Merge branch 'master' into ownJsonParsing

Author: sheetalkamat

src/compiler/binder.ts

@@ -2333,7 +2333,7 @@ namespace ts {
             // A common practice in node modules is to set 'export = module.exports = {}', this ensures that 'exports'
             // is still pointing to 'module.exports'.
             // We do not want to consider this as 'export=' since a module can have only one of these.
-            // Similarlly we do not want to treat 'module.exports = exports' as an 'export='.
+            // Similarly we do not want to treat 'module.exports = exports' as an 'export='.
             const assignedExpression = getRightMostAssignedExpression(node.right);
             if (isEmptyObjectLiteral(assignedExpression) || isExportsOrModuleExportsOrAlias(assignedExpression)) {
                 // Mark it as a module in case there are no other exports in the file
@@ -2741,6 +2741,10 @@ namespace ts {
             transformFlags |= TransformFlags.AssertES2015;
         }
 
+        if (expression.kind === SyntaxKind.ImportKeyword) {
+            transformFlags |= TransformFlags.ContainsDynamicImport;
+        }
+
         node.transformFlags = transformFlags | TransformFlags.HasComputedFlags;
         return transformFlags & ~TransformFlags.ArrayLiteralOrCallOrNewExcludes;
     }

src/compiler/checker.ts

@@ -8372,6 +8372,12 @@ namespace ts {
         /**
          * This is *not* a bi-directional relationship.
          * If one needs to check both directions for comparability, use a second call to this function or 'checkTypeComparableTo'.
+         *
+         * A type S is comparable to a type T if some (but not necessarily all) of the possible values of S are also possible values of T.
+         * It is used to check following cases:
+         *   - the types of the left and right sides of equality/inequality operators (`===`, `!==`, `==`, `!=`).
+         *   - the types of `case` clause expressions and their respective `switch` expressions.
+         *   - the type of an expression in a type assertion with the type being asserted.
          */
         function isTypeComparableTo(source: Type, target: Type): boolean {
             return isTypeRelatedTo(source, target, comparableRelation);
@@ -8599,6 +8605,7 @@ namespace ts {
 
         function isEmptyObjectType(type: Type): boolean {
             return type.flags & TypeFlags.Object ? isEmptyResolvedType(resolveStructuredTypeMembers(<ObjectType>type)) :
+                type.flags & TypeFlags.NonPrimitive ? true :
                 type.flags & TypeFlags.Union ? forEach((<UnionType>type).types, isEmptyObjectType) :
                 type.flags & TypeFlags.Intersection ? !forEach((<UnionType>type).types, t => !isEmptyObjectType(t)) :
                 false;
@@ -16179,6 +16186,35 @@ namespace ts {
             return getReturnTypeOfSignature(signature);
         }
 
+        function checkImportCallExpression(node: ImportCall): Type {
+            // Check grammar of dynamic import
+            checkGrammarArguments(node, node.arguments) || checkGrammarImportCallExpression(node);
+
+            if (node.arguments.length === 0) {
+                return createPromiseReturnType(node, anyType);
+            }
+            const specifier = node.arguments[0];
+            const specifierType = checkExpressionCached(specifier);
+            // Even though multiple arugments is grammatically incorrect, type-check extra arguments for completion
+            for (let i = 1; i < node.arguments.length; ++i) {
+                checkExpressionCached(node.arguments[i]);
+            }
+
+            if (specifierType.flags & TypeFlags.Undefined || specifierType.flags & TypeFlags.Null || !isTypeAssignableTo(specifierType, stringType)) {
+                error(specifier, Diagnostics.Dynamic_import_s_specifier_must_be_of_type_string_but_here_has_type_0, typeToString(specifierType));
+            }
+
+            // resolveExternalModuleName will return undefined if the moduleReferenceExpression is not a string literal
+            const moduleSymbol = resolveExternalModuleName(node, specifier);
+            if (moduleSymbol) {
+                const esModuleSymbol = resolveESModuleSymbol(moduleSymbol, specifier, /*dontRecursivelyResolve*/ true);
+                if (esModuleSymbol) {
+                    return createPromiseReturnType(node, getTypeOfSymbol(esModuleSymbol));
+                }
+            }
+            return createPromiseReturnType(node, anyType);
+        }
+
         function isCommonJsRequire(node: Node) {
             if (!isRequireCall(node, /*checkArgumentIsStringLiteral*/ true)) {
                 return false;
@@ -16385,14 +16421,18 @@ namespace ts {
             return emptyObjectType;
         }
 
