Use NodeFlags to detect nodes in ambient contexts instead of climbing ancestors

src/compiler/binder.ts

@@ -1550,7 +1550,7 @@ namespace ts {
         function setExportContextFlag(node: ModuleDeclaration | SourceFile) {
             // A declaration source file or ambient module declaration that contains no export declarations (but possibly regular
             // declarations with export modifiers) is an export context in which declarations are implicitly exported.
-            if (isInAmbientContext(node) && !hasExportDeclarations(node)) {
+            if (node.flags & NodeFlags.Ambient && !hasExportDeclarations(node)) {
                 node.flags |= NodeFlags.ExportContext;
             }
             else {
@@ -1726,7 +1726,7 @@ namespace ts {
                 node.originalKeywordKind >= SyntaxKind.FirstFutureReservedWord &&
                 node.originalKeywordKind <= SyntaxKind.LastFutureReservedWord &&
                 !isIdentifierName(node) &&
-                !isInAmbientContext(node)) {
+                !(node.flags & NodeFlags.Ambient)) {
 
                 // Report error only if there are no parse errors in file
                 if (!file.parseDiagnostics.length) {
@@ -2481,7 +2481,7 @@ namespace ts {
         }
 
         function bindParameter(node: ParameterDeclaration) {
-            if (inStrictMode && !isInAmbientContext(node)) {
+            if (inStrictMode && !(node.flags & NodeFlags.Ambient)) {
                 // It is a SyntaxError if the identifier eval or arguments appears within a FormalParameterList of a
                 // strict mode FunctionLikeDeclaration or FunctionExpression(13.1)
                 checkStrictModeEvalOrArguments(node, node.name);
@@ -2503,7 +2503,7 @@ namespace ts {
         }
 
         function bindFunctionDeclaration(node: FunctionDeclaration) {
-            if (!file.isDeclarationFile && !isInAmbientContext(node)) {
+            if (!file.isDeclarationFile && !(node.flags & NodeFlags.Ambient)) {
                 if (isAsyncFunction(node)) {
                     emitFlags |= NodeFlags.HasAsyncFunctions;
                 }
@@ -2520,7 +2520,7 @@ namespace ts {
         }
 
         function bindFunctionExpression(node: FunctionExpression) {
-            if (!file.isDeclarationFile && !isInAmbientContext(node)) {
+            if (!file.isDeclarationFile && !(node.flags & NodeFlags.Ambient)) {
                 if (isAsyncFunction(node)) {
                     emitFlags |= NodeFlags.HasAsyncFunctions;
                 }
@@ -2534,7 +2534,7 @@ namespace ts {
         }
 
         function bindPropertyOrMethodOrAccessor(node: Declaration, symbolFlags: SymbolFlags, symbolExcludes: SymbolFlags) {
-            if (!file.isDeclarationFile && !isInAmbientContext(node) && isAsyncFunction(node)) {
+            if (!file.isDeclarationFile && !(node.flags & NodeFlags.Ambient) && isAsyncFunction(node)) {
                 emitFlags |= NodeFlags.HasAsyncFunctions;
             }
 
@@ -2583,7 +2583,7 @@ namespace ts {
                     //   On the other side we do want to report errors on non-initialized 'lets' because of TDZ
                     const reportUnreachableCode =
                         !options.allowUnreachableCode &&
-                        !isInAmbientContext(node) &&
+                        !(node.flags & NodeFlags.Ambient) &&
                         (
                             node.kind !== SyntaxKind.VariableStatement ||
                             getCombinedNodeFlags((<VariableStatement>node).declarationList) & NodeFlags.BlockScoped ||

src/compiler/parser.ts

@@ -627,6 +627,7 @@ namespace ts {
         }
 
         export function parseIsolatedEntityName(content: string, languageVersion: ScriptTarget): EntityName {
+            // Choice of `isDeclarationFile` should be arbitrary
             initializeState(content, languageVersion, /*syntaxCursor*/ undefined, ScriptKind.JS);
             // Prime the scanner.
             nextToken();
@@ -639,7 +640,7 @@ namespace ts {
         export function parseJsonText(fileName: string, sourceText: string): JsonSourceFile {
             initializeState(sourceText, ScriptTarget.ES2015, /*syntaxCursor*/ undefined, ScriptKind.JSON);
             // Set source file so that errors will be reported with this file name
-            sourceFile = createSourceFile(fileName, ScriptTarget.ES2015, ScriptKind.JSON);
+            sourceFile = createSourceFile(fileName, ScriptTarget.ES2015, ScriptKind.JSON, /*isDeclaration*/ false);
             const result = <JsonSourceFile>sourceFile;
 
