Merge #8783

8783: internal: introduce `ast::make::ext` module with common shortcuts r=matklad a=matklad

bors r+
🤖

Co-authored-by: Aleksey Kladov <aleksey.kladov@gmail.com>

crates/ide_assists/src/handlers/early_return.rs

@@ -130,9 +130,7 @@ pub(crate) fn convert_to_guarded_return(acc: &mut Assists, ctx: &AssistContext)
                                 once(make::ident_pat(make::name("it")).into()),
                             );
                             let expr = {
-                                let name_ref = make::name_ref("it");
+                                let path = make::ext::ident_path("it");
-                                let segment = make::path_segment(name_ref);
-                                let path = make::path_unqualified(segment);
                                 make::expr_path(path)
                             };
                             make::match_arm(once(pat.into()), expr)

crates/ide_assists/src/handlers/expand_glob_import.rs

@@ -65,8 +65,7 @@ pub(crate) fn expand_glob_import(acc: &mut Assists, ctx: &AssistContext) -> Opti
 
             let names_to_import = find_names_to_import(ctx, refs_in_target, imported_defs);
             let expanded = make::use_tree_list(names_to_import.iter().map(|n| {
-                let path =
+                let path = make::ext::ident_path(&n.to_string());
-                    make::path_unqualified(make::path_segment(make::name_ref(&n.to_string())));
                 make::use_tree(path, None, None, false)
             }))
             .clone_for_update();

crates/ide_assists/src/handlers/extract_function.rs

@@ -956,10 +956,10 @@ fn format_replacement(ctx: &AssistContext, fun: &Function, indent: IndentLevel)
     let args = fun.params.iter().map(|param| param.to_arg(ctx));
     let args = make::arg_list(args);
     let call_expr = if fun.self_param.is_some() {
-        let self_arg = make::expr_path(make_path_from_text("self"));
+        let self_arg = make::expr_path(make::ext::ident_path("self"));
         make::expr_method_call(self_arg, &fun.name, args)
     } else {
-        let func = make::expr_path(make_path_from_text(&fun.name));
+        let func = make::expr_path(make::ext::ident_path(&fun.name));
         make::expr_call(func, args)
     };
 
@@ -1054,11 +1054,11 @@ fn make_call_expr(&self, call_expr: ast::Expr) -> ast::Expr {
                 make::expr_if(condition, block, None)
             }
             FlowHandler::IfOption { action } => {
-                let path = make_path_from_text("Some");
+                let path = make::ext::ident_path("Some");
                 let value_pat = make::ident_pat(make::name("value"));
                 let pattern = make::tuple_struct_pat(path, iter::once(value_pat.into()));
                 let cond = make::condition(call_expr, Some(pattern.into()));
-                let value = make::expr_path(make_path_from_text("value"));
+                let value = make::expr_path(make::ext::ident_path("value"));
                 let action_expr = action.make_result_handler(Some(value));
                 let action_stmt = make::expr_stmt(action_expr);
                 let then = make::block_expr(iter::once(action_stmt.into()), None);
@@ -1068,14 +1068,14 @@ fn make_call_expr(&self, call_expr: ast::Expr) -> ast::Expr {
                 let some_name = "value";
 
                 let some_arm = {
-                    let path = make_path_from_text("Some");
+                    let path = make::ext::ident_path("Some");
                     let value_pat = make::ident_pat(make::name(some_name));
                     let pat = make::tuple_struct_pat(path, iter::once(value_pat.into()));
-                    let value = make::expr_path(make_path_from_text(some_name));
+                    let value = make::expr_path(make::ext::ident_path(some_name));
                     make::match_arm(iter::once(pat.into()), value)
                 };
                 let none_arm = {
-                    let path = make_path_from_text("None");
+                    let path = make::ext::ident_path("None");
                     let pat = make::path_pat(path);
                     make::match_arm(iter::once(pat), none.make_result_handler(None))
                 };
@@ -1087,17 +1087,17 @@ fn make_call_expr(&self, call_expr: ast::Expr) -> ast::Expr {
                 let err_name = "value";
 
