From ecc1ff8f330b93b51e728c8e38b6e90caa6fcab3 Mon Sep 17 00:00:00 2001
From: Shoyu Vanilla <modulo641@gmail.com>
Date: Sat, 22 Mar 2025 23:50:20 +0900
Subject: [PATCH] Render layout and other extra informations on hovering `Self`

---
 crates/ide/src/hover.rs        | 16 ++++++----
 crates/ide/src/hover/render.rs | 10 +++++--
 crates/ide/src/hover/tests.rs  | 54 ++++++++++++++++++++++++++++++++++
 3 files changed, 73 insertions(+), 7 deletions(-)

diff --git a/crates/ide/src/hover.rs b/crates/ide/src/hover.rs
index ea1f673e5b..5cab8efa79 100644
--- a/crates/ide/src/hover.rs
+++ b/crates/ide/src/hover.rs
@@ -18,7 +18,11 @@ use ide_db::{
 };
 use itertools::{Itertools, multizip};
 use span::Edition;
-use syntax::{AstNode, SyntaxKind::*, SyntaxNode, T, ast};
+use syntax::{
+    AstNode,
+    SyntaxKind::{self, *},
+    SyntaxNode, T, ast,
+};
 
 use crate::{
     FileId, FilePosition, NavigationTarget, RangeInfo, Runnable, TryToNav,
@@ -274,11 +278,13 @@ fn hover_offset(
                         }
 
                         class => {
-                            let is_def = matches!(class, IdentClass::NameClass(_));
+                            let render_extras = matches!(class, IdentClass::NameClass(_))
+                                // Render extra information for `Self` keyword as well
+                                || ast::NameRef::cast(node.clone()).is_some_and(|name_ref| name_ref.token_kind() == SyntaxKind::SELF_TYPE_KW);
                             multizip((
                                 class.definitions(),
                                 iter::repeat(None),
-                                iter::repeat(is_def),
+                                iter::repeat(render_extras),
                                 iter::repeat(node),
                             ))
                             .collect::<Vec<_>>()
@@ -422,7 +428,7 @@ pub(crate) fn hover_for_definition(
     subst: Option<GenericSubstitution>,
     scope_node: &SyntaxNode,
     macro_arm: Option<u32>,
-    hovered_definition: bool,
+    render_extras: bool,
     config: &HoverConfig,
     edition: Edition,
     display_target: DisplayTarget,
@@ -456,7 +462,7 @@ pub(crate) fn hover_for_definition(
         famous_defs.as_ref(),
         &notable_traits,
         macro_arm,
-        hovered_definition,
+        render_extras,
         subst_types.as_ref(),
         config,
         edition,
diff --git a/crates/ide/src/hover/render.rs b/crates/ide/src/hover/render.rs
index cf2ff1c956..a4cb869ac1 100644
--- a/crates/ide/src/hover/render.rs
+++ b/crates/ide/src/hover/render.rs
@@ -477,7 +477,7 @@ pub(super) fn definition(
     famous_defs: Option<&FamousDefs<'_, '_>>,
     notable_traits: &[(Trait, Vec<(Option<Type>, Name)>)],
     macro_arm: Option<u32>,
-    hovered_definition: bool,
+    render_extras: bool,
     subst_types: Option<&Vec<(Symbol, Type)>>,
     config: &HoverConfig,
     edition: Edition,
@@ -640,6 +640,12 @@ pub(super) fn definition(
         Definition::Local(it) => {
             render_memory_layout(config.memory_layout, || it.ty(db).layout(db), |_| None, |_| None)
         }
+        Definition::SelfType(it) => render_memory_layout(
+            config.memory_layout,
+            || it.self_ty(db).layout(db),
+            |_| None,
+            |_| None,
+        ),
         _ => None,
     };
 
@@ -741,7 +747,7 @@ pub(super) fn definition(
     };
 
     let mut extra = String::new();
-    if hovered_definition {
+    if render_extras {
         if let Some(notable_traits) =
             render_notable_trait(db, notable_traits, edition, display_target)
         {
diff --git a/crates/ide/src/hover/tests.rs b/crates/ide/src/hover/tests.rs
index 0266b87499..c5f8791030 100644
--- a/crates/ide/src/hover/tests.rs
+++ b/crates/ide/src/hover/tests.rs
@@ -2089,6 +2089,10 @@ impl Thing {
                 x: u32,
             }
             ```
+
+            ---
+
+            size = 4, align = 4
         "#]],
     );
     check_hover_fields_limit(
@@ -2109,6 +2113,10 @@ impl Thing {
             ```rust
             struct Thing
             ```
+
+            ---
+
+            size = 4, align = 4
         "#]],
     );
     check(
@@ -2130,6 +2138,10 @@ impl Thing {
                 x: u32,
             }
             ```
+
+            ---
+
+            size = 4, align = 4
         "#]],
     );
     check(
@@ -2151,6 +2163,10 @@ impl Thing {
                 A,
             }
             ```
+
+            ---
+
+            size = 0, align = 1
         "#]],
     );
     check(
@@ -2172,6 +2188,10 @@ impl Thing {
                 A,
             }
             ```
+
+            ---
+
+            size = 0, align = 1
         "#]],
     );
     check(
@@ -2190,6 +2210,10 @@ impl usize {
             ```rust
             usize
             ```
+
+            ---
+
+            size = 8, align = 8
         "#]],
     );
     check(
@@ -2208,6 +2232,36 @@ impl fn() -> usize {
             ```rust
             fn() -> usize
             ```
+
+            ---
+
+            size = 8, align = 8, niches = 1
+        "#]],
+    );
+    check(
+        r#"
+pub struct Foo
+where
+    Self$0:;
+"#,
+        expect![[r#"
+            *Self*
+
+            ```rust
+            ra_test_fixture
+            ```
+
+            ```rust
+            pub struct Foo
+            ```
+
+            ---
+
+            size = 0, align = 1
+
+            ---
+
+            does not contain types with destructors (drop glue); doesn't have a destructor
         "#]],
     );
 }