internal: Migrate unwrap_return_type assist to use SyntaxEditor

Also changes `make::expr_empty_block()` to return `ast::BlockExpr` instead of `ast::Expr`

Author: Giga-Bowser

crates/ide-assists/src/handlers/unwrap_return_type.rs

@@ -1,11 +1,11 @@
+use either::Either;
 use ide_db::{
     famous_defs::FamousDefs,
     syntax_helpers::node_ext::{for_each_tail_expr, walk_expr},
 };
-use itertools::Itertools;
 use syntax::{
-    ast::{self, Expr, HasGenericArgs},
-    match_ast, AstNode, NodeOrToken, SyntaxKind, TextRange,
+    ast::{self, syntax_factory::SyntaxFactory, HasArgList, HasGenericArgs},
+    match_ast, AstNode, NodeOrToken, SyntaxKind,
 };
 
 use crate::{AssistContext, AssistId, AssistKind, Assists};
@@ -39,11 +39,11 @@ use crate::{AssistContext, AssistId, AssistKind, Assists};
 pub(crate) fn unwrap_return_type(acc: &mut Assists, ctx: &AssistContext<'_>) -> Option<()> {
     let ret_type = ctx.find_node_at_offset::<ast::RetType>()?;
     let parent = ret_type.syntax().parent()?;
-    let body = match_ast! {
+    let body_expr = match_ast! {
         match parent {
-            ast::Fn(func) => func.body()?,
+            ast::Fn(func) => func.body()?.into(),
             ast::ClosureExpr(closure) => match closure.body()? {
-                Expr::BlockExpr(block) => block,
+                ast::Expr::BlockExpr(block) => block.into(),
                 // closures require a block when a return type is specified
                 _ => return None,
             },
@@ -65,72 +65,96 @@ pub(crate) fn unwrap_return_type(acc: &mut Assists, ctx: &AssistContext<'_>) ->
     let happy_type = extract_wrapped_type(type_ref)?;
 
     acc.add(kind.assist_id(), kind.label(), type_ref.syntax().text_range(), |builder| {
-        let body = ast::Expr::BlockExpr(body);
+        let mut editor = builder.make_editor(&parent);
+        let make = SyntaxFactory::new();
 
         let mut exprs_to_unwrap = Vec::new();
         let tail_cb = &mut |e: &_| tail_cb_impl(&mut exprs_to_unwrap, e);
-        walk_expr(&body, &mut |expr| {
-            if let Expr::ReturnExpr(ret_expr) = expr {
+        walk_expr(&body_expr, &mut |expr| {
+            if let ast::Expr::ReturnExpr(ret_expr) = expr {
                 if let Some(ret_expr_arg) = &ret_expr.expr() {
                     for_each_tail_expr(ret_expr_arg, tail_cb);
                 }
             }
         });
-        for_each_tail_expr(&body, tail_cb);
+        for_each_tail_expr(&body_expr, tail_cb);
 
         let is_unit_type = is_unit_type(&happy_type);
         if is_unit_type {
-            let mut text_range = ret_type.syntax().text_range();
-
             if let Some(NodeOrToken::Token(token)) = ret_type.syntax().next_sibling_or_token() {
                 if token.kind() == SyntaxKind::WHITESPACE {
-                    text_range = TextRange::new(text_range.start(), token.text_range().end());
+                    editor.delete(token);
                 }
             }
 
-            builder.delete(text_range);
+            editor.delete(ret_type.syntax());
         } else {
-            builder.replace(type_ref.syntax().text_range(), happy_type.syntax().text());
+            // FIXME: remove `clone_for_update` when `SyntaxEditor` handles it for us
+            editor.replace(type_ref.syntax(), happy_type.syntax().clone_for_update());
         }
 
