Add MethodCallExpr::get_or_create_generic_arg_list

Mirrors `PathSegment's` version, except that it always generates a
turbofish

Author: DropDemBits

crates/syntax/src/ast/edit_in_place.rs

@@ -14,7 +14,7 @@ use crate::{
     SyntaxNode, SyntaxToken,
 };
 
-use super::HasName;
+use super::{HasArgList, HasName};
 
 pub trait GenericParamsOwnerEdit: ast::HasGenericParams {
     fn get_or_create_generic_param_list(&self) -> ast::GenericParamList;
@@ -362,6 +362,24 @@ impl ast::PathSegment {
     }
 }
 
+impl ast::MethodCallExpr {
+    pub fn get_or_create_generic_arg_list(&self) -> ast::GenericArgList {
+        if self.generic_arg_list().is_none() {
+            let generic_arg_list = make::turbofish_generic_arg_list(empty()).clone_for_update();
+
+            if let Some(arg_list) = self.arg_list() {
+                ted::insert_raw(
+                    ted::Position::before(arg_list.syntax()),
+                    generic_arg_list.syntax(),
+                );
+            } else {
+                ted::append_child(self.syntax(), generic_arg_list.syntax());
+            }
+        }
+        self.generic_arg_list().unwrap()
+    }
+}
+
 impl Removable for ast::UseTree {
     fn remove(&self) {
         for dir in [Direction::Next, Direction::Prev] {

crates/syntax/src/ast/make.rs

@@ -941,6 +941,13 @@ pub fn lifetime_arg(lifetime: ast::Lifetime) -> ast::LifetimeArg {
     ast_from_text(&format!("const S: T<{lifetime}> = ();"))
 }
 
+pub fn turbofish_generic_arg_list(
+    args: impl IntoIterator<Item = ast::GenericArg>,
+) -> ast::GenericArgList {
+    let args = args.into_iter().join(", ");
+    ast_from_text(&format!("const S: T::<{args}> = ();"))
+}
+
 pub(crate) fn generic_arg_list(
     args: impl IntoIterator<Item = ast::GenericArg>,
 ) -> ast::GenericArgList {