Merge pull request #7707 from Microsoft/transforms-unary-operators-system

fix emit for unary operators on exported variables in system modules

Author: vladima

src/compiler/transformers/module/system.ts

@@ -1092,13 +1092,16 @@ namespace ts {
             if (substitute) {
                 const exportDeclaration = resolver.getReferencedExportContainer(<Identifier>operand);
                 if (exportDeclaration) {
-                    const expr = createPostfix(operand, node.operator, node);
+                    const expr = createPrefix(node.operator, operand, node);
                     setNodeEmitFlags(expr, NodeEmitFlags.NoSubstitution);
                     const call = createExportExpression(<Identifier>operand, expr);
                     if (node.kind === SyntaxKind.PrefixUnaryExpression) {
                         return call;
                     }
                     else {
+                        // export function returns the value that was passes as the second argument
+                        // however for postfix unary expressions result value should be the value before modification.
+                        // emit 'x++' as '(export('x', ++x) - 1)' and 'x--' as '(export('x', --x) + 1)'
                         return operator === SyntaxKind.PlusPlusToken
                             ? createSubtract(call, createLiteral(1))
                             : createAdd(call, createLiteral(1));

tests/baselines/reference/prefixUnaryOperatorsOnExportedVariables.js

@@ -31,13 +31,13 @@ if (++y) {
 }
 
 //// [prefixUnaryOperatorsOnExportedVariables.js]
-System.register([], function(exports_1, context_1) {
+System.register([], function (exports_1, context_1) {
     "use strict";
     var __moduleName = context_1 && context_1.id;
     var x, y;
     return {
-        setters:[],
-        execute: function() {
+        setters: [],
+        execute: function () {
             exports_1("x", x = false);
             exports_1("y", y = 1);
             if (!x) {
@@ -55,5 +55,5 @@ System.register([], function(exports_1, context_1) {
             if (exports_1("y", ++y)) {
             }
         }
-    }
+    };
 });

tests/baselines/reference/systemModule10.js

@@ -10,7 +10,7 @@ export {n2}
 export {n2 as n3}
 
 //// [systemModule10.js]
-System.register(['file1', 'file2'], function (exports_1, context_1) {
+System.register(["file1", "file2"], function (exports_1, context_1) {
     "use strict";
     var __moduleName = context_1 && context_1.id;
     var file1_1, n2;

tests/baselines/reference/systemModule10_ES5.js

@@ -10,7 +10,7 @@ export {n2}
 export {n2 as n3}
 
 //// [systemModule10_ES5.js]
-System.register(['file1', 'file2'], function (exports_1, context_1) {
+System.register(["file1", "file2"], function (exports_1, context_1) {
     "use strict";
     var __moduleName = context_1 && context_1.id;
     var file1_1, n2;

tests/baselines/reference/systemModule17.js

@@ -65,8 +65,8 @@ System.register(["f1"], function (exports_1, context_1) {
     var x, N, IX, f1_1;
     return {
         setters: [
-            function (_1) {
-                f1_1 = _1;
+            function (f1_1_1) {
+                f1_1 = f1_1_1;
             }
         ],
         execute: function () {

tests/baselines/reference/systemModule8.js

@@ -42,10 +42,10 @@ System.register([], function (exports_1, context_1) {
         setters: [],
         execute: function () {
             exports_1("x", x = 1);
-            exports_1("x", x++) - 1;
-            exports_1("x", x--) + 1;
-            exports_1("x", x++);
-            exports_1("x", x--);
+            exports_1("x", ++x) - 1;
+            exports_1("x", --x) + 1;
+            exports_1("x", ++x);
+            exports_1("x", --x);
             exports_1("x", x += 1);
             exports_1("x", x -= 1);
             exports_1("x", x *= 1);
@@ -56,10 +56,10 @@ System.register([], function (exports_1, context_1) {
             x - 1;
             x & 1;
             x | 1;
-            for (exports_1("x", x = 5);; exports_1("x", x++) - 1) { }
-            for (exports_1("x", x = 8);; exports_1("x", x--) + 1) { }
-            for (exports_1("x", x = 15);; exports_1("x", x++)) { }
-            for (exports_1("x", x = 18);; exports_1("x", x--)) { }
+            for (exports_1("x", x = 5);; exports_1("x", ++x) - 1) { }
+            for (exports_1("x", x = 8);; exports_1("x", --x) + 1) { }
+            for (exports_1("x", x = 15);; exports_1("x", ++x)) { }
+            for (exports_1("x", x = 18);; exports_1("x", --x)) { }
             for (x = 50;;) { }
             exports_1("y", y = [1][0]);
             _a = { a: true, b: { c: "123" } }, exports_1("z0", z0 = _a.a), exports_1("z1", z1 = _a.b.c);