[[FIX]] singleGroups: Allow grouping for integers

The grouping operator is necessary when accessing properties of number
literals when the literal describes an integer (the period character
would otherwise be interpreted as a decimal point). Update the
`singleGroups` enforcement logic to allow for this usage.

src/jshint.js

@@ -2523,7 +2523,11 @@ var JSHINT = (function() {
           // operator.
           (isFunctor(ret) && !isEndOfExpr()) ||
           // Used as the return value of a single-statement arrow function
-          (ret.id === "{" && preceeding.id === "=>");
+          (ret.id === "{" && preceeding.id === "=>") ||
+          // Used to delineate an integer number literal from a dereferencing
+          // punctuator (otherwise interpreted as a decimal point)
+          (ret.type === "(number)" &&
+            checkPunctuator(pn, ".") && /^\d+$/.test(ret.value));
       }
     }
 

tests/unit/options.js

@@ -2681,6 +2681,39 @@ singleGroups.unary = function (test) {
   test.done();
 };
 
+singleGroups.numberLiterals = function (test) {
+  var code = [
+    "(3).toString();",
+    "(3.1).toString();",
+    "(.3).toString();",
+    "(3.).toString();",
+    "(1e3).toString();",
+    "(1e-3).toString();",
+    "(1.1e3).toString();",
+    "(1.1e-3).toString();",
+    "(3)[methodName]();",
+    "var x = (3) + 3;",
+    "('3').toString();"
+  ];
+
+  TestRun(test)
+    .addError(2, "Unnecessary grouping operator.")
+    .addError(3, "Unnecessary grouping operator.")
+    .addError(3, "A leading decimal point can be confused with a dot: '.3'.")
+    .addError(4, "Unnecessary grouping operator.")
+    .addError(4, "A trailing decimal point can be confused with a dot: '3.'.")
+    .addError(5, "Unnecessary grouping operator.")
+    .addError(6, "Unnecessary grouping operator.")
+    .addError(7, "Unnecessary grouping operator.")
+    .addError(8, "Unnecessary grouping operator.")
+    .addError(9, "Unnecessary grouping operator.")
+    .addError(10, "Unnecessary grouping operator.")
+    .addError(11, "Unnecessary grouping operator.")
+    .test(code, { singleGroups: true });
+
+  test.done();
+};
+
 exports.elision = function (test) {
   var code = [
     "var a = [1,,2];",