             // Prime the scanner.
@@ -681,7 +682,16 @@ namespace ts {
             identifierCount = 0;
             nodeCount = 0;
 
-            contextFlags = scriptKind === ScriptKind.JS || scriptKind === ScriptKind.JSX || scriptKind === ScriptKind.JSON ? NodeFlags.JavaScriptFile : NodeFlags.None;
+            switch (scriptKind) {
+                case ScriptKind.JS:
+                case ScriptKind.JSX:
+                case ScriptKind.JSON:
+                    contextFlags = NodeFlags.JavaScriptFile;
+                    break;
+                default:
+                    contextFlags = NodeFlags.None;
+                    break;
+            }
             parseErrorBeforeNextFinishedNode = false;
 
             // Initialize and prime the scanner before parsing the source elements.
@@ -705,7 +715,12 @@ namespace ts {
         }
 
         function parseSourceFileWorker(fileName: string, languageVersion: ScriptTarget, setParentNodes: boolean, scriptKind: ScriptKind): SourceFile {
-            sourceFile = createSourceFile(fileName, languageVersion, scriptKind);
+            const isDeclarationFile = isDeclarationFileName(fileName);
+            if (isDeclarationFile) {
+                contextFlags |= NodeFlags.Ambient;
+            }
+
+            sourceFile = createSourceFile(fileName, languageVersion, scriptKind, isDeclarationFile);
             sourceFile.flags = contextFlags;
 
             // Prime the scanner.
@@ -782,7 +797,7 @@ namespace ts {
             }
         }
 
-        function createSourceFile(fileName: string, languageVersion: ScriptTarget, scriptKind: ScriptKind): SourceFile {
+        function createSourceFile(fileName: string, languageVersion: ScriptTarget, scriptKind: ScriptKind, isDeclarationFile: boolean): SourceFile {
             // code from createNode is inlined here so createNode won't have to deal with special case of creating source files
             // this is quite rare comparing to other nodes and createNode should be as fast as possible
             const sourceFile = <SourceFile>new SourceFileConstructor(SyntaxKind.SourceFile, /*pos*/ 0, /* end */ sourceText.length);
@@ -793,7 +808,7 @@ namespace ts {
             sourceFile.languageVersion = languageVersion;
             sourceFile.fileName = normalizePath(fileName);
             sourceFile.languageVariant = getLanguageVariant(scriptKind);
-            sourceFile.isDeclarationFile = fileExtensionIs(sourceFile.fileName, Extension.Dts);
+            sourceFile.isDeclarationFile = isDeclarationFile;
             sourceFile.scriptKind = scriptKind;
 
             return sourceFile;
@@ -5089,6 +5104,18 @@ namespace ts {
             const fullStart = getNodePos();
             const decorators = parseDecorators();
             const modifiers = parseModifiers();
+            if (some(modifiers, m => m.kind === SyntaxKind.DeclareKeyword)) {
+                for (const m of modifiers) {
+                    m.flags |= NodeFlags.Ambient;
+                }
+                return doInsideOfContext(NodeFlags.Ambient, () => parseDeclarationWorker(fullStart, decorators, modifiers));
+            }
+            else {
+                return parseDeclarationWorker(fullStart, decorators, modifiers);
+            }
+        }
+
+        function parseDeclarationWorker(fullStart: number, decorators: NodeArray<Decorator> | undefined, modifiers: NodeArray<Modifier> | undefined): Statement {
             switch (token()) {
                 case SyntaxKind.VarKeyword:
                 case SyntaxKind.LetKeyword:
@@ -5446,8 +5473,8 @@ namespace ts {
             return false;
         }
 
-        function parseDecorators(): NodeArray<Decorator> {
-            let list: Decorator[];
+        function parseDecorators(): NodeArray<Decorator> | undefined {
+            let list: Decorator[] | undefined;
             const listPos = getNodePos();
             while (true) {
                 const decoratorStart = getNodePos();
@@ -6131,7 +6158,7 @@ namespace ts {
         export namespace JSDocParser {
             export function parseJSDocTypeExpressionForTests(content: string, start: number, length: number): { jsDocTypeExpression: JSDocTypeExpression, diagnostics: Diagnostic[] } | undefined {
                 initializeState(content, ScriptTarget.Latest, /*_syntaxCursor:*/ undefined, ScriptKind.JS);
-                sourceFile = createSourceFile("file.js", ScriptTarget.Latest, ScriptKind.JS);
+                sourceFile = createSourceFile("file.js", ScriptTarget.Latest, ScriptKind.JS, /*isDeclarationFile*/ false);
                 scanner.setText(content, start, length);
                 currentToken = scanner.scan();
                 const jsDocTypeExpression = parseJSDocTypeExpression();
@@ -7461,4 +7488,8 @@ namespace ts {
             Value = -1
         }
     }
+
+    function isDeclarationFileName(fileName: string): boolean {
+        return fileExtensionIs(fileName, Extension.Dts);
+    }
 }

