Check if imported file is a proper external module

Author: vladima

src/compiler/checker.ts

@@ -976,8 +976,8 @@ namespace ts {
                 }
             }
 
-            let fileName = getResolvedModuleFileName(getSourceFile(location), moduleReferenceLiteral.text);
-            let sourceFile = fileName && host.getSourceFile(fileName);
+            let resolvedModule = getResolvedModule(getSourceFile(location), moduleReferenceLiteral.text);
+            let sourceFile = resolvedModule && host.getSourceFile(resolvedModule.resolvedFileName);
             if (sourceFile) {
                 if (sourceFile.symbol) {
                     return sourceFile.symbol;

src/compiler/diagnosticInformationMap.generated.ts

@@ -427,6 +427,8 @@ namespace ts {
         Cannot_emit_namespaced_JSX_elements_in_React: { code: 2650, category: DiagnosticCategory.Error, key: "Cannot emit namespaced JSX elements in React" },
         A_member_initializer_in_a_enum_declaration_cannot_reference_members_declared_after_it_including_members_defined_in_other_enums: { code: 2651, category: DiagnosticCategory.Error, key: "A member initializer in a enum declaration cannot reference members declared after it, including members defined in other enums." },
         Merged_declaration_0_cannot_include_a_default_export_declaration_Consider_adding_a_separate_export_default_0_declaration_instead: { code: 2652, category: DiagnosticCategory.Error, key: "Merged declaration '{0}' cannot include a default export declaration. Consider adding a separate 'export default {0}' declaration instead." },
+        Proper_external_module_that_carries_external_typings_cannot_contain_tripleslash_references: { code: 2654, category: DiagnosticCategory.Error, key: "Proper external module that carries external typings cannot contain tripleslash references." },
+        Proper_external_module_that_carries_external_typings_should_be_d_ts_file: { code: 2655, category: DiagnosticCategory.Error, key: "Proper external module that carries external typings should be '.d.ts' file." },
         Import_declaration_0_is_using_private_name_1: { code: 4000, category: DiagnosticCategory.Error, key: "Import declaration '{0}' is using private name '{1}'." },
         Type_parameter_0_of_exported_class_has_or_is_using_private_name_1: { code: 4002, category: DiagnosticCategory.Error, key: "Type parameter '{0}' of exported class has or is using private name '{1}'." },
         Type_parameter_0_of_exported_interface_has_or_is_using_private_name_1: { code: 4004, category: DiagnosticCategory.Error, key: "Type parameter '{0}' of exported interface has or is using private name '{1}'." },

src/compiler/diagnosticMessages.json

@@ -1697,6 +1697,14 @@
         "category": "Error",
         "code": 2652
     },
+    "Proper external module that carries external typings cannot contain tripleslash references.": {
+        "category": "Error",
+        "code": 2654
+    },
+    "Proper external module that carries external typings should be '.d.ts' file.": {
+        "category": "Error",
+        "code": 2655
+    },
     "Import declaration '{0}' is using private name '{1}'.": {
         "category": "Error",
         "code": 4000

src/compiler/program.ts

@@ -36,7 +36,7 @@ namespace ts {
         return normalizePath(referencedFileName);
     }
 
-    export function resolveModuleName(moduleName: string, containingFile: string, compilerOptions: CompilerOptions, host: ModuleResolutionHost): ResolvedModule {
+    export function resolveModuleName(moduleName: string, containingFile: string, compilerOptions: CompilerOptions, host: ModuleResolutionHost): ResolvedModuleWithFailedLookupLocations {
         let moduleResolution = compilerOptions.moduleResolution !== undefined 
             ? compilerOptions.moduleResolution
             : compilerOptions.module === ModuleKind.CommonJS ? ModuleResolutionKind.NodeJs : ModuleResolutionKind.Classic;
@@ -47,7 +47,7 @@ namespace ts {
         }
     }
 
-    export function nodeModuleNameResolver(moduleName: string, containingFile: string, host: ModuleResolutionHost): ResolvedModule {
+    export function nodeModuleNameResolver(moduleName: string, containingFile: string, host: ModuleResolutionHost): ResolvedModuleWithFailedLookupLocations {
         let containingDirectory = getDirectoryPath(containingFile);        
 
         if (getRootLength(moduleName) !== 0 || nameStartsWithDotSlashOrDotDotSlash(moduleName)) {
@@ -56,11 +56,13 @@ namespace ts {
             let resolvedFileName = loadNodeModuleFromFile(candidate, /* loadOnlyDts */ false, failedLookupLocations, host);
 
             if (resolvedFileName) {
-                return { resolvedFileName, failedLookupLocations };
+                return { resolvedModule: { resolvedFileName }, failedLookupLocations };
             }
 
             resolvedFileName = loadNodeModuleFromDirectory(candidate, /* loadOnlyDts */ false, failedLookupLocations, host);
-            return { resolvedFileName, failedLookupLocations };
+            return resolvedFileName
+                ? { resolvedModule: { resolvedFileName }, failedLookupLocations }
+                : { resolvedModule: undefined, failedLookupLocations };
         }
         else {
             return loadModuleFromNodeModules(moduleName, containingDirectory, host);
@@ -117,7 +119,7 @@ namespace ts {
         return loadNodeModuleFromFile(combinePaths(candidate, "index"), loadOnlyDts, failedLookupLocation, host);
     }
 
-    function loadModuleFromNodeModules(moduleName: string, directory: string, host: ModuleResolutionHost): ResolvedModule {
+    function loadModuleFromNodeModules(moduleName: string, directory: string, host: ModuleResolutionHost): ResolvedModuleWithFailedLookupLocations {
         let failedLookupLocations: string[] = []; 
         directory = normalizeSlashes(directory);
         while (true) {
@@ -127,12 +129,12 @@ namespace ts {
                 let candidate = normalizePath(combinePaths(nodeModulesFolder, moduleName));
                 let result = loadNodeModuleFromFile(candidate, /* loadOnlyDts */ true, failedLookupLocations, host);
                 if (result) {
-                    return { resolvedFileName: result, failedLookupLocations };
+                    return { resolvedModule: { resolvedFileName: result, shouldBeProperExternalModule: true }, failedLookupLocations };
                 }
 
                 result = loadNodeModuleFromDirectory(candidate, /* loadOnlyDts */ true, failedLookupLocations, host);
                 if (result) {
-                    return { resolvedFileName: result, failedLookupLocations };
+                    return { resolvedModule: { resolvedFileName: result, shouldBeProperExternalModule: true }, failedLookupLocations };
                 }
             }
 
@@ -144,47 +146,19 @@ namespace ts {
             directory = parentPath;
         }
 
-        return { resolvedFileName: undefined, failedLookupLocations };
-    }
-    
-    export function baseUrlModuleNameResolver(moduleName: string, containingFile: string, baseUrl: string, host: ModuleResolutionHost): ResolvedModule {
-        Debug.assert(baseUrl !== undefined);
-        
-        let normalizedModuleName = normalizeSlashes(moduleName);         
-        let basePart = useBaseUrl(moduleName) ? baseUrl : getDirectoryPath(containingFile);        
-        let candidate = normalizePath(combinePaths(basePart, moduleName));
-        
-        let failedLookupLocations: string[] = [];
-        
-        return forEach(supportedExtensions, ext => tryLoadFile(candidate + ext)) || { resolvedFileName: undefined, failedLookupLocations }; 
-        
-        function tryLoadFile(location: string): ResolvedModule {
-            if (host.fileExists(location)) {
-                return { resolvedFileName: location, failedLookupLocations }; 
-            }
-            else {
-                failedLookupLocations.push(location);
-                return undefined;
-            }
-        }
+        return { resolvedModule: undefined, failedLookupLocations };
     }
 
     function nameStartsWithDotSlashOrDotDotSlash(name: string) {
         let i = name.lastIndexOf("./", 1);
         return i === 0 || (i === 1 && name.charCodeAt(0) === CharacterCodes.dot);
     }
-    
-    function useBaseUrl(moduleName: string): boolean {
-        // path is not rooted
-        // module name does not start with './' or '../'
-        return getRootLength(moduleName) === 0 && !nameStartsWithDotSlashOrDotDotSlash(moduleName);
-    }
 
-    export function classicNameResolver(moduleName: string, containingFile: string, compilerOptions: CompilerOptions, host: ModuleResolutionHost): ResolvedModule {
+    export function classicNameResolver(moduleName: string, containingFile: string, compilerOptions: CompilerOptions, host: ModuleResolutionHost): ResolvedModuleWithFailedLookupLocations {
 
         // module names that contain '!' are used to reference resources and are not resolved to actual files on disk
         if (moduleName.indexOf('!') != -1) {
-            return { resolvedFileName: undefined, failedLookupLocations: [] };
+            return { resolvedModule: undefined, failedLookupLocations: [] };
         }
 
         let searchPath = getDirectoryPath(containingFile);
@@ -222,7 +196,9 @@ namespace ts {
             searchPath = parentPath;
         }
 
-        return { resolvedFileName: referencedSourceFile, failedLookupLocations };
+        return referencedSourceFile
+            ? { resolvedModule: { resolvedFileName: referencedSourceFile  }, failedLookupLocations }
+            : { resolvedModule: undefined, failedLookupLocations };
     }
 
     /* @internal */
@@ -372,9 +348,9 @@ namespace ts {
 
         host = host || createCompilerHost(options);
 
-        const resolveModuleNamesWorker =
-            host.resolveModuleNames || 
-            ((moduleNames, containingFile) => map(moduleNames, moduleName => resolveModuleName(moduleName, containingFile, options, host).resolvedFileName));
+        const resolveModuleNamesWorker = host.resolveModuleNames
+            ? ((moduleNames: string[], containingFile: string) => host.resolveModuleNames(moduleNames, containingFile))
+            : ((moduleNames: string[], containingFile: string) => map(moduleNames, moduleName => resolveModuleName(moduleName, containingFile, options, host).resolvedModule));
 
         let filesByName = createFileMap<SourceFile>(fileName => host.getCanonicalFileName(fileName));
 
@@ -494,10 +470,17 @@ namespace ts {
                         let resolutions = resolveModuleNamesWorker(moduleNames, newSourceFile.fileName);
                         // ensure that module resolution results are still correct
                         for (let i = 0; i < moduleNames.length; ++i) {
-                            let oldResolution = getResolvedModuleFileName(oldSourceFile, moduleNames[i]);
-                            if (oldResolution !== resolutions[i]) {
+                            let newResolution = resolutions[i];
+                            let oldResolution = getResolvedModule(oldSourceFile, moduleNames[i]);
+                            let resolutