Use FamousDefs for shorten_iterator hint

crates/assists/src/utils.rs

@@ -274,24 +274,54 @@ 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(crate) struct FamousDefs<'a, 'b>(pub(crate) &'a Semantics<'b, RootDatabase>, pub(crate) Crate);
+pub struct FamousDefs<'a, 'b>(pub &'a Semantics<'b, RootDatabase>, pub Crate);
 
 #[allow(non_snake_case)]
 impl FamousDefs<'_, '_> {
-    #[cfg(test)]
-    pub(crate) const FIXTURE: &'static str = r#"//- /libcore.rs crate:core
+    pub const FIXTURE: &'static str = r#"//- /libcore.rs crate:core
 pub mod convert {
     pub trait From<T> {
         fn from(T) -> Self;
     }
 }
 
+pub mod iter {
+    pub use self::traits::iterator::Iterator;
+    mod traits { mod iterator {
+        use crate::option::Option;
+        pub trait Iterator {
+            type Item;
+            fn next(&mut self) -> Option<Self::Item>;
+        }
+    } }
+
+    pub use self::sources::*;
+    mod sources {
+        use super::Iterator;
+        pub struct Repeat<A> {
+            element: A,
+        }
+
+        pub fn repeat<T: Clone>(elt: T) -> Repeat<T> {
+            Repeat { element: elt }
+        }
+
+        impl<A: Clone> Iterator for Repeat<A> {
+            type Item = A;
+
+            fn next(&mut self) -> Option<A> {
+                Some(self.element.clone())
+            }
+        }
+    }
+}
+
 pub mod option {
     pub enum Option<T> { None, Some(T)}
 }
 
 pub mod prelude {
-    pub use crate::{convert::From, option::Option::{self, *}};
+    pub use crate::{convert::From, iter::Iterator, option::Option::{self, *}};
 }
 #[prelude_import]
 pub use prelude::*;
@@ -305,6 +335,10 @@ pub use prelude::*;
         self.find_enum("core:option:Option")
     }
 
+    pub fn core_iter_Iterator(&self) -> Option<Trait> {
+        self.find_trait("core:iter:traits:iterator:Iterator")
+    }
+
     fn find_trait(&self, path: &str) -> Option<Trait> {
         match self.find_def(path)? {
             hir::ScopeDef::ModuleDef(hir::ModuleDef::Trait(it)) => Some(it),
@@ -324,18 +358,21 @@ pub use prelude::*;
         let mut path = path.split(':');
         let trait_ = path.next_back()?;
         let std_crate = path.next()?;
-        let std_crate = self
+        let std_crate = if self
             .1
-            .dependencies(db)
-            .into_iter()
-            .find(|dep| &dep.name.to_string() == std_crate)?
-            .krate;
-
+            .declaration_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 mut module = std_crate.root_module(db);
         for segment in path {
             module = module.children(db).find_map(|child| {
                 let name = child.name(db)?;
-                if &name.to_string() == segment {
+                if name.to_string() == segment {
                     Some(child)
                 } else {
                     None
@@ -343,7 +380,7 @@ pub use prelude::*;
             })?;
         }
         let def =
-            module.scope(db, None).into_iter().find(|(name, _def)| &name.to_string() == trait_)?.1;
+            module.scope(db, None).into_iter().find(|(name, _def)| name.to_string() == trait_)?.1;
         Some(def)
     }
 }