                 let ok_arm = {
-                    let path = make_path_from_text("Ok");
+                    let path = make::ext::ident_path("Ok");
                     let value_pat = make::ident_pat(make::name(ok_name));
                     let pat = make::tuple_struct_pat(path, iter::once(value_pat.into()));
-                    let value = make::expr_path(make_path_from_text(ok_name));
+                    let value = make::expr_path(make::ext::ident_path(ok_name));
                     make::match_arm(iter::once(pat.into()), value)
                 };
                 let err_arm = {
-                    let path = make_path_from_text("Err");
+                    let path = make::ext::ident_path("Err");
                     let value_pat = make::ident_pat(make::name(err_name));
                     let pat = make::tuple_struct_pat(path, iter::once(value_pat.into()));
-                    let value = make::expr_path(make_path_from_text(err_name));
+                    let value = make::expr_path(make::ext::ident_path(err_name));
                     make::match_arm(iter::once(pat.into()), err.make_result_handler(Some(value)))
                 };
                 let arms = make::match_arm_list(vec![ok_arm, err_arm]);
@@ -1107,13 +1107,9 @@ fn make_call_expr(&self, call_expr: ast::Expr) -> ast::Expr {
     }
 }
 
-fn make_path_from_text(text: &str) -> ast::Path {
-    make::path_unqualified(make::path_segment(make::name_ref(text)))
-}
-
 fn path_expr_from_local(ctx: &AssistContext, var: Local) -> ast::Expr {
     let name = var.name(ctx.db()).unwrap().to_string();
-    make::expr_path(make_path_from_text(&name))
+    make::expr_path(make::ext::ident_path(&name))
 }
 
 fn format_function(
@@ -1179,7 +1175,7 @@ fn make_ret_ty(ctx: &AssistContext, module: hir::Module, fun: &Function) -> Opti
             fun_ty.make_ty(ctx, module)
         }
         FlowHandler::Try { kind: TryKind::Option } => {
-            make::ty_generic(make::name_ref("Option"), iter::once(fun_ty.make_ty(ctx, module)))
+            make::ext::ty_option(fun_ty.make_ty(ctx, module))
         }
         FlowHandler::Try { kind: TryKind::Result { ty: parent_ret_ty } } => {
             let handler_ty = parent_ret_ty
@@ -1187,29 +1183,21 @@ fn make_ret_ty(ctx: &AssistContext, module: hir::Module, fun: &Function) -> Opti
                 .nth(1)
                 .map(|ty| make_ty(&ty, ctx, module))
                 .unwrap_or_else(make::ty_unit);
-            make::ty_generic(
+            make::ext::ty_result(fun_ty.make_ty(ctx, module), handler_ty)
-                make::name_ref("Result"),
-                vec![fun_ty.make_ty(ctx, module), handler_ty],
-            )
         }
-        FlowHandler::If { .. } => make::ty_bool(),
+        FlowHandler::If { .. } => make::ext::ty_bool(),
         FlowHandler::IfOption { action } => {
             let handler_ty = action
                 .expr_ty(ctx)
                 .map(|ty| make_ty(&ty, ctx, module))
                 .unwrap_or_else(make::ty_unit);
-            make::ty_generic(make::name_ref("Option"), iter::once(handler_ty))
+            make::ext::ty_option(handler_ty)
-        }
-        FlowHandler::MatchOption { .. } => {
-            make::ty_generic(make::name_ref("Option"), iter::once(fun_ty.make_ty(ctx, module)))
         }
+        FlowHandler::MatchOption { .. } => make::ext::ty_option(fun_ty.make_ty(ctx, module)),
         FlowHandler::MatchResult { err } => {
             let handler_ty =
                 err.expr_ty(ctx).map(|ty| make_ty(&ty, ctx, module)).unwrap_or_else(make::ty_unit);
-            make::ty_generic(
+            make::ext::ty_result(fun_ty.make_ty(ctx, module), handler_ty)
-                make::name_ref("Result"),
-                vec![fun_ty.make_ty(ctx, module), handler_ty],
-            )
         }
     };
     Some(make::ret_type(ret_ty))
@@ -1296,7 +1284,7 @@ fn make_body(
                     TryKind::Option => "Some",
                     TryKind::Result { .. } => "Ok",
                 };
-                let func = make::expr_path(make_path_from_text(constructor));
+                let func = make::expr_path(make::ext::ident_path(constructor));
                 let args = make::arg_list(iter::once(tail_expr));
                 make::expr_call(func, args)
             })
@@ -1306,16 +1294,16 @@ fn make_body(
             with_tail_expr(block, lit_false.into())
         }
         FlowHandler::IfOption { .. } => {
-            let none = make::expr_path(make_path_from_text("None"));
+            let none = make::expr_path(make::ext::ident_path("None"));
             with_tail_expr(block, none)
         }
         FlowHandler::MatchOption { .. } => map_tail_expr(block, |tail_expr| {
-            let some = make::expr_path(make_path_from_text("Some"));
+            let some = make::expr_path(make::ext::ident_path("Some"));
             let args = make::arg_list(iter::once(tail_expr));
             make::expr_call(some, args)
         }),
         FlowHandler::MatchResult { .. } => map_tail_expr(block, |tail_expr| {
-            let ok = make::expr_path(make_path_from_text("Ok"));
+            let ok = make::expr_path(make::ext::ident_path("Ok"));
             let args = make::arg_list(iter::once(tail_expr));
             make::expr_call(ok, args)
         }),
@@ -1483,13 +1471,13 @@ fn make_rewritten_flow(handler: &FlowHandler, arg_expr: Option<ast::Expr>) -> Op
         FlowHandler::IfOption { .. } => {
             let expr = arg_expr.unwrap_or_else(|| make::expr_tuple(Vec::new()));
             let args = make::arg_list(iter::once(expr));
-            make::expr_call(make::expr_path(make_path_from_text("Some")), args)
+            make::expr_call(make::expr_path(make::ext::ident_path("Some")), args)
         }
-        FlowHandler::MatchOption { .. } => make::expr_path(make_path_from_text("None")),
+        FlowHandler::MatchOption { .. } => make::expr_path(make::ext::ident_path("None")),
         FlowHandler::MatchResult { .. } => {
             let expr = arg_expr.unwrap_or_else(|| make::expr_tuple(Vec::new()));
             let args = make::arg_list(iter::once(expr));
-            make::expr_call(make::expr_path(make_path_from_text("Err")), args)
+            make::expr_call(make::expr_path(make::ext::ident_path("Err")), args)
         }
     };
     Some(make::expr_return(Some(value)).clone_for_update())

