Check exported bindings are defined (#9589)

* Check exported bindings are defined

* Add tests

* Update flow whitelist

* Add tests for builtins

packages/babel-generator/test/fixtures/edgecase/unary-op/options.json

@@ -0,0 +1,3 @@
+{
+  "strictMode": false
+}

packages/babel-generator/test/fixtures/flow/declare-exports/input.js

@@ -17,6 +17,7 @@ declare export * from 'asd';
 declare export { a, b };
 declare export {};
 declare export { c, d } from 'bar';
+var a, b;
 
 declare module B {
   declare export type B = {};

packages/babel-generator/test/fixtures/flow/declare-exports/output.js

@@ -26,6 +26,7 @@ declare export * from 'asd';
 declare export { a, b };
 declare export {};
 declare export { c, d } from 'bar';
+var a, b;
 declare module B {
   declare export type B = {};
   declare export interface Moon {}

packages/babel-generator/test/fixtures/flow/type-annotations/input.js

@@ -107,7 +107,7 @@ import { type Foo12 } from "bar";
 import { typeof Foo13 } from "bar";
 import { type Foo as Bar1 } from "bar";
 import { typeof Foo as Bar2 } from "bar";
-export type { foo };
+export type { foo1 };
 export type { bar } from "bar";
 export interface baz { p: number }
 export interface qux<T> { p: T }

packages/babel-generator/test/fixtures/flow/type-annotations/output.js

@@ -231,7 +231,7 @@ import { type Foo12 } from "bar";
 import { typeof Foo13 } from "bar";
 import { type Foo as Bar1 } from "bar";
 import { typeof Foo as Bar2 } from "bar";
-export type { foo };
+export type { foo1 };
 export type { bar } from "bar";
 export interface baz {
   p: number
@@ -293,4 +293,4 @@ function foo27(numVal: number = 2) {}
 
 function foo28(numVal?: number = 2) {}
 
-export type * from "foo";
+export type * from "foo";

packages/babel-generator/test/fixtures/harmony-edgecase/exports/input.js

@@ -1,3 +1,4 @@
+var a, c;
 export * from "OK"
 export { name } from "OK"
 export { a as b, c as d } from "hello"

packages/babel-generator/test/fixtures/harmony-edgecase/exports/output.js

@@ -1,3 +1,4 @@
+var a, c;
 export * from "OK";
 export { name } from "OK";
 export { a as b, c as d } from "hello";

packages/babel-generator/test/fixtures/types/ExportSpecifier11/input.js

@@ -1 +1,2 @@
 export { foo };
+var foo;

packages/babel-generator/test/fixtures/types/ExportSpecifier11/output.js

@@ -1 +1,2 @@
-export { foo };
+export { foo };
+var foo;

packages/babel-generator/test/fixtures/types/ExportSpecifier12/input.js

@@ -1 +1,2 @@
 export { foo, bar };
+var foo, bar;

packages/babel-generator/test/fixtures/types/ExportSpecifier12/output.js

@@ -1 +1,2 @@
-export { foo, bar };
+export { foo, bar };
+var foo, bar;

packages/babel-generator/test/fixtures/types/ExportSpecifier13/input.js

@@ -1 +1,2 @@
 export { foo as bar };
+var foo;

packages/babel-generator/test/fixtures/types/ExportSpecifier13/output.js

@@ -1 +1,2 @@
-export { foo as bar };
+export { foo as bar };
+var foo;

packages/babel-generator/test/fixtures/types/ExportSpecifier14/input.js

@@ -1 +1,2 @@
 export { foo as default };
+var foo;

packages/babel-generator/test/fixtures/types/ExportSpecifier14/output.js

@@ -1 +1,2 @@
-export { foo as default };
+export { foo as default };
+var foo;

packages/babel-generator/test/fixtures/types/ExportSpecifier15/input.js

@@ -1 +1,2 @@
 export { foo as default, bar };
+var foo, bar;

