fix: improve alias merging (vitejs#6497)

bbbboom · Jan 13, 2022 · e57d8c6 · e57d8c6
1 parent 6ecf9b0
commit e57d8c6
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Showing 2 changed files with 56 additions and 12 deletions.
diff --git a/packages/vite/src/node/__tests__/config.spec.ts b/packages/vite/src/node/__tests__/config.spec.ts
@@ -27,17 +27,17 @@ describe('mergeConfig', () => {
     const mergedConfig: UserConfigExport = {
       resolve: {
         alias: [
-          {
-            find: 'foo',
-            replacement: 'foo-value'
-          },
           {
             find: 'bar',
             replacement: 'bar-value'
           },
           {
             find: 'baz',
             replacement: 'baz-value'
+          },
+          {
+            find: 'foo',
+            replacement: 'foo-value'
           }
         ]
       }
@@ -46,6 +46,38 @@ describe('mergeConfig', () => {
     expect(mergeConfig(baseConfig, newConfig)).toEqual(mergedConfig)
   })
 
+  test('keep object alias schema', () => {
+    const baseConfig = {
+      resolve: {
+        alias: {
+          bar: 'bar-value',
+          baz: 'baz-value'
+        }
+      }
+    }
+
+    const newConfig = {
+      resolve: {
+        alias: {
+          bar: 'bar-value-2',
+          foo: 'foo-value'
+        }
+      }
+    }
+
+    const mergedConfig = {
+      resolve: {
+        alias: {
+          bar: 'bar-value-2',
+          baz: 'baz-value',
+          foo: 'foo-value'
+        }
+      }
+    }
+
+    expect(mergeConfig(baseConfig, newConfig)).toEqual(mergedConfig)
+  })
+
   test('handles arrays', () => {
     const baseConfig: UserConfigExport = {
       envPrefix: 'string1'

diff --git a/packages/vite/src/node/config.ts b/packages/vite/src/node/config.ts
@@ -362,11 +362,13 @@ export async function resolveConfig(
   ]
 
   // resolve alias with internal client alias
-  const resolvedAlias = mergeAlias(
-    // @ts-ignore because @rollup/plugin-alias' type doesn't allow function
-    // replacement, but its implementation does work with function values.
-    clientAlias,
-    config.resolve?.alias || config.alias || []
+  const resolvedAlias = normalizeAlias(
+    mergeAlias(
+      // @ts-ignore because @rollup/plugin-alias' type doesn't allow function
+      // replacement, but its implementation does work with function values.
+      clientAlias,
+      config.resolve?.alias || config.alias || []
+    )
   )
 
   const resolveOptions: ResolvedConfig['resolve'] = {
@@ -768,11 +770,21 @@ export function mergeConfig(
   return mergeConfigRecursively(defaults, overrides, isRoot ? '' : '.')
 }
 
-function mergeAlias(a: AliasOptions = [], b: AliasOptions = []): Alias[] {
-  return [...normalizeAlias(a), ...normalizeAlias(b)]
+function mergeAlias(
+  a?: AliasOptions,
+  b?: AliasOptions
+): AliasOptions | undefined {
+  if (!a) return b
+  if (!b) return a
+  if (isObject(a) && isObject(b)) {
+    return { ...a, ...b }
+  }
+  // the order is flipped because the alias is resolved from top-down,
+  // where the later should have higher priority
+  return [...normalizeAlias(b), ...normalizeAlias(a)]
 }
 
-function normalizeAlias(o: AliasOptions): Alias[] {
+function normalizeAlias(o: AliasOptions = []): Alias[] {
   return Array.isArray(o)
     ? o.map(normalizeSingleAlias)
     : Object.keys(o).map((find) =>