Merge #9039

9039: feat: Complete fields and methods with `self.` prefixed when inside methods r=matklad a=Veykril


![w65NbjkZiG](https://user-images.githubusercontent.com/3757771/119984385-a0111700-bfc1-11eb-9dbf-52fdaa4d72b5.gif)
Closes #7173

Co-authored-by: Lukas Wirth <[email protected]>

14 files changed, 170 insertions, 26 deletions

diff --git a/crates/ide_completion/src/completions.rs b/crates/ide_completion/src/completions.rs
index 151bf3783..ffdcdc930 100644
--- a/crates/ide_completion/src/completions.rs
+++ b/crates/ide_completion/src/completions.rs
@@ -69,18 +69,25 @@ impl Completions {
         items.into_iter().for_each(|item| self.add(item.into()))
     }
 
-    pub(crate) fn add_field(&mut self, ctx: &CompletionContext, field: hir::Field, ty: &hir::Type) {
-        let item = render_field(RenderContext::new(ctx), field, ty);
+    pub(crate) fn add_field(
+        &mut self,
+        ctx: &CompletionContext,
+        receiver: Option<hir::Name>,
+        field: hir::Field,
+        ty: &hir::Type,
+    ) {
+        let item = render_field(RenderContext::new(ctx), receiver, field, ty);
         self.add(item);
     }
 
     pub(crate) fn add_tuple_field(
         &mut self,
         ctx: &CompletionContext,
+        receiver: Option<hir::Name>,
         field: usize,
         ty: &hir::Type,
     ) {
-        let item = render_tuple_field(RenderContext::new(ctx), field, ty);
+        let item = render_tuple_field(RenderContext::new(ctx), receiver, field, ty);
         self.add(item);
     }
 
@@ -132,9 +139,11 @@ impl Completions {
         &mut self,
         ctx: &CompletionContext,
         func: hir::Function,
+        receiver: Option<hir::Name>,
         local_name: Option<hir::Name>,
     ) {
-        if let Some(item) = render_method(RenderContext::new(ctx), None, local_name, func) {
+        if let Some(item) = render_method(RenderContext::new(ctx), None, receiver, local_name, func)
+        {
             self.add(item)
         }
     }
diff --git a/crates/ide_completion/src/completions/dot.rs b/crates/ide_completion/src/completions/dot.rs
index fd9738743..302c9ccbd 100644
--- a/crates/ide_completion/src/completions/dot.rs
+++ b/crates/ide_completion/src/completions/dot.rs
@@ -1,6 +1,7 @@
 //! Completes references after dot (fields and method calls).
 
-use hir::{HasVisibility, Type};
+use either::Either;
+use hir::{HasVisibility, ScopeDef};
 use rustc_hash::FxHashSet;
 
 use crate::{context::CompletionContext, Completions};
@@ -9,7 +10,7 @@ use crate::{context::CompletionContext, Completions};
 pub(crate) fn complete_dot(acc: &mut Completions, ctx: &CompletionContext) {
     let dot_receiver = match &ctx.dot_receiver {
         Some(expr) => expr,
-        _ => return,
+        _ => return complete_undotted_self(acc, ctx),
     };
 
     let receiver_ty = match ctx.sema.type_of_expr(&dot_receiver) {
@@ -20,12 +21,43 @@ pub(crate) fn complete_dot(acc: &mut Completions, ctx: &CompletionContext) {
     if ctx.is_call {
         cov_mark::hit!(test_no_struct_field_completion_for_method_call);
     } else {
-        complete_fields(acc, ctx, &receiver_ty);
+        complete_fields(ctx, &receiver_ty, |field, ty| match field {
+            Either::Left(field) => acc.add_field(ctx, None, field, &ty),
+            Either::Right(tuple_idx) => acc.add_tuple_field(ctx, None, tuple_idx, &ty),
+        });
     }
-    complete_methods(acc, ctx, &receiver_ty);
+    complete_methods(ctx, &receiver_ty, |func| acc.add_method(ctx, func, None, None));
+}
+
+fn complete_undotted_self(acc: &mut Completions, ctx: &CompletionContext) {
+    if !ctx.is_trivial_path || !ctx.config.enable_self_on_the_fly {
+        return;
+    }
+    ctx.scope.process_all_names(&mut |name, def| {
+        if let ScopeDef::Local(local) = &def {
+            if local.is_self(ctx.db) {
+                let ty = local.ty(ctx.db);
+                complete_fields(ctx, &ty, |field, ty| match field {
+                    either::Either::Left(field) => {
+                        acc.add_field(ctx, Some(name.clone()), field, &ty)
+                    }
+                    either::Either::Right(tuple_idx) => {
+                        acc.add_tuple_field(ctx, Some(name.clone()), tuple_idx, &ty)
+                    }
+                });
+                complete_methods(ctx, &ty, |func| {
+                    acc.add_method(ctx, func, Some(name.clone()), None)
+                });
+            }
+        }
+    });
 }
 
