From 9a72b7bccde54d901f3d89300777e0685790aefd Mon Sep 17 00:00:00 2001
From: Kirill Bulatov <mail4score@gmail.com>
Date: Sat, 10 Oct 2020 19:51:02 +0300
Subject: Add a test

---
 crates/ide/src/inlay_hints.rs | 62 +++++++++++++++++++++++++++----------------
 1 file changed, 39 insertions(+), 23 deletions(-)

diff --git a/crates/ide/src/inlay_hints.rs b/crates/ide/src/inlay_hints.rs
index 7d716577e..08ef49a27 100644
--- a/crates/ide/src/inlay_hints.rs
+++ b/crates/ide/src/inlay_hints.rs
@@ -228,6 +228,8 @@ fn hint_iterator(
             _ => None,
         })?;
         if let Some(ty) = ty.normalize_trait_assoc_type(db, iter_trait, &[], assoc_type_item) {
+            // TODO kb also check for the iterator impls for this ty
+            dbg!(ty.display(db).to_string());
             const LABEL_START: &str = "impl Iterator<Item = ";
             const LABEL_END: &str = ">";
 
@@ -1002,18 +1004,6 @@ fn main() {
 
     println!("Unit expr");
 }
-
-//- /alloc.rs crate:alloc deps:core
-mod collections {
-    struct Vec<T> {}
-    impl<T> Vec<T> {
-        fn new() -> Self { Vec {} }
-        fn push(&mut self, t: T) { }
-    }
-    impl<T> IntoIterator for Vec<T> {
-        type Item=T;
-    }
-}
 "#,
         );
     }
@@ -1043,17 +1033,6 @@ fn main() {
         //^ &str
     }
 }
-//- /alloc.rs crate:alloc deps:core
-mod collections {
-    struct Vec<T> {}
-    impl<T> Vec<T> {
-        fn new() -> Self { Vec {} }
-        fn push(&mut self, t: T) { }
-    }
-    impl<T> IntoIterator for Vec<T> {
-        type Item=T;
-    }
-}
 "#,
         );
     }
@@ -1183,4 +1162,41 @@ fn main() {
             "#]],
         );
     }
+
+    #[test]
+    fn shorten_iterators_in_associated_params() {
+        check_with_config(
+            InlayHintsConfig {
+                parameter_hints: false,
+                type_hints: true,
+                chaining_hints: true,
+                max_length: None,
+            },
+            r#"
+use core::iter;
+
+pub struct SomeIter<T> {}
+
+impl<T> SomeIter<T> {
+    pub fn new() -> Self { SomeIter {} }
+    pub fn push(&mut self, t: T) {}
+}
+
+impl<T> Iterator for SomeIter<T> {
+    type Item = T;
+    fn next(&mut self) -> Option<Self::Item> {
+        None
+    }
+}
+
+fn main() {
+    let mut some_iter = SomeIter::new();
+      //^^^^^^^^^^^^^ SomeIter<Take<Repeat<i32>>>
+      some_iter.push(iter::repeat(2).take(2));
+    let zz = some_iter.take(2);
+      //^^ impl Iterator<Item = Take<Repeat<i32>>>
+}
+"#,
+        );
+    }
 }
-- 
cgit v1.2.3


From 2bb80a4f0350045503258518d354a4e63e4c68fd Mon Sep 17 00:00:00 2001
From: Kirill Bulatov <mail4score@gmail.com>
Date: Sat, 10 Oct 2020 21:37:20 +0300
Subject: Also replace the associated types with iter

---
 crates/hir/src/code_model.rs  |  6 +++++-
 crates/ide/src/inlay_hints.rs | 25 ++++++++++++++-----------
 2 files changed, 19 insertions(+), 12 deletions(-)

diff --git a/crates/hir/src/code_model.rs b/crates/hir/src/code_model.rs
index 031c91ccf..9aaa280c8 100644
--- a/crates/hir/src/code_model.rs
+++ b/crates/hir/src/code_model.rs
@@ -1372,7 +1372,7 @@ impl Type {
         r#trait: Trait,
         args: &[Type],
         alias: TypeAlias,
-    ) -> Option<Ty> {
+    ) -> Option<Type> {
         let subst = Substs::build_for_def(db, r#trait.id)
             .push(self.ty.value.clone())
             .fill(args.iter().map(|t| t.ty.value.clone()))
@@ -1393,6 +1393,10 @@ impl Type {
             Solution::Unique(SolutionVariables(subst)) => subst.value.first().cloned(),
             Solution::Ambig(_) => None,
         }
+        .map(|ty| Type {
+            krate: self.krate,
+            ty: InEnvironment { value: ty, environment: Arc::clone(&self.ty.environment) },
+        })
     }
 
     pub fn is_copy(&self, db: &dyn HirDatabase) -> bool {
diff --git a/crates/ide/src/inlay_hints.rs b/crates/ide/src/inlay_hints.rs
index 08ef49a27..2ed84095d 100644
--- a/crates/ide/src/inlay_hints.rs
+++ b/crates/ide/src/inlay_hints.rs
@@ -228,17 +228,20 @@ fn hint_iterator(
             _ => None,
         })?;
         if let Some(ty) = ty.normalize_trait_assoc_type(db, iter_trait, &[], assoc_type_item) {
-            // TODO kb also check for the iterator impls for this ty
-            dbg!(ty.display(db).to_string());
             const LABEL_START: &str = "impl Iterator<Item = ";
             const LABEL_END: &str = ">";
 
-            let ty_display = ty.display_truncated(
-                db,
-                config
-                    .max_length
-                    .map(|len| len.saturating_sub(LABEL_START.len() + LABEL_END.len())),
-            );
+            let ty_display = hint_iterator(sema, config, &ty)
+                .map(|assoc_type_impl| assoc_type_impl.to_string())
+                .unwrap_or_else(|| {
+                    ty.display_truncated(
+                        db,
+                        config
+                            .max_length
+                            .map(|len| len.saturating_sub(LABEL_START.len() + LABEL_END.len())),
+                    )
+                    .to_string()
+                });
             return Some(format!("{}{}{}", LABEL_START, ty_display, LABEL_END).into());
         }
     }
@@ -1169,7 +1172,7 @@ fn main() {
             InlayHintsConfig {
                 parameter_hints: false,
                 type_hints: true,
-                chaining_hints: true,
+                chaining_hints: false,
                 max_length: None,
             },
             r#"
@@ -1193,8 +1196,8 @@ fn main() {
     let mut some_iter = SomeIter::new();
       //^^^^^^^^^^^^^ SomeIter<Take<Repeat<i32>>>
       some_iter.push(iter::repeat(2).take(2));
-    let zz = some_iter.take(2);
-      //^^ impl Iterator<Item = Take<Repeat<i32>>>
+    let iter_of_iters = some_iter.take(2);
+      //^^^^^^^^^^^^^ impl Iterator<Item = impl Iterator<Item = i32>>
 }
 "#,
         );
-- 
cgit v1.2.3