Call dynamic import transform on expression used by export equal statement (#18028)

* Call dynamic import transform on expression used by export equal statement

* Use Debug.fail

src/compiler/transformers/module/module.ts

@@ -430,26 +430,32 @@ namespace ts {
          */
         function addExportEqualsIfNeeded(statements: Statement[], emitAsReturn: boolean) {
             if (currentModuleInfo.exportEquals) {
-                if (emitAsReturn) {
-                    const statement = createReturn(currentModuleInfo.exportEquals.expression);
-                    setTextRange(statement, currentModuleInfo.exportEquals);
-                    setEmitFlags(statement, EmitFlags.NoTokenSourceMaps | EmitFlags.NoComments);
-                    statements.push(statement);
-                }
-                else {
-                    const statement = createStatement(
-                        createAssignment(
-                            createPropertyAccess(
-                                createIdentifier("module"),
-                                "exports"
-                            ),
-                            currentModuleInfo.exportEquals.expression
-                        )
-                    );
+                const expressionResult = importCallExpressionVisitor(currentModuleInfo.exportEquals.expression);
+                if (expressionResult) {
+                    if (expressionResult instanceof Array) {
+                        return Debug.fail("export= expression should never be replaced with multiple expressions!");
+                    }
+                    if (emitAsReturn) {
+                        const statement = createReturn(expressionResult);
+                        setTextRange(statement, currentModuleInfo.exportEquals);
+                        setEmitFlags(statement, EmitFlags.NoTokenSourceMaps | EmitFlags.NoComments);
+                        statements.push(statement);
+                    }
+                    else {
+                        const statement = createStatement(
+                            createAssignment(
+                                createPropertyAccess(
+                                    createIdentifier("module"),
+                                    "exports"
+                                ),
+                                expressionResult
+                            )
+                        );
 
-                    setTextRange(statement, currentModuleInfo.exportEquals);
-                    setEmitFlags(statement, EmitFlags.NoComments);
-                    statements.push(statement);
+                        setTextRange(statement, currentModuleInfo.exportEquals);
+                        setEmitFlags(statement, EmitFlags.NoComments);
+                        statements.push(statement);
+                    }
                 }
             }
         }
@@ -497,7 +503,7 @@ namespace ts {
             }
         }
 
-        function importCallExpressionVisitor(node: Node): VisitResult<Node> {
+        function importCallExpressionVisitor(node: Expression): VisitResult<Expression> {
             // This visitor does not need to descend into the tree if there is no dynamic import,
             // as export/import statements are only transformed at the top level of a file.
             if (!(node.transformFlags & TransformFlags.ContainsDynamicImport)) {

tests/baselines/reference/importCallExpressionInExportEqualsAMD.js

@@ -0,0 +1,22 @@
+//// [tests/cases/conformance/dynamicImport/importCallExpressionInExportEqualsAMD.ts] ////
+
+//// [something.ts]
+export = 42;
+
+//// [index.ts]
+export = async function() {
+    const something = await import("./something");
+};
+
+//// [something.js]
+define(["require", "exports"], function (require, exports) {
+    "use strict";
+    return 42;
+});
+//// [index.js]
+define(["require", "exports"], function (require, exports) {
+    "use strict";
+    return async function () {
+        const something = await new Promise(function (resolve_1, reject_1) { require(["./something"], resolve_1, reject_1); });
+    };
+});

tests/baselines/reference/importCallExpressionInExportEqualsAMD.symbols

@@ -0,0 +1,10 @@
+=== tests/cases/conformance/dynamicImport/something.ts ===
+export = 42;
+No type information for this code.
+No type information for this code.=== tests/cases/conformance/dynamicImport/index.ts ===
+export = async function() {
+    const something = await import("./something");
+>something : Symbol(something, Decl(index.ts, 1, 9))
+>"./something" : Symbol("tests/cases/conformance/dynamicImport/something", Decl(something.ts, 0, 0))
+
+};

tests/baselines/reference/importCallExpressionInExportEqualsAMD.types

@@ -0,0 +1,14 @@
+=== tests/cases/conformance/dynamicImport/something.ts ===
+export = 42;
+No type information for this code.
+No type information for this code.=== tests/cases/conformance/dynamicImport/index.ts ===
+export = async function() {
+>async function() {    const something = await import("./something");} : () => Promise<void>
+
+    const something = await import("./something");
+>something : 42
+>await import("./something") : 42
+>import("./something") : Promise<42>
+>"./something" : "./something"
+
+};

tests/baselines/reference/importCallExpressionInExportEqualsCJS.js

@@ -0,0 +1,18 @@
+//// [tests/cases/conformance/dynamicImport/importCallExpressionInExportEqualsCJS.ts] ////
+
+//// [something.ts]
+export = 42;
+
+//// [index.ts]
+export = async function() {
+    const something = await import("./something");
+};
+
+//// [something.js]
+"use strict";
+module.exports = 42;
+//// [index.js]
+"use strict";
+module.exports = async function () {
+    const something = await Promise.resolve().then(function () { return require("./something"); });
+};