crates/ide_assists/src/handlers/generate_function.rs

@@ -175,7 +175,7 @@ fn from_call(
     }
 
     fn render(self) -> FunctionTemplate {
-        let placeholder_expr = make::expr_todo();
+        let placeholder_expr = make::ext::expr_todo();
         let fn_body = make::block_expr(vec![], Some(placeholder_expr));
         let visibility = if self.needs_pub { Some(make::visibility_pub_crate()) } else { None };
         let mut fn_def = make::fn_(

crates/ide_assists/src/handlers/move_bounds.rs

@@ -63,11 +63,7 @@ pub(crate) fn move_bounds_to_where_clause(acc: &mut Assists, ctx: &AssistContext
 }
 
 fn build_predicate(param: ast::TypeParam) -> Option<ast::WherePred> {
-    let path = {
+    let path = make::ext::ident_path(&param.name()?.syntax().to_string());
-        let name_ref = make::name_ref(&param.name()?.syntax().to_string());
-        let segment = make::path_segment(name_ref);
-        make::path_unqualified(segment)
-    };
     let predicate = make::where_pred(path, param.type_bound_list()?.bounds());
     Some(predicate.clone_for_update())
 }

crates/ide_assists/src/handlers/replace_derive_with_manual_impl.rs

@@ -84,7 +84,7 @@ pub(crate) fn replace_derive_with_manual_impl(
         add_assist(acc, ctx, &attr, &args, &trait_path, Some(trait_), &adt)?;
     }
     if no_traits_found {
-        let trait_path = make::path_unqualified(make::path_segment(make::name_ref(trait_name)));
+        let trait_path = make::ext::ident_path(trait_name);
         add_assist(acc, ctx, &attr, &args, &trait_path, None, &adt)?;
     }
     Some(())
@@ -159,10 +159,8 @@ fn impl_def_from_trait(
     if trait_items.is_empty() {
         return None;
     }
-    let impl_def = make::impl_trait(
+    let impl_def =
-        trait_path.clone(),
+        make::impl_trait(trait_path.clone(), make::ext::ident_path(&annotated_name.text()));
-        make::path_unqualified(make::path_segment(make::name_ref(&annotated_name.text()))),
-    );
     let (impl_def, first_assoc_item) =
         add_trait_assoc_items_to_impl(sema, trait_items, trait_, impl_def, target_scope);
     Some((impl_def, first_assoc_item))

