From cd953bb41b740c7ccb627b34a8999ddc203d0260 Mon Sep 17 00:00:00 2001
From: Oskar Eichler <oskar@songstats.com>
Date: Mon, 31 Aug 2026 02:49:36 +0300
Subject: [PATCH 1/2] Preserve Platform write targets

---
 .../src/__tests__/inline-plugin-test.js       | 18 ++++++++++
 .../src/inline-plugin.js                      | 36 +++++++++++++++----
 2 files changed, 48 insertions(+), 6 deletions(-)

diff --git a/packages/metro-transform-plugins/src/__tests__/inline-plugin-test.js b/packages/metro-transform-plugins/src/__tests__/inline-plugin-test.js
index a1b1010354..e9e1d39267 100644
--- a/packages/metro-transform-plugins/src/__tests__/inline-plugin-test.js
+++ b/packages/metro-transform-plugins/src/__tests__/inline-plugin-test.js
@@ -709,6 +709,24 @@ describe('inline constants', () => {
     });
   });
 
+  test("doesn't replace Platform.OS in other write targets", () => {
+    const code = `
+      Platform.OS++;
+      delete Platform.OS;
+      [Platform.OS] = values;
+      ({os: Platform.OS} = value);
+      for (Platform.OS in object) {}
+      for ([Platform.OS] in nestedObject) {}
+      for (Platform.OS of values) {}
+      for ([Platform.OS] of nestedValues) {}
+    `;
+
+    compare([inlinePlugin], code, code, {
+      inlinePlatform: true,
+      platform: 'ios',
+    });
+  });
+
   test('replaces Platform.OS in the code if Platform is the right hand side of an assignment expression', () => {
     const code = `
       function a() {
diff --git a/packages/metro-transform-plugins/src/inline-plugin.js b/packages/metro-transform-plugins/src/inline-plugin.js
index 2cc055d260..8a21273330 100644
--- a/packages/metro-transform-plugins/src/inline-plugin.js
+++ b/packages/metro-transform-plugins/src/inline-plugin.js
@@ -44,7 +44,6 @@ export default function inlinePlugin(
   options: Options,
 ): PluginObj<State> {
   const {
-    isAssignmentExpression,
     isIdentifier,
     isMemberExpression,
     isObjectExpression,
@@ -69,10 +68,35 @@ export default function inlinePlugin(
     return !binding || isFlowDeclared(binding);
   }
 
-  const isLeftHandSideOfAssignmentExpression = (
-    node: Node,
-    parent: Node,
-  ): boolean => isAssignmentExpression(parent) && parent.left === node;
+  function isWriteTarget(path: NodePath<MemberExpression>): boolean {
+    let child: Node = path.node;
+    let parentPath = path.parentPath;
+
+    while (parentPath != null) {
+      const parent = parentPath.node;
+      if (
+        (parent.type === 'AssignmentExpression' ||
+          parent.type === 'ForInStatement' ||
+          parent.type === 'ForOfStatement') &&
+        parent.left === child
+      ) {
+        return true;
+      }
+      if (parent.type === 'UpdateExpression' && parent.argument === child) {
+        return true;
+      }
+      if (
+        parent.type === 'UnaryExpression' &&
+        parent.operator === 'delete' &&
+        parent.argument === child
+      ) {
+        return true;
+      }
+      child = parent;
+      parentPath = parentPath.parentPath;
+    }
+    return false;
+  }
 
   const isProcessEnvNodeEnv = (node: MemberExpression, scope: Scope): boolean =>
     isIdentifier(node.property, nodeEnv) &&
@@ -138,7 +162,7 @@ export default function inlinePlugin(
         const scope = path.scope;
         const opts = state.opts;
 
-        if (!isLeftHandSideOfAssignmentExpression(node, path.parent)) {
+        if (!isWriteTarget(path)) {
           if (
             opts.inlinePlatform &&
             isPlatformNode(node, scope, !!opts.isWrapped)

From 01ffb6fd716446ea9a9fe7896bf1a141e5751fe1 Mon Sep 17 00:00:00 2001
From: Oskar Eichler <oskar@songstats.com>
Date: Mon, 31 Aug 2026 16:57:37 +0700
Subject: [PATCH 2/2] Keep reads inside write targets inlineable

---
 .../src/__tests__/inline-plugin-test.js             | 13 +++++++++++++
 .../metro-transform-plugins/src/inline-plugin.js    | 11 +++++++++++
 2 files changed, 24 insertions(+)

diff --git a/packages/metro-transform-plugins/src/__tests__/inline-plugin-test.js b/packages/metro-transform-plugins/src/__tests__/inline-plugin-test.js
index e9e1d39267..711781d543 100644
--- a/packages/metro-transform-plugins/src/__tests__/inline-plugin-test.js
+++ b/packages/metro-transform-plugins/src/__tests__/inline-plugin-test.js
@@ -727,6 +727,19 @@ describe('inline constants', () => {
     });
   });
 
+  test('replaces Platform.OS when it is read inside a write target', () => {
+    const code = `
+      target[Platform.OS] = value;
+      [target[Platform.OS]] = values;
+      ({[Platform.OS]: target} = value);
+    `;
+
+    compare([inlinePlugin], code, code.replaceAll('Platform.OS', '"ios"'), {
+      inlinePlatform: true,
+      platform: 'ios',
+    });
+  });
+
   test('replaces Platform.OS in the code if Platform is the right hand side of an assignment expression', () => {
     const code = `
       function a() {
diff --git a/packages/metro-transform-plugins/src/inline-plugin.js b/packages/metro-transform-plugins/src/inline-plugin.js
index 8a21273330..d548fcb1f5 100644
--- a/packages/metro-transform-plugins/src/inline-plugin.js
+++ b/packages/metro-transform-plugins/src/inline-plugin.js
@@ -92,6 +92,17 @@ export default function inlinePlugin(
       ) {
         return true;
       }
+
+      const nestedWriteTarget =
+        parent.type === 'ArrayPattern' ||
+        parent.type === 'ObjectPattern' ||
+        (parent.type === 'ObjectProperty' && parent.value === child) ||
+        (parent.type === 'RestElement' && parent.argument === child) ||
+        (parent.type === 'AssignmentPattern' && parent.left === child);
+      if (!nestedWriteTarget) {
+        return false;
+      }
+
       child = parent;
       parentPath = parentPath.parentPath;
     }