tests/baselines/reference/importCallExpressionInExportEqualsCJS.symbols

@@ -0,0 +1,10 @@
+=== tests/cases/conformance/dynamicImport/something.ts ===
+export = 42;
+No type information for this code.
+No type information for this code.=== tests/cases/conformance/dynamicImport/index.ts ===
+export = async function() {
+    const something = await import("./something");
+>something : Symbol(something, Decl(index.ts, 1, 9))
+>"./something" : Symbol("tests/cases/conformance/dynamicImport/something", Decl(something.ts, 0, 0))
+
+};

tests/baselines/reference/importCallExpressionInExportEqualsCJS.types

@@ -0,0 +1,14 @@
+=== tests/cases/conformance/dynamicImport/something.ts ===
+export = 42;
+No type information for this code.
+No type information for this code.=== tests/cases/conformance/dynamicImport/index.ts ===
+export = async function() {
+>async function() {    const something = await import("./something");} : () => Promise<void>
+
+    const something = await import("./something");
+>something : 42
+>await import("./something") : 42
+>import("./something") : Promise<42>
+>"./something" : "./something"
+
+};

tests/baselines/reference/importCallExpressionInExportEqualsUMD.js

@@ -0,0 +1,39 @@
+//// [tests/cases/conformance/dynamicImport/importCallExpressionInExportEqualsUMD.ts] ////
+
+//// [something.ts]
+export = 42;
+
+//// [index.ts]
+export = async function() {
+    const something = await import("./something");
+};
+
+//// [something.js]
+(function (factory) {
+    if (typeof module === "object" && typeof module.exports === "object") {
+        var v = factory(require, exports);
+        if (v !== undefined) module.exports = v;
+    }
+    else if (typeof define === "function" && define.amd) {
+        define(["require", "exports"], factory);
+    }
+})(function (require, exports) {
+    "use strict";
+    return 42;
+});
+//// [index.js]
+(function (factory) {
+    if (typeof module === "object" && typeof module.exports === "object") {
+        var v = factory(require, exports);
+        if (v !== undefined) module.exports = v;
+    }
+    else if (typeof define === "function" && define.amd) {
+        define(["require", "exports"], factory);
+    }
+})(function (require, exports) {
+    "use strict";
+    var __syncRequire = typeof module === "object" && typeof module.exports === "object";
+    return async function () {
+        const something = await (__syncRequire ? Promise.resolve().then(function () { return require("./something"); }) : new Promise(function (resolve_1, reject_1) { require(["./something"], resolve_1, reject_1); }));
+    };
+});

tests/baselines/reference/importCallExpressionInExportEqualsUMD.symbols

@@ -0,0 +1,10 @@
+=== tests/cases/conformance/dynamicImport/something.ts ===
+export = 42;
+No type information for this code.
+No type information for this code.=== tests/cases/conformance/dynamicImport/index.ts ===
+export = async function() {
+    const something = await import("./something");
+>something : Symbol(something, Decl(index.ts, 1, 9))
+>"./something" : Symbol("tests/cases/conformance/dynamicImport/something", Decl(something.ts, 0, 0))
+
+};

tests/baselines/reference/importCallExpressionInExportEqualsUMD.types

@@ -0,0 +1,14 @@
+=== tests/cases/conformance/dynamicImport/something.ts ===
+export = 42;
+No type information for this code.
+No type information for this code.=== tests/cases/conformance/dynamicImport/index.ts ===
+export = async function() {
+>async function() {    const something = await import("./something");} : () => Promise<void>
+
+    const something = await import("./something");
+>something : 42
+>await import("./something") : 42
+>import("./something") : Promise<42>
+>"./something" : "./something"
+
+};

tests/cases/conformance/dynamicImport/importCallExpressionInExportEqualsAMD.ts

@@ -0,0 +1,9 @@
+// @module: amd
+// @target: esnext
+// @filename: something.ts
+export = 42;
+
+// @filename: index.ts
+export = async function() {
+    const something = await import("./something");
+};

tests/cases/conformance/dynamicImport/importCallExpressionInExportEqualsCJS.ts

@@ -0,0 +1,9 @@
+// @module: commonjs
+// @target: esnext
+// @filename: something.ts
+export = 42;
+
+// @filename: index.ts
+export = async function() {
+    const something = await import("./something");
+};

tests/cases/conformance/dynamicImport/importCallExpressionInExportEqualsUMD.ts

@@ -0,0 +1,9 @@
+// @module: umd
+// @target: esnext
+// @filename: something.ts
+export = 42;
+
+// @filename: index.ts
+export = async function() {
+    const something = await import("./something");
+};