-        function createPromiseReturnType(func: FunctionLikeDeclaration, promisedType: Type) {
+        function createPromiseReturnType(func: FunctionLikeDeclaration | ImportCall, promisedType: Type) {
             const promiseType = createPromiseType(promisedType);
             if (promiseType === emptyObjectType) {
-                error(func, Diagnostics.An_async_function_or_method_must_return_a_Promise_Make_sure_you_have_a_declaration_for_Promise_or_include_ES2015_in_your_lib_option);
+                error(func, isImportCall(func) ?
+                    Diagnostics.A_dynamic_import_call_returns_a_Promise_Make_sure_you_have_a_declaration_for_Promise_or_include_ES2015_in_your_lib_option :
+                    Diagnostics.An_async_function_or_method_must_return_a_Promise_Make_sure_you_have_a_declaration_for_Promise_or_include_ES2015_in_your_lib_option);
                 return unknownType;
             }
             else if (!getGlobalPromiseConstructorSymbol(/*reportErrors*/ true)) {
-                error(func, Diagnostics.An_async_function_or_method_in_ES5_SlashES3_requires_the_Promise_constructor_Make_sure_you_have_a_declaration_for_the_Promise_constructor_or_include_ES2015_in_your_lib_option);
+                error(func, isImportCall(func) ?
+                    Diagnostics.A_dynamic_import_call_in_ES5_SlashES3_requires_the_Promise_constructor_Make_sure_you_have_a_declaration_for_the_Promise_constructor_or_include_ES2015_in_your_lib_option :
+                    Diagnostics.An_async_function_or_method_in_ES5_SlashES3_requires_the_Promise_constructor_Make_sure_you_have_a_declaration_for_the_Promise_constructor_or_include_ES2015_in_your_lib_option);
             }
 
             return promiseType;
@@ -17751,6 +17791,10 @@ namespace ts {
                 case SyntaxKind.ElementAccessExpression:
                     return checkIndexedAccess(<ElementAccessExpression>node);
                 case SyntaxKind.CallExpression:
+                    if ((<CallExpression>node).expression.kind === SyntaxKind.ImportKeyword) {
+                        return checkImportCallExpression(<ImportCall>node);
+                    }
+                    /* falls through */
                 case SyntaxKind.NewExpression:
                     return checkCallExpression(<CallExpression>node);
                 case SyntaxKind.TaggedTemplateExpression:
@@ -24676,6 +24720,27 @@ namespace ts {
             });
             return result;
         }
+
+        function checkGrammarImportCallExpression(node: ImportCall): boolean {
+            if (modulekind === ModuleKind.ES2015) {
+                return grammarErrorOnNode(node, Diagnostics.Dynamic_import_cannot_be_used_when_targeting_ECMAScript_2015_modules);
+            }
+
+            if (node.typeArguments) {
+                return grammarErrorOnNode(node, Diagnostics.Dynamic_import_cannot_have_type_arguments);
+            }
+
+            const arguments = node.arguments;
+            if (arguments.length !== 1) {
+                return grammarErrorOnNode(node, Diagnostics.Dynamic_import_must_have_one_specifier_as_an_argument);
+            }
+
+            // see: parseArgumentOrArrayLiteralElement...we use this function which parse arguments of callExpression to parse specifier for dynamic import.
+            // parseArgumentOrArrayLiteralElement allows spread element to be in an argument list which is not allowed as specifier in dynamic import.
+            if (isSpreadElement(arguments[0])) {
+                return grammarErrorOnNode(arguments[0], Diagnostics.Specifier_of_dynamic_import_cannot_be_spread_element);
+            }
+        }
     }
 
     /** Like 'isDeclarationName', but returns true for LHS of `import { x as y }` or `export { x as y }`. */

src/compiler/commandLineParser.ts

@@ -100,11 +100,12 @@ namespace ts {
                 "umd": ModuleKind.UMD,
                 "es6": ModuleKind.ES2015,
                 "es2015": ModuleKind.ES2015,
+                "esnext": ModuleKind.ESNext
             }),
             paramType: Diagnostics.KIND,
             showInSimplifiedHelpView: true,
             category: Diagnostics.Basic_Options,
-            description: Diagnostics.Specify_module_code_generation_Colon_commonjs_amd_system_umd_or_es2015,
+            description: Diagnostics.Specify_module_code_generation_Colon_commonjs_amd_system_umd_es2015_or_ESNext,
         },
         {
             name: "lib",

