internal: Make CompletionItem label and lookup fields SmolStrs

crates/cfg/src/lib.rs

@@ -66,24 +66,21 @@ impl CfgOptions {
         }
     }
 
-    pub fn get_cfg_keys(&self) -> Vec<&SmolStr> {
-        self.enabled
-            .iter()
-            .map(|x| match x {
-                CfgAtom::Flag(key) => key,
-                CfgAtom::KeyValue { key, .. } => key,
-            })
-            .collect()
+    pub fn get_cfg_keys(&self) -> impl Iterator<Item = &SmolStr> {
+        self.enabled.iter().map(|x| match x {
+            CfgAtom::Flag(key) => key,
+            CfgAtom::KeyValue { key, .. } => key,
+        })
     }
 
-    pub fn get_cfg_values(&self, cfg_key: &str) -> Vec<&SmolStr> {
-        self.enabled
-            .iter()
-            .filter_map(|x| match x {
-                CfgAtom::KeyValue { key, value } if cfg_key == key => Some(value),
-                _ => None,
-            })
-            .collect()
+    pub fn get_cfg_values<'a>(
+        &'a self,
+        cfg_key: &'a str,
+    ) -> impl Iterator<Item = &'a SmolStr> + 'a {
+        self.enabled.iter().filter_map(move |x| match x {
+            CfgAtom::KeyValue { key, value } if cfg_key == key => Some(value),
+            _ => None,
+        })
     }
 }
 

crates/ide_completion/src/completions/attribute.rs

@@ -104,7 +104,7 @@ fn complete_new_attribute(acc: &mut Completions, ctx: &CompletionContext, attrib
                 let mut item = CompletionItem::new(
                     CompletionItemKind::Attribute,
                     ctx.source_range(),
-                    name.to_string(),
+                    name.to_smol_str(),
                 );
                 if let Some(docs) = mac.docs(ctx.sema.db) {
                     item.documentation(docs);

crates/ide_completion/src/completions/attribute/cfg.rs

@@ -31,26 +31,21 @@ pub(crate) fn complete_cfg(acc: &mut Completions, ctx: &CompletionContext) {
         Some("target_endian") => ["little", "big"].into_iter().for_each(add_completion),
         Some(name) => {
             if let Some(krate) = ctx.krate {
-                krate.potential_cfg(ctx.db).get_cfg_values(&name).iter().for_each(|s| {
-                    let mut item = CompletionItem::new(
-                        CompletionItemKind::Attribute,
-                        ctx.source_range(),
-                        s.as_str(),
-                    );
-                    item.insert_text(format!(r#""{}""#, s));
+                krate.potential_cfg(ctx.db).get_cfg_values(&name).cloned().for_each(|s| {
+                    let insert_text = format!(r#""{}""#, s);
+                    let mut item =
+                        CompletionItem::new(CompletionItemKind::Attribute, ctx.source_range(), s);
+                    item.insert_text(insert_text);
 
                     acc.add(item.build());
                 })
             };
         }
         None => {
             if let Some(krate) = ctx.krate {
-                krate.potential_cfg(ctx.db).get_cfg_keys().iter().for_each(|s| {
-                    let item = CompletionItem::new(
-                        CompletionItemKind::Attribute,
-                        ctx.source_range(),
-                        s.as_str(),
-                    );
+                krate.potential_cfg(ctx.db).get_cfg_keys().cloned().for_each(|s| {
+                    let item =
+                        CompletionItem::new(CompletionItemKind::Attribute, ctx.source_range(), s);
                     acc.add(item.build());
                 })
             }

crates/ide_completion/src/completions/attribute/derive.rs

@@ -3,7 +3,7 @@ use hir::{HasAttrs, MacroDef, MacroKind};
 use ide_db::helpers::{import_assets::ImportAssets, insert_use::ImportScope, FamousDefs};
 use itertools::Itertools;
 use rustc_hash::FxHashSet;
-use syntax::{ast, SyntaxKind};
+use syntax::{ast, SmolStr, SyntaxKind};
 
 use crate::{
     completions::flyimport::compute_fuzzy_completion_order_key,
@@ -30,7 +30,6 @@ pub(super) fn complete_derive(
         }
 
         let name = name.to_smol_str();
-        let label;
         let (label, lookup) = match core.zip(mac.module(ctx.db).map(|it| it.krate())) {
             // show derive dependencies for `core`/`std` derives
             Some((core, mac_krate)) if core == mac_krate => {
@@ -48,13 +47,13 @@ pub(super) fn complete_derive(
                         },
                     ));
                     let lookup = components.join(", ");
-                    label = components.iter().rev().join(", ");
-                    (label.as_str(), Some(lookup))
+                    let label = Itertools::intersperse(components.into_iter().rev(), ", ");
+                    (SmolStr::from_iter(label), Some(lookup))
                 } else {
-                    (&*name, None)
+                    (name, None)
                 }
             }
-            _ => (&*name, None),
+            _ => (name, None),
         };
 
         let mut item =
@@ -68,7 +67,7 @@ pub(super) fn complete_derive(
         item.add_to(acc);
     }
 
-    flyimport_attribute(ctx, acc);
+    flyimport_attribute(acc, ctx);
 }
 
 fn get_derives_in_scope(ctx: &CompletionContext) -> Vec<(hir::Name, MacroDef)> {
@@ -83,7 +82,7 @@ fn get_derives_in_scope(ctx: &CompletionContext) -> Vec<(hir::Name, MacroDef)> {
     result
 }
 
-fn flyimport_attribute(ctx: &CompletionContext, acc: &mut Completions) -> Option<()> {
+fn flyimport_attribute(acc: &mut Completions, ctx: &CompletionContext) -> Option<()> {
     if ctx.token.kind() != SyntaxKind::IDENT {
         return None;
     };
@@ -115,7 +114,7 @@ fn flyimport_attribute(ctx: &CompletionContext, acc: &mut Completions) -> Option
                 let mut item = CompletionItem::new(
                     CompletionItemKind::Attribute,
                     ctx.source_range(),
-                    mac.name(ctx.db)?.to_string(),
+                    mac.name(ctx.db)?.to_smol_str(),
                 );
                 item.add_import(ImportEdit { import, scope: import_scope.clone() });
                 if let Some(docs) = mac.docs(ctx.db) {

crates/ide_completion/src/completions/fn_param.rs

@@ -30,6 +30,7 @@ pub(crate) fn complete_fn_param(acc: &mut Completions, ctx: &CompletionContext)
         }
         func.param_list().into_iter().flat_map(|it| it.params()).for_each(|param| {
             if let Some(pat) = param.pat() {
+                // FIXME: We should be able to turn these into SmolStr without having to allocate a String
                 let text = param.syntax().text().to_string();
                 let lookup = pat.syntax().text().to_string();
                 params.entry(text).or_insert(lookup);
@@ -59,7 +60,7 @@ pub(crate) fn complete_fn_param(acc: &mut Completions, ctx: &CompletionContext)
 
     let self_completion_items = ["self", "&self", "mut self", "&mut self"];
     if ctx.impl_def.is_some() && me?.param_list()?.params().next().is_none() {
-        self_completion_items.iter().for_each(|self_item| {
+        self_completion_items.into_iter().for_each(|self_item| {
             add_new_item_to_acc(ctx, acc, self_item.to_string(), self_item.to_string())
         });
     }

crates/ide_completion/src/completions/keyword.rs

@@ -27,7 +27,7 @@ pub(crate) fn complete_expr_keyword(acc: &mut Completions, ctx: &CompletionConte
         return;
     }
 
-    let mut add_keyword = |kw, snippet| add_keyword(ctx, acc, kw, snippet);
+    let mut add_keyword = |kw, snippet| add_keyword(acc, ctx, kw, snippet);
 
     let expects_assoc_item = ctx.expects_assoc_item();
     let has_block_expr_parent = ctx.has_block_expr_parent();
@@ -157,7 +157,7 @@ pub(crate) fn complete_expr_keyword(acc: &mut Completions, ctx: &CompletionConte
     )
 }
 
-fn add_keyword(ctx: &CompletionContext, acc: &mut Completions, kw: &str, snippet: &str) {
+fn add_keyword(acc: &mut Completions, ctx: &CompletionContext, kw: &str, snippet: &str) {
     let mut item = CompletionItem::new(CompletionItemKind::Keyword, ctx.source_range(), kw);
 
     match ctx.config.snippet_cap {

crates/ide_completion/src/completions/qualified_path.rs

@@ -93,7 +93,7 @@ pub(crate) fn complete_qualified_path(acc: &mut Completions, ctx: &CompletionCon
                 if ctx.in_use_tree() {
                     if let hir::ScopeDef::Unknown = def {
                         if let Some(ast::NameLike::NameRef(name_ref)) = ctx.name_syntax.as_ref() {
-                            if name_ref.syntax().text() == name.to_string().as_str() {
+                            if name_ref.syntax().text() == name.to_smol_str().as_str() {
                                 // for `use self::foo$0`, don't suggest `foo` as a completion
                                 cov_mark::hit!(dont_complete_current_use);
                                 continue;

