Add support for import.meta in System modules (microsoft#32797)

Author: rbuckton

src/compiler/checker.ts

@@ -23161,8 +23161,8 @@ namespace ts {
         }
 
         function checkImportMetaProperty(node: MetaProperty) {
-            if (languageVersion < ScriptTarget.ESNext || moduleKind < ModuleKind.ESNext) {
-                error(node, Diagnostics.The_import_meta_meta_property_is_only_allowed_using_ESNext_for_the_target_and_module_compiler_options);
+            if (moduleKind !== ModuleKind.ESNext && moduleKind !== ModuleKind.System) {
+                error(node, Diagnostics.The_import_meta_meta_property_is_only_allowed_when_the_module_option_is_esnext_or_system);
             }
             const file = getSourceFileOfNode(node);
             Debug.assert(!!(file.flags & NodeFlags.PossiblyContainsImportMeta), "Containing file is missing import meta node flag.");

src/compiler/diagnosticMessages.json

@@ -979,7 +979,7 @@
         "category": "Error",
         "code": 1342
     },
-    "The 'import.meta' meta-property is only allowed using 'ESNext' for the 'target' and 'module' compiler options.": {
+    "The 'import.meta' meta-property is only allowed when the '--module' option is 'esnext' or 'system'.": {
         "category": "Error",
         "code": 1343
     },

src/compiler/transformers/module/system.ts

@@ -24,12 +24,14 @@ namespace ts {
         context.enableSubstitution(SyntaxKind.BinaryExpression); // Substitutes assignments to exported symbols.
         context.enableSubstitution(SyntaxKind.PrefixUnaryExpression); // Substitutes updates to exported symbols.
         context.enableSubstitution(SyntaxKind.PostfixUnaryExpression); // Substitutes updates to exported symbols.
+        context.enableSubstitution(SyntaxKind.MetaProperty); // Substitutes 'import.meta'
         context.enableEmitNotification(SyntaxKind.SourceFile); // Restore state when substituting nodes in a file.
 
         const moduleInfoMap: ExternalModuleInfo[] = []; // The ExternalModuleInfo for each file.
         const deferredExports: (Statement[] | undefined)[] = []; // Exports to defer until an EndOfDeclarationMarker is found.
         const exportFunctionsMap: Identifier[] = []; // The export function associated with a source file.
         const noSubstitutionMap: boolean[][] = []; // Set of nodes for which substitution rules should be ignored for each file.
+        const contextObjectMap: Identifier[] = []; // The context object associated with a source file.
 
         let currentSourceFile: SourceFile; // The current file.
         let moduleInfo: ExternalModuleInfo; // ExternalModuleInfo for the current file.
@@ -75,7 +77,7 @@ namespace ts {
             // existing identifiers.
             exportFunction = createUniqueName("exports");
             exportFunctionsMap[id] = exportFunction;
-            contextObject = createUniqueName("context");
+            contextObject = contextObjectMap[id] = createUniqueName("context");
 
             // Add the body of the module.
             const dependencyGroups = collectDependencyGroups(moduleInfo.externalImports);
@@ -1586,6 +1588,7 @@ namespace ts {
                 moduleInfo = moduleInfoMap[id];
                 exportFunction = exportFunctionsMap[id];
                 noSubstitution = noSubstitutionMap[id];
+                contextObject = contextObjectMap[id];
 
                 if (noSubstitution) {
                     delete noSubstitutionMap[id];
@@ -1596,6 +1599,7 @@ namespace ts {
                 currentSourceFile = undefined!;
                 moduleInfo = undefined!;
                 exportFunction = undefined!;
+                contextObject = undefined!;
                 noSubstitution = undefined;
             }
             else {
@@ -1641,6 +1645,7 @@ namespace ts {
             }
             return node;
         }
+
         /**
          * Substitution for a ShorthandPropertyAssignment whose name that may contain an imported or exported symbol.
          *
@@ -1694,6 +1699,8 @@ namespace ts {
                 case SyntaxKind.PrefixUnaryExpression:
                 case SyntaxKind.PostfixUnaryExpression:
                     return substituteUnaryExpression(<PrefixUnaryExpression | PostfixUnaryExpression>node);
+                case SyntaxKind.MetaProperty:
+                    return substituteMetaProperty(<MetaProperty>node);
             }
 
             return node;
@@ -1830,6 +1837,13 @@ namespace ts {
             return node;
         }
 
