do not use associated types placeholder for inlay hint

Signed-off-by: Benjamin Coenen <[email protected]>

Author: bnjjj

crates/hir_ty/src/display.rs

@@ -332,7 +332,11 @@ impl HirDisplay for ApplicationTy {
                     let ret_display = if f.omit_verbose_types() {
                         ret.display_truncated(f.db, f.max_size)
                     } else {
-                        ret.display(f.db)
+                        if f.display_target.is_test() {
+                            ret.display_test(f.db)
+                        } else {
+                            ret.display(f.db)
+                        }
                     };
                     write!(f, " -> {}", ret_display)?;
                 }
@@ -472,7 +476,11 @@ impl HirDisplay for ApplicationTy {
                     let ret_display = if f.omit_verbose_types() {
                         sig.ret().display_truncated(f.db, f.max_size)
                     } else {
-                        sig.ret().display(f.db)
+                        if f.display_target.is_test() {
+                            sig.ret().display_test(f.db)
+                        } else {
+                            sig.ret().display(f.db)
+                        }
                     };
                     write!(f, " -> {}", ret_display)?;
                 } else {

crates/hir_ty/src/tests.rs

@@ -74,7 +74,7 @@ fn check_types_impl(ra_fixture: &str, display_source: bool) {
                 let module = db.module_for_file(file_id);
                 ty.display_source_code(&db, module).unwrap()
             } else {
-                ty.display(&db).to_string()
+                ty.display_test(&db).to_string()
             };
             assert_eq!(expected, actual);
             checked_one = true;

crates/hir_ty/src/tests/regression.rs

@@ -832,7 +832,7 @@ fn issue_4966() {
             365..390 'Repeat...nner }': Repeat<Map<|&f64| -> f64>>
             383..388 'inner': Map<|&f64| -> f64>
             401..404 'vec': Vec<IntoIterator::Item<Repeat<Map<|&f64| -> f64>>>>
-            407..416 'from_iter': fn from_iter<IntoIterator::Item<Repeat<Map<|&f64| -> f64>>>, Repeat<Map<|&f64| -> f64>>>(Repeat<Map<|&f64| -> f64>>) -> Vec<<Repeat<Map<|&f64| -> f64>> as IntoIterator>::Item>
+            407..416 'from_iter': fn from_iter<IntoIterator::Item<Repeat<Map<|&f64| -> f64>>>, Repeat<Map<|&f64| -> f64>>>(Repeat<Map<|&f64| -> f64>>) -> Vec<IntoIterator::Item<Repeat<Map<|&f64| -> f64>>>>
             407..424 'from_i...epeat)': Vec<IntoIterator::Item<Repeat<Map<|&f64| -> f64>>>>
             417..423 'repeat': Repeat<Map<|&f64| -> f64>>
             431..434 'vec': Vec<IntoIterator::Item<Repeat<Map<|&f64| -> f64>>>>

crates/hir_ty/src/tests/traits.rs

@@ -907,7 +907,8 @@ fn test<T: Trait>(t: T) { (*t); }
 }
 
 #[test]
-fn associated_type_inlay_hints() {
+fn associated_type_placeholder() {
+    // inside the generic function, the associated type gets normalized to a placeholder `ApplL::Out<T>` [https://rust-lang.github.io/rustc-guide/traits/associated-types.html#placeholder-associated-types].
     check_types(
         r#"
 pub trait ApplyL {
@@ -923,13 +924,13 @@ impl<T> ApplyL for RefMutL<T> {
 fn test<T: ApplyL>() {
     let y: <RefMutL<T> as ApplyL>::Out = no_matter;
     y;
-} //^ <T as ApplyL>::Out
+} //^ ApplyL::Out<T>
 "#,
     );
 }
 
 #[test]
-fn associated_type_inlay_hints_2() {
+fn associated_type_placeholder_2() {
     check_types(
         r#"
 pub trait ApplyL {
@@ -940,7 +941,7 @@ fn foo<T: ApplyL>(t: T) -> <T as ApplyL>::Out;
 fn test<T: ApplyL>(t: T) {
     let y = foo(t);
     y;
-} //^ <T as ApplyL>::Out
+} //^ ApplyL::Out<T>
 "#,
     );
 }