packages/babel-generator/test/fixtures/types/ExportSpecifier15/output.js

@@ -1 +1,2 @@
-export { foo as default, bar };
+export { foo as default, bar };
+var foo, bar;

packages/babel-generator/test/fixtures/types/UnaryExpression/options.json

@@ -0,0 +1,3 @@
+{
+  "strictMode": false
+}

packages/babel-generator/test/fixtures/types/WithStatement/options.json

@@ -0,0 +1,3 @@
+{
+  "strictMode": false
+}

packages/babel-generator/test/index.js

@@ -489,7 +489,7 @@ suites.forEach(function(testSuite) {
             const actualAst = parse(actualCode, {
               filename: actual.loc,
               plugins: task.options.plugins || [],
-              strictMode: false,
+              strictMode: task.options.strictMode === false ? false : true,
               sourceType: "module",
               sourceMaps: !!task.sourceMap,
             });

packages/babel-parser/src/parser/statement.js

@@ -49,6 +49,14 @@ export default class StatementParser extends ExpressionParser {
 
     this.parseBlockBody(program, true, true, tt.eof);
 
+    if (this.inModule && this.scope.undefinedExports.size > 0) {
+      for (const [name] of Array.from(this.scope.undefinedExports)) {
+        const pos = this.scope.undefinedExports.get(name);
+        // $FlowIssue
+        this.raise(pos, `Export '${name}' is not defined`);
+      }
+    }
+
     file.program = this.finishNode(program, "Program");
     file.comments = this.state.comments;
 
@@ -1631,7 +1639,7 @@ export default class StatementParser extends ExpressionParser {
     }
 
     if (isFromRequired || hasSpecifiers || hasDeclaration) {
-      this.checkExport(node, true);
+      this.checkExport(node, true, false, !!node.source);
       return this.finishNode(node, "ExportNamedDeclaration");
     }
 
@@ -1845,8 +1853,9 @@ export default class StatementParser extends ExpressionParser {
 
   checkExport(
     node: N.ExportNamedDeclaration,
-    checkNames: ?boolean,
+    checkNames?: boolean,
     isDefault?: boolean,
+    isFrom?: boolean,
   ): void {
     if (checkNames) {
       // Check for duplicate exports
@@ -1857,6 +1866,11 @@ export default class StatementParser extends ExpressionParser {
         // Named exports
         for (const specifier of node.specifiers) {
           this.checkDuplicateExports(specifier, specifier.exported.name);
+          // check if export is defined
+          // $FlowIgnore
+          if (!isFrom && specifier.local) {
+            this.scope.checkLocalExport(specifier.local);
+          }
         }
       } else if (node.declaration) {
         // Exported declarations

packages/babel-parser/src/types.js

@@ -831,6 +831,7 @@ export type ExportNamedDeclaration = NodeBase & {
 export type ExportSpecifier = NodeBase & {
   type: "ExportSpecifier",
   exported: Identifier,
+  local: Identifier,
 };
 
 export type ExportDefaultSpecifier = NodeBase & {

packages/babel-parser/src/util/scope.js

@@ -16,6 +16,7 @@ import {
   type BindingTypes,
   SCOPE_CLASS,
 } from "./scopeflags";
+import * as N from "../types";
 
 // Start an AST node, attaching a start offset.
 class Scope {
@@ -40,6 +41,7 @@ export default class ScopeHandler {
   scopeStack: Array<Scope> = [];
   raise: raiseFunction;
   inModule: boolean;
+  undefinedExports: Map<string, number> = new Map();
 
   constructor(raise: raiseFunction, inModule: boolean) {
     this.raise = raise;
@@ -95,6 +97,9 @@ export default class ScopeHandler {
         scope.functions.indexOf(name) > -1 ||
         scope.var.indexOf(name) > -1;
       scope.lexical.push(name);
+      if (this.inModule && scope.flags & SCOPE_PROGRAM) {
+        this.undefinedExports.delete(name);
+      }
     } else if (bindingType === BIND_SIMPLE_CATCH) {
       const scope = this.currentScope();
       scope.lexical.push(name);
@@ -122,6 +127,10 @@ export default class ScopeHandler {
         }
         scope.var.push(name);
 
+        if (this.inModule && scope.flags & SCOPE_PROGRAM) {
+          this.undefinedExports.delete(name);
+        }
+
         if (scope.flags & SCOPE_VAR) break;
       }
     }
@@ -130,6 +139,16 @@ export default class ScopeHandler {
     }
   }
 
+  checkLocalExport(id: N.Identifier) {
+    // scope.functions must be empty as Module code is always strict.
+    if (
+      this.scopeStack[0].lexical.indexOf(id.name) === -1 &&
+      this.scopeStack[0].var.indexOf(id.name) === -1
+    ) {
+      this.undefinedExports.set(id.name, id.start);
+    }
+  }
+
   currentScope(): Scope {
     return this.scopeStack[this.scopeStack.length - 1];
   }

packages/babel-parser/test/fixtures/core/scope/undecl-export-as-default/input.js

@@ -0,0 +1 @@
+export { encrypt as default };

packages/babel-parser/test/fixtures/core/scope/undecl-export-as-default/options.json

@@ -0,0 +1,4 @@
+{
+  "sourceType": "module",
+  "throws": "Export 'encrypt' is not defined (1:9)"
+}

packages/babel-parser/test/fixtures/core/scope/undecl-export-as/input.js

@@ -0,0 +1,2 @@
+export { encrypt as decrypt };
+function decrypt() {}

packages/babel-parser/test/fixtures/core/scope/undecl-export-as/options.json

@@ -0,0 +1,4 @@
+{
+  "sourceType": "module",
+  "throws": "Export 'encrypt' is not defined (1:9)"
+}

packages/babel-parser/test/fixtures/core/scope/undecl-export-block/input.js

@@ -0,0 +1,4 @@
+{
+  function encrypt() {}
+}
+export { encrypt }

packages/babel-parser/test/fixtures/core/scope/undecl-export-block/options.json

@@ -0,0 +1,4 @@
+{
+  "sourceType": "module",
+  "throws": "Export 'encrypt' is not defined (4:9)"
+}

packages/babel-parser/test/fixtures/core/scope/undecl-export-builtin-as/input.js

@@ -0,0 +1 @@
+export { Object as Obj };

packages/babel-parser/test/fixtures/core/scope/undecl-export-builtin-as/options.json

@@ -0,0 +1,4 @@
+{
+  "sourceType": "module",
+  "throws": "Export 'Object' is not defined (1:9)"
+}

packages/babel-parser/test/fixtures/core/scope/undecl-export-builtin/input.js

@@ -0,0 +1 @@
+export { Object };

packages/babel-parser/test/fixtures/core/scope/undecl-export-builtin/options.json

@@ -0,0 +1,4 @@
+{
+  "sourceType": "module",
+  "throws": "Export 'Object' is not defined (1:9)"
+}

packages/babel-parser/test/fixtures/core/scope/undecl-export-if/input.js

@@ -0,0 +1,2 @@
+export { encrypt };
+if (true) function encrypt() {}

packages/babel-parser/test/fixtures/core/scope/undecl-export-if/options.json

@@ -0,0 +1,4 @@
+{
+  "sourceType": "module",
+  "throws": "In strict mode code, functions can only be declared at top level or inside a block (2:10)"
+}

packages/babel-parser/test/fixtures/core/scope/undecl-export-var/input.js

@@ -0,0 +1,4 @@
+{
+  var encrypt
+}
+export { encrypt }

packages/babel-parser/test/fixtures/core/scope/undecl-export-var/options.json

@@ -0,0 +1,3 @@
+{
+  "sourceType": "module"
+}