From dbf19076f328d4b0ddec609b058b22665eeeae1f Mon Sep 17 00:00:00 2001
From: Armaan Aggarwal <49625265+Armster15@users.noreply.github.com>
Date: Thu, 30 Apr 2026 08:04:53 -0700
Subject: [PATCH] fix: negated `os` / `cpu` skipped under multi-platform
 `supportedArchitectures` (#11375)

* fix: bug with checkList fn

* refactor: simplify checkList, add changeset

---------

Co-authored-by: Zoltan Kochan <z@kochan.io>
---
 .changeset/check-platform-multi-negation.md   |  6 +++++
 .../src/checkPlatform.ts                      |  6 ++---
 .../test/checkPlatform.ts                     | 26 +++++++++++++++++++
 3 files changed, 35 insertions(+), 3 deletions(-)
 create mode 100644 .changeset/check-platform-multi-negation.md

diff --git a/.changeset/check-platform-multi-negation.md b/.changeset/check-platform-multi-negation.md
new file mode 100644
index 0000000000..83691c1815
--- /dev/null
+++ b/.changeset/check-platform-multi-negation.md
@@ -0,0 +1,6 @@
+---
+"@pnpm/config.package-is-installable": patch
+"pnpm": patch
+---
+
+Fix negated `os` / `cpu` entries (e.g. `["!win32"]`) being incorrectly rejected when `supportedArchitectures` expands to multiple platforms [#11375](https://github.com/pnpm/pnpm/pull/11375).
\ No newline at end of file
diff --git a/config/package-is-installable/src/checkPlatform.ts b/config/package-is-installable/src/checkPlatform.ts
index 7e3420a41f..ae66c2a649 100644
--- a/config/package-is-installable/src/checkPlatform.ts
+++ b/config/package-is-installable/src/checkPlatform.ts
@@ -56,7 +56,6 @@ export type WantedPlatform = Partial<Platform>
 function checkList (value: string | string[], list: string | string[]): boolean {
   let tmp
   let match = false
-  let blc = 0
 
   if (typeof list === 'string') {
     list = [list]
@@ -76,13 +75,14 @@ function checkList (value: string | string[], list: string | string[]): boolean
         if (tmp === value) {
           return false
         }
-        ++blc
       } else {
         match = match || tmp === value
       }
     }
   }
-  return match || blc === list.length
+  // No negation rejected any value. Accept if a positive entry matched, or if the list
+  // contains only negations (no positive constraints to satisfy).
+  return match || list.every(entry => entry[0] === '!')
 }
 
 function dedupeCurrent (current: string, supported: string[]): string[] {
diff --git a/config/package-is-installable/test/checkPlatform.ts b/config/package-is-installable/test/checkPlatform.ts
index ea6e91bdfe..242b04a49e 100644
--- a/config/package-is-installable/test/checkPlatform.ts
+++ b/config/package-is-installable/test/checkPlatform.ts
@@ -151,3 +151,29 @@ test('accept another libc', () => {
     libc: ['current', 'glibc'],
   })).toBeNull()
 })
+
+test('accept negated os with multi-valued supportedArchitectures', () => {
+  expect(checkPlatform(packageId, { cpu: 'any', os: ['!win32'], libc: 'any' }, {
+    os: ['linux', 'current'],
+    cpu: ['current'],
+    libc: ['current'],
+  })).toBeNull()
+})
+
+test('accept negated cpu with multi-valued supportedArchitectures', () => {
+  expect(checkPlatform(packageId, { cpu: ['!ia32'], os: 'any', libc: 'any' }, {
+    os: ['current'],
+    cpu: ['x64', 'current'],
+    libc: ['current'],
+  })).toBeNull()
+})
+
+test('reject negated os when any supported value matches the negation', () => {
+  const err = checkPlatform(packageId, { cpu: 'any', os: ['!win32'], libc: 'any' }, {
+    os: ['win32', 'current'],
+    cpu: ['current'],
+    libc: ['current'],
+  })
+  expect(err).toBeTruthy()
+  expect(err?.code).toBe('ERR_PNPM_UNSUPPORTED_PLATFORM')
+})