35 files changed, 263 insertions, 95 deletions

diff --git a/Cargo.lock b/Cargo.lock
index 7f666ca61..b36bca0ab 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -1,5 +1,7 @@
 # This file is automatically @generated by Cargo.
 # It is not intended for manual editing.
+version = 3
+
 [[package]]
 name = "addr2line"
 version = "0.14.1"
@@ -47,9 +49,9 @@ checksum = "33954243bd79057c2de7338850b85983a44588021f8a5fee574a8888c6de4344"
 
 [[package]]
 name = "arrayvec"
-version = "0.5.2"
+version = "0.6.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "23b62fc65de8e4e7f52534fb52b0f3ed04746ae267519eef2a83941e8085068b"
+checksum = "682f88bd1270f264991da8922b89ee1fb520b0da73f97c9f73cda54980123017"
 
 [[package]]
 name = "atty"
diff --git a/crates/hir/Cargo.toml b/crates/hir/Cargo.toml
index 55e9c3f0c..2ef5bcbc9 100644
--- a/crates/hir/Cargo.toml
+++ b/crates/hir/Cargo.toml
@@ -13,7 +13,7 @@ doctest = false
 log = "0.4.8"
 rustc-hash = "1.1.0"
 either = "1.5.3"
-arrayvec = "0.5.1"
+arrayvec = "0.6"
 itertools = "0.10.0"
 smallvec = "1.4.0"
 
diff --git a/crates/hir/src/lib.rs b/crates/hir/src/lib.rs
index 6fa676c4d..4ee08ef21 100644
--- a/crates/hir/src/lib.rs
+++ b/crates/hir/src/lib.rs
@@ -51,7 +51,7 @@ use hir_def::{
 };
 use hir_expand::{diagnostics::DiagnosticSink, name::name, MacroDefKind};
 use hir_ty::{
-    autoderef,
+    autoderef, could_unify,
     method_resolution::{self, TyFingerprint},
     primitive::UintTy,
     to_assoc_type_id,
@@ -2154,6 +2154,10 @@ impl Type {
 
         walk_type(db, self, &mut cb);
     }
+
+    pub fn could_unify_with(&self, other: &Type) -> bool {
+        could_unify(&self.ty, &other.ty)
+    }
 }
 
 // FIXME: closures
@@ -2238,7 +2242,7 @@ pub enum ScopeDef {
 }
 
 impl ScopeDef {
-    pub fn all_items(def: PerNs) -> ArrayVec<[Self; 3]> {
+    pub fn all_items(def: PerNs) -> ArrayVec<Self, 3> {
         let mut items = ArrayVec::new();
 
         match (def.take_types(), def.take_values()) {
diff --git a/crates/hir/src/semantics.rs b/crates/hir/src/semantics.rs
index 1198e3f0b..3ff135f41 100644
--- a/crates/hir/src/semantics.rs
+++ b/crates/hir/src/semantics.rs
@@ -445,7 +445,7 @@ impl<'db> SemanticsImpl<'db> {
                 }
             };
             gpl.lifetime_params()
-                .find(|tp| tp.lifetime().as_ref().map(|lt| lt.text()) == Some(text))
+                .find(|tp| tp.lifetime().as_ref().map(|lt| lt.text()).as_ref() == Some(&text))
         })?;
         let src = self.find_file(lifetime_param.syntax().clone()).with_value(lifetime_param);
         ToDef::to_def(self, src)
diff --git a/crates/hir_expand/src/name.rs b/crates/hir_expand/src/name.rs
index 0aeea48d5..cd691b1d2 100644
--- a/crates/hir_expand/src/name.rs
+++ b/crates/hir_expand/src/name.rs
@@ -75,14 +75,14 @@ impl AsName for ast::NameRef {
     fn as_name(&self) -> Name {
         match self.as_tuple_field() {
             Some(idx) => Name::new_tuple_field(idx),
-            None => Name::resolve(self.text()),
+            None => Name::resolve(&self.text()),
         }
     }
 }
 
 impl AsName for ast::Name {
     fn as_name(&self) -> Name {
-        Name::resolve(self.text())
+        Name::resolve(&self.text())
     }
 }
 
diff --git a/crates/hir_ty/Cargo.toml b/crates/hir_ty/Cargo.toml
index 0ef27cd37..030b7eebe 100644
--- a/crates/hir_ty/Cargo.toml
+++ b/crates/hir_ty/Cargo.toml
@@ -12,7 +12,7 @@ doctest = false
 [dependencies]
 cov-mark = { version = "1.1", features = ["thread-local"] }
 itertools = "0.10.0"
-arrayvec = "0.5.1"
+arrayvec = "0.6"
 smallvec = "1.2.0"
 ena = "0.14.0"
 log = "0.4.8"
diff --git a/crates/hir_ty/src/display.rs b/crates/hir_ty/src/display.rs
index 6149067c7..51480304b 100644
--- a/crates/hir_ty/src/display.rs
+++ b/crates/hir_ty/src/display.rs
@@ -1,8 +1,7 @@
 //! FIXME: write short doc here
 
-use std::fmt;
+use std::{array, fmt};
 
