Care about esnext where we look for es2015 (microsoft#18331)

* Care about esnext where we look for es2015

* Update diagnostic message to be more agnostic

Author: weswigham

src/compiler/checker.ts

@@ -22149,9 +22149,9 @@ namespace ts {
                     }
                 }
                 else {
-                    if (modulekind === ModuleKind.ES2015 && !isInAmbientContext(node)) {
+                    if (modulekind >= ModuleKind.ES2015 && !isInAmbientContext(node)) {
                         // Import equals declaration is deprecated in es6 or above
-                        grammarErrorOnNode(node, Diagnostics.Import_assignment_cannot_be_used_when_targeting_ECMAScript_2015_modules_Consider_using_import_Asterisk_as_ns_from_mod_import_a_from_mod_import_d_from_mod_or_another_module_format_instead);
+                        grammarErrorOnNode(node, Diagnostics.Import_assignment_cannot_be_used_when_targeting_ECMAScript_modules_Consider_using_import_Asterisk_as_ns_from_mod_import_a_from_mod_import_d_from_mod_or_another_module_format_instead);
                     }
                 }
             }
@@ -22187,7 +22187,7 @@ namespace ts {
                         error(node.moduleSpecifier, Diagnostics.Module_0_uses_export_and_cannot_be_used_with_export_Asterisk, symbolToString(moduleSymbol));
                     }
 
-                    if (modulekind !== ModuleKind.System && modulekind !== ModuleKind.ES2015) {
+                    if (modulekind !== ModuleKind.System && modulekind !== ModuleKind.ES2015 && modulekind !== ModuleKind.ESNext) {
                         checkExternalEmitHelpers(node, ExternalEmitHelpers.ExportStar);
                     }
                 }
@@ -22249,9 +22249,9 @@ namespace ts {
             checkExternalModuleExports(container);
 
             if (node.isExportEquals && !isInAmbientContext(node)) {
-                if (modulekind === ModuleKind.ES2015) {
+                if (modulekind >= ModuleKind.ES2015) {
                     // export assignment is not supported in es6 modules
-                    grammarErrorOnNode(node, Diagnostics.Export_assignment_cannot_be_used_when_targeting_ECMAScript_2015_modules_Consider_using_export_default_or_another_module_format_instead);
+                    grammarErrorOnNode(node, Diagnostics.Export_assignment_cannot_be_used_when_targeting_ECMAScript_modules_Consider_using_export_default_or_another_module_format_instead);
                 }
                 else if (modulekind === ModuleKind.System) {
                     // system modules does not support export assignment
@@ -24851,7 +24851,7 @@ namespace ts {
                 }
             }
 
-            if (compilerOptions.module !== ModuleKind.ES2015 && compilerOptions.module !== ModuleKind.System && !compilerOptions.noEmit &&
+            if (compilerOptions.module !== ModuleKind.ES2015 && compilerOptions.module !== ModuleKind.ESNext && compilerOptions.module !== ModuleKind.System && !compilerOptions.noEmit &&
                 !isInAmbientContext(node.parent.parent) && hasModifier(node.parent.parent, ModifierFlags.Export)) {
                 checkESModuleMarker(node.name);
             }

src/compiler/diagnosticMessages.json

@@ -627,11 +627,11 @@
         "category": "Error",
         "code": 1200
     },
-    "Import assignment cannot be used when targeting ECMAScript 2015 modules. Consider using 'import * as ns from \"mod\"', 'import {a} from \"mod\"', 'import d from \"mod\"', or another module format instead.": {
+    "Import assignment cannot be used when targeting ECMAScript modules. Consider using 'import * as ns from \"mod\"', 'import {a} from \"mod\"', 'import d from \"mod\"', or another module format instead.": {
         "category": "Error",
         "code": 1202
     },
-    "Export assignment cannot be used when targeting ECMAScript 2015 modules. Consider using 'export default' or another module format instead.": {
+    "Export assignment cannot be used when targeting ECMAScript modules. Consider using 'export default' or another module format instead.": {
         "category": "Error",
         "code": 1203
     },

src/compiler/factory.ts

@@ -4158,7 +4158,8 @@ namespace ts {
             const moduleKind = getEmitModuleKind(compilerOptions);
             let create = hasExportStarsToExportValues
                 && moduleKind !== ModuleKind.System
-                && moduleKind !== ModuleKind.ES2015;
+                && moduleKind !== ModuleKind.ES2015
+                && moduleKind !== ModuleKind.ESNext;
             if (!create) {
                 const helpers = getEmitHelpers(node);
                 if (helpers) {

src/compiler/transformers/ts.ts

@@ -521,7 +521,7 @@ namespace ts {
 
         function visitSourceFile(node: SourceFile) {
             const alwaysStrict = (compilerOptions.alwaysStrict === undefined ? compilerOptions.strict : compilerOptions.alwaysStrict) &&
-                !(isExternalModule(node) && moduleKind === ModuleKind.ES2015);
+                !(isExternalModule(node) && moduleKind >= ModuleKind.ES2015);
             return updateSourceFileNode(
                 node,
                 visitLexicalEnvironment(node.statements, sourceElementVisitor, context, /*start*/ 0, alwaysStrict));
@@ -2665,6 +2665,7 @@ namespace ts {
             return isExportOfNamespace(node)
                 || (isExternalModuleExport(node)
                     && moduleKind !== ModuleKind.ES2015
+                    && moduleKind !== ModuleKind.ESNext
                     && moduleKind !== ModuleKind.System);
         }
 

tests/baselines/reference/es6ExportAssignment.errors.txt

@@ -1,8 +1,8 @@
-tests/cases/compiler/es6ExportAssignment.ts(2,1): error TS1203: Export assignment cannot be used when targeting ECMAScript 2015 modules. Consider using 'export default' or another module format instead.
+tests/cases/compiler/es6ExportAssignment.ts(2,1): error TS1203: Export assignment cannot be used when targeting ECMAScript modules. Consider using 'export default' or another module format instead.
 