crates/ide_assists/src/handlers/replace_let_with_if_let.rs

@@ -53,7 +53,7 @@ pub(crate) fn replace_let_with_if_let(acc: &mut Assists, ctx: &AssistContext) ->
             let with_placeholder: ast::Pat = match happy_variant {
                 None => make::wildcard_pat().into(),
                 Some(var_name) => make::tuple_struct_pat(
-                    make::path_unqualified(make::path_segment(make::name_ref(var_name))),
+                    make::ext::ident_path(var_name),
                     once(make::wildcard_pat().into()),
                 )
                 .into(),

crates/ide_assists/src/handlers/replace_unwrap_with_match.rs

@@ -32,7 +32,7 @@
 // fn main() {
 //     let x: Result<i32, i32> = Result::Ok(92);
 //     let y = match x {
-//         Ok(a) => a,
+//         Ok(it) => it,
 //         $0_ => unreachable!(),
 //     };
 // }
@@ -52,16 +52,17 @@ pub(crate) fn replace_unwrap_with_match(acc: &mut Assists, ctx: &AssistContext)
         "Replace unwrap with match",
         target,
         |builder| {
-            let ok_path = make::path_unqualified(make::path_segment(make::name_ref(happy_variant)));
+            let ok_path = make::ext::ident_path(happy_variant);
-            let it = make::ident_pat(make::name("a")).into();
+            let it = make::ident_pat(make::name("it")).into();
             let ok_tuple = make::tuple_struct_pat(ok_path, iter::once(it)).into();
 
-            let bind_path = make::path_unqualified(make::path_segment(make::name_ref("a")));
+            let bind_path = make::ext::ident_path("it");
             let ok_arm = make::match_arm(iter::once(ok_tuple), make::expr_path(bind_path));
 
-            let unreachable_call = make::expr_unreachable();
+            let err_arm = make::match_arm(
-            let err_arm =
+                iter::once(make::wildcard_pat().into()),
-                make::match_arm(iter::once(make::wildcard_pat().into()), unreachable_call);
+                make::ext::expr_unreachable(),
+            );
 
             let match_arm_list = make::match_arm_list(vec![ok_arm, err_arm]);
             let match_expr = make::expr_match(caller.clone(), match_arm_list)
@@ -110,7 +111,7 @@ fn i<T>(a: T) -> T { a }
 fn main() {
     let x: Result<i32, i32> = Result::Ok(92);
     let y = match i(x) {
-        Ok(a) => a,
+        Ok(it) => it,
         $0_ => unreachable!(),
     };
 }
@@ -136,7 +137,7 @@ fn i<T>(a: T) -> T { a }
 fn main() {
     let x = Option::Some(92);
     let y = match i(x) {
-        Some(a) => a,
+        Some(it) => it,
         $0_ => unreachable!(),
     };
 }
@@ -162,7 +163,7 @@ fn i<T>(a: T) -> T { a }
 fn main() {
     let x: Result<i32, i32> = Result::Ok(92);
     let y = match i(x) {
-        Ok(a) => a,
+        Ok(it) => it,
         $0_ => unreachable!(),
     }.count_zeroes();
 }

crates/ide_assists/src/handlers/wrap_return_type_in_result.rs

@@ -54,9 +54,7 @@ pub(crate) fn wrap_return_type_in_result(acc: &mut Assists, ctx: &AssistContext)
 
             for ret_expr_arg in tail_return_expr_collector.exprs_to_wrap {
                 let ok_wrapped = make::expr_call(
-                    make::expr_path(make::path_unqualified(make::path_segment(make::name_ref(
+                    make::expr_path(make::ext::ident_path("Ok")),
-                        "Ok",
-                    )))),
                     make::arg_list(iter::once(ret_expr_arg.clone())),
                 );
                 builder.replace_ast(ret_expr_arg, ok_wrapped);

crates/ide_assists/src/tests/generated.rs

@@ -1531,7 +1531,7 @@ enum Result<T, E> { Ok(T), Err(E) }
 fn main() {
     let x: Result<i32, i32> = Result::Ok(92);
     let y = match x {
-        Ok(a) => a,
+        Ok(it) => it,
         $0_ => unreachable!(),
     };
 }

crates/ide_assists/src/utils.rs

@@ -159,8 +159,8 @@ fn add_body(fn_def: ast::Fn) -> ast::Fn {
         match fn_def.body() {
             Some(_) => fn_def,
             None => {
-                let body =
+                let body = make::block_expr(None, Some(make::ext::expr_todo()))
-                    make::block_expr(None, Some(make::expr_todo())).indent(edit::IndentLevel(1));
+                    .indent(edit::IndentLevel(1));
                 fn_def.with_body(body)
             }
         }