-use arrayvec::ArrayVec;
 use chalk_ir::Mutability;
 use hir_def::{
     db::DefDatabase,
@@ -669,8 +668,7 @@ fn fn_traits(db: &dyn DefDatabase, trait_: TraitId) -> impl Iterator<Item = Trai
         db.lang_item(krate, "fn_mut".into()),
         db.lang_item(krate, "fn_once".into()),
     ];
-    // FIXME: Replace ArrayVec when into_iter is a thing on arrays
-    ArrayVec::from(fn_traits).into_iter().flatten().flat_map(|it| it.as_trait())
+    array::IntoIter::new(fn_traits).into_iter().flatten().flat_map(|it| it.as_trait())
 }
 
 pub fn write_bounds_like_dyn_trait_with_prefix(
diff --git a/crates/hir_ty/src/infer.rs b/crates/hir_ty/src/infer.rs
index 8f9cf7480..e4407ff50 100644
--- a/crates/hir_ty/src/infer.rs
+++ b/crates/hir_ty/src/infer.rs
@@ -45,6 +45,11 @@ use crate::{
     to_assoc_type_id, to_chalk_trait_id, AliasEq, AliasTy, Interner, TyKind,
 };
 
+// This lint has a false positive here. See the link below for details.
+//
+// https://github.com/rust-lang/rust/issues/57411
+#[allow(unreachable_pub)]
+pub use unify::could_unify;
 pub(crate) use unify::unify;
 
 mod unify;
diff --git a/crates/hir_ty/src/infer/unify.rs b/crates/hir_ty/src/infer/unify.rs
index 75250a369..6e7b0f5a6 100644
--- a/crates/hir_ty/src/infer/unify.rs
+++ b/crates/hir_ty/src/infer/unify.rs
@@ -157,6 +157,10 @@ impl<T> Canonicalized<T> {
     }
 }
 
+pub fn could_unify(t1: &Ty, t2: &Ty) -> bool {
+    InferenceTable::new().unify(t1, t2)
+}
+
 pub(crate) fn unify(tys: &Canonical<(Ty, Ty)>) -> Option<Substitution> {
     let mut table = InferenceTable::new();
     let vars = Substitution(
diff --git a/crates/hir_ty/src/lib.rs b/crates/hir_ty/src/lib.rs
index 69265286f..6f9c698e6 100644
--- a/crates/hir_ty/src/lib.rs
+++ b/crates/hir_ty/src/lib.rs
@@ -41,7 +41,7 @@ use crate::{
 };
 
 pub use autoderef::autoderef;
-pub use infer::{InferenceResult, InferenceVar};
+pub use infer::{could_unify, InferenceResult, InferenceVar};
 pub use lower::{
     associated_type_shorthand_candidates, callable_item_sig, CallableDefId, ImplTraitLoweringMode,
     TyDefId, TyLoweringContext, ValueTyDefId,
diff --git a/crates/hir_ty/src/method_resolution.rs b/crates/hir_ty/src/method_resolution.rs
index 84d9a1e18..bf7d5eded 100644
--- a/crates/hir_ty/src/method_resolution.rs
+++ b/crates/hir_ty/src/method_resolution.rs
@@ -228,12 +228,12 @@ impl Ty {
         &self,
         db: &dyn HirDatabase,
         cur_crate: CrateId,
-    ) -> Option<ArrayVec<[CrateId; 2]>> {
+    ) -> Option<ArrayVec<CrateId, 2>> {
         // Types like slice can have inherent impls in several crates, (core and alloc).
         // The corresponding impls are marked with lang items, so we can use them to find the required crates.
         macro_rules! lang_item_crate {
             ($($name:expr),+ $(,)?) => {{
-                let mut v = ArrayVec::<[LangItemTarget; 2]>::new();
+                let mut v = ArrayVec::<LangItemTarget, 2>::new();
                 $(
                     v.extend(db.lang_item(cur_crate, $name.into()));
                 )+
diff --git a/crates/ide/src/diagnostics/fixes.rs b/crates/ide/src/diagnostics/fixes.rs
index 2f840909c..5fb3e2d91 100644
--- a/crates/ide/src/diagnostics/fixes.rs
+++ b/crates/ide/src/diagnostics/fixes.rs
@@ -210,7 +210,7 @@ fn missing_record_expr_field_fix(
     }
     let new_field = make::record_field(
         None,
-        make::name(record_expr_field.field_name()?.text()),
+        make::name(&record_expr_field.field_name()?.text()),
         make::ty(&new_field_type.display_source_code(sema.db, module.into()).ok()?),
     );
 
diff --git a/crates/ide/src/inlay_hints.rs b/crates/ide/src/inlay_hints.rs
index 16c04eeee..25f96222c 100644
--- a/crates/ide/src/inlay_hints.rs
+++ b/crates/ide/src/inlay_hints.rs
@@ -416,7 +416,7 @@ fn get_string_representation(expr: &ast::Expr) -> Option<String> {
     match expr {
         ast::Expr::MethodCallExpr(method_call_expr) => {
             let name_ref = method_call_expr.name_ref()?;
-            match name_ref.text() {
+            match name_ref.text().as_str() {
                 "clone" => method_call_expr.receiver().map(|rec| rec.to_string()),
                 name_ref => Some(name_ref.to_owned()),
             }
diff --git a/crates/ide/src/runnables.rs b/crates/ide/src/runnables.rs
index 5b488e2c5..7e4c5a078 100644
--- a/crates/ide/src/runnables.rs
+++ b/crates/ide/src/runnables.rs
@@ -226,7 +226,9 @@ pub(crate) fn runnable_fn(sema: &Semantics<RootDatabase>, def: hir::Function) ->
     let func = def.source(sema.db)?;
     let name_string = def.name(sema.db).to_string();
 
-    let kind = if name_string == "main" {
+    let root = def.krate(sema.db)?.root_module(sema.db);
+
+    let kind = if name_string == "main" && def.module(sema.db) == root {
         RunnableKind::Bin
     } else {
         let canonical_path = {
@@ -444,6 +446,10 @@ fn test_foo() {}
 
