Cherry-pick PR microsoft#38712 into release-3.9

Component commits:
1378ebb Preserve module marker in es2015+ module emit for tool compatability

src/compiler/transformers/module/esnextAnd2015.ts

@@ -18,25 +18,36 @@ namespace ts {
             }
 
             if (isExternalModule(node) || compilerOptions.isolatedModules) {
-                const externalHelpersImportDeclaration = createExternalHelpersImportDeclarationIfNeeded(node, compilerOptions);
-                if (externalHelpersImportDeclaration) {
-                    const statements: Statement[] = [];
-                    const statementOffset = addPrologue(statements, node.statements);
-                    append(statements, externalHelpersImportDeclaration);
-
-                    addRange(statements, visitNodes(node.statements, visitor, isStatement, statementOffset));
-                    return updateSourceFileNode(
-                        node,
-                        setTextRange(createNodeArray(statements), node.statements));
-                }
-                else {
-                    return visitEachChild(node, visitor, context);
+                const result = updateExternalModule(node);
+                if (!isExternalModule(node) || some(result.statements, isExternalModuleIndicator)) {
+                    return result;
                 }
+                return updateSourceFileNode(
+                    result,
+                    setTextRange(createNodeArray([...result.statements, createEmptyExports()]), result.statements),
+                );
             }
 
             return node;
         }
 
+        function updateExternalModule(node: SourceFile) {
+            const externalHelpersImportDeclaration = createExternalHelpersImportDeclarationIfNeeded(node, compilerOptions);
+            if (externalHelpersImportDeclaration) {
+                const statements: Statement[] = [];
+                const statementOffset = addPrologue(statements, node.statements);
+                append(statements, externalHelpersImportDeclaration);
+
+                addRange(statements, visitNodes(node.statements, visitor, isStatement, statementOffset));
+                return updateSourceFileNode(
+                    node,
+                    setTextRange(createNodeArray(statements), node.statements));
+            }
+            else {
+                return visitEachChild(node, visitor, context);
+            }
+        }
+
         function visitor(node: Node): VisitResult<Node> {
             switch (node.kind) {
                 case SyntaxKind.ImportEqualsDeclaration:

tests/baselines/reference/asyncAwaitIsolatedModules_es2017.js

@@ -71,3 +71,4 @@ var M;
     async function f1() { }
     M.f1 = f1;
 })(M || (M = {}));
+export {};

tests/baselines/reference/asyncAwaitIsolatedModules_es6.js

@@ -112,3 +112,4 @@ var M;
     }
     M.f1 = f1;
 })(M || (M = {}));
+export {};

tests/baselines/reference/computedPropertyName.js

@@ -65,3 +65,4 @@ class F {
 }
 class G {
 }
+export {};

tests/baselines/reference/decoratedClassFromExternalModule.js

@@ -27,3 +27,4 @@ let Decorated = /** @class */ (() => {
 })();
 export default Decorated;
 //// [undecorated.js]
+export {};

tests/baselines/reference/es6ExportAssignment.js

@@ -4,3 +4,4 @@ export = a;
 
 //// [es6ExportAssignment.js]
 var a = 10;
+export {};

tests/baselines/reference/es6ExportAssignment2.js

@@ -10,4 +10,6 @@ import * as a from "a";
 
 //// [a.js]
 var a = 10;
+export {};
 //// [b.js]
+export {};

tests/baselines/reference/es6ExportAssignment3.js

@@ -9,3 +9,4 @@ import * as a from "a";
 
 
 //// [b.js]
+export {};

tests/baselines/reference/es6ExportAssignment4.js

@@ -11,3 +11,4 @@ import * as a from "a";
 
 
 //// [b.js]
+export {};

tests/baselines/reference/es6ImportEqualsDeclaration.js

@@ -9,4 +9,6 @@ import a = require("server");
 
