Fix #lastIndex in IE8 and move NPCG check from #split to #exec

IE8 is not fully fixed yet

packages/core-js-builder/config.js

@@ -95,6 +95,7 @@ module.exports = {
     'es.string.sub',
     'es.string.sup',
     'es.regexp.constructor',
+    'es.regexp.exec',
     'es.regexp.flags',
     'es.regexp.to-string',
     'es.parse-int',

packages/core-js/es/index.js

@@ -80,6 +80,7 @@ require('../modules/es.string.strike');
 require('../modules/es.string.sub');
 require('../modules/es.string.sup');
 require('../modules/es.regexp.constructor');
+require('../modules/es.regexp.exec');
 require('../modules/es.regexp.flags');
 require('../modules/es.regexp.to-string');
 require('../modules/es.parse-int');

packages/core-js/es/regexp/index.js

@@ -1,5 +1,6 @@
 require('../../modules/es.regexp.constructor');
 require('../../modules/es.regexp.to-string');
+require('../../modules/es.regexp.exec');
 require('../../modules/es.regexp.flags');
 require('../../modules/es.string.match');
 require('../../modules/es.string.replace');

packages/core-js/index.js

@@ -92,6 +92,7 @@ require('./modules/es.string.strike');
 require('./modules/es.string.sub');
 require('./modules/es.string.sup');
 require('./modules/es.regexp.constructor');
+require('./modules/es.regexp.exec');
 require('./modules/es.regexp.flags');
 require('./modules/es.regexp.to-string');
 require('./modules/es.parse-int');

packages/core-js/internals/fix-regexp-well-known-symbol-logic.js

@@ -4,8 +4,8 @@ var redefine = require('../internals/redefine');
 var fails = require('../internals/fails');
 var requireObjectCoercible = require('../internals/require-object-coercible');
 var wellKnownSymbol = require('../internals/well-known-symbol');
+var regexpExec = require('../internals/regexp-exec');
 
-var nativeExec = RegExp.prototype.exec;
 var SPECIES = wellKnownSymbol('species');
 
 module.exports = function (KEY, length, exec, sham) {
@@ -69,7 +69,7 @@ module.exports = function (KEY, length, exec, sham) {
       SYMBOL,
       ''[KEY],
       function maybeCallNative(nativeMethod, regexp, str, arg2, forceStringMethod) {
-        if (regexp.exec === nativeExec) {
+        if (regexp.exec === regexpExec.impl) {
           if (delegatesToSymbol && !forceStringMethod) {
             // The native String method already delegates to @@method (this
             // polyfilled function), leasing to infinite recursion.

packages/core-js/internals/regexp-exec-abstract.js

@@ -1,5 +1,5 @@
 var classof = require('./classof-raw');
-var builtinExec = RegExp.prototype.exec;
+var regexpExec = require('./regexp-exec');
 
 // `RegExpExec` abstract operation
 // https://tc39.github.io/ecma262/#sec-regexpexec
@@ -17,6 +17,6 @@ module.exports = function (R, S) {
     throw new TypeError('RegExp#exec called on incompatible receiver');
   }
 
-  return builtinExec.call(R, S);
+  return regexpExec.impl.call(R, S);
 };
 

packages/core-js/internals/regexp-exec.js

@@ -0,0 +1,58 @@
+'use strict';
+
+var regexpFlags = require('./regexp-flags');
+
+var nativeExec = RegExp.prototype.exec;
+// This always refers to the native implementation, because the
+// String#replace polyfill uses ./fix-regexp-well-known-symbol-logic.js,
+// which loads this file before patching the method.
+var nativeReplace = String.prototype.replace;
+
+var patchedExec = nativeExec;
+
+var LAST_INDEX = 'lastIndex';
+
+var UPDATES_LAST_INDEX_NON_GLOBAL = (function () {
+  var re = /a/;
+  nativeExec.call(re, 'a');
+  return re[LAST_INDEX] !== 0;
+})();
+
+// nonparticipating capturing group, copied from es5-shim's String#split patch.
+var NPCG_INCLUDED = /()??/.exec('')[1] !== undefined;
+
+var patch = UPDATES_LAST_INDEX_NON_GLOBAL || NPCG_INCLUDED;
+
+if (patch) {
+  patchedExec = function exec(str) {
+    var re = this;
+    var lastIndex, reCopy, match, i;
+
+    if (NPCG_INCLUDED) {
+      reCopy = new RegExp('^' + re.source + '$(?!\\s)', regexpFlags.call(re));
+    }
+    if (UPDATES_LAST_INDEX_NON_GLOBAL) lastIndex = this[LAST_INDEX];
+
+    match = nativeExec.call(this, str);
+
+    if (UPDATES_LAST_INDEX_NON_GLOBAL && !this.global) this[LAST_INDEX] = lastIndex;
+    if (NPCG_INCLUDED && match && match.length > 1) {
+      // Fix browsers whose `exec` methods don't consistently return `undefined`
+      // for NPCG, like IE8. NOTE: This doesn' work for /(.?)?/
+      // eslint-disable-next-line no-loop-func
+      nativeReplace.call(match[0], reCopy, function () {
+        for (i = 1; i < arguments.length - 2; i++) {
+          if (arguments[i] === undefined) match[i] = undefined;
+        }
+      });
+    }
+
+    return match;
+  };
+}
+
+module.exports = {
+  orig: nativeExec,
+  impl: patchedExec,
+  patched: patch
+};