 #[bench]
 fn bench() {}
+
+mod not_a_root {
+    fn main() {}
+}
 "#,
             &[&BIN, &TEST, &TEST, &BENCH],
             expect![[r#"
diff --git a/crates/ide/src/syntax_highlighting/format.rs b/crates/ide/src/syntax_highlighting/format.rs
index e503abc93..5bbadb0f4 100644
--- a/crates/ide/src/syntax_highlighting/format.rs
+++ b/crates/ide/src/syntax_highlighting/format.rs
@@ -31,7 +31,7 @@ fn is_format_string(string: &ast::String) -> Option<()> {
     let parent = string.syntax().parent()?;
 
     let name = parent.parent().and_then(ast::MacroCall::cast)?.path()?.segment()?.name_ref()?;
-    if !matches!(name.text(), "format_args" | "format_args_nl") {
+    if !matches!(name.text().as_str(), "format_args" | "format_args_nl") {
         return None;
     }
 
diff --git a/crates/ide_assists/src/handlers/extract_struct_from_enum_variant.rs b/crates/ide_assists/src/handlers/extract_struct_from_enum_variant.rs
index 596c536a7..a8d6355bd 100644
--- a/crates/ide_assists/src/handlers/extract_struct_from_enum_variant.rs
+++ b/crates/ide_assists/src/handlers/extract_struct_from_enum_variant.rs
@@ -195,7 +195,7 @@ fn extract_struct_def(
 
 fn update_variant(rewriter: &mut SyntaxRewriter, variant: &ast::Variant) -> Option<()> {
     let name = variant.name()?;
-    let tuple_field = make::tuple_field(None, make::ty(name.text()));
+    let tuple_field = make::tuple_field(None, make::ty(&name.text()));
     let replacement = make::variant(
         name,
         Some(ast::FieldList::TupleFieldList(make::tuple_field_list(iter::once(tuple_field)))),
diff --git a/crates/ide_assists/src/handlers/generate_enum_is_method.rs b/crates/ide_assists/src/handlers/generate_enum_is_method.rs
index 7e181a480..a9f71a703 100644
--- a/crates/ide_assists/src/handlers/generate_enum_is_method.rs
+++ b/crates/ide_assists/src/handlers/generate_enum_is_method.rs
@@ -44,7 +44,7 @@ pub(crate) fn generate_enum_is_method(acc: &mut Assists, ctx: &AssistContext) ->
     };
 
     let enum_lowercase_name = to_lower_snake_case(&parent_enum.name()?.to_string());
-    let fn_name = format!("is_{}", &to_lower_snake_case(variant_name.text()));
+    let fn_name = format!("is_{}", &to_lower_snake_case(&variant_name.text()));
 
     // Return early if we've found an existing new fn
     let impl_def = find_struct_impl(&ctx, &parent_enum, &fn_name)?;
diff --git a/crates/ide_assists/src/handlers/generate_enum_projection_method.rs b/crates/ide_assists/src/handlers/generate_enum_projection_method.rs
index 871bcab50..e2f572ba3 100644
--- a/crates/ide_assists/src/handlers/generate_enum_projection_method.rs
+++ b/crates/ide_assists/src/handlers/generate_enum_projection_method.rs
@@ -132,7 +132,8 @@ fn generate_enum_projection_method(
         ast::StructKind::Unit => return None,
     };
 
-    let fn_name = format!("{}_{}", props.fn_name_prefix, &to_lower_snake_case(variant_name.text()));
+    let fn_name =
+        format!("{}_{}", props.fn_name_prefix, &to_lower_snake_case(&variant_name.text()));
 
     // Return early if we've found an existing new fn
     let impl_def = find_struct_impl(&ctx, &parent_enum, &fn_name)?;
diff --git a/crates/ide_assists/src/handlers/replace_derive_with_manual_impl.rs b/crates/ide_assists/src/handlers/replace_derive_with_manual_impl.rs
index 4f0ef52ca..f872d20c8 100644
--- a/crates/ide_assists/src/handlers/replace_derive_with_manual_impl.rs
+++ b/crates/ide_assists/src/handlers/replace_derive_with_manual_impl.rs
@@ -165,7 +165,7 @@ fn impl_def_from_trait(
     }
     let impl_def = make::impl_trait(
         trait_path.clone(),
-        make::path_unqualified(make::path_segment(make::name_ref(annotated_name.text()))),
+        make::path_unqualified(make::path_segment(make::name_ref(&annotated_name.text()))),
     );
     let (impl_def, first_assoc_item) =
         add_trait_assoc_items_to_impl(sema, trait_items, trait_, impl_def, target_scope);
@@ -178,12 +178,13 @@ fn update_attribute(
     trait_name: &ast::NameRef,
     attr: &ast::Attr,
 ) {
+    let trait_name = trait_name.text();
     let new_attr_input = input
         .syntax()
         .descendants_with_tokens()
         .filter(|t| t.kind() == IDENT)
         .filter_map(|t| t.into_token().map(|t| t.text().to_string()))
-        .filter(|t| t != trait_name.text())
+        .filter(|t| t != &trait_name)
         .collect::<Vec<_>>();
     let has_more_derives = !new_attr_input.is_empty();
 
diff --git a/crates/ide_assists/src/utils.rs b/crates/ide_assists/src/utils.rs
index 62f959082..9de9e4dbd 100644
--- a/crates/ide_assists/src/utils.rs
+++ b/crates/ide_assists/src/utils.rs
@@ -246,7 +246,7 @@ fn invert_special_case(sema: &Semantics<RootDatabase>, expr: &ast::Expr) -> Opti
             let method = mce.name_ref()?;
             let arg_list = mce.arg_list()?;
 
