fix: merge environments.ssr.resolve with root ssr config (#18857)

Author: hi-ogawa

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

@@ -359,3 +359,125 @@ describe('resolveConfig', () => {
     await resolveConfig({ root: './inc?ud#s', customLogger: logger }, 'build')
   })
 })
+
+test('config compat 1', async () => {
+  const config = await resolveConfig(
+    {
+      resolve: {
+        conditions: ['client1'],
+      },
+      ssr: {
+        resolve: {
+          conditions: ['ssr1'],
+        },
+      },
+      plugins: [
+        {
+          name: 'test',
+          config() {
+            return {
+              environments: {
+                client: {
+                  resolve: {
+                    conditions: ['client2'],
+                  },
+                },
+                ssr: {
+                  resolve: {
+                    conditions: ['ssr2'],
+                  },
+                },
+              },
+            }
+          },
+        },
+      ],
+    },
+    'serve',
+  )
+  expect(config.resolve.conditions).toMatchInlineSnapshot(`
+    [
+      "client1",
+      "client2",
+    ]
+  `)
+  expect(config.environments.client.resolve.conditions).toMatchInlineSnapshot(`
+    [
+      "client1",
+      "client2",
+    ]
+  `)
+  expect(config.ssr.resolve?.conditions).toMatchInlineSnapshot(`
+    [
+      "ssr1",
+      "ssr2",
+    ]
+  `)
+  expect(config.environments.ssr.resolve?.conditions).toMatchInlineSnapshot(`
+    [
+      "ssr1",
+      "ssr2",
+    ]
+  `)
+})
+
+test('config compat 2', async () => {
+  const config = await resolveConfig(
+    {
+      environments: {
+        client: {
+          resolve: {
+            conditions: ['client1'],
+          },
+        },
+        ssr: {
+          resolve: {
+            conditions: ['ssr1'],
+          },
+        },
+      },
+      plugins: [
+        {
+          name: 'test',
+          config() {
+            return {
+              resolve: {
+                conditions: ['client2'],
+              },
+              ssr: {
+                resolve: {
+                  conditions: ['ssr2'],
+                },
+              },
+            }
+          },
+        },
+      ],
+    },
+    'serve',
+  )
+  expect(config.resolve.conditions).toMatchInlineSnapshot(`
+    [
+      "client2",
+      "client1",
+    ]
+  `)
+  expect(config.environments.client.resolve.conditions).toMatchInlineSnapshot(`
+    [
+      "client2",
+      "client1",
+    ]
+  `)
+  expect(config.ssr.resolve?.conditions).toMatchInlineSnapshot(`
+    [
+      "ssr2",
+      "ssr1",
+    ]
+  `)
+  expect(config.environments.ssr.resolve?.conditions).toMatchInlineSnapshot(`
+    [
+      "ssr2",
+      "ssr1",
+    ]
+  `)
+})

packages/vite/src/node/config.ts

@@ -1083,13 +1083,16 @@ export async function resolveConfig(
       configEnvironmentsSsr.optimizeDeps ?? {},
     )
 
-    configEnvironmentsSsr.resolve ??= {}
-    configEnvironmentsSsr.resolve.conditions ??= config.ssr?.resolve?.conditions
-    configEnvironmentsSsr.resolve.externalConditions ??=
-      config.ssr?.resolve?.externalConditions
-    configEnvironmentsSsr.resolve.mainFields ??= config.ssr?.resolve?.mainFields
-    configEnvironmentsSsr.resolve.external ??= config.ssr?.external
-    configEnvironmentsSsr.resolve.noExternal ??= config.ssr?.noExternal
+    configEnvironmentsSsr.resolve = mergeConfig(
+      {
+        conditions: config.ssr?.resolve?.conditions,
+        externalConditions: config.ssr?.resolve?.externalConditions,
+        mainFields: config.ssr?.resolve?.mainFields,
+        external: config.ssr?.external,
+        noExternal: config.ssr?.noExternal,
+      } satisfies EnvironmentResolveOptions,
+      configEnvironmentsSsr.resolve ?? {},
+    )
   }
 
   if (config.build?.ssrEmitAssets !== undefined) {
@@ -1146,6 +1149,11 @@ export async function resolveConfig(
     config.ssr?.target === 'webworker',
   )
 
+  // Backward compatibility: merge config.environments.client.resolve back into config.resolve
+  config.resolve ??= {}
+  config.resolve.conditions = config.environments.client.resolve?.conditions
+  config.resolve.mainFields = config.environments.client.resolve?.mainFields
+
   const resolvedDefaultResolve = resolveResolveOptions(config.resolve, logger)
 
   const resolvedEnvironments: Record<string, ResolvedEnvironmentOptions> = {}