 //// [server.js]
 var a = 10;
+export {};
 //// [client.js]
+export {};

tests/baselines/reference/es6ImportEqualsDeclaration2.js

@@ -20,3 +20,4 @@ import {a} from "server";
 
 
 //// [client.js]
+export {};

tests/baselines/reference/es6ImportEqualsExportModuleEs2015Error.js

@@ -17,6 +17,7 @@ var a = /** @class */ (function () {
     }
     return a;
 }());
+export {};
 //// [main.js]
 import * as a from "./a";
 a;

tests/baselines/reference/es6ImportNamedImportIdentifiersParsing.js

@@ -6,3 +6,4 @@ import { default as yield } from "somemodule"; // no error
 import { default as default } from "somemodule"; // default as is ok, error of default binding name
 
 //// [es6ImportNamedImportIdentifiersParsing.js]
+export {};

tests/baselines/reference/es6ImportWithoutFromClauseNonInstantiatedModule.js

@@ -8,6 +8,7 @@ export interface i {
 import "es6ImportWithoutFromClauseNonInstantiatedModule_0";
 
 //// [es6ImportWithoutFromClauseNonInstantiatedModule_0.js]
+export {};
 //// [es6ImportWithoutFromClauseNonInstantiatedModule_1.js]
 import "es6ImportWithoutFromClauseNonInstantiatedModule_0";
 

tests/baselines/reference/es6modulekindWithES5Target10.js

@@ -7,3 +7,4 @@ namespace N {
 export = N; // Error
 
 //// [es6modulekindWithES5Target10.js]
+export {};

tests/baselines/reference/esnextmodulekindWithES5Target10.js

@@ -7,3 +7,4 @@ namespace N {
 export = N; // Error
 
 //// [esnextmodulekindWithES5Target10.js]
+export {};

tests/baselines/reference/exportAssignmentWithoutAllowSyntheticDefaultImportsError.js

@@ -9,4 +9,6 @@ import bar from './bar';
 
 //// [bar.js]
 function bar() { }
+export {};
 //// [foo.js]
+export {};

tests/baselines/reference/exportDefaultForNonInstantiatedModule.js

@@ -7,3 +7,4 @@ module m {
 export default m;
 
 //// [exportDefaultForNonInstantiatedModule.js]
+export {};

tests/baselines/reference/importCallExpressionIncorrect2.js

@@ -11,3 +11,4 @@ var x = import { foo } from './0';
 export function foo() { return "foo"; }
 //// [1.js]
 var x = ;
+export {};

tests/baselines/reference/importMeta(module=esnext,target=es5).js

@@ -95,6 +95,7 @@ var __generator = (this && this.__generator) || function (thisArg, body) {
         }
     });
 }); })();
+export {};
 //// [moduleLookingFile01.js]
 export var x = import.meta;
 export var y = import.metal;
@@ -103,6 +104,7 @@ export var z = import.import.import.malkovich;
 var globalA = import.meta;
 var globalB = import.metal;
 var globalC = import.import.import.malkovich;
+export {};
 //// [assignmentTargets.js]
 export var foo = import.meta.blah = import.meta.blue = import.meta;
 import.meta = foo;

tests/baselines/reference/importMeta(module=esnext,target=esnext).js

@@ -49,6 +49,7 @@ const { a, b, c } = import.meta.wellKnownProperty;
     image.width = image.height = size;
     document.body.appendChild(image);
 })();
+export {};
 //// [moduleLookingFile01.js]
 export let x = import.meta;
 export let y = import.metal;
@@ -57,6 +58,7 @@ export let z = import.import.import.malkovich;
 let globalA = import.meta;
 let globalB = import.metal;
 let globalC = import.import.import.malkovich;
+export {};
 //// [assignmentTargets.js]
 export const foo = import.meta.blah = import.meta.blue = import.meta;
 import.meta = foo;