-fn complete_fields(acc: &mut Completions, ctx: &CompletionContext, receiver: &Type) {
+fn complete_fields(
+    ctx: &CompletionContext,
+    receiver: &hir::Type,
+    mut f: impl FnMut(Either<hir::Field, usize>, hir::Type),
+) {
     for receiver in receiver.autoderef(ctx.db) {
         for (field, ty) in receiver.fields(ctx.db) {
             if ctx.scope.module().map_or(false, |m| !field.is_visible_from(ctx.db, m)) {
@@ -33,16 +65,20 @@ fn complete_fields(acc: &mut Completions, ctx: &CompletionContext, receiver: &Ty
                 // field is editable, we should show the completion
                 continue;
             }
-            acc.add_field(ctx, field, &ty);
+            f(Either::Left(field), ty);
         }
         for (i, ty) in receiver.tuple_fields(ctx.db).into_iter().enumerate() {
             // FIXME: Handle visibility
-            acc.add_tuple_field(ctx, i, &ty);
+            f(Either::Right(i), ty);
         }
     }
 }
 
-fn complete_methods(acc: &mut Completions, ctx: &CompletionContext, receiver: &Type) {
+fn complete_methods(
+    ctx: &CompletionContext,
+    receiver: &hir::Type,
+    mut f: impl FnMut(hir::Function),
+) {
     if let Some(krate) = ctx.krate {
         let mut seen_methods = FxHashSet::default();
         let traits_in_scope = ctx.scope.traits_in_scope();
@@ -51,7 +87,7 @@ fn complete_methods(acc: &mut Completions, ctx: &CompletionContext, receiver: &T
                 && ctx.scope.module().map_or(true, |m| func.is_visible_from(ctx.db, m))
                 && seen_methods.insert(func.name(ctx.db))
             {
-                acc.add_method(ctx, func, None);
+                f(func);
             }
             None::<()>
         });
@@ -484,4 +520,34 @@ impl S {
             "#]],
         );
     }
+
+    #[test]
+    fn completes_bare_fields_and_methods_in_methods() {
+        check(
+            r#"
+struct Foo { field: i32 }
+
+impl Foo { fn foo(&self) { $0 } }"#,
+            expect![[r#"
+                lc self       &Foo
+                sp Self
+                st Foo
+                fd self.field i32
+                me self.foo() fn(&self)
+            "#]],
+        );
+        check(
+            r#"
+struct Foo(i32);
+
+impl Foo { fn foo(&mut self) { $0 } }"#,
+            expect![[r#"
+                lc self       &mut Foo
+                sp Self
+                st Foo
+                fd self.0     i32
+                me self.foo() fn(&mut self)
+            "#]],
+        );
+    }
 }
diff --git a/crates/ide_completion/src/completions/record.rs b/crates/ide_completion/src/completions/record.rs
index 227c08d01..0ac47cdbe 100644
--- a/crates/ide_completion/src/completions/record.rs
+++ b/crates/ide_completion/src/completions/record.rs
@@ -39,7 +39,7 @@ pub(crate) fn complete_record(acc: &mut Completions, ctx: &CompletionContext) ->
     };
 
     for (field, ty) in missing_fields {
-        acc.add_field(ctx, field, &ty);
+        acc.add_field(ctx, None, field, &ty);
     }
 