crates/ide_completion/src/completions/trait_impl.rs

@@ -133,7 +133,7 @@ fn add_function_impl(
     func: hir::Function,
     impl_def: hir::Impl,
 ) {
-    let fn_name = func.name(ctx.db).to_string();
+    let fn_name = func.name(ctx.db).to_smol_str();
 
     let label = if func.assoc_fn_params(ctx.db).is_empty() {
         format!("fn {}()", fn_name)
@@ -205,12 +205,12 @@ fn add_type_alias_impl(
     ctx: &CompletionContext,
     type_alias: hir::TypeAlias,
 ) {
-    let alias_name = type_alias.name(ctx.db).to_string();
+    let alias_name = type_alias.name(ctx.db).to_smol_str();
 
     let snippet = format!("type {} = ", alias_name);
 
     let range = replacement_range(ctx, type_def_node);
-    let mut item = CompletionItem::new(SymbolKind::TypeAlias, ctx.source_range(), snippet.clone());
+    let mut item = CompletionItem::new(SymbolKind::TypeAlias, ctx.source_range(), &snippet);
     item.text_edit(TextEdit::replace(range, snippet))
         .lookup_by(alias_name)
         .set_documentation(type_alias.docs(ctx.db));
@@ -224,7 +224,7 @@ fn add_const_impl(
     const_: hir::Const,
     impl_def: hir::Impl,
 ) {
-    let const_name = const_.name(ctx.db).map(|n| n.to_string());
+    let const_name = const_.name(ctx.db).map(|n| n.to_smol_str());
 
     if let Some(const_name) = const_name {
         if let Some(source) = const_.source(ctx.db) {
@@ -238,8 +238,7 @@ fn add_const_impl(
                 let snippet = make_const_compl_syntax(&transformed_const);
 
                 let range = replacement_range(ctx, const_def_node);
-                let mut item =
-                    CompletionItem::new(SymbolKind::Const, ctx.source_range(), snippet.clone());
+                let mut item = CompletionItem::new(SymbolKind::Const, ctx.source_range(), &snippet);
                 item.text_edit(TextEdit::replace(range, snippet))
                     .lookup_by(const_name)
                     .set_documentation(const_.docs(ctx.db));

crates/ide_completion/src/item.rs

@@ -12,8 +12,8 @@ use ide_db::{
     SymbolKind,
 };
 use smallvec::SmallVec;
-use stdx::{format_to, impl_from, never};
-use syntax::{algo, TextRange};
+use stdx::{impl_from, never};
+use syntax::{algo, SmolStr, TextRange};
 use text_edit::TextEdit;
 
 /// `CompletionItem` describes a single completion variant in the editor pop-up.
@@ -22,7 +22,7 @@ use text_edit::TextEdit;
 #[derive(Clone)]
 pub struct CompletionItem {
     /// Label in the completion pop up which identifies completion.
-    label: String,
+    label: SmolStr,
     /// Range of identifier that is being completed.
     ///
     /// It should be used primarily for UI, but we also use this to convert
@@ -46,7 +46,7 @@ pub struct CompletionItem {
     ///
     /// That is, in `foo.bar$0` lookup of `abracadabra` will be accepted (it
     /// contains `bar` sub sequence), and `quux` will rejected.
-    lookup: Option<String>,
+    lookup: Option<SmolStr>,
 
     /// Additional info to show in the UI pop up.
     detail: Option<String>,
@@ -268,7 +268,7 @@ impl CompletionItem {
     pub(crate) fn new(
         kind: impl Into<CompletionItemKind>,
         source_range: TextRange,
-        label: impl Into<String>,
+        label: impl Into<SmolStr>,
     ) -> Builder {
         let label = label.into();
         Builder {
@@ -379,13 +379,13 @@ impl ImportEdit {
 pub(crate) struct Builder {
     source_range: TextRange,
     imports_to_add: SmallVec<[ImportEdit; 1]>,
-    trait_name: Option<String>,
-    label: String,
+    trait_name: Option<SmolStr>,
+    label: SmolStr,
     insert_text: Option<String>,
     is_snippet: bool,
     detail: Option<String>,
     documentation: Option<Documentation>,
-    lookup: Option<String>,
+    lookup: Option<SmolStr>,
     kind: CompletionItemKind,
     text_edit: Option<TextEdit>,
     deprecated: bool,
@@ -400,25 +400,21 @@ impl Builder {
 