-            let method = match method.text() {
+            let method = match method.text().as_str() {
                 "is_some" => "is_none",
                 "is_none" => "is_some",
                 "is_ok" => "is_err",
@@ -442,7 +442,7 @@ fn generate_impl_text_inner(adt: &ast::Adt, trait_text: Option<&str>, code: &str
         buf.push_str(trait_text);
         buf.push_str(" for ");
     }
-    buf.push_str(adt.name().unwrap().text());
+    buf.push_str(&adt.name().unwrap().text());
     if let Some(generic_params) = generic_params {
         let lifetime_params = generic_params
             .lifetime_params()
diff --git a/crates/ide_completion/src/item.rs b/crates/ide_completion/src/item.rs
index 9a4b5217a..cc4ac9ea2 100644
--- a/crates/ide_completion/src/item.rs
+++ b/crates/ide_completion/src/item.rs
@@ -122,7 +122,7 @@ impl fmt::Debug for CompletionItem {
     }
 }
 
-#[derive(Debug, Clone, Copy, Ord, PartialOrd, Eq, PartialEq, Default)]
+#[derive(Debug, Clone, Copy, Eq, PartialEq, Default)]
 pub struct CompletionRelevance {
     /// This is set in cases like these:
     ///
@@ -134,31 +134,41 @@ pub struct CompletionRelevance {
     /// }
     /// ```
     pub exact_name_match: bool,
+    /// See CompletionRelevanceTypeMatch doc comments for cases where this is set.
+    pub type_match: Option<CompletionRelevanceTypeMatch>,
     /// This is set in cases like these:
     ///
     /// ```
-    /// fn f(spam: String) {}
-    /// fn main {
-    ///     let foo = String::new();
-    ///     f($0) // type of local matches the type of param
+    /// fn foo(a: u32) {
+    ///     let b = 0;
+    ///     $0 // `a` and `b` are local
     /// }
     /// ```
-    pub exact_type_match: bool,
+    pub is_local: bool,
+}
+
+#[derive(Debug, Clone, Copy, Eq, PartialEq)]
+pub enum CompletionRelevanceTypeMatch {
     /// This is set in cases like these:
     ///
     /// ```
-    /// fn foo(bar: u32) {
-    ///     $0 // `bar` is local
+    /// enum Option<T> { Some(T), None }
+    /// fn f(a: Option<u32>) {}
+    /// fn main {
+    ///     f(Option::N$0) // type `Option<T>` could unify with `Option<u32>`
     /// }
     /// ```
+    CouldUnify,
+    /// This is set in cases like these:
     ///
     /// ```
-    /// fn foo() {
-    ///     let bar = 0;
-    ///     $0 // `bar` is local
+    /// fn f(spam: String) {}
+    /// fn main {
+    ///     let foo = String::new();
+    ///     f($0) // type of local matches the type of param
     /// }
     /// ```
-    pub is_local: bool,
+    Exact,
 }
 
 impl CompletionRelevance {
@@ -177,9 +187,11 @@ impl CompletionRelevance {
         if self.exact_name_match {
             score += 1;
         }
-        if self.exact_type_match {
-            score += 3;
-        }
+        score += match self.type_match {
+            Some(CompletionRelevanceTypeMatch::Exact) => 4,
+            Some(CompletionRelevanceTypeMatch::CouldUnify) => 3,
+            None => 0,
+        };
         if self.is_local {
             score += 1;
         }
@@ -342,7 +354,7 @@ impl CompletionItem {
         // match, but with exact type match set because self.ref_match
         // is only set if there is an exact type match.
         let mut relevance = self.relevance;
-        relevance.exact_type_match = true;
+        relevance.type_match = Some(CompletionRelevanceTypeMatch::Exact);
 
         self.ref_match.map(|mutability| (mutability, relevance))
     }
@@ -523,7 +535,7 @@ mod tests {
     use itertools::Itertools;
     use test_utils::assert_eq_text;
 
-    use super::CompletionRelevance;
+    use super::{CompletionRelevance, CompletionRelevanceTypeMatch};
 
     /// Check that these are CompletionRelevance are sorted in ascending order
     /// by their relevance score.
@@ -576,15 +588,22 @@ mod tests {
                 is_local: true,
                 ..CompletionRelevance::default()
             }],
-            vec![CompletionRelevance { exact_type_match: true, ..CompletionRelevance::default() }],
+            vec![CompletionRelevance {
+                type_match: Some(CompletionRelevanceTypeMatch::CouldUnify),
+                ..CompletionRelevance::default()
+            }],
+            vec![CompletionRelevance {
+                type_match: Some(CompletionRelevanceTypeMatch::Exact),
+                ..CompletionRelevance::default()
+            }],
             vec![CompletionRelevance {
                 exact_name_match: true,
-                exact_type_match: true,
+                type_match: Some(CompletionRelevanceTypeMatch::Exact),
                 ..CompletionRelevance::default()
             }],
             vec![CompletionRelevance {
                 exact_name_match: true,
-                exact_type_match: true,
+                type_match: Some(CompletionRelevanceTypeMatch::Exact),
                 is_local: true,
             }],
         ];
diff --git a/crates/ide_completion/src/render.rs b/crates/ide_completion/src/render.rs
index 9ce49074f..1a762d3dc 100644
--- a/crates/ide_completion/src/render.rs
+++ b/crates/ide_completion/src/render.rs
@@ -20,8 +20,8 @@ use ide_db::{
 use syntax::TextRange;
 