     Some(())
diff --git a/crates/ide_completion/src/completions/unqualified_path.rs b/crates/ide_completion/src/completions/unqualified_path.rs
index 9db8516d0..20188a7dd 100644
--- a/crates/ide_completion/src/completions/unqualified_path.rs
+++ b/crates/ide_completion/src/completions/unqualified_path.rs
@@ -11,6 +11,7 @@ pub(crate) fn complete_unqualified_path(acc: &mut Completions, ctx: &CompletionC
     if ctx.is_path_disallowed() || ctx.expects_item() {
         return;
     }
+
     if ctx.expects_assoc_item() {
         ctx.scope.process_all_names(&mut |name, def| {
             if let ScopeDef::MacroDef(macro_def) = def {
@@ -32,6 +33,7 @@ pub(crate) fn complete_unqualified_path(acc: &mut Completions, ctx: &CompletionC
         });
         return;
     }
+
     if let Some(hir::Adt::Enum(e)) =
         ctx.expected_type.as_ref().and_then(|ty| ty.strip_references().as_adt())
     {
diff --git a/crates/ide_completion/src/config.rs b/crates/ide_completion/src/config.rs
index d70ed6c1c..c300ce887 100644
--- a/crates/ide_completion/src/config.rs
+++ b/crates/ide_completion/src/config.rs
@@ -10,6 +10,7 @@ use ide_db::helpers::{insert_use::InsertUseConfig, SnippetCap};
 pub struct CompletionConfig {
     pub enable_postfix_completions: bool,
     pub enable_imports_on_the_fly: bool,
+    pub enable_self_on_the_fly: bool,
     pub add_call_parenthesis: bool,
     pub add_call_argument_snippets: bool,
     pub snippet_cap: Option<SnippetCap>,
diff --git a/crates/ide_completion/src/render.rs b/crates/ide_completion/src/render.rs
index 425dd0247..a49a60711 100644
--- a/crates/ide_completion/src/render.rs
+++ b/crates/ide_completion/src/render.rs
@@ -25,18 +25,20 @@ use crate::{
 
 pub(crate) fn render_field<'a>(
     ctx: RenderContext<'a>,
+    receiver: Option<hir::Name>,
     field: hir::Field,
     ty: &hir::Type,
 ) -> CompletionItem {
-    Render::new(ctx).render_field(field, ty)
+    Render::new(ctx).render_field(receiver, field, ty)
 }
 
 pub(crate) fn render_tuple_field<'a>(
     ctx: RenderContext<'a>,
+    receiver: Option<hir::Name>,
     field: usize,
     ty: &hir::Type,
 ) -> CompletionItem {
-    Render::new(ctx).render_tuple_field(field, ty)
+    Render::new(ctx).render_tuple_field(receiver, field, ty)
 }
 
 pub(crate) fn render_resolution<'a>(
@@ -126,11 +128,19 @@ impl<'a> Render<'a> {
         Render { ctx }
     }
 
-    fn render_field(&self, field: hir::Field, ty: &hir::Type) -> CompletionItem {
+    fn render_field(
+        &self,
+        receiver: Option<hir::Name>,
+        field: hir::Field,
+        ty: &hir::Type,
+    ) -> CompletionItem {
         let is_deprecated = self.ctx.is_deprecated(field);
         let name = field.name(self.ctx.db()).to_string();
-        let mut item =
-            CompletionItem::new(CompletionKind::Reference, self.ctx.source_range(), name.clone());
+        let mut item = CompletionItem::new(
+            CompletionKind::Reference,
+            self.ctx.source_range(),
+            receiver.map_or_else(|| name.clone(), |receiver| format!("{}.{}", receiver, name)),
+        );
         item.kind(SymbolKind::Field)
             .detail(ty.display(self.ctx.db()).to_string())
             .set_documentation(field.docs(self.ctx.db()))
@@ -151,11 +161,17 @@ impl<'a> Render<'a> {
         item.build()
     }
 
-    fn render_tuple_field(&self, field: usize, ty: &hir::Type) -> CompletionItem {
+    fn render_tuple_field(
+        &self,
+        receiver: Option<hir::Name>,
+        field: usize,
+        ty: &hir::Type,
+    ) -> CompletionItem {
         let mut item = CompletionItem::new(
             CompletionKind::Reference,
             self.ctx.source_range(),
-            field.to_string(),
+            receiver
+                .map_or_else(|| field.to_string(), |receiver| format!("{}.{}", receiver, field)),
         );
 
         item.kind(SymbolKind::Field).detail(ty.display(self.ctx.db()).to_string());
diff --git a/crates/ide_completion/src/render/function.rs b/crates/ide_completion/src/render/function.rs
index 63bd66926..3ec77ca0f 100644
--- a/crates/ide_completion/src/render/function.rs
+++ b/crates/ide_completion/src/render/function.rs
@@ -20,23 +20,25 @@ pub(crate) fn render_fn<'a>(
     fn_: hir::Function,
 ) -> Option<CompletionItem> {
     let _p = profile::span("render_fn");
-    Some(FunctionRender::new(ctx, local_name, fn_, false)?.render(import_to_add))
+    Some(FunctionRender::new(ctx, None, local_name, fn_, false)?.render(import_to_add))
 }
 
 pub(crate) fn render_method<'a>(
     ctx: RenderContext<'a>,
     import_to_add: Option<ImportEdit>,
+    receiver: Option<hir::Name>,
     local_name: Option<hir::Name>,
     fn_: hir::Function,
 ) -> Option<CompletionItem> {
     let _p = profile::span("render_method");
-    Some(FunctionRender::new(ctx, local_name, fn_, true)?.render(import_to_add))
+    Some(FunctionRender::new(ctx, receiver, local_name, fn_, true)?.render(import_to_add))
 }
 
