Add a fixme to remove hacks

Author: WaffleLapkin

crates/ide/src/inlay_hints/adjustment.rs

@@ -196,6 +196,8 @@ fn needs_parens_for_adjustment_hints(expr: &ast::Expr, postfix: bool) -> (bool,
     // and "parent" is the parent of the original expression...
     //
     // For this we utilize mutable mutable trees, which is a HACK, but it works.
+    //
+    // FIXME: comeup with a better API for `needs_parens_in`, so that we don't have to do *this*
 
     // Make `&expr`/`expr?`
     let dummy_expr = {