Merge pull request #22167 from Microsoft/requireJson

Resolve the modue names with "modulename.json" to json files when doing node module resolution

Author: sheetalkamat

src/compiler/binder.ts

@@ -281,6 +281,10 @@ namespace ts {
                     return InternalSymbolName.Index;
                 case SyntaxKind.ExportDeclaration:
                     return InternalSymbolName.ExportStar;
+                case SyntaxKind.SourceFile:
+                    // json file should behave as
+                    // module.exports = ...
+                    return InternalSymbolName.ExportEquals;
                 case SyntaxKind.BinaryExpression:
                     if (getSpecialPropertyAssignmentKind(node as BinaryExpression) === SpecialPropertyAssignmentKind.ModuleExports) {
                         // module.exports = ...
@@ -2234,6 +2238,13 @@ namespace ts {
             if (isExternalModule(file)) {
                 bindSourceFileAsExternalModule();
             }
+            else if (isJsonSourceFile(file)) {
+                bindSourceFileAsExternalModule();
+                // Create symbol equivalent for the module.exports = {}
+                const originalSymbol = file.symbol;
+                declareSymbol(file.symbol.exports, file.symbol, file, SymbolFlags.Property, SymbolFlags.All);
+                file.symbol = originalSymbol;
+            }
         }
 
         function bindSourceFileAsExternalModule() {

src/compiler/checker.ts

@@ -2207,7 +2207,7 @@ namespace ts {
             }
 
             // May be an untyped module. If so, ignore resolutionDiagnostic.
-            if (resolvedModule && !extensionIsTypeScript(resolvedModule.extension) && resolutionDiagnostic === undefined || resolutionDiagnostic === Diagnostics.Could_not_find_a_declaration_file_for_module_0_1_implicitly_has_an_any_type) {
+            if (resolvedModule && !resolutionExtensionIsTypeScriptOrJson(resolvedModule.extension) && resolutionDiagnostic === undefined || resolutionDiagnostic === Diagnostics.Could_not_find_a_declaration_file_for_module_0_1_implicitly_has_an_any_type) {
                 if (isForAugmentation) {
                     const diag = Diagnostics.Invalid_module_name_in_augmentation_Module_0_resolves_to_an_untyped_module_at_1_which_cannot_be_augmented;
                     error(errorNode, diag, moduleReference, resolvedModule.resolvedFileName);
@@ -4718,6 +4718,10 @@ namespace ts {
                     return links.type = anyType;
                 }
                 // Handle export default expressions
+                if (isSourceFile(declaration)) {
+                    const jsonSourceFile = cast(declaration, isJsonSourceFile);
+                    return links.type = jsonSourceFile.statements.length ? checkExpression(jsonSourceFile.statements[0].expression) : emptyObjectType;
+                }
                 if (declaration.kind === SyntaxKind.ExportAssignment) {
                     return links.type = checkExpression((<ExportAssignment>declaration).expression);
                 }
@@ -15597,7 +15601,7 @@ namespace ts {
             const contextualType = getApparentTypeOfContextualType(node);
             const contextualTypeHasPattern = contextualType && contextualType.pattern &&
                 (contextualType.pattern.kind === SyntaxKind.ObjectBindingPattern || contextualType.pattern.kind === SyntaxKind.ObjectLiteralExpression);
-            const isInJSFile = isInJavaScriptFile(node);
+            const isInJSFile = isInJavaScriptFile(node) && !isInJsonFile(node);
             const isJSObjectLiteral = !contextualType && isInJSFile;
             let typeFlags: TypeFlags = 0;
             let patternWithComputedProperties = false;