-        for ret_expr_arg in exprs_to_unwrap {
-            let ret_expr_str = ret_expr_arg.to_string();
-
-            let needs_replacing = match kind {
-                UnwrapperKind::Option => ret_expr_str.starts_with("Some("),
-                UnwrapperKind::Result => {
-                    ret_expr_str.starts_with("Ok(") || ret_expr_str.starts_with("Err(")
-                }
-            };
+        for tail_expr in exprs_to_unwrap {
+            match &tail_expr {
+                ast::Expr::CallExpr(call_expr) => {
+                    let ast::Expr::PathExpr(path_expr) = call_expr.expr().unwrap() else {
+                        continue;
+                    };
+
+                    let path_str = path_expr.path().unwrap().to_string();
+                    let needs_replacing = match kind {
+                        UnwrapperKind::Option => path_str == "Some",
+                        UnwrapperKind::Result => path_str == "Ok" || path_str == "Err",
+                    };
+
+                    if !needs_replacing {
+                        continue;
+                    }
 
-            if needs_replacing {
-                let arg_list = ret_expr_arg.syntax().children().find_map(ast::ArgList::cast);
-                if let Some(arg_list) = arg_list {
+                    let arg_list = call_expr.arg_list().unwrap();
                     if is_unit_type {
-                        match ret_expr_arg.syntax().prev_sibling_or_token() {
-                            // Useful to delete the entire line without leaving trailing whitespaces
-                            Some(whitespace) => {
-                                let new_range = TextRange::new(
-                                    whitespace.text_range().start(),
-                                    ret_expr_arg.syntax().text_range().end(),
-                                );
-                                builder.delete(new_range);
+                        let tail_parent = tail_expr
+                            .syntax()
+                            .parent()
+                            .and_then(Either::<ast::ReturnExpr, ast::StmtList>::cast)
+                            .unwrap();
+                        match tail_parent {
+                            Either::Left(ret_expr) => {
+                                editor.replace(ret_expr.syntax(), make.expr_return(None).syntax())
                             }
-                            None => {
-                                builder.delete(ret_expr_arg.syntax().text_range());
+                            Either::Right(stmt_list) => {
+                                let new_block = if stmt_list.statements().next().is_none() {
+                                    make.expr_empty_block()
+                                } else {
+                                    make.block_expr(stmt_list.statements(), None)
+                                };
+                                editor.replace(
+                                    stmt_list.syntax(),
+                                    new_block.stmt_list().unwrap().syntax(),
+                                );
                             }
                         }
-                    } else {
-                        builder.replace(
-                            ret_expr_arg.syntax().text_range(),
-                            arg_list.args().join(", "),
-                        );
+                    } else if let Some(first_arg) = arg_list.args().next() {
+                        // FIXME: remove `clone_for_update` when `SyntaxEditor` handles it for us
+                        editor.replace(tail_expr.syntax(), first_arg.syntax().clone_for_update());
                     }
                 }
-            } else if matches!(kind, UnwrapperKind::Option if ret_expr_str == "None") {
-                builder.replace(ret_expr_arg.syntax().text_range(), "()");
+                ast::Expr::PathExpr(path_expr) => {
+                    let UnwrapperKind::Option = kind else {
+                        continue;
+                    };
+
+                    if path_expr.path().unwrap().to_string() != "None" {
+                        continue;
+                    }
+
+                    editor.replace(path_expr.syntax(), make.expr_unit().syntax());
+                }
+                _ => (),
             }
         }
+
+        editor.add_mappings(make.finish_with_mappings());
+        builder.add_file_edits(ctx.file_id(), editor);
     })
 }
 