tests/baselines/reference/importNonExportedMember6.js

@@ -13,4 +13,6 @@ var Foo = /** @class */ (function () {
     }
     return Foo;
 }());
+export {};
 //// [b.js]
+export {};

tests/baselines/reference/importNonExportedMember7.js

@@ -13,4 +13,6 @@ var Foo = /** @class */ (function () {
     }
     return Foo;
 }());
+export {};
 //// [b.js]
+export {};

tests/baselines/reference/instantiateContextualTypes.js

@@ -236,3 +236,4 @@ let obj = {
     foo(bar) { }
 };
 assignPartial(obj, { foo(...args) { } }); // args has type [string]
+export {};

tests/baselines/reference/isolatedModulesDontElideReExportStar.js

@@ -8,5 +8,6 @@ export * from "./a";
 
 
 //// [a.js]
+export {};
 //// [b.js]
 export * from "./a";

tests/baselines/reference/potentiallyUncalledDecorators.js

@@ -217,3 +217,4 @@ let G = /** @class */ (() => {
     ], G);
     return G;
 })();
+export {};

tests/baselines/reference/requireOfJsonFileWithModuleNodeResolutionEmitEs2015.js

@@ -15,3 +15,4 @@ import * as b from './b.json';
     "b": "hello"
 }
 //// [out/file1.js]
+export {};

tests/baselines/reference/requireOfJsonFileWithModuleNodeResolutionEmitEsNext.js

@@ -15,3 +15,4 @@ import * as b  from './b.json';
     "b": "hello"
 }
 //// [out/file1.js]
+export {};

tests/baselines/reference/scannerUnicodeEscapeInKeyword2.js

@@ -48,6 +48,7 @@ var \u0079ield = 12; // ok
 function* gen() {
     yield 12; //not ok
 }
+export {};
 //// [file2.js]
 var x = "hello"; // not ok
 var \u{0061}wait = 12; // ok
@@ -59,4 +60,5 @@ function* gen() {
     yield 12; //not ok
 }
 const a = { def\u0061ult: 12 }; // OK, `default` not in keyword position
+export {};
 // chrome and jsc may still error on this, ref https://bugs.chromium.org/p/chromium/issues/detail?id=993000 and https://bugs.webkit.org/show_bug.cgi?id=200638

tests/baselines/reference/strictModeWordInImportDeclaration.js

@@ -6,3 +6,4 @@ import public from "./1"
 
 //// [strictModeWordInImportDeclaration.js]
 "use strict";
+export {};

tests/baselines/reference/taggedTemplatesWithTypeArguments2.js

@@ -59,3 +59,4 @@ class SomeDerived extends SomeBase {
         super. `hello world`;
     }
 }
+export {};

tests/baselines/reference/tsxResolveExternalModuleExportsTypes.js

@@ -24,3 +24,4 @@ const Foo = (<h1></h1>);
 
 //// [foo.jsx]
 var Foo = (<h1></h1>);
+export {};

tests/baselines/reference/umdGlobalAugmentationNoCrash.js

@@ -21,6 +21,7 @@ React.foo;
 
 //// [some_module.js]
 React.foo;
+export {};
 //// [emits.js]
 "use strict";
 console.log("hello");

tests/baselines/reference/umdNamespaceMergedWithGlobalAugmentationIsNotCircular.js

@@ -25,6 +25,7 @@ React.createRef;
 
 //// [some_module.js]
 React.createRef;
+export {};
 //// [emits.js]
 "use strict";
 console.log("hello");

tests/baselines/reference/unionAndIntersectionInference3.js

@@ -105,3 +105,4 @@ let x2 = foo2(sa); // unknown
 let y2 = foo2(sx); // { extra: number }
 withRouter(MyComponent);
 let z = foo(ab); // [AB<string>, string]
+export {};

tests/baselines/reference/unionTypeInference.js

@@ -111,3 +111,4 @@ async function fun(deepPromised) {
     }
 }
 baz(xx);
+export {};