4 files changed, 29 insertions, 19 deletions

diff --git a/crates/assists/src/handlers/fill_match_arms.rs b/crates/assists/src/handlers/fill_match_arms.rs
index 676f5ad92..eda45f5b3 100644
--- a/crates/assists/src/handlers/fill_match_arms.rs
+++ b/crates/assists/src/handlers/fill_match_arms.rs
@@ -59,7 +59,7 @@ pub(crate) fn fill_match_arms(acc: &mut Assists, ctx: &AssistContext) -> Option<
             .filter(|variant_pat| is_variant_missing(&mut arms, variant_pat))
             .map(|pat| make::match_arm(iter::once(pat), make::expr_empty_block()))
             .collect::<Vec<_>>();
-        if Some(enum_def) == FamousDefs(&ctx.sema, module.krate()).core_option_Option() {
+        if Some(enum_def) == FamousDefs(&ctx.sema, Some(module.krate())).core_option_Option() {
             // Match `Some` variant first.
             mark::hit!(option_order);
             variants.reverse()
diff --git a/crates/assists/src/handlers/generate_from_impl_for_enum.rs b/crates/assists/src/handlers/generate_from_impl_for_enum.rs
index 7f04b9572..674e5a175 100644
--- a/crates/assists/src/handlers/generate_from_impl_for_enum.rs
+++ b/crates/assists/src/handlers/generate_from_impl_for_enum.rs
@@ -75,7 +75,7 @@ fn existing_from_impl(
     let enum_ = variant.parent_enum(sema.db);
     let krate = enum_.module(sema.db).krate();
 
-    let from_trait = FamousDefs(sema, krate).core_convert_From()?;
+    let from_trait = FamousDefs(sema, Some(krate)).core_convert_From()?;
 
     let enum_type = enum_.ty(sema.db);
 
diff --git a/crates/assists/src/utils.rs b/crates/assists/src/utils.rs
index 4e89a7aed..1a6b48b45 100644
--- a/crates/assists/src/utils.rs
+++ b/crates/assists/src/utils.rs
@@ -275,7 +275,7 @@ impl TryEnum {
 /// somewhat similar to the known paths infra inside hir, but it different; We
 /// want to make sure that IDE specific paths don't become interesting inside
 /// the compiler itself as well.
-pub struct FamousDefs<'a, 'b>(pub &'a Semantics<'b, RootDatabase>, pub Crate);
+pub struct FamousDefs<'a, 'b>(pub &'a Semantics<'b, RootDatabase>, pub Option<Crate>);
 
 #[allow(non_snake_case)]
 impl FamousDefs<'_, '_> {
@@ -362,6 +362,10 @@ pub mod prelude {
 pub use prelude::*;
 "#;
 
+    pub fn core(&self) -> Option<Crate> {
+        self.find_crate("core")
+    }
+
     pub(crate) fn core_convert_From(&self) -> Option<Trait> {
         self.find_trait("core:convert:From")
     }
@@ -399,21 +403,20 @@ pub use prelude::*;
         }
     }
 
+    fn find_crate(&self, name: &str) -> Option<Crate> {
+        let krate = self.1?;
+        let db = self.0.db;
+        let res =
+            krate.dependencies(db).into_iter().find(|dep| dep.name.to_string() == name)?.krate;
+        Some(res)
+    }
+
     fn find_def(&self, path: &str) -> Option<ScopeDef> {
         let db = self.0.db;
         let mut path = path.split(':');
         let trait_ = path.next_back()?;
         let std_crate = path.next()?;
-        let std_crate = if self
-            .1
-            .display_name(db)
-            .map(|name| name.to_string() == std_crate)
-            .unwrap_or(false)
-        {
-            self.1
-        } else {
-            self.1.dependencies(db).into_iter().find(|dep| dep.name.to_string() == std_crate)?.krate
-        };
+        let std_crate = self.find_crate(std_crate)?;
         let mut module = std_crate.root_module(db);
         for segment in path {
             module = module.children(db).find_map(|child| {
diff --git a/crates/ide/src/inlay_hints.rs b/crates/ide/src/inlay_hints.rs
index 56b985e80..cccea129a 100644
--- a/crates/ide/src/inlay_hints.rs
+++ b/crates/ide/src/inlay_hints.rs
@@ -99,6 +99,9 @@ fn get_chaining_hints(
         return None;
     }
 
+    let krate = sema.scope(expr.syntax()).module().map(|it| it.krate());
+    let famous_defs = FamousDefs(&sema, krate);
+
     let mut tokens = expr
         .syntax()
         .siblings_with_tokens(Direction::Next)
@@ -128,7 +131,7 @@ fn get_chaining_hints(
         acc.push(InlayHint {
             range: expr.syntax().text_range(),
             kind: InlayKind::ChainingHint,
-            label: hint_iterator(sema, config, &ty).unwrap_or_else(|| {
+            label: hint_iterator(sema, &famous_defs, config, &ty).unwrap_or_else(|| {
                 ty.display_truncated(sema.db, config.max_length).to_string().into()
             }),
         });
@@ -188,6 +191,9 @@ fn get_bind_pat_hints(
         return None;
     }
 
+    let krate = sema.scope(pat.syntax()).module().map(|it| it.krate());
+    let famous_defs = FamousDefs(&sema, krate);
+
     let ty = sema.type_of_pat(&pat.clone().into())?;
 
     if should_not_display_type_hint(sema, &pat, &ty) {
@@ -196,7 +202,7 @@ fn get_bind_pat_hints(
     acc.push(InlayHint {
         range: pat.syntax().text_range(),
         kind: InlayKind::TypeHint,
-        label: hint_iterator(sema, config, &ty)
+        label: hint_iterator(sema, &famous_defs, config, &ty)
             .unwrap_or_else(|| ty.display_truncated(sema.db, config.max_length).to_string().into()),
     });
 
@@ -206,6 +212,7 @@ fn get_bind_pat_hints(
 /// Checks if the type is an Iterator from std::iter and replaces its hint with an `impl Iterator<Item = Ty>`.
 fn hint_iterator(
     sema: &Semantics<RootDatabase>,
+    famous_defs: &FamousDefs,
     config: &InlayHintsConfig,
     ty: &hir::Type,
 ) -> Option<SmolStr> {
@@ -214,11 +221,11 @@ fn hint_iterator(
         .last()
         .and_then(|strukt| strukt.as_adt())?;
     let krate = strukt.krate(db)?;
-    if krate.display_name(db).as_deref() != Some("core") {
+    if krate != famous_defs.core()? {
         return None;
     }
-    let iter_trait = FamousDefs(sema, krate).core_iter_Iterator()?;
-    let iter_mod = FamousDefs(sema, krate).core_iter()?;
+    let iter_trait = famous_defs.core_iter_Iterator()?;
+    let iter_mod = famous_defs.core_iter()?;
     // assert this struct comes from `core::iter`
     iter_mod.visibility_of(db, &strukt.into()).filter(|&vis| vis == hir::Visibility::Public)?;
     if ty.impls_trait(db, iter_trait, &[]) {
@@ -230,7 +237,7 @@ fn hint_iterator(
             const LABEL_START: &str = "impl Iterator<Item = ";
             const LABEL_END: &str = ">";
 
-            let ty_display = hint_iterator(sema, config, &ty)
+            let ty_display = hint_iterator(sema, famous_defs, config, &ty)
                 .map(|assoc_type_impl| assoc_type_impl.to_string())
                 .unwrap_or_else(|| {
                     ty.display_truncated(