+        function substituteMetaProperty(node: MetaProperty) {
+            if (isImportMeta(node)) {
+                return createPropertyAccess(contextObject, createIdentifier("meta"));
+            }
+            return node;
+        }
+
         /**
          * Gets the exports of a name.
          *

src/compiler/types.ts

@@ -1864,6 +1864,12 @@ namespace ts {
         name: Identifier;
     }
 
+    /* @internal */
+    export interface ImportMetaProperty extends MetaProperty {
+        keywordToken: SyntaxKind.ImportKeyword;
+        name: Identifier & { escapedText: __String & "meta" };
+    }
+
     /// A JSX expression of the form <TagName attrs>...</TagName>
     export interface JsxElement extends PrimaryExpression {
         kind: SyntaxKind.JsxElement;

src/compiler/utilities.ts

@@ -987,6 +987,12 @@ namespace ts {
         return n.kind === SyntaxKind.CallExpression && (<CallExpression>n).expression.kind === SyntaxKind.ImportKeyword;
     }
 
+    export function isImportMeta(n: Node): n is ImportMetaProperty {
+        return isMetaProperty(n)
+            && n.keywordToken === SyntaxKind.ImportKeyword
+            && n.name.escapedText === "meta";
+    }
+
     export function isLiteralImportTypeNode(n: Node): n is LiteralImportTypeNode {
         return isImportTypeNode(n) && isLiteralTypeNode(n.argument) && isStringLiteral(n.argument.literal);
     }

tests/baselines/reference/importMetaES5.errors.txt renamed to tests/baselines/reference/importMeta(module=commonjs,target=es5).errors.txt