src/compiler/types.ts

@@ -451,15 +451,16 @@ namespace ts {
         /* @internal */
         PossiblyContainsDynamicImport = 1 << 19,
         JSDoc =              1 << 20, // If node was parsed inside jsdoc
-        /* @internal */ InWithStatement =    1 << 21, // If any ancestor of node was the `statement` of a WithStatement (not the `expression`)
+        /* @internal */ Ambient =         1 << 21, // If node was inside an ambient context -- a declaration file, or inside something with the `declare` modifier.
+        /* @internal */ InWithStatement = 1 << 22, // If any ancestor of node was the `statement` of a WithStatement (not the `expression`)
 
         BlockScoped = Let | Const,
 
         ReachabilityCheckFlags = HasImplicitReturn | HasExplicitReturn,
         ReachabilityAndEmitFlags = ReachabilityCheckFlags | HasAsyncFunctions,
 
         // Parsing context flags
-        ContextFlags = DisallowInContext | YieldContext | DecoratorContext | AwaitContext | JavaScriptFile | InWithStatement,
+        ContextFlags = DisallowInContext | YieldContext | DecoratorContext | AwaitContext | JavaScriptFile | InWithStatement | Ambient,
 
         // Exclude these flags when parsing a Type
         TypeExcludesFlags = YieldContext | AwaitContext,

src/compiler/utilities.ts

@@ -1718,16 +1718,6 @@ namespace ts {
         return false;
     }
 
-    export function isInAmbientContext(node: Node): boolean {
-        while (node) {
-            if (hasModifier(node, ModifierFlags.Ambient) || (node.kind === SyntaxKind.SourceFile && (node as SourceFile).isDeclarationFile)) {
-                return true;
-            }
-            node = node.parent;
-        }
-        return false;
-    }
-
     // True if the given identifier, string literal, or number literal is the name of a declaration node
     export function isDeclarationName(name: Node): boolean {
         switch (name.kind) {

src/harness/unittests/incrementalParser.ts

@@ -591,7 +591,7 @@ module m3 { }\
             const index = 0;
             const newTextAndChange = withInsert(oldText, index, "declare ");
 
-            compareTrees(oldText, newTextAndChange.text, newTextAndChange.textChangeRange, 3);
+            compareTrees(oldText, newTextAndChange.text, newTextAndChange.textChangeRange, 0);
         });
 
         it("Insert function above arrow function with comment", () => {
@@ -674,7 +674,7 @@ module m3 { }\
             const oldText = ScriptSnapshot.fromString(source);
             const newTextAndChange = withInsert(oldText, 0, "{");
 
-            compareTrees(oldText, newTextAndChange.text, newTextAndChange.textChangeRange, 9);
+            compareTrees(oldText, newTextAndChange.text, newTextAndChange.textChangeRange, 4);
         });
 
         it("Removing block around function declarations", () => {
@@ -683,7 +683,7 @@ module m3 { }\
             const oldText = ScriptSnapshot.fromString(source);
             const newTextAndChange = withDelete(oldText, 0, "{".length);
 
-            compareTrees(oldText, newTextAndChange.text, newTextAndChange.textChangeRange, 9);
+            compareTrees(oldText, newTextAndChange.text, newTextAndChange.textChangeRange, 4);
         });
 
         it("Moving methods from class to object literal", () => {

src/services/breakpoints.ts

@@ -31,7 +31,7 @@ namespace ts.BreakpointResolver {
         }
 
         // Cannot set breakpoint in ambient declarations
-        if (isInAmbientContext(tokenAtLocation)) {
+        if (tokenAtLocation.flags & NodeFlags.Ambient) {
             return undefined;
         }
 

src/services/refactors/extractSymbol.ts

@@ -335,7 +335,7 @@ namespace ts.refactor.extractSymbol {
                 return [createDiagnosticForNode(nodeToCheck, Messages.StatementOrExpressionExpected)];
             }
 