crates/ide_db/src/helpers/merge_imports.rs

@@ -137,7 +137,7 @@ fn recursive_merge(
                             None,
                             false,
                         );
-                        use_trees.insert(idx, make::glob_use_tree());
+                        use_trees.insert(idx, make::use_tree_glob());
                         continue;
                     }
 

crates/ide_db/src/ty_filter.rs

@@ -43,7 +43,7 @@ pub fn happy_case(self) -> &'static str {
     pub fn sad_pattern(self) -> ast::Pat {
         match self {
             TryEnum::Result => make::tuple_struct_pat(
-                make::path_unqualified(make::path_segment(make::name_ref("Err"))),
+                make::ext::ident_path("Err"),
                 iter::once(make::wildcard_pat().into()),
             )
             .into(),
@@ -54,12 +54,12 @@ pub fn sad_pattern(self) -> ast::Pat {
     pub fn happy_pattern(self) -> ast::Pat {
         match self {
             TryEnum::Result => make::tuple_struct_pat(
-                make::path_unqualified(make::path_segment(make::name_ref("Ok"))),
+                make::ext::ident_path("Ok"),
                 iter::once(make::wildcard_pat().into()),
             )
             .into(),
             TryEnum::Option => make::tuple_struct_pat(
-                make::path_unqualified(make::path_segment(make::name_ref("Some"))),
+                make::ext::ident_path("Some"),
                 iter::once(make::wildcard_pat().into()),
             )
             .into(),

crates/syntax/src/ast/make.rs

@@ -3,7 +3,7 @@
 //!
 //! Note that all functions here intended to be stupid constructors, which just
 //! assemble a finish node from immediate children. If you want to do something
-//! smarter than that, it probably doesn't belong in this module.
+//! smarter than that, it belongs to the `ext` submodule.
 //!
 //! Keep in mind that `from_text` functions should be kept private. The public
 //! API should require to assemble every node piecewise. The trick of
@@ -14,13 +14,49 @@
 
 use crate::{ast, AstNode, SourceFile, SyntaxKind, SyntaxNode, SyntaxToken};
 
+/// While the parent module defines basic atomic "constructors", the `ext`
+/// module defines shortcuts for common things.
+///
+/// It's named `ext` rather than `shortcuts` just to keep it short.
+pub mod ext {
+    use super::*;
+
+    pub fn ident_path(ident: &str) -> ast::Path {
+        path_unqualified(path_segment(name_ref(ident)))
+    }
+
+    pub fn expr_unreachable() -> ast::Expr {
+        expr_from_text("unreachable!()")
+    }
+    pub fn expr_todo() -> ast::Expr {
+        expr_from_text("todo!()")
+    }
+
+    pub fn ty_bool() -> ast::Type {
+        ty_path(ident_path("bool"))
+    }
+    pub fn ty_option(t: ast::Type) -> ast::Type {
+        ty_from_text(&format!("Option<{}>", t))
+    }
+    pub fn ty_result(t: ast::Type, e: ast::Type) -> ast::Type {
+        ty_from_text(&format!("Result<{}, {}>", t, e))
+    }
+}
+
 pub fn name(text: &str) -> ast::Name {
     ast_from_text(&format!("mod {}{};", raw_ident_esc(text), text))
 }
-
 pub fn name_ref(text: &str) -> ast::NameRef {
     ast_from_text(&format!("fn f() {{ {}{}; }}", raw_ident_esc(text), text))
 }
+fn raw_ident_esc(ident: &str) -> &'static str {
+    let is_keyword = parser::SyntaxKind::from_keyword(ident).is_some();
+    if is_keyword && !matches!(ident, "self" | "crate" | "super" | "Self") {
+        "r#"
+    } else {
+        ""
+    }
+}
 
 pub fn lifetime(text: &str) -> ast::Lifetime {
     let mut text = text;
@@ -32,15 +68,6 @@ pub fn lifetime(text: &str) -> ast::Lifetime {
     ast_from_text(&format!("fn f<{}>() {{ }}", text))
 }
 
