fix: better determinate template in to option

src/preProcessPattern.js

@@ -4,12 +4,10 @@ import isGlob from 'is-glob';
 import globParent from 'glob-parent';
 
 import normalize from './utils/normalize';
+import isTemplateLike from './utils/isTemplateLike';
 import isObject from './utils/isObject';
 import { stat } from './utils/promisify';
 
-// https://www.debuggex.com/r/VH2yS2mvJOitiyr3
-const isTemplateLike = /(\[ext\])|(\[name\])|(\[path\])|(\[folder\])|(\[emoji(:\d+)?\])|(\[(\w+:)?(hash|contenthash)(:\w+)?(:\d+)?\])|(\[\d+\])/;
-
 /* eslint-disable no-param-reassign */
 
 export default function preProcessPattern(globalRef, pattern) {
@@ -62,7 +60,7 @@ export default function preProcessPattern(globalRef, pattern) {
     // if toType already exists
     case !!pattern.toType:
       break;
-    case isTemplateLike.test(pattern.to):
+    case isTemplateLike(pattern.to):
       pattern.toType = 'template';
       break;
     case isToDirectory:

src/utils/isTemplateLike.js

@@ -0,0 +1,4 @@
+export default (pattern) =>
+  /(\[ext\])|(\[name\])|(\[path\])|(\[folder\])|(\[emoji(?::(\d+))?\])|(\[(?:([^:\]]+):)?(?:hash|contenthash)(?::([a-z]+\d*))?(?::(\d+))?\])/.test(
+    pattern
+  );

test/CopyPlugin.test.js

@@ -1350,6 +1350,34 @@ describe('apply function', () => {
         .catch(done);
     });
 
+    it('allows pattern to contain custoh `contenthash` digest', (done) => {
+      runEmit({
+        expectedAssetKeys: ['directory/c2a6.txt'],
+        patterns: [
+          {
+            from: 'directory/directoryfile.txt',
+            to: 'directory/[sha1:contenthash:hex:4].txt',
+          },
+        ],
+      })
+        .then(done)
+        .catch(done);
+    });
+
+    it('allows pattern to contain `hashType` without `hash` or `contenthash`', (done) => {
+      runEmit({
+        expectedAssetKeys: ['directory/[md5::base64:20].txt'],
+        patterns: [
+          {
+            from: 'directory/directoryfile.txt',
+            to: 'directory/[md5::base64:20].txt',
+          },
+        ],
+      })
+        .then(done)
+        .catch(done);
+    });
+
     it('transform with promise', (done) => {
       runEmit({
         expectedAssetKeys: ['file.txt'],