Use strict iteration option

Author: markerikson

src/core/current.ts

@@ -21,18 +21,24 @@ function currentImpl(value: any): any {
 	if (!isDraftable(value) || isFrozen(value)) return value
 	const state: ImmerState | undefined = value[DRAFT_STATE]
 	let copy: any
+	let strict = true // Default to strict for compatibility
 	if (state) {
 		if (!state.modified_) return state.base_
 		// Optimization: avoid generating new drafts during copying
 		state.finalized_ = true
 		copy = shallowCopy(value, state.scope_.immer_.useStrictShallowCopy_)
+		strict = state.scope_.immer_.shouldUseStrictIteration(value)
 	} else {
 		copy = shallowCopy(value, true)
 	}
 	// recurse
-	each(copy, (key, childValue) => {
-		set(copy, key, currentImpl(childValue))
-	})
+	each(
+		copy,
+		(key, childValue) => {
+			set(copy, key, currentImpl(childValue))
+		},
+		strict
+	)
 	if (state) {
 		state.finalized_ = false
 	}

src/core/finalize.ts

@@ -59,8 +59,11 @@ function finalize(rootScope: ImmerScope, value: any, path?: PatchPath) {
 	const state: ImmerState = value[DRAFT_STATE]
 	// A plain object, might need freezing, might contain drafts
 	if (!state) {
-		each(value, (key, childValue) =>
-			finalizeProperty(rootScope, state, value, key, childValue, path)
+		each(
+			value,
+			(key, childValue) =>
+				finalizeProperty(rootScope, state, value, key, childValue, path),
+			rootScope.immer_.shouldUseStrictIteration(value)
 		)
 		return value
 	}
@@ -87,8 +90,19 @@ function finalize(rootScope: ImmerScope, value: any, path?: PatchPath) {
 			result.clear()
 			isSet = true
 		}
-		each(resultEach, (key, childValue) =>
-			finalizeProperty(rootScope, state, result, key, childValue, path, isSet)
+		each(
+			resultEach,
+			(key, childValue) =>
+				finalizeProperty(
+					rootScope,
+					state,
+					result,
+					key,
+					childValue,
+					path,
+					isSet
+				),
+			rootScope.immer_.shouldUseStrictIteration(resultEach)
 		)
 		// everything inside is frozen, we can freeze here
 		maybeFreeze(rootScope, result, false)