-fn raw_ident_esc(ident: &str) -> &'static str {
-    let is_keyword = parser::SyntaxKind::from_keyword(ident).is_some();
-    if is_keyword && !matches!(ident, "self" | "crate" | "super" | "Self") {
-        "r#"
-    } else {
-        ""
-    }
-}
-
 // FIXME: replace stringly-typed constructor with a family of typed ctors, a-la
 // `expr_xxx`.
 pub fn ty(text: &str) -> ast::Type {
@@ -49,9 +76,6 @@ pub fn ty(text: &str) -> ast::Type {
 pub fn ty_unit() -> ast::Type {
     ty_from_text("()")
 }
-pub fn ty_bool() -> ast::Type {
-    ty_path(path_unqualified(path_segment(name_ref("bool"))))
-}
 pub fn ty_tuple(types: impl IntoIterator<Item = ast::Type>) -> ast::Type {
     let mut count: usize = 0;
     let mut contents = types.into_iter().inspect(|_| count += 1).join(", ");
@@ -61,11 +85,6 @@ pub fn ty_tuple(types: impl IntoIterator<Item = ast::Type>) -> ast::Type {
 
     ty_from_text(&format!("({})", contents))
 }
-// FIXME: handle path to type
-pub fn ty_generic(name: ast::NameRef, types: impl IntoIterator<Item = ast::Type>) -> ast::Type {
-    let contents = types.into_iter().join(", ");
-    ty_from_text(&format!("{}<{}>", name, contents))
-}
 pub fn ty_ref(target: ast::Type, exclusive: bool) -> ast::Type {
     ty_from_text(&if exclusive { format!("&mut {}", target) } else { format!("&{}", target) })
 }
@@ -107,7 +126,7 @@ pub fn path_unqualified(segment: ast::PathSegment) -> ast::Path {
 pub fn path_qualified(qual: ast::Path, segment: ast::PathSegment) -> ast::Path {
     ast_from_text(&format!("{}::{}", qual, segment))
 }
-
+// FIXME: path concatenation operation doesn't make sense as AST op.
 pub fn path_concat(first: ast::Path, second: ast::Path) -> ast::Path {
     ast_from_text(&format!("{}::{}", first, second))
 }
@@ -123,15 +142,14 @@ pub fn path_from_segments(
         format!("use {};", segments)
     })
 }
-
+// FIXME: should not be pub
 pub fn path_from_text(text: &str) -> ast::Path {
     ast_from_text(&format!("fn main() {{ let test = {}; }}", text))
 }
 
-pub fn glob_use_tree() -> ast::UseTree {
+pub fn use_tree_glob() -> ast::UseTree {
     ast_from_text("use *;")
 }
-
 pub fn use_tree(
     path: ast::Path,
     use_tree_list: Option<ast::UseTreeList>,
@@ -226,15 +244,6 @@ pub fn expr_literal(text: &str) -> ast::Literal {
 pub fn expr_empty_block() -> ast::Expr {
     expr_from_text("{}")
 }
-pub fn expr_unimplemented() -> ast::Expr {
-    expr_from_text("unimplemented!()")
-}
-pub fn expr_unreachable() -> ast::Expr {
-    expr_from_text("unreachable!()")
-}
-pub fn expr_todo() -> ast::Expr {
-    expr_from_text("todo!()")
-}
 pub fn expr_path(path: ast::Path) -> ast::Expr {
     expr_from_text(&path.to_string())
 }
@@ -463,17 +472,6 @@ pub fn expr_stmt(expr: ast::Expr) -> ast::ExprStmt {
     ast_from_text(&format!("fn f() {{ {}{} (); }}", expr, semi))
 }
 
-pub fn token(kind: SyntaxKind) -> SyntaxToken {
-    tokens::SOURCE_FILE
-        .tree()
-        .syntax()
-        .clone_for_update()
-        .descendants_with_tokens()
-        .filter_map(|it| it.into_token())
-        .find(|it| it.kind() == kind)
-        .unwrap_or_else(|| panic!("unhandled token: {:?}", kind))
-}
-
 pub fn param(pat: ast::Pat, ty: ast::Type) -> ast::Param {
     ast_from_text(&format!("fn f({}: {}) {{ }}", pat, ty))
 }
@@ -611,6 +609,17 @@ fn unroot(n: SyntaxNode) -> SyntaxNode {
     SyntaxNode::new_root(n.green().into())
 }
 
+pub fn token(kind: SyntaxKind) -> SyntaxToken {
+    tokens::SOURCE_FILE
+        .tree()
+        .syntax()
+        .clone_for_update()
+        .descendants_with_tokens()
+        .filter_map(|it| it.into_token())
+        .find(|it| it.kind() == kind)
+        .unwrap_or_else(|| panic!("unhandled token: {:?}", kind))
+}
+
 pub mod tokens {
     use once_cell::sync::Lazy;