@@ -168,12 +192,12 @@ impl UnwrapperKind {
 
 fn tail_cb_impl(acc: &mut Vec<ast::Expr>, e: &ast::Expr) {
     match e {
-        Expr::BreakExpr(break_expr) => {
+        ast::Expr::BreakExpr(break_expr) => {
             if let Some(break_expr_arg) = break_expr.expr() {
                 for_each_tail_expr(&break_expr_arg, &mut |e| tail_cb_impl(acc, e))
             }
         }
-        Expr::ReturnExpr(_) => {
+        ast::Expr::ReturnExpr(_) => {
             // all return expressions have already been handled by the walk loop
         }
         e => acc.push(e.clone()),
@@ -238,8 +262,7 @@ fn foo() -> Option<()$0> {
 }
 "#,
             r#"
-fn foo() {
-}
+fn foo() {}
 "#,
             "Unwrap Option return type",
         );
@@ -254,8 +277,7 @@ fn foo() -> Option<()$0>{
 }
 "#,
             r#"
-fn foo() {
-}
+fn foo() {}
 "#,
             "Unwrap Option return type",
         );
@@ -1262,8 +1284,7 @@ fn foo() -> Result<(), Box<dyn Error$0>> {
 }
 "#,
             r#"
-fn foo() {
-}
+fn foo() {}
 "#,
             "Unwrap Result return type",
         );
@@ -1278,8 +1299,7 @@ fn foo() -> Result<(), Box<dyn Error$0>>{
 }
 "#,
             r#"
-fn foo() {
-}
+fn foo() {}
 "#,
             "Unwrap Result return type",
         );

crates/ide-assists/src/utils/gen_trait_fn_body.rs

@@ -599,7 +599,7 @@ fn gen_partial_ord(adt: &ast::Adt, func: &ast::Fn, trait_ref: Option<TraitRef>)
         let variant_name =
             make::path_pat(make::ext::path_from_idents(["core", "cmp", "Ordering", "Equal"])?);
         let lhs = make::tuple_struct_pat(make::ext::path_from_idents(["Some"])?, [variant_name]);
-        arms.push(make::match_arm(Some(lhs.into()), None, make::expr_empty_block()));
+        arms.push(make::match_arm(Some(lhs.into()), None, make::expr_empty_block().into()));
 
         arms.push(make::match_arm(
             [make::ident_pat(false, false, make::name("ord")).into()],

crates/syntax/src/ast/make.rs

@@ -555,8 +555,8 @@ pub fn expr_const_value(text: &str) -> ast::ConstArg {
     ast_from_text(&format!("trait Foo<const N: usize = {text}> {{}}"))
 }
 
-pub fn expr_empty_block() -> ast::Expr {
-    expr_from_text("{}")
+pub fn expr_empty_block() -> ast::BlockExpr {
+    ast_from_text("const C: () = {};")
 }
 pub fn expr_path(path: ast::Path) -> ast::Expr {
     expr_from_text(&path.to_string())

crates/syntax/src/ast/syntax_factory/constructors.rs

@@ -172,6 +172,18 @@ impl SyntaxFactory {
         ast
     }
 
+    pub fn expr_empty_block(&self) -> ast::BlockExpr {
+        make::expr_empty_block().clone_for_update()
+    }
+
+    pub fn expr_unit(&self) -> ast::TupleExpr {
+        let ast::Expr::TupleExpr(ast) = make::expr_unit().clone_for_update() else {
+            unreachable!()
+        };
+
+        ast
+    }
+
     pub fn expr_path(&self, path: ast::Path) -> ast::Expr {
         let ast::Expr::PathExpr(ast) = make::expr_path(path.clone()).clone_for_update() else {
             unreachable!()
@@ -233,6 +245,22 @@ impl SyntaxFactory {
         ast.into()
     }
 
+    pub fn expr_return(&self, expr: Option<ast::Expr>) -> ast::ReturnExpr {
+        let ast::Expr::ReturnExpr(ast) = make::expr_return(expr.clone()).clone_for_update() else {
+            unreachable!()
+        };
+
+        if let Some(mut mapping) = self.mappings() {
+            let mut builder = SyntaxMappingBuilder::new(ast.syntax().clone());
+            if let Some(input) = expr {
+                builder.map_node(input.syntax().clone(), ast.expr().unwrap().syntax().clone());
+            }
+            builder.finish(&mut mapping);
+        }
+
+        ast
+    }
+
     pub fn let_stmt(
         &self,
         pattern: ast::Pat,