         let mut label = self.label;
         let mut lookup = self.lookup;
-        let mut insert_text = self.insert_text;
+        let insert_text = self.insert_text.unwrap_or_else(|| label.to_string());
 
         if let [import_edit] = &*self.imports_to_add {
             // snippets can have multiple imports, but normal completions only have up to one
             if let Some(original_path) = import_edit.import.original_path.as_ref() {
                 lookup = lookup.or_else(|| Some(label.clone()));
-                insert_text = insert_text.or_else(|| Some(label.clone()));
-                format_to!(label, " (use {})", original_path)
+                label = SmolStr::from(format!("{} (use {})", label, original_path));
             }
         } else if let Some(trait_name) = self.trait_name {
-            insert_text = insert_text.or_else(|| Some(label.clone()));
-            format_to!(label, " (as {})", trait_name)
+            label = SmolStr::from(format!("{} (as {})", label, trait_name));
         }
 
         let text_edit = match self.text_edit {
             Some(it) => it,
-            None => {
-                TextEdit::replace(self.source_range, insert_text.unwrap_or_else(|| label.clone()))
-            }
+            None => TextEdit::replace(self.source_range, insert_text),
         };
 
         CompletionItem {
@@ -437,16 +433,16 @@ impl Builder {
             import_to_add: self.imports_to_add,
         }
     }
-    pub(crate) fn lookup_by(&mut self, lookup: impl Into<String>) -> &mut Builder {
+    pub(crate) fn lookup_by(&mut self, lookup: impl Into<SmolStr>) -> &mut Builder {
         self.lookup = Some(lookup.into());
         self
     }
-    pub(crate) fn label(&mut self, label: impl Into<String>) -> &mut Builder {
+    pub(crate) fn label(&mut self, label: impl Into<SmolStr>) -> &mut Builder {
         self.label = label.into();
         self
     }
-    pub(crate) fn trait_name(&mut self, trait_name: impl Into<String>) -> &mut Builder {
-        self.trait_name = Some(trait_name.into());
+    pub(crate) fn trait_name(&mut self, trait_name: SmolStr) -> &mut Builder {
+        self.trait_name = Some(trait_name);
         self
     }
     pub(crate) fn insert_text(&mut self, insert_text: impl Into<String>) -> &mut Builder {

crates/ide_completion/src/render.rs

@@ -83,11 +83,11 @@ pub(crate) fn render_field(
     ty: &hir::Type,
 ) -> CompletionItem {
     let is_deprecated = ctx.is_deprecated(field);
-    let name = field.name(ctx.db()).to_string();
+    let name = field.name(ctx.db()).to_smol_str();
     let mut item = CompletionItem::new(
         SymbolKind::Field,
         ctx.source_range(),
-        receiver.map_or_else(|| name.clone(), |receiver| format!("{}.{}", receiver, name)),
+        receiver.map_or_else(|| name.clone(), |receiver| format!("{}.{}", receiver, name).into()),
     );
     item.set_relevance(CompletionRelevance {
         type_match: compute_type_match(ctx.completion, ty),
@@ -97,7 +97,7 @@ pub(crate) fn render_field(
     item.detail(ty.display(ctx.db()).to_string())
         .set_documentation(field.docs(ctx.db()))
         .set_deprecated(is_deprecated)
-        .lookup_by(name.as_str());
+        .lookup_by(name.clone());
     let is_keyword = SyntaxKind::from_keyword(name.as_str()).is_some();
     if is_keyword && !matches!(name.as_str(), "self" | "crate" | "super" | "Self") {
         item.insert_text(format!("r#{}", name));
@@ -199,7 +199,7 @@ fn render_resolution_(
             let mut item = CompletionItem::new(
                 CompletionItemKind::UnresolvedReference,
                 ctx.source_range(),
-                local_name.to_string(),
+                local_name.to_smol_str(),
             );
             if let Some(import_to_add) = import_to_add {
                 item.add_import(import_to_add);
@@ -208,7 +208,7 @@ fn render_resolution_(
         }
     };
 
-    let local_name = local_name.to_string();
+    let local_name = local_name.to_smol_str();
     let mut item = CompletionItem::new(kind, ctx.source_range(), local_name.clone());
     if let hir::ScopeDef::Local(local) = resolution {
         let ty = local.ty(ctx.db());