fix: only handle merge ssr.noExternal (#8003)

Author: bluwy

packages/vite/src/node/__tests__/config.spec.ts

@@ -157,6 +157,30 @@ describe('mergeConfig', () => {
 
     expect(mergeConfig(baseConfig, newConfig)).toEqual(mergedConfig)
   })
+
+  test('handles ssr.noExternal', () => {
+    const baseConfig = {
+      ssr: {
+        noExternal: true
+      }
+    }
+
+    const newConfig = {
+      ssr: {
+        noExternal: ['foo']
+      }
+    }
+
+    const mergedConfig = {
+      ssr: {
+        noExternal: true
+      }
+    }
+
+    // merging either ways, `ssr.noExternal: true` should take highest priority
+    expect(mergeConfig(baseConfig, newConfig)).toEqual(mergedConfig)
+    expect(mergeConfig(newConfig, baseConfig)).toEqual(mergedConfig)
+  })
 })
 
 describe('resolveConfig', () => {

packages/vite/src/node/config.ts

@@ -745,7 +745,11 @@ function mergeConfigRecursively(
     } else if (key === 'assetsInclude' && rootPath === '') {
       merged[key] = [].concat(existing, value)
       continue
-    } else if (key === 'noExternal' && (existing === true || value === true)) {
+    } else if (
+      key === 'noExternal' &&
+      rootPath === 'ssr' &&
+      (existing === true || value === true)
+    ) {
       merged[key] = true
       continue
     }