 use crate::{
-    item::ImportEdit, CompletionContext, CompletionItem, CompletionItemKind, CompletionKind,
-    CompletionRelevance,
+    item::{CompletionRelevanceTypeMatch, ImportEdit},
+    CompletionContext, CompletionItem, CompletionItemKind, CompletionKind, CompletionRelevance,
 };
 
 use crate::render::{enum_variant::render_variant, function::render_fn, macro_::render_macro};
@@ -143,7 +143,7 @@ impl<'a> Render<'a> {
             .set_deprecated(is_deprecated);
 
         item.set_relevance(CompletionRelevance {
-            exact_type_match: compute_exact_type_match(self.ctx.completion, ty),
+            type_match: compute_type_match(self.ctx.completion, ty),
             exact_name_match: compute_exact_name_match(self.ctx.completion, name.to_string()),
             ..CompletionRelevance::default()
         });
@@ -245,7 +245,7 @@ impl<'a> Render<'a> {
             }
 
             item.set_relevance(CompletionRelevance {
-                exact_type_match: compute_exact_type_match(self.ctx.completion, &ty),
+                type_match: compute_type_match(self.ctx.completion, &ty),
                 exact_name_match: compute_exact_name_match(self.ctx.completion, &local_name),
                 is_local: true,
                 ..CompletionRelevance::default()
@@ -309,14 +309,24 @@ impl<'a> Render<'a> {
     }
 }
 
-fn compute_exact_type_match(ctx: &CompletionContext, completion_ty: &hir::Type) -> bool {
-    match ctx.expected_type.as_ref() {
-        Some(expected_type) => {
-            // We don't ever consider unit type to be an exact type match, since
-            // nearly always this is not meaningful to the user.
-            completion_ty == expected_type && !expected_type.is_unit()
-        }
-        None => false,
+fn compute_type_match(
+    ctx: &CompletionContext,
+    completion_ty: &hir::Type,
+) -> Option<CompletionRelevanceTypeMatch> {
+    let expected_type = ctx.expected_type.as_ref()?;
+
+    // We don't ever consider unit type to be an exact type match, since
+    // nearly always this is not meaningful to the user.
+    if expected_type.is_unit() {
+        return None;
+    }
+
+    if completion_ty == expected_type {
+        Some(CompletionRelevanceTypeMatch::Exact)
+    } else if expected_type.could_unify_with(completion_ty) {
+        Some(CompletionRelevanceTypeMatch::CouldUnify)
+    } else {
+        None
     }
 }
 
@@ -348,6 +358,7 @@ mod tests {
     use itertools::Itertools;
 
     use crate::{
+        item::CompletionRelevanceTypeMatch,
         test_utils::{check_edit, do_completion, get_all_items, TEST_CONFIG},
         CompletionKind, CompletionRelevance,
     };
@@ -360,7 +371,11 @@ mod tests {
     fn check_relevance(ra_fixture: &str, expect: Expect) {
         fn display_relevance(relevance: CompletionRelevance) -> String {
             let relevance_factors = vec![
-                (relevance.exact_type_match, "type"),
+                (relevance.type_match == Some(CompletionRelevanceTypeMatch::Exact), "type"),
+                (
+                    relevance.type_match == Some(CompletionRelevanceTypeMatch::CouldUnify),
+                    "type_could_unify",
+                ),
                 (relevance.exact_name_match, "name"),
                 (relevance.is_local, "local"),
             ]
@@ -533,7 +548,9 @@ fn main() { let _: m::Spam = S$0 }
                         detail: "(i32)",
                         relevance: CompletionRelevance {
                             exact_name_match: false,
-                            exact_type_match: true,
+                            type_match: Some(
+                                Exact,
+                            ),
                             is_local: false,
                         },
                         trigger_call_info: true,
@@ -559,7 +576,9 @@ fn main() { let _: m::Spam = S$0 }
                         detail: "()",
                         relevance: CompletionRelevance {
                             exact_name_match: false,
-                            exact_type_match: true,
+                            type_match: Some(
+                                Exact,
+                            ),
                             is_local: false,
                         },
                     },
@@ -1108,7 +1127,7 @@ fn main() {
                         detail: "S",
                         relevance: CompletionRelevance {
                             exact_name_match: true,
-                            exact_type_match: false,
+                            type_match: None,
                             is_local: true,
                         },
                         ref_match: "&mut ",
@@ -1353,4 +1372,34 @@ fn foo(f: Foo) { let _: &u32 = f.b$0 }
             "#]],
         );
     }
+
+    #[test]
+    fn generic_enum() {
+        check_relevance(
+            r#"
+enum Foo<T> { A(T), B }
+// bar() should not be an exact type match
+// because the generic parameters are different
+fn bar() -> Foo<u8> { Foo::B }
+// FIXME baz() should be an exact type match
+// because the types could unify, but it currently
+// is not. This is due to the T here being
+// TyKind::Placeholder rather than TyKind::Missing.
+fn baz<T>() -> Foo<T> { Foo::B }
+fn foo() {
+    let foo: Foo<u32> = Foo::B;
+    let _: Foo<u32> = f$0;
+}
+"#,
+            expect![[r#"
+                ev Foo::A(…) [type_could_unify]
+                ev Foo::B [type_could_unify]
+                lc foo [type+local]
+                en Foo []
+                fn baz() []
+                fn bar() []
+                fn foo() []
+            "#]],
+        );
+    }
 }
diff --git a/crates/ide_completion/src/render/enum_variant.rs b/crates/ide_completion/src/render/enum_variant.rs
index 374247b05..832f5ced1 100644
--- a/crates/ide_completion/src/render/enum_variant.rs
+++ b/crates/ide_completion/src/render/enum_variant.rs
@@ -6,7 +6,7 @@ use itertools::Itertools;
 
 use crate::{
     item::{CompletionItem, CompletionKind, ImportEdit},
-    render::{builder_ext::Params, compute_exact_type_match, compute_ref_match, RenderContext},
+    render::{builder_ext::Params, compute_ref_match, compute_type_match, RenderContext},
     CompletionRelevance,
 };
 