 
 ==== tests/cases/compiler/es6ExportAssignment.ts (1 errors) ====
     var a = 10;
     export = a;
     ~~~~~~~~~~~
-!!! error TS1203: Export assignment cannot be used when targeting ECMAScript 2015 modules. Consider using 'export default' or another module format instead.
+!!! error TS1203: Export assignment cannot be used when targeting ECMAScript modules. Consider using 'export default' or another module format instead.

tests/baselines/reference/es6ExportAssignment2.errors.txt

@@ -1,11 +1,11 @@
-tests/cases/compiler/a.ts(2,1): error TS1203: Export assignment cannot be used when targeting ECMAScript 2015 modules. Consider using 'export default' or another module format instead.
+tests/cases/compiler/a.ts(2,1): error TS1203: Export assignment cannot be used when targeting ECMAScript modules. Consider using 'export default' or another module format instead.
 
 
 ==== tests/cases/compiler/a.ts (1 errors) ====
     var a = 10;
     export = a;  // Error: export = not allowed in ES6
     ~~~~~~~~~~~
-!!! error TS1203: Export assignment cannot be used when targeting ECMAScript 2015 modules. Consider using 'export default' or another module format instead.
+!!! error TS1203: Export assignment cannot be used when targeting ECMAScript modules. Consider using 'export default' or another module format instead.
 
 ==== tests/cases/compiler/b.ts (0 errors) ====
     import * as a from "a";

tests/baselines/reference/es6ExportEquals.errors.txt

@@ -1,4 +1,4 @@
-tests/cases/compiler/es6ExportEquals.ts(3,1): error TS1203: Export assignment cannot be used when targeting ECMAScript 2015 modules. Consider using 'export default' or another module format instead.
+tests/cases/compiler/es6ExportEquals.ts(3,1): error TS1203: Export assignment cannot be used when targeting ECMAScript modules. Consider using 'export default' or another module format instead.
 tests/cases/compiler/es6ExportEquals.ts(3,1): error TS2309: An export assignment cannot be used in a module with other exported elements.
 
 
@@ -7,7 +7,7 @@ tests/cases/compiler/es6ExportEquals.ts(3,1): error TS2309: An export assignment
 
     export = f;
     ~~~~~~~~~~~
-!!! error TS1203: Export assignment cannot be used when targeting ECMAScript 2015 modules. Consider using 'export default' or another module format instead.
+!!! error TS1203: Export assignment cannot be used when targeting ECMAScript modules. Consider using 'export default' or another module format instead.
     ~~~~~~~~~~~
 !!! error TS2309: An export assignment cannot be used in a module with other exported elements.
 

tests/baselines/reference/es6ImportEqualsDeclaration.errors.txt

@@ -1,14 +1,14 @@
-tests/cases/compiler/client.ts(1,1): error TS1202: Import assignment cannot be used when targeting ECMAScript 2015 modules. Consider using 'import * as ns from "mod"', 'import {a} from "mod"', 'import d from "mod"', or another module format instead.
-tests/cases/compiler/server.ts(2,1): error TS1203: Export assignment cannot be used when targeting ECMAScript 2015 modules. Consider using 'export default' or another module format instead.
+tests/cases/compiler/client.ts(1,1): error TS1202: Import assignment cannot be used when targeting ECMAScript modules. Consider using 'import * as ns from "mod"', 'import {a} from "mod"', 'import d from "mod"', or another module format instead.
+tests/cases/compiler/server.ts(2,1): error TS1203: Export assignment cannot be used when targeting ECMAScript modules. Consider using 'export default' or another module format instead.
 
 
 ==== tests/cases/compiler/client.ts (1 errors) ====
     import a = require("server");
     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-!!! error TS1202: Import assignment cannot be used when targeting ECMAScript 2015 modules. Consider using 'import * as ns from "mod"', 'import {a} from "mod"', 'import d from "mod"', or another module format instead.
+!!! error TS1202: Import assignment cannot be used when targeting ECMAScript modules. Consider using 'import * as ns from "mod"', 'import {a} from "mod"', 'import d from "mod"', or another module format instead.
 ==== tests/cases/compiler/server.ts (1 errors) ====
     var a = 10;
     export = a;
     ~~~~~~~~~~~
-!!! error TS1203: Export assignment cannot be used when targeting ECMAScript 2015 modules. Consider using 'export default' or another module format instead.
+!!! error TS1203: Export assignment cannot be used when targeting ECMAScript modules. Consider using 'export default' or another module format instead.
 

tests/baselines/reference/es6modulekind.symbols

@@ -1,4 +1,4 @@
-=== tests/cases/compiler/es6modulekind.ts ===
+=== tests/cases/conformance/externalModules/es6/es6modulekind.ts ===
 export default class A
 >A : Symbol(A, Decl(es6modulekind.ts, 0, 0))
 {

tests/baselines/reference/es6modulekind.types

@@ -1,4 +1,4 @@
-=== tests/cases/compiler/es6modulekind.ts ===
+=== tests/cases/conformance/externalModules/es6/es6modulekind.ts ===
 export default class A
 >A : A
 {