@@ -1,26 +1,26 @@
 error TS2468: Cannot find global value 'Promise'.
-tests/cases/conformance/es2019/importMeta/assignmentTargets.ts(1,32): error TS1343: The 'import.meta' meta-property is only allowed using 'ESNext' for the 'target' and 'module' compiler options.
+tests/cases/conformance/es2019/importMeta/assignmentTargets.ts(1,32): error TS1343: The 'import.meta' meta-property is only allowed when the '--module' option is 'esnext' or 'system'.
 tests/cases/conformance/es2019/importMeta/assignmentTargets.ts(1,44): error TS2339: Property 'blah' does not exist on type 'ImportMeta'.
-tests/cases/conformance/es2019/importMeta/assignmentTargets.ts(1,51): error TS1343: The 'import.meta' meta-property is only allowed using 'ESNext' for the 'target' and 'module' compiler options.
+tests/cases/conformance/es2019/importMeta/assignmentTargets.ts(1,51): error TS1343: The 'import.meta' meta-property is only allowed when the '--module' option is 'esnext' or 'system'.
 tests/cases/conformance/es2019/importMeta/assignmentTargets.ts(1,63): error TS2339: Property 'blue' does not exist on type 'ImportMeta'.
-tests/cases/conformance/es2019/importMeta/assignmentTargets.ts(1,70): error TS1343: The 'import.meta' meta-property is only allowed using 'ESNext' for the 'target' and 'module' compiler options.
-tests/cases/conformance/es2019/importMeta/assignmentTargets.ts(2,1): error TS1343: The 'import.meta' meta-property is only allowed using 'ESNext' for the 'target' and 'module' compiler options.
+tests/cases/conformance/es2019/importMeta/assignmentTargets.ts(1,70): error TS1343: The 'import.meta' meta-property is only allowed when the '--module' option is 'esnext' or 'system'.
+tests/cases/conformance/es2019/importMeta/assignmentTargets.ts(2,1): error TS1343: The 'import.meta' meta-property is only allowed when the '--module' option is 'esnext' or 'system'.
 tests/cases/conformance/es2019/importMeta/assignmentTargets.ts(2,1): error TS2364: The left-hand side of an assignment expression must be a variable or a property access.
-tests/cases/conformance/es2019/importMeta/assignmentTargets.ts(11,21): error TS1343: The 'import.meta' meta-property is only allowed using 'ESNext' for the 'target' and 'module' compiler options.
+tests/cases/conformance/es2019/importMeta/assignmentTargets.ts(11,21): error TS1343: The 'import.meta' meta-property is only allowed when the '--module' option is 'esnext' or 'system'.
 tests/cases/conformance/es2019/importMeta/example.ts(2,2): error TS2705: An async function or method in ES5/ES3 requires the 'Promise' constructor.  Make sure you have a declaration for the 'Promise' constructor or include 'ES2015' in your `--lib` option.
-tests/cases/conformance/es2019/importMeta/example.ts(3,59): error TS1343: The 'import.meta' meta-property is only allowed using 'ESNext' for the 'target' and 'module' compiler options.
+tests/cases/conformance/es2019/importMeta/example.ts(3,59): error TS1343: The 'import.meta' meta-property is only allowed when the '--module' option is 'esnext' or 'system'.
 tests/cases/conformance/es2019/importMeta/example.ts(3,71): error TS2339: Property 'url' does not exist on type 'ImportMeta'.
-tests/cases/conformance/es2019/importMeta/example.ts(6,16): error TS1343: The 'import.meta' meta-property is only allowed using 'ESNext' for the 'target' and 'module' compiler options.
+tests/cases/conformance/es2019/importMeta/example.ts(6,16): error TS1343: The 'import.meta' meta-property is only allowed when the '--module' option is 'esnext' or 'system'.
 tests/cases/conformance/es2019/importMeta/example.ts(6,28): error TS2339: Property 'scriptElement' does not exist on type 'ImportMeta'.
-tests/cases/conformance/es2019/importMeta/moduleLookingFile01.ts(1,16): error TS1343: The 'import.meta' meta-property is only allowed using 'ESNext' for the 'target' and 'module' compiler options.
-tests/cases/conformance/es2019/importMeta/moduleLookingFile01.ts(2,16): error TS1343: The 'import.meta' meta-property is only allowed using 'ESNext' for the 'target' and 'module' compiler options.
+tests/cases/conformance/es2019/importMeta/moduleLookingFile01.ts(1,16): error TS1343: The 'import.meta' meta-property is only allowed when the '--module' option is 'esnext' or 'system'.
+tests/cases/conformance/es2019/importMeta/moduleLookingFile01.ts(2,16): error TS1343: The 'import.meta' meta-property is only allowed when the '--module' option is 'esnext' or 'system'.
 tests/cases/conformance/es2019/importMeta/moduleLookingFile01.ts(2,23): error TS17012: 'metal' is not a valid meta-property for keyword 'import'. Did you mean 'meta'?
-tests/cases/conformance/es2019/importMeta/moduleLookingFile01.ts(3,16): error TS1343: The 'import.meta' meta-property is only allowed using 'ESNext' for the 'target' and 'module' compiler options.
+tests/cases/conformance/es2019/importMeta/moduleLookingFile01.ts(3,16): error TS1343: The 'import.meta' meta-property is only allowed when the '--module' option is 'esnext' or 'system'.
 tests/cases/conformance/es2019/importMeta/moduleLookingFile01.ts(3,23): error TS17012: 'import' is not a valid meta-property for keyword 'import'. Did you mean 'meta'?
-tests/cases/conformance/es2019/importMeta/scriptLookingFile01.ts(1,15): error TS1343: The 'import.meta' meta-property is only allowed using 'ESNext' for the 'target' and 'module' compiler options.
-tests/cases/conformance/es2019/importMeta/scriptLookingFile01.ts(2,15): error TS1343: The 'import.meta' meta-property is only allowed using 'ESNext' for the 'target' and 'module' compiler options.
+tests/cases/conformance/es2019/importMeta/scriptLookingFile01.ts(1,15): error TS1343: The 'import.meta' meta-property is only allowed when the '--module' option is 'esnext' or 'system'.
+tests/cases/conformance/es2019/importMeta/scriptLookingFile01.ts(2,15): error TS1343: The 'import.meta' meta-property is only allowed when the '--module' option is 'esnext' or 'system'.
 tests/cases/conformance/es2019/importMeta/scriptLookingFile01.ts(2,22): error TS17012: 'metal' is not a valid meta-property for keyword 'import'. Did you mean 'meta'?
-tests/cases/conformance/es2019/importMeta/scriptLookingFile01.ts(3,15): error TS1343: The 'import.meta' meta-property is only allowed using 'ESNext' for the 'target' and 'module' compiler options.
+tests/cases/conformance/es2019/importMeta/scriptLookingFile01.ts(3,15): error TS1343: The 'import.meta' meta-property is only allowed when the '--module' option is 'esnext' or 'system'.
 tests/cases/conformance/es2019/importMeta/scriptLookingFile01.ts(3,22): error TS17012: 'import' is not a valid meta-property for keyword 'import'. Did you mean 'meta'?
 