@@ -77,7 +77,7 @@ impl<'a> EnumRender<'a> {
 
         let ty = self.variant.parent_enum(self.ctx.completion.db).ty(self.ctx.completion.db);
         item.set_relevance(CompletionRelevance {
-            exact_type_match: compute_exact_type_match(self.ctx.completion, &ty),
+            type_match: compute_type_match(self.ctx.completion, &ty),
             ..CompletionRelevance::default()
         });
 
diff --git a/crates/ide_completion/src/render/function.rs b/crates/ide_completion/src/render/function.rs
index b1eba20e8..d681e2c91 100644
--- a/crates/ide_completion/src/render/function.rs
+++ b/crates/ide_completion/src/render/function.rs
@@ -8,7 +8,7 @@ use syntax::ast::Fn;
 use crate::{
     item::{CompletionItem, CompletionItemKind, CompletionKind, CompletionRelevance, ImportEdit},
     render::{
-        builder_ext::Params, compute_exact_name_match, compute_exact_type_match, compute_ref_match,
+        builder_ext::Params, compute_exact_name_match, compute_ref_match, compute_type_match,
         RenderContext,
     },
 };
@@ -73,7 +73,7 @@ impl<'a> FunctionRender<'a> {
 
         let ret_type = self.func.ret_type(self.ctx.db());
         item.set_relevance(CompletionRelevance {
-            exact_type_match: compute_exact_type_match(self.ctx.completion, &ret_type),
+            type_match: compute_type_match(self.ctx.completion, &ret_type),
             exact_name_match: compute_exact_name_match(self.ctx.completion, self.name.clone()),
             ..CompletionRelevance::default()
         });
diff --git a/crates/ide_db/src/defs.rs b/crates/ide_db/src/defs.rs
index 75167ff39..ab23dd7ac 100644
--- a/crates/ide_db/src/defs.rs
+++ b/crates/ide_db/src/defs.rs
@@ -343,7 +343,7 @@ impl NameRefClass {
                         hir::AssocItem::TypeAlias(it) => Some(*it),
                         _ => None,
                     })
-                    .find(|alias| &alias.name(sema.db).to_string() == name_ref.text())
+                    .find(|alias| &alias.name(sema.db).to_string() == &name_ref.text())
                 {
                     return Some(NameRefClass::Definition(Definition::ModuleDef(
                         ModuleDef::TypeAlias(ty),
diff --git a/crates/ide_db/src/helpers/import_assets.rs b/crates/ide_db/src/helpers/import_assets.rs
index 1881c746f..3deb0d159 100644
--- a/crates/ide_db/src/helpers/import_assets.rs
+++ b/crates/ide_db/src/helpers/import_assets.rs
@@ -288,7 +288,7 @@ fn path_applicable_imports(
                 import_for_item(
                     sema.db,
                     mod_path,
-                    unresolved_first_segment,
+                    &unresolved_first_segment,
                     &unresolved_qualifier,
                     item,
                 )
diff --git a/crates/ide_db/src/helpers/insert_use.rs b/crates/ide_db/src/helpers/insert_use.rs
index 20c195f82..e681ced80 100644
--- a/crates/ide_db/src/helpers/insert_use.rs
+++ b/crates/ide_db/src/helpers/insert_use.rs
@@ -509,7 +509,7 @@ impl ImportGroup {
             PathSegmentKind::SelfKw => ImportGroup::ThisModule,
             PathSegmentKind::SuperKw => ImportGroup::SuperModule,
             PathSegmentKind::CrateKw => ImportGroup::ThisCrate,
-            PathSegmentKind::Name(name) => match name.text() {
+            PathSegmentKind::Name(name) => match name.text().as_str() {
                 "std" => ImportGroup::Std,
                 "core" => ImportGroup::Std,
                 _ => ImportGroup::ExternCrate,
diff --git a/crates/ide_ssr/src/resolving.rs b/crates/ide_ssr/src/resolving.rs
index dc7835473..541da4122 100644
--- a/crates/ide_ssr/src/resolving.rs
+++ b/crates/ide_ssr/src/resolving.rs
@@ -150,7 +150,7 @@ impl Resolver<'_, '_> {
     fn path_contains_placeholder(&self, path: &ast::Path) -> bool {
         if let Some(segment) = path.segment() {
             if let Some(name_ref) = segment.name_ref() {
-                if self.placeholders_by_stand_in.contains_key(name_ref.text()) {
+                if self.placeholders_by_stand_in.contains_key(name_ref.text().as_str()) {
                     return true;
                 }
             }
diff --git a/crates/rust-analyzer/src/to_proto.rs b/crates/rust-analyzer/src/to_proto.rs
index 25169005f..530c8a5a4 100644
--- a/crates/rust-analyzer/src/to_proto.rs
+++ b/crates/rust-analyzer/src/to_proto.rs
@@ -1138,7 +1138,7 @@ mod tests {
                 (
                     "&arg",
                     Some(
-                        "fffffffa",
+                        "fffffff9",
                     ),
                 ),
                 (
diff --git a/crates/syntax/Cargo.toml b/crates/syntax/Cargo.toml
index 0c3fec3c7..9f01acc26 100644
--- a/crates/syntax/Cargo.toml
+++ b/crates/syntax/Cargo.toml
@@ -16,7 +16,7 @@ itertools = "0.10.0"
 rowan = "0.13.0-pre.3"
 rustc_lexer = { version = "710.0.0", package = "rustc-ap-rustc_lexer" }
 rustc-hash = "1.1.0"
-arrayvec = "0.5.1"
+arrayvec = "0.6"
 once_cell = "1.3.1"
 indexmap = "1.4.0"
 smol_str = { version = "0.1.15", features = ["serde"] }
diff --git a/crates/syntax/src/ast/edit.rs b/crates/syntax/src/ast/edit.rs
index 18820786a..8c60927e4 100644
--- a/crates/syntax/src/ast/edit.rs
+++ b/crates/syntax/src/ast/edit.rs
@@ -2,7 +2,7 @@
 //! immutable, all function here return a fresh copy of the tree, instead of
 //! doing an in-place modification.
 use std::{
-    fmt, iter,
+    array, fmt, iter,
     ops::{self, RangeInclusive},
 };
 