 #[derive(Debug)]
 struct FunctionRender<'a> {
     ctx: RenderContext<'a>,
     name: String,
+    receiver: Option<hir::Name>,
     func: hir::Function,
     ast_node: Fn,
     is_method: bool,
@@ -45,6 +47,7 @@ struct FunctionRender<'a> {
 impl<'a> FunctionRender<'a> {
     fn new(
         ctx: RenderContext<'a>,
+        receiver: Option<hir::Name>,
         local_name: Option<hir::Name>,
         fn_: hir::Function,
         is_method: bool,
@@ -52,11 +55,14 @@ impl<'a> FunctionRender<'a> {
         let name = local_name.unwrap_or_else(|| fn_.name(ctx.db())).to_string();
         let ast_node = fn_.source(ctx.db())?.value;
 
-        Some(FunctionRender { ctx, name, func: fn_, ast_node, is_method })
+        Some(FunctionRender { ctx, name, receiver, func: fn_, ast_node, is_method })
     }
 
-    fn render(self, import_to_add: Option<ImportEdit>) -> CompletionItem {
+    fn render(mut self, import_to_add: Option<ImportEdit>) -> CompletionItem {
         let params = self.params();
+        if let Some(receiver) = &self.receiver {
+            self.name = format!("{}.{}", receiver, &self.name)
+        }
         let mut item = CompletionItem::new(
             CompletionKind::Reference,
             self.ctx.source_range(),
@@ -148,7 +154,7 @@ impl<'a> FunctionRender<'a> {
         };
 
         let mut params_pats = Vec::new();
-        let params_ty = if self.ctx.completion.dot_receiver.is_some() {
+        let params_ty = if self.ctx.completion.dot_receiver.is_some() || self.receiver.is_some() {
             self.func.method_params(self.ctx.db()).unwrap_or_default()
         } else {
             if let Some(s) = ast_params.self_param() {
@@ -255,6 +261,26 @@ fn bar(s: &S) {
 }
 "#,
         );
+
+        check_edit(
+            "self.foo",
+            r#"
+struct S {}
+impl S {
+    fn foo(&self, x: i32) {
+        $0
+    }
+}
+"#,
+            r#"
+struct S {}
+impl S {
+    fn foo(&self, x: i32) {
+        self.foo(${1:x})$0
+    }
+}
+"#,
+        );
     }
 
     #[test]
diff --git a/crates/ide_completion/src/test_utils.rs b/crates/ide_completion/src/test_utils.rs
index 93c7c872c..b0a4b2026 100644
--- a/crates/ide_completion/src/test_utils.rs
+++ b/crates/ide_completion/src/test_utils.rs
@@ -19,6 +19,7 @@ use crate::{item::CompletionKind, CompletionConfig, CompletionItem};
 pub(crate) const TEST_CONFIG: CompletionConfig = CompletionConfig {
     enable_postfix_completions: true,
     enable_imports_on_the_fly: true,
+    enable_self_on_the_fly: true,
     add_call_parenthesis: true,
     add_call_argument_snippets: true,
     snippet_cap: SnippetCap::new(true),
diff --git a/crates/rust-analyzer/src/config.rs b/crates/rust-analyzer/src/config.rs
index a67b0bb25..ae78fd4f6 100644
--- a/crates/rust-analyzer/src/config.rs
+++ b/crates/rust-analyzer/src/config.rs
@@ -100,6 +100,9 @@ config_data! {
         /// Toggles the additional completions that automatically add imports when completed.
         /// Note that your client must specify the `additionalTextEdits` LSP client capability to truly have this feature enabled.
         completion_autoimport_enable: bool       = "true",
+        /// Toggles the additional completions that automatically show method calls and field accesses
+        /// with `self` prefixed to them when inside a method.
+        completion_autoself_enable: bool       = "true",
 