packages/core-js/modules/es.regexp.exec.js

@@ -0,0 +1,11 @@
+'use strict';
+
+var regexpExec = require('../internals/regexp-exec');
+
+require('../internals/export')({
+  target: 'RegExp',
+  proto: true,
+  forced: regexpExec.patched
+}, {
+  exec: regexpExec.impl
+});

packages/core-js/modules/es.string.split.js

@@ -5,7 +5,8 @@ var anObject = require('../internals/an-object');
 var speciesConstructor = require('../internals/species-constructor');
 var advanceStringIndex = require('../internals/advance-string-index');
 var toLength = require('../internals/to-length');
-var regExpExec = require('../internals/regexp-exec-abstract');
+var callRegExpExec = require('../internals/regexp-exec-abstract');
+var regexpExec = require('../internals/regexp-exec');
 var arrayPush = [].push;
 var min = Math.min;
 var LENGTH = 'length';
@@ -27,7 +28,6 @@ require('../internals/fix-regexp-well-known-symbol-logic')(
       '.'.split(/()()/)[LENGTH] > 1 ||
       ''.split(/.?/)[LENGTH]
     ) {
-      var NPCG = /()??/.exec('')[1] === undefined; // nonparticipating capturing group
       // based on es5-shim implementation, need to rework it
       internalSplit = function (separator, limit) {
         var string = String(this);
@@ -45,19 +45,12 @@ require('../internals/fix-regexp-well-known-symbol-logic')(
         var splitLimit = limit === undefined ? 4294967295 : limit >>> 0;
         // Make `global` and avoid `lastIndex` issues by working with a copy
         var separatorCopy = new RegExp(separator.source, flags + 'g');
-        var separator2, match, lastIndex, lastLength, i;
-        // Doesn't need flags gy, but they don't hurt
-        if (!NPCG) separator2 = new RegExp('^' + separatorCopy.source + '$(?!\\s)', flags);
-        while (match = separatorCopy.exec(string)) {
+        var match, lastIndex, lastLength;
+        while (match = regexpExec.impl.call(separatorCopy, string)) {
           // `separatorCopy.lastIndex` is not reliable cross-browser
           lastIndex = match.index + match[0][LENGTH];
           if (lastIndex > lastLastIndex) {
             output.push(string.slice(lastLastIndex, match.index));
-            // Fix browsers whose `exec` methods don't consistently return `undefined` for NPCG
-            // eslint-disable-next-line no-loop-func
-            if (!NPCG && match[LENGTH] > 1) match[0].replace(separator2, function () {
-              for (i = 1; i < arguments[LENGTH] - 2; i++) if (arguments[i] === undefined) match[i] = undefined;
-            });
             if (match[LENGTH] > 1 && match.index < string[LENGTH]) arrayPush.apply(output, match.slice(1));
             lastLength = match[0][LENGTH];
             lastLastIndex = lastIndex;
@@ -111,13 +104,13 @@ require('../internals/fix-regexp-well-known-symbol-logic')(
         var splitter = new C(SUPPORTS_Y ? rx : '^(?:' + rx.source + ')', flags);
         var lim = limit === undefined ? 0xffffffff : limit >>> 0;
         if (lim === 0) return [];
-        if (S.length === 0) return regExpExec(splitter, S) === null ? [S] : [];
+        if (S.length === 0) return callRegExpExec(splitter, S) === null ? [S] : [];
         var p = 0;
         var q = 0;
         var A = [];
         while (q < S.length) {
           splitter.lastIndex = SUPPORTS_Y ? q : 0;
-          var z = regExpExec(splitter, SUPPORTS_Y ? S : S.slice(q));
+          var z = callRegExpExec(splitter, SUPPORTS_Y ? S : S.slice(q));
           var e;
           if (
             z === null ||