fix export name mapping syntax

lib/output.js

@@ -1297,16 +1297,25 @@ function OutputStream(options) {
     });
 
     DEFPRINT(AST_NameMapping, function(self, output) {
+        var is_import = output.parent() instanceof AST_Import;
         var definition = self.name.definition();
         var names_are_different =
             (definition && definition.mangled_name || self.name.name) !==
             self.foreign_name.name;
         if (names_are_different) {
+            if (is_import) {
                 output.print(self.foreign_name.name);
+            } else {
+                self.name.print(output);
+            }
             output.space();
             output.print("as");
             output.space();
+            if (is_import) {
                 self.name.print(output);
+            } else {
+                output.print(self.foreign_name.name);
+            }
         } else {
             self.name.print(output);
         }

lib/parse.js

@@ -2333,18 +2333,22 @@ function parse($TEXT, options) {
         var foreign_name;
         var name;
 
-        if (peek().value === "as" && peek().type === "name") {
+        if (is_import) {
             foreign_name = as_symbol(foreign_type);
-            next();  // The "as" word
-        }
+        } else {
             name = as_symbol(type);
-
-        if (foreign_name === undefined) {
-            foreign_name = new foreign_type({
-                name: name.name,
-                start: name.start,
-                end: name.end,
-            });
+        }
+        if (is("name", "as")) {
+            next();  // The "as" word
+            if (is_import) {
+                name = as_symbol(type);
+            } else {
+                foreign_name = as_symbol(foreign_type);
+            }
+        } else if (is_import) {
+            name = new type(foreign_name);
+        } else {
+            foreign_name = new foreign_type(name);
         }
 
         return new AST_NameMapping({

test/compress/export.js

@@ -36,7 +36,7 @@ issue_2038_2: {
         let a = 1;
         const c = 2;
         var n = 3;
-        export { LET as a, CONST as c, VAR as n };
+        export { a as LET, c as CONST, n as VAR };
     }
 }
 
@@ -67,3 +67,21 @@ issue_2124: {
         }
     }
 }
+
+issue_2126: {
+    mangle = {
+        toplevel: true,
+    }
+    input: {
+        import { foo as bar, cat as dog } from "stuff";
+        console.log(bar, dog);
+        export { bar as qux };
+        export { dog };
+    }
+    expect: {
+        import { foo as o, cat as f } from "stuff";
+        console.log(o, f);
+        export { o as qux };
+        export { f as dog };
+    }
+}

test/mocha/export.js

@@ -3,7 +3,6 @@ var uglify = require("../node");
 
 describe("Export", function() {
     it("Should parse export directives", function() {
-
         var inputs = [
             ['export * from "a.js"', ['*'], "a.js"],
             ['export {A} from "a.js"', ['A'], "a.js"],
@@ -12,17 +11,17 @@ describe("Export", function() {
             ['export {A, B} from "a.js"', ['A', 'B'], "a.js"],
         ];
 
-        var test = function(code) {
+        function test(code) {
             return uglify.parse(code);
-        };
+        }
 
-        var extractNames = function(symbols) {
+        function extractNames(symbols) {
             var ret = [];
             for (var i = 0; i < symbols.length; i++) {
-                ret.push(symbols[i].name.name)
+                ret.push(symbols[i].foreign_name.name);
             }
             return ret;
-        };
+        }
 
         for (var i = 0; i < inputs.length; i++) {
             var ast = test(inputs[i][0]);
@@ -34,7 +33,7 @@ describe("Export", function() {
             assert(st instanceof uglify.AST_Export);
             var actualNames = extractNames(st.exported_names);
             assert.deepEqual(actualNames, names);
-            assert.equal(st.module_name.value, filename)
+            assert.equal(st.module_name.value, filename);
         }
-    })
+    });
 });