support rendering __doc__ on hover

crates/ty_ide/src/hover.rs

@@ -2739,6 +2739,86 @@ def function():
         assert_snapshot!(test.hover(), @"Hover provided no content");
     }
 
+    #[test]
+    fn hover_dunder_doc() {
+        let test = cursor_test(
+            r#"
+            class My<CURSOR>Class:
+                __doc__ = "hello there"
+            "#,
+        );
+
+        assert_snapshot!(test.hover(), @r#"
+        <class 'MyClass'>
+        ---------------------------------------------
+        hello there
+
+        ---------------------------------------------
+        ```xml
+        <class 'MyClass'>
+        ```
+        ---
+        hello there
+        ---------------------------------------------
+        info[hover]: Hovered content is
+         --> main.py:2:7
+          |
+        2 | class MyClass:
+          |       ^^-^^^^
+          |       | |
+          |       | Cursor offset
+          |       source
+        3 |     __doc__ = "hello there"
+          |
+        "#);
+    }
+
+    #[test]
+    fn hover_dunder_doc_complex() {
+        let test = cursor_test(
+            r#"
+            class My<CURSOR>Class:
+                __doc__ = (
+                    r"""This is some extremely complex docstring
+
+                Designed to make
+                """
+                    + r"""
+
+                A typechecker
+            """
+                    """
+                Fall to its knees and sob
+            """
+                    r"""
+                Witness my works and 
+                weep before them
+                """
+                )
+        "#,
+        );
+
+        assert_snapshot!(test.hover(), @r#"
+        <class 'MyClass'>
+        ---------------------------------------------
+        ```xml
+        <class 'MyClass'>
+        ```
+        ---------------------------------------------
+        info[hover]: Hovered content is
+         --> main.py:2:7
+          |
+        2 | class MyClass:
+          |       ^^-^^^^
+          |       | |
+          |       | Cursor offset
+          |       source
+        3 |     __doc__ = (
+        4 |         r"""This is some extremely complex docstring
+          |
+        "#);
+    }
+
     #[test]
     fn hover_class_typevar_variance() {
         let test = cursor_test(

crates/ty_python_semantic/src/semantic_index/definition.rs

@@ -2,7 +2,7 @@ use std::ops::Deref;
 
 use ruff_db::files::{File, FileRange};
 use ruff_db::parsed::{ParsedModuleRef, parsed_module};
-use ruff_python_ast as ast;
+use ruff_python_ast::{self as ast, Expr};
 use ruff_text_size::{Ranged, TextRange};
 
 use crate::Db;
@@ -133,6 +133,10 @@ pub(crate) fn module_docstring(db: &dyn Db, file: File) -> Option<String> {
 
 /// Extract a docstring from a function, module, or class body.
 fn docstring_from_body(body: &[ast::Stmt]) -> Option<&ast::ExprStringLiteral> {
+    docstring_from_body_normal(body).or_else(|| docstring_from_body_dunder_doc(body))
+}
+
+fn docstring_from_body_normal(body: &[ast::Stmt]) -> Option<&ast::ExprStringLiteral> {
     let stmt = body.first()?;
     // Require the docstring to be a standalone expression.
     let ast::Stmt::Expr(ast::StmtExpr {
@@ -147,6 +151,27 @@ fn docstring_from_body(body: &[ast::Stmt]) -> Option<&ast::ExprStringLiteral> {
     value.as_string_literal_expr()
 }
 
+fn docstring_from_body_dunder_doc(body: &[ast::Stmt]) -> Option<&ast::ExprStringLiteral> {
+    for stmt in body {
+        let Some(stmt) = stmt.as_assign_stmt() else {
+            continue;
+        };
+        let [Expr::Name(name)] = &stmt.targets[..] else {
+            continue;
+        };
+        if name.id.as_str() != "__doc__" {
+            continue;
+        }
+        let Expr::StringLiteral(literal) = &*stmt.value else {
+            continue;
+        };
+
+        return Some(literal);
+    }
+
+    None
+}
+
 /// One or more [`Definition`]s.
 #[derive(Debug, Default, PartialEq, Eq, salsa::Update, get_size2::GetSize)]
 pub struct Definitions<'db> {