 
@@ -32,14 +32,14 @@ tests/cases/conformance/es2019/importMeta/scriptLookingFile01.ts(3,22): error TS
 !!! error TS2705: An async function or method in ES5/ES3 requires the 'Promise' constructor.  Make sure you have a declaration for the 'Promise' constructor or include 'ES2015' in your `--lib` option.
       const response = await fetch(new URL("../hamsters.jpg", import.meta.url).toString());
                                                               ~~~~~~~~~~~
-!!! error TS1343: The 'import.meta' meta-property is only allowed using 'ESNext' for the 'target' and 'module' compiler options.
+!!! error TS1343: The 'import.meta' meta-property is only allowed when the '--module' option is 'esnext' or 'system'.
                                                                           ~~~
 !!! error TS2339: Property 'url' does not exist on type 'ImportMeta'.
       const blob = await response.blob();
 
       const size = import.meta.scriptElement.dataset.size || 300;
                    ~~~~~~~~~~~
-!!! error TS1343: The 'import.meta' meta-property is only allowed using 'ESNext' for the 'target' and 'module' compiler options.
+!!! error TS1343: The 'import.meta' meta-property is only allowed when the '--module' option is 'esnext' or 'system'.
                                ~~~~~~~~~~~~~
 !!! error TS2339: Property 'scriptElement' does not exist on type 'ImportMeta'.
 
@@ -53,48 +53,48 @@ tests/cases/conformance/es2019/importMeta/scriptLookingFile01.ts(3,22): error TS
 ==== tests/cases/conformance/es2019/importMeta/moduleLookingFile01.ts (5 errors) ====
     export let x = import.meta;
                    ~~~~~~~~~~~
-!!! error TS1343: The 'import.meta' meta-property is only allowed using 'ESNext' for the 'target' and 'module' compiler options.
+!!! error TS1343: The 'import.meta' meta-property is only allowed when the '--module' option is 'esnext' or 'system'.
     export let y = import.metal;
                    ~~~~~~~~~~~~
-!!! error TS1343: The 'import.meta' meta-property is only allowed using 'ESNext' for the 'target' and 'module' compiler options.
+!!! error TS1343: The 'import.meta' meta-property is only allowed when the '--module' option is 'esnext' or 'system'.
                           ~~~~~
 !!! error TS17012: 'metal' is not a valid meta-property for keyword 'import'. Did you mean 'meta'?
     export let z = import.import.import.malkovich;
                    ~~~~~~~~~~~~~
-!!! error TS1343: The 'import.meta' meta-property is only allowed using 'ESNext' for the 'target' and 'module' compiler options.
+!!! error TS1343: The 'import.meta' meta-property is only allowed when the '--module' option is 'esnext' or 'system'.
                           ~~~~~~
 !!! error TS17012: 'import' is not a valid meta-property for keyword 'import'. Did you mean 'meta'?
 
