From 7d25bc113655efeef573c0ad6174b63b2257dda6 Mon Sep 17 00:00:00 2001
From: Zoltan Kochan <z@kochan.io>
Date: Mon, 20 Apr 2026 01:08:15 +0200
Subject: [PATCH] fix: suppress packageManager/devEngines.packageManager
 conflict warning when values match exactly (#11307)
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- Suppress the `Cannot use both "packageManager" and "devEngines.packageManager" in package.json. "packageManager" will be ignored` warning only when both fields specify the exact same package manager name and the exact same version string. Any other divergence (different name, range vs. exact version, prefixed versions like `v1.2.3`, etc.) still warns.
- Lets projects keep both fields during migration (e.g. so v10 installs still auto-switch via `packageManager`, while v11 uses `devEngines.packageManager` and `npm install` still errors) without a noisy warning — as long as the two values are kept in sync.

Closes #11301
---
 .../dev-engines-package-manager-compatible.md |  6 +++
 config/reader/src/index.ts                    |  5 +-
 pnpm/test/packageManagerCheck.test.ts         | 51 +++++++++++++++++++
 3 files changed, 61 insertions(+), 1 deletion(-)
 create mode 100644 .changeset/dev-engines-package-manager-compatible.md

diff --git a/.changeset/dev-engines-package-manager-compatible.md b/.changeset/dev-engines-package-manager-compatible.md
new file mode 100644
index 0000000000..a1f217a5fe
--- /dev/null
+++ b/.changeset/dev-engines-package-manager-compatible.md
@@ -0,0 +1,6 @@
+---
+"@pnpm/config.reader": patch
+"pnpm": patch
+---
+
+Do not print the `Cannot use both "packageManager" and "devEngines.packageManager" in package.json. "packageManager" will be ignored` warning when the two fields specify the exact same package manager name and version string. This lets projects keep both fields during the migration from `packageManager` to `devEngines.packageManager` without a noisy warning [#11301](https://github.com/pnpm/pnpm/issues/11301).
diff --git a/config/reader/src/index.ts b/config/reader/src/index.ts
index 2800876c3d..b30e6bfbc9 100644
--- a/config/reader/src/index.ts
+++ b/config/reader/src/index.ts
@@ -669,7 +669,10 @@ function getWantedPackageManager (manifest: ProjectManifest): { pm?: WantedPacka
       pmFromDevEngines.version = undefined
     }
     if (manifest.packageManager) {
-      warnings.push('Cannot use both "packageManager" and "devEngines.packageManager" in package.json. "packageManager" will be ignored')
+      const legacyPm = parsePackageManager(manifest.packageManager)
+      if (legacyPm.name !== pmFromDevEngines.name || legacyPm.version !== pmFromDevEngines.version) {
+        warnings.push('Cannot use both "packageManager" and "devEngines.packageManager" in package.json. "packageManager" will be ignored')
+      }
     }
     return { pm: { ...pmFromDevEngines, fromDevEngines: true }, warnings }
   }
diff --git a/pnpm/test/packageManagerCheck.test.ts b/pnpm/test/packageManagerCheck.test.ts
index 126b9dd98d..a4a1648a0c 100644
--- a/pnpm/test/packageManagerCheck.test.ts
+++ b/pnpm/test/packageManagerCheck.test.ts
@@ -247,6 +247,57 @@ test('devEngines.packageManager takes precedence over packageManager field', asy
   expect(stderr.toString()).toContain('"packageManager" will be ignored')
 })
 
+test('no warning when packageManager and devEngines.packageManager specify the same exact version', async () => {
+  prepare({
+    packageManager: 'pnpm@1.2.3',
+    devEngines: {
+      packageManager: {
+        name: 'pnpm',
+        version: '1.2.3',
+        onFail: 'ignore',
+      },
+    },
+  })
+
+  const { stderr } = execPnpmSync(['install'])
+
+  expect(stderr.toString()).not.toContain('Cannot use both')
+})
+
+test('warns when packageManager specifies a different package manager from devEngines.packageManager', async () => {
+  prepare({
+    packageManager: 'yarn@1.2.3',
+    devEngines: {
+      packageManager: {
+        name: 'pnpm',
+        version: '1.2.3',
+        onFail: 'ignore',
+      },
+    },
+  })
+
+  const { stderr } = execPnpmSync(['install'])
+
+  expect(stderr.toString()).toContain('Cannot use both "packageManager" and "devEngines.packageManager"')
+})
+
+test('warns when packageManager version does not match the devEngines.packageManager version string exactly', async () => {
+  prepare({
+    packageManager: 'pnpm@1.2.3',
+    devEngines: {
+      packageManager: {
+        name: 'pnpm',
+        version: '>=1.0.0',
+        onFail: 'ignore',
+      },
+    },
+  })
+
+  const { stderr } = execPnpmSync(['install'])
+
+  expect(stderr.toString()).toContain('Cannot use both "packageManager" and "devEngines.packageManager"')
+})
+
 test('pmOnFail=ignore via env var bypasses the devEngines.packageManager check', async () => {
   prepare({
     devEngines: {