@@ -32,7 +32,7 @@ impl ast::BinExpr {
 impl ast::Fn {
     #[must_use]
     pub fn with_body(&self, body: ast::BlockExpr) -> ast::Fn {
-        let mut to_insert: ArrayVec<[SyntaxElement; 2]> = ArrayVec::new();
+        let mut to_insert: ArrayVec<SyntaxElement, 2> = ArrayVec::new();
         let old_body_or_semi: SyntaxElement = if let Some(old_body) = self.body() {
             old_body.syntax().clone().into()
         } else if let Some(semi) = self.semicolon_token() {
@@ -55,9 +55,8 @@ impl ast::Fn {
 
         let anchor = self.name().expect("The function must have a name").syntax().clone();
 
-        let mut to_insert: ArrayVec<[SyntaxElement; 1]> = ArrayVec::new();
-        to_insert.push(generic_args.syntax().clone().into());
-        self.insert_children(InsertPosition::After(anchor.into()), to_insert)
+        let to_insert = [generic_args.syntax().clone().into()];
+        self.insert_children(InsertPosition::After(anchor.into()), array::IntoIter::new(to_insert))
     }
 }
 
@@ -96,7 +95,7 @@ where
 impl ast::Impl {
     #[must_use]
     pub fn with_assoc_item_list(&self, items: ast::AssocItemList) -> ast::Impl {
-        let mut to_insert: ArrayVec<[SyntaxElement; 2]> = ArrayVec::new();
+        let mut to_insert: ArrayVec<SyntaxElement, 2> = ArrayVec::new();
         if let Some(old_items) = self.assoc_item_list() {
             let to_replace: SyntaxElement = old_items.syntax().clone().into();
             to_insert.push(items.syntax().clone().into());
@@ -141,7 +140,7 @@ impl ast::AssocItemList {
             },
         };
         let ws = tokens::WsBuilder::new(&format!("{}{}", whitespace, indent));
-        let to_insert: ArrayVec<[SyntaxElement; 2]> =
+        let to_insert: ArrayVec<SyntaxElement, 2> =
             [ws.ws().into(), item.syntax().clone().into()].into();
         self.insert_children(position, to_insert)
     }
@@ -192,7 +191,7 @@ impl ast::RecordExprFieldList {
             tokens::single_space()
         };
 
-        let mut to_insert: ArrayVec<[SyntaxElement; 4]> = ArrayVec::new();
+        let mut to_insert: ArrayVec<SyntaxElement, 4> = ArrayVec::new();
         to_insert.push(space.into());
         to_insert.push(field.syntax().clone().into());
         to_insert.push(make::token(T![,]).into());
@@ -305,7 +304,7 @@ impl ast::PathSegment {
                 iter::once(type_args.syntax().clone().into()),
             );
         }
-        let mut to_insert: ArrayVec<[SyntaxElement; 2]> = ArrayVec::new();
+        let mut to_insert: ArrayVec<SyntaxElement, 2> = ArrayVec::new();
         if turbo {
             to_insert.push(make::token(T![::]).into());
         }
@@ -444,7 +443,7 @@ impl ast::MatchArmList {
         let arm_ws = tokens::WsBuilder::new("    ");
         let match_indent = &leading_indent(self.syntax()).unwrap_or_default();
         let match_ws = tokens::WsBuilder::new(&format!("\n{}", match_indent));
-        let to_insert: ArrayVec<[SyntaxElement; 3]> =
+        let to_insert: ArrayVec<SyntaxElement, 3> =
             [arm_ws.ws().into(), item.syntax().clone().into(), match_ws.ws().into()].into();
         self.insert_children(position, to_insert)
     }
@@ -465,7 +464,7 @@ impl ast::GenericParamList {
     pub fn append_param(&self, item: ast::GenericParam) -> ast::GenericParamList {
         let space = tokens::single_space();
 