 ==== tests/cases/conformance/es2019/importMeta/scriptLookingFile01.ts (5 errors) ====
     let globalA = import.meta;
                   ~~~~~~~~~~~
-!!! error TS1343: The 'import.meta' meta-property is only allowed using 'ESNext' for the 'target' and 'module' compiler options.
+!!! error TS1343: The 'import.meta' meta-property is only allowed when the '--module' option is 'esnext' or 'system'.
     let globalB = import.metal;
                   ~~~~~~~~~~~~
-!!! error TS1343: The 'import.meta' meta-property is only allowed using 'ESNext' for the 'target' and 'module' compiler options.
+!!! error TS1343: The 'import.meta' meta-property is only allowed when the '--module' option is 'esnext' or 'system'.
                          ~~~~~
 !!! error TS17012: 'metal' is not a valid meta-property for keyword 'import'. Did you mean 'meta'?
     let globalC = import.import.import.malkovich;
                   ~~~~~~~~~~~~~
-!!! error TS1343: The 'import.meta' meta-property is only allowed using 'ESNext' for the 'target' and 'module' compiler options.
+!!! error TS1343: The 'import.meta' meta-property is only allowed when the '--module' option is 'esnext' or 'system'.
                          ~~~~~~
 !!! error TS17012: 'import' is not a valid meta-property for keyword 'import'. Did you mean 'meta'?
 
 ==== tests/cases/conformance/es2019/importMeta/assignmentTargets.ts (8 errors) ====
     export const foo: ImportMeta = import.meta.blah = import.meta.blue = import.meta;
                                    ~~~~~~~~~~~
-!!! error TS1343: The 'import.meta' meta-property is only allowed using 'ESNext' for the 'target' and 'module' compiler options.
+!!! error TS1343: The 'import.meta' meta-property is only allowed when the '--module' option is 'esnext' or 'system'.
                                                ~~~~
 !!! error TS2339: Property 'blah' does not exist on type 'ImportMeta'.
                                                       ~~~~~~~~~~~
-!!! error TS1343: The 'import.meta' meta-property is only allowed using 'ESNext' for the 'target' and 'module' compiler options.
+!!! error TS1343: The 'import.meta' meta-property is only allowed when the '--module' option is 'esnext' or 'system'.
                                                                   ~~~~
 !!! error TS2339: Property 'blue' does not exist on type 'ImportMeta'.
                                                                          ~~~~~~~~~~~
-!!! error TS1343: The 'import.meta' meta-property is only allowed using 'ESNext' for the 'target' and 'module' compiler options.
+!!! error TS1343: The 'import.meta' meta-property is only allowed when the '--module' option is 'esnext' or 'system'.
     import.meta = foo;
     ~~~~~~~~~~~
-!!! error TS1343: The 'import.meta' meta-property is only allowed using 'ESNext' for the 'target' and 'module' compiler options.
+!!! error TS1343: The 'import.meta' meta-property is only allowed when the '--module' option is 'esnext' or 'system'.
     ~~~~~~~~~~~
 !!! error TS2364: The left-hand side of an assignment expression must be a variable or a property access.
 
@@ -107,4 +107,4 @@ tests/cases/conformance/es2019/importMeta/scriptLookingFile01.ts(3,22): error TS
 
     const { a, b, c } = import.meta.wellKnownProperty;
                         ~~~~~~~~~~~
-!!! error TS1343: The 'import.meta' meta-property is only allowed using 'ESNext' for the 'target' and 'module' compiler options.
+!!! error TS1343: The 'import.meta' meta-property is only allowed when the '--module' option is 'esnext' or 'system'.

tests/baselines/reference/importMetaES5.js renamed to tests/baselines/reference/importMeta(module=commonjs,target=es5).js

@@ -1,4 +1,4 @@
-//// [tests/cases/conformance/es2019/importMeta/importMetaES5.ts] ////
+//// [tests/cases/conformance/es2019/importMeta/importMeta.ts] ////
 
 //// [example.ts]
 // Adapted from https://github.com/tc39/proposal-import-meta/tree/c3902a9ffe2e69a7ac42c19d7ea74cbdcea9b7fb#example