         /// Whether to show native rust-analyzer diagnostics.
         diagnostics_enable: bool                = "true",
@@ -666,6 +669,7 @@ impl Config {
             enable_postfix_completions: self.data.completion_postfix_enable,
             enable_imports_on_the_fly: self.data.completion_autoimport_enable
                 && completion_item_edit_resolve(&self.caps),
+            enable_self_on_the_fly: self.data.completion_autoself_enable,
             add_call_parenthesis: self.data.completion_addCallParenthesis,
             add_call_argument_snippets: self.data.completion_addCallArgumentSnippets,
             insert_use: self.insert_use_config(),
diff --git a/crates/rust-analyzer/src/integrated_benchmarks.rs b/crates/rust-analyzer/src/integrated_benchmarks.rs
index 781073fe5..ec36a5f5c 100644
--- a/crates/rust-analyzer/src/integrated_benchmarks.rs
+++ b/crates/rust-analyzer/src/integrated_benchmarks.rs
@@ -132,6 +132,7 @@ fn integrated_completion_benchmark() {
         let config = CompletionConfig {
             enable_postfix_completions: true,
             enable_imports_on_the_fly: true,
+            enable_self_on_the_fly: true,
             add_call_parenthesis: true,
             add_call_argument_snippets: true,
             snippet_cap: SnippetCap::new(true),
@@ -166,6 +167,7 @@ fn integrated_completion_benchmark() {
         let config = CompletionConfig {
             enable_postfix_completions: true,
             enable_imports_on_the_fly: true,
+            enable_self_on_the_fly: true,
             add_call_parenthesis: true,
             add_call_argument_snippets: true,
             snippet_cap: SnippetCap::new(true),
diff --git a/crates/rust-analyzer/src/to_proto.rs b/crates/rust-analyzer/src/to_proto.rs
index 85898f495..7428a3043 100644
--- a/crates/rust-analyzer/src/to_proto.rs
+++ b/crates/rust-analyzer/src/to_proto.rs
@@ -1178,6 +1178,7 @@ mod tests {
                 &ide::CompletionConfig {
                     enable_postfix_completions: true,
                     enable_imports_on_the_fly: true,
+                    enable_self_on_the_fly: true,
                     add_call_parenthesis: true,
                     add_call_argument_snippets: true,
                     snippet_cap: SnippetCap::new(true),
diff --git a/docs/dev/architecture.md b/docs/dev/architecture.md
index 39edf9e19..2624069a5 100644
--- a/docs/dev/architecture.md
+++ b/docs/dev/architecture.md
@@ -447,3 +447,8 @@ This is cheap enough to enable in production.
 
 Similarly, we save live object counting (`RA_COUNT=1`).
 It is not cheap enough to enable in prod, and this is a bug which should be fixed.
+
+### Configurability
+
+rust-analyzer strives to be as configurable as possible while offering reasonable defaults where no configuration exists yet.
+There will always be features that some people find more annoying than helpful, so giving the users the ability to tweak or disable these is a big part of offering a good user experience.
diff --git a/docs/user/generated_config.adoc b/docs/user/generated_config.adoc
index 4a5782a57..dbd9a3503 100644
--- a/docs/user/generated_config.adoc
+++ b/docs/user/generated_config.adoc
@@ -136,6 +136,12 @@ Whether to show postfix snippets like `dbg`, `if`, `not`, etc.
 Toggles the additional completions that automatically add imports when completed.
 Note that your client must specify the `additionalTextEdits` LSP client capability to truly have this feature enabled.
 --
+[[rust-analyzer.completion.autoself.enable]]rust-analyzer.completion.autoself.enable (default: `true`)::
++
+--
+Toggles the additional completions that automatically show method calls and field accesses
+with `self` prefixed to them when inside a method.
+--
 [[rust-analyzer.diagnostics.enable]]rust-analyzer.diagnostics.enable (default: `true`)::
 +
 --
diff --git a/editors/code/package.json b/editors/code/package.json
index 5b80cc1f9..42a06e137 100644
--- a/editors/code/package.json
+++ b/editors/code/package.json
@@ -572,6 +572,11 @@
                     "default": true,
                     "type": "boolean"
                 },
+                "rust-analyzer.completion.autoself.enable": {
+                    "markdownDescription": "Toggles the additional completions that automatically show method calls and field accesses\nwith `self` prefixed to them when inside a method.",
+                    "default": true,
+                    "type": "boolean"
+                },
                 "rust-analyzer.diagnostics.enable": {
                     "markdownDescription": "Whether to show native rust-analyzer diagnostics.",
                     "default": true,