-            if (isInAmbientContext(nodeToCheck)) {
+            if (nodeToCheck.flags & NodeFlags.Ambient) {
                 return [createDiagnosticForNode(nodeToCheck, Messages.CannotExtractAmbientBlock)];
             }
 

src/services/services.ts

@@ -41,6 +41,7 @@ namespace ts {
             kind === SyntaxKind.Identifier ? new IdentifierObject(SyntaxKind.Identifier, pos, end) :
                 new TokenObject(kind, pos, end);
         node.parent = parent;
+        node.flags = parent.flags & NodeFlags.ContextFlags;
         return node;
     }
 

src/services/utilities.ts

@@ -947,7 +947,7 @@ namespace ts {
         if (flags & ModifierFlags.Static) result.push(ScriptElementKindModifier.staticModifier);
         if (flags & ModifierFlags.Abstract) result.push(ScriptElementKindModifier.abstractModifier);
         if (flags & ModifierFlags.Export) result.push(ScriptElementKindModifier.exportedModifier);
-        if (isInAmbientContext(node)) result.push(ScriptElementKindModifier.ambientModifier);
+        if (node.flags & NodeFlags.Ambient) result.push(ScriptElementKindModifier.ambientModifier);
 
         return result.length > 0 ? result.join(",") : ScriptElementKindModifier.none;
     }

tests/baselines/reference/api/tsserverlibrary.d.ts

@@ -408,7 +408,7 @@ declare namespace ts {
         BlockScoped = 3,
         ReachabilityCheckFlags = 384,
         ReachabilityAndEmitFlags = 1408,
-        ContextFlags = 2193408,
+        ContextFlags = 6387712,
         TypeExcludesFlags = 20480,
     }
     enum ModifierFlags {

tests/baselines/reference/api/typescript.d.ts

@@ -408,7 +408,7 @@ declare namespace ts {
         BlockScoped = 3,
         ReachabilityCheckFlags = 384,
         ReachabilityAndEmitFlags = 1408,
-        ContextFlags = 2193408,
+        ContextFlags = 6387712,
         TypeExcludesFlags = 20480,
     }
     enum ModifierFlags {

tests/baselines/reference/parserConstructorDeclaration4.errors.txt

@@ -1,12 +1,9 @@
 tests/cases/conformance/parser/ecmascript5/ConstructorDeclarations/parserConstructorDeclaration4.ts(2,3): error TS1031: 'declare' modifier cannot appear on a class element.
-tests/cases/conformance/parser/ecmascript5/ConstructorDeclarations/parserConstructorDeclaration4.ts(2,25): error TS1183: An implementation cannot be declared in ambient contexts.
 
 
-==== tests/cases/conformance/parser/ecmascript5/ConstructorDeclarations/parserConstructorDeclaration4.ts (2 errors) ====
+==== tests/cases/conformance/parser/ecmascript5/ConstructorDeclarations/parserConstructorDeclaration4.ts (1 errors) ====
     class C {
       declare constructor() { }
       ~~~~~~~
 !!! error TS1031: 'declare' modifier cannot appear on a class element.
-                            ~
-!!! error TS1183: An implementation cannot be declared in ambient contexts.
     }

tests/baselines/reference/parserMemberAccessorDeclaration11.errors.txt

@@ -1,9 +1,12 @@
 tests/cases/conformance/parser/ecmascript5/MemberAccessorDeclarations/parserMemberAccessorDeclaration11.ts(2,5): error TS1031: 'declare' modifier cannot appear on a class element.
+tests/cases/conformance/parser/ecmascript5/MemberAccessorDeclarations/parserMemberAccessorDeclaration11.ts(2,17): error TS2378: A 'get' accessor must return a value.
 
 
-==== tests/cases/conformance/parser/ecmascript5/MemberAccessorDeclarations/parserMemberAccessorDeclaration11.ts (1 errors) ====
+==== tests/cases/conformance/parser/ecmascript5/MemberAccessorDeclarations/parserMemberAccessorDeclaration11.ts (2 errors) ====
     class C {
         declare get Foo() { }
         ~~~~~~~
 !!! error TS1031: 'declare' modifier cannot appear on a class element.
+                    ~~~
+!!! error TS2378: A 'get' accessor must return a value.
     }

tests/baselines/reference/parserMemberFunctionDeclaration5.errors.txt

@@ -1,12 +1,9 @@
 tests/cases/conformance/parser/ecmascript5/MemberFunctionDeclarations/parserMemberFunctionDeclaration5.ts(2,5): error TS1031: 'declare' modifier cannot appear on a class element.
-tests/cases/conformance/parser/ecmascript5/MemberFunctionDeclarations/parserMemberFunctionDeclaration5.ts(2,19): error TS1183: An implementation cannot be declared in ambient contexts.
 
 
-==== tests/cases/conformance/parser/ecmascript5/MemberFunctionDeclarations/parserMemberFunctionDeclaration5.ts (2 errors) ====
+==== tests/cases/conformance/parser/ecmascript5/MemberFunctionDeclarations/parserMemberFunctionDeclaration5.ts (1 errors) ====
     class C {
         declare Foo() { }
         ~~~~~~~
 !!! error TS1031: 'declare' modifier cannot appear on a class element.
-                      ~
-!!! error TS1183: An implementation cannot be declared in ambient contexts.
     }