-        let mut to_insert: ArrayVec<[SyntaxElement; 4]> = ArrayVec::new();
+        let mut to_insert: ArrayVec<SyntaxElement, 4> = ArrayVec::new();
         if self.generic_params().next().is_some() {
             to_insert.push(space.into());
         }
diff --git a/crates/syntax/src/ast/make.rs b/crates/syntax/src/ast/make.rs
index c08f2c14f..c6a7b99b7 100644
--- a/crates/syntax/src/ast/make.rs
+++ b/crates/syntax/src/ast/make.rs
@@ -268,14 +268,14 @@ pub fn arg_list(args: impl IntoIterator<Item = ast::Expr>) -> ast::ArgList {
 }
 
 pub fn ident_pat(name: ast::Name) -> ast::IdentPat {
-    return from_text(name.text());
+    return from_text(&name.text());
 
     fn from_text(text: &str) -> ast::IdentPat {
         ast_from_text(&format!("fn f({}: ())", text))
     }
 }
 pub fn ident_mut_pat(name: ast::Name) -> ast::IdentPat {
-    return from_text(name.text());
+    return from_text(&name.text());
 
     fn from_text(text: &str) -> ast::IdentPat {
         ast_from_text(&format!("fn f(mut {}: ())", text))
diff --git a/crates/syntax/src/ast/node_ext.rs b/crates/syntax/src/ast/node_ext.rs
index bdf907a21..2772d7364 100644
--- a/crates/syntax/src/ast/node_ext.rs
+++ b/crates/syntax/src/ast/node_ext.rs
@@ -8,23 +8,23 @@ use parser::SyntaxKind;
 
 use crate::{
     ast::{self, support, AstNode, AstToken, AttrsOwner, NameOwner, SyntaxNode},
-    SmolStr, SyntaxElement, SyntaxToken, T,
+    SmolStr, SyntaxElement, SyntaxToken, TokenText, T,
 };
 
 impl ast::Lifetime {
-    pub fn text(&self) -> &str {
+    pub fn text(&self) -> TokenText {
         text_of_first_token(self.syntax())
     }
 }
 
 impl ast::Name {
-    pub fn text(&self) -> &str {
+    pub fn text(&self) -> TokenText {
         text_of_first_token(self.syntax())
     }
 }
 
 impl ast::NameRef {
-    pub fn text(&self) -> &str {
+    pub fn text(&self) -> TokenText {
         text_of_first_token(self.syntax())
     }
 
@@ -33,10 +33,11 @@ impl ast::NameRef {
     }
 }
 
-fn text_of_first_token(node: &SyntaxNode) -> &str {
-    let t =
-        node.green().children().next().and_then(|it| it.into_token()).unwrap().text().to_string();
-    Box::leak(Box::new(t))
+fn text_of_first_token(node: &SyntaxNode) -> TokenText {
+    let first_token =
+        node.green().children().next().and_then(|it| it.into_token()).unwrap().to_owned();
+
+    TokenText(first_token)
 }
 
 pub enum Macro {
@@ -378,7 +379,7 @@ impl fmt::Display for NameOrNameRef {
 }
 
 impl NameOrNameRef {
-    pub fn text(&self) -> &str {
+    pub fn text(&self) -> TokenText {
         match self {
             NameOrNameRef::Name(name) => name.text(),
             NameOrNameRef::NameRef(name_ref) => name_ref.text(),
diff --git a/crates/syntax/src/lib.rs b/crates/syntax/src/lib.rs
index 2a5c61171..90de6bef6 100644
--- a/crates/syntax/src/lib.rs
+++ b/crates/syntax/src/lib.rs
@@ -29,6 +29,7 @@ mod syntax_error;
 mod parsing;
 mod validation;
 mod ptr;
+mod token_text;
 #[cfg(test)]
 mod tests;
 
@@ -55,6 +56,7 @@ pub use crate::{
         SyntaxElement, SyntaxElementChildren, SyntaxNode, SyntaxNodeChildren, SyntaxToken,
         SyntaxTreeBuilder,
     },
+    token_text::TokenText,
 };
 pub use parser::{SyntaxKind, T};
 pub use rowan::{
diff --git a/crates/syntax/src/token_text.rs b/crates/syntax/src/token_text.rs
new file mode 100644
index 000000000..d2ed0a12a
--- /dev/null
+++ b/crates/syntax/src/token_text.rs
@@ -0,0 +1,77 @@
+//! Yet another version of owned string, backed by a syntax tree token.
+
+use std::{cmp::Ordering, fmt, ops};
+
+pub struct TokenText(pub(crate) rowan::GreenToken);
+
+impl TokenText {
+    pub fn as_str(&self) -> &str {
+        self.0.text()
+    }
+}
+
+impl ops::Deref for TokenText {
+    type Target = str;
+
+    fn deref(&self) -> &str {
+        self.as_str()
+    }
+}
+impl AsRef<str> for TokenText {
+    fn as_ref(&self) -> &str {
+        self.as_str()
+    }
+}
+
+impl From<TokenText> for String {
+    fn from(token_text: TokenText) -> Self {
+        token_text.as_str().into()
+    }
+}
+
+impl PartialEq<&'_ str> for TokenText {
+    fn eq(&self, other: &&str) -> bool {
+        self.as_str() == *other
+    }
+}
+impl PartialEq<TokenText> for &'_ str {
+    fn eq(&self, other: &TokenText) -> bool {
+        other == self
+    }
+}
+impl PartialEq<String> for TokenText {
+    fn eq(&self, other: &String) -> bool {
+        self.as_str() == other.as_str()
+    }
+}
+impl PartialEq<TokenText> for String {
+    fn eq(&self, other: &TokenText) -> bool {
+        other == self
+    }
+}
+impl PartialEq for TokenText {
+    fn eq(&self, other: &TokenText) -> bool {
+        self.as_str() == other.as_str()
+    }
+}
+impl Eq for TokenText {}
+impl Ord for TokenText {
+    fn cmp(&self, other: &Self) -> Ordering {
+        self.as_str().cmp(other.as_str())
+    }
+}
+impl PartialOrd for TokenText {
+    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
+        Some(self.cmp(other))
+    }
+}
+impl fmt::Display for TokenText {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        fmt::Display::fmt(self.as_str(), f)
+    }
+}
+impl fmt::Debug for TokenText {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        fmt::Debug::fmt(self.as_str(), f)
+    }
+}