabase) -> Cancelable<Arc<VariantData>> {
-        Ok(db.struct_data(self.def_id)?.variant_data.clone())
+    pub fn fields(&self, db: &impl HirDatabase) -> Cancelable<Vec<StructField>> {
+        let res = db
+            .struct_data(self.def_id)?
+            .variant_data
+            .fields()
+            .iter()
+            .map(|it| StructField {
+                struct_: self.clone(),
+                name: it.name.clone(),
+            })
+            .collect();
+        Ok(res)
     }
 }
 

crates/ra_hir/src/lib.rs

@@ -56,6 +56,6 @@ pub use self::code_model_api::{
     Crate, CrateDependency,
     Def,
     Module, ModuleSource, Problem,
-    Struct, Enum, VariantData, StructField,
+    Struct, Enum,
     Function, FnSignature,
 };

crates/ra_ide_api/src/completion/complete_dot.rs

@@ -28,13 +28,13 @@ fn complete_fields(acc: &mut Completions, ctx: &CompletionContext, receiver: Ty)
             Ty::Adt { def_id, .. } => {
                 match def_id.resolve(ctx.db)? {
                     Def::Struct(s) => {
-                        let variant_data = s.variant_data(ctx.db)?;
-                        for field in variant_data.fields() {
+                        for field in s.fields(ctx.db)? {
                             CompletionItem::new(
                                 CompletionKind::Reference,
                                 field.name().to_string(),
                             )
                             .kind(CompletionItemKind::Field)
+                            .set_detail(field.ty(ctx.db)?.map(|ty| ty.to_string()))
                             .add_to(acc);
                         }
                     }
@@ -72,7 +72,7 @@ mod tests {
                a.<|>
             }
             ",
-            r#"the_field"#,
+            r#"the_field "u32""#,
         );
     }
 
@@ -80,14 +80,14 @@ mod tests {
     fn test_struct_field_completion_self() {
         check_ref_completion(
             r"
-            struct A { the_field: u32 }
+            struct A { the_field: (u32,) }
             impl A {
                 fn foo(self) {
                     self.<|>
                 }
             }
             ",
-            r#"the_field"#,
+            r#"the_field "(u32,)""#,
         );
     }
 
@@ -95,14 +95,14 @@ mod tests {
     fn test_struct_field_completion_autoderef() {
         check_ref_completion(
             r"
-            struct A { the_field: u32 }
+            struct A { the_field: (u32, i32) }
             impl A {
                 fn foo(&self) {
                     self.<|>
                 }
             }
             ",
-            r#"the_field"#,
+            r#"the_field "(u32, i32)""#,
         );
     }
 

crates/ra_ide_api/src/completion/completion_item.rs

@@ -11,6 +11,7 @@ pub struct CompletionItem {
     /// completion.
     completion_kind: CompletionKind,
     label: String,
+    detail: Option<String>,
     lookup: Option<String>,
     snippet: Option<String>,
     kind: Option<CompletionItemKind>,
@@ -51,6 +52,7 @@ impl CompletionItem {
         Builder {
             completion_kind,
             label,
+            detail: None,
             lookup: None,
             snippet: None,
             kind: None,
@@ -60,6 +62,10 @@ impl CompletionItem {
     pub fn label(&self) -> &str {
         &self.label
     }
+    /// Short one-line additional information, like a type
+    pub fn detail(&self) -> Option<&str> {
+        self.detail.as_ref().map(|it| it.as_str())
+    }
     /// What string is used for filtering.
     pub fn lookup(&self) -> &str {
         self.lookup
@@ -87,6 +93,7 @@ impl CompletionItem {
 pub(crate) struct Builder {
     completion_kind: CompletionKind,
     label: String,
+    detail: Option<String>,
     lookup: Option<String>,
     snippet: Option<String>,
     kind: Option<CompletionItemKind>,
@@ -100,6 +107,7 @@ impl Builder {
     pub(crate) fn build(self) -> CompletionItem {
         CompletionItem {
             label: self.label,
+            detail: self.detail,
             lookup: self.lookup,
             snippet: self.snippet,
             kind: self.kind,
@@ -118,6 +126,14 @@ impl Builder {
         self.kind = Some(kind);
         self
     }
+    #[allow(unused)]
+    pub(crate) fn detail(self, detail: impl Into<String>) -> Builder {
+        self.set_detail(Some(detail))
+    }
+    pub(crate) fn set_detail(mut self, detail: Option<impl Into<String>>) -> Builder {
+        self.detail = detail.map(Into::into);
+        self
+    }
     pub(super) fn from_resolution(
         mut self,
         ctx: &CompletionContext,
@@ -227,6 +243,9 @@ impl Completions {
                 } else {
                     res.push_str(&c.label);
                 }
+                if let Some(detail) = &c.detail {
+                    res.push_str(&format!(" {:?}", detail));
+                }
                 if let Some(snippet) = &c.snippet {
                     res.push_str(&format!(" {:?}", snippet));
                 }

crates/ra_lsp_server/src/conv.rs

@@ -75,6 +75,7 @@ impl Conv for CompletionItem {
     fn conv(self) -> <Self as Conv>::Output {
         let mut res = ::languageserver_types::CompletionItem {
             label: self.label().to_string(),
+            detail: self.detail().map(|it| it.to_string()),
             filter_text: Some(self.lookup().to_string()),
             kind: self.kind().map(|it| it.conv()),
             ..Default::default()