notes

packages/svelte/src/compiler/phases/3-transform/client/utils.js

@@ -543,15 +543,19 @@ export function should_proxy_or_freeze(node) {
  * @returns {boolean}
  */
 export function can_inline_variable(binding, name) {
-	// TODO: allow object expressions that are not passed to functions or components as props
-	// and expressions as long as they do not reference non-hoistable variables
 	return (
 		!!binding &&
 		binding.kind === 'normal' &&
 		binding.scope.is_top_level &&
+		// TODO: allow object expressions that are not passed to functions or components as props
+		// and expressions as long as they do not reference non-hoistable variables
+		binding.initial?.type === 'Literal' &&
+		// Checking that it's not mutated or reassigned is a bit simplistic
+		// If it's not state and thus not reactive, we could hoist the variable and mutation
+		// E.g. if you have `let x = 0; x++` you could hoist both statements
 		!binding.mutated &&
 		!binding.reassigned &&
-		binding.initial?.type === 'Literal' &&
+		// Avoid conflicts. It would be nice to rename the variable, but keeping it simple for now
 		!binding.scope.declared_in_outer_scope(name) &&
 		!GlobalBindings.has(name)
 	);