src/compiler/diagnosticMessages.json

@@ -883,14 +883,31 @@
         "category": "Error",
         "code": 1322
     },
-    "String literal with double quotes expected.": {
+    "Dynamic import cannot be used when targeting ECMAScript 2015 modules.": {
         "category": "Error",
         "code": 1323
     },
-    "Property value can only be string literal, numeric literal, 'true', 'false', 'null', object literal or array literal.": {
+    "Dynamic import must have one specifier as an argument.": {
         "category": "Error",
         "code": 1324
     },
+    "Specifier of dynamic import cannot be spread element.": {
+        "category": "Error",
+        "code": 1325
+    },
+    "Dynamic import cannot have type arguments": {
+        "category": "Error",
+        "code": 1326
+    },
+    "String literal with double quotes expected.": {
+        "category": "Error",
+        "code": 1327
+    },
+    "Property value can only be string literal, numeric literal, 'true', 'false', 'null', object literal or array literal.": {
+        "category": "Error",
+        "code": 1328
+    },
+
     "Duplicate identifier '{0}'.": {
         "category": "Error",
         "code": 2300
@@ -1935,10 +1952,6 @@
         "category": "Error",
         "code": 2649
     },
-    "Cannot emit namespaced JSX elements in React.": {
-        "category": "Error",
-        "code": 2650
-    },
     "A member initializer in a enum declaration cannot reference members declared after it, including members defined in other enums.": {
         "category": "Error",
         "code": 2651
@@ -2171,6 +2184,14 @@
         "category": "Error",
         "code": 2710
     },
+    "A dynamic import call returns a 'Promise'. Make sure you have a declaration for 'Promise' or include 'ES2015' in your `--lib` option.": {
+        "category": "Error",
+        "code": 2711
+    },
+    "A dynamic import call in ES5/ES3 requires the 'Promise' constructor.  Make sure you have a declaration for the 'Promise' constructor or include 'ES2015' in your `--lib` option.": {
+        "category": "Error",
+        "code": 2712
+    },
 
     "Import declaration '{0}' is using private name '{1}'.": {
         "category": "Error",
@@ -2637,7 +2658,7 @@
         "category": "Message",
         "code": 6015
     },
-    "Specify module code generation: 'commonjs', 'amd', 'system', 'umd' or 'es2015'.": {
+    "Specify module code generation: 'commonjs', 'amd', 'system', 'umd', 'es2015', or 'ESNext'.": {
         "category": "Message",
         "code": 6016
     },
@@ -3373,6 +3394,11 @@
         "category": "Error",
         "code": 7035
     },
+    "Dynamic import's specifier must be of type 'string', but here has type '{0}'.": {
+        "category": "Error",
+        "code": 7036
+    },
+
     "You cannot rename this element.": {
         "category": "Error",
         "code": 8000
@@ -3603,7 +3629,7 @@
         "category": "Message",
         "code": 90024
     },
-    
+
     "Convert function to an ES2015 class": {
         "category": "Message",
         "code": 95001

src/compiler/emitter.ts

@@ -740,6 +740,7 @@ namespace ts {
                 case SyntaxKind.SuperKeyword:
                 case SyntaxKind.TrueKeyword:
                 case SyntaxKind.ThisKeyword:
+                case SyntaxKind.ImportKeyword:
                     writeTokenNode(node);
                     return;
 

src/compiler/factory.ts

@@ -2495,8 +2495,9 @@ namespace ts {
             helpers
         } = sourceEmitNode;
         if (!destEmitNode) destEmitNode = {};
-        if (leadingComments) destEmitNode.leadingComments = concatenate(leadingComments, destEmitNode.leadingComments);
-        if (trailingComments) destEmitNode.trailingComments = concatenate(trailingComments, destEmitNode.trailingComments);
+        // We are using `.slice()` here in case `destEmitNode.leadingComments` is pushed to later.
+        if (leadingComments) destEmitNode.leadingComments = addRange(leadingComments.slice(), destEmitNode.leadingComments);
+        if (trailingComments) destEmitNode.trailingComments = addRange(trailingComments.slice(), destEmitNode.trailingComments);
         if (flags) destEmitNode.flags = flags;
         if (commentRange) destEmitNode.commentRange = commentRange;
         if (sourceMapRange) destEmitNode.sourceMapRange = sourceMapRange;