fix unsafe evaluate of AST_Function (#2920)

fixes #2919

lib/compress.js

@@ -2313,7 +2313,9 @@ merge(Compressor.prototype, {
         AST_Node.DEFMETHOD("evaluate", function(compressor){
             if (!compressor.option("evaluate")) return this;
             var val = this._eval(compressor, 1);
-            return !val || val instanceof RegExp || typeof val != "object" ? val : this;
+            if (!val || val instanceof RegExp) return val;
+            if (typeof val == "function" || typeof val == "object") return this;
+            return val;
         });
         var unaryPrefix = makePredicate("! ~ - + void");
         AST_Node.DEFMETHOD("is_constant", function(){
@@ -2335,15 +2337,22 @@ merge(Compressor.prototype, {
         def(AST_Constant, function(){
             return this.getValue();
         });
+        def(AST_Function, function(compressor) {
+            if (compressor.option("unsafe")) {
+                var node = this;
+                var fn = function() {};
+                fn.toString = function() {
+                    return node.print_to_string();
+                };
+                return fn;
+            }
+            return this;
+        });
         def(AST_Array, function(compressor, depth) {
             if (compressor.option("unsafe")) {
                 var elements = [];
                 for (var i = 0, len = this.elements.length; i < len; i++) {
                     var element = this.elements[i];
-                    if (element instanceof AST_Function) {
-                        elements.push(element);
-                        continue;
-                    }
                     var value = element._eval(compressor, depth);
                     if (element === value) return this;
                     elements.push(value);

test/compress/evaluate.js

@@ -1489,3 +1489,16 @@ issue_2916_2: {
     }
     expect_stdout: "PASS"
 }
+
+issue_2919: {
+    options = {
+        evaluate: true,
+        unsafe: true,
+    }
+    input: {
+        console.log([ function() {} ].toString());
+    }
+    expect: {
+        console.log("function(){}");
+    }
+}

test/compress/reduce_vars.js

@@ -5527,3 +5527,21 @@ issue_2869: {
     }
     expect_stdout: "PASS"
 }
+
+issue_2919: {
+    options = {
+        evaluate: true,
+        reduce_vars: true,
+        toplevel: true,
+        unsafe: true,
+        unused: true,
+    }
+    input: {
+        var arr = [ function() {} ];
+        console.log(typeof arr[0]);
+    }
+    expect: {
+        console.log("function");
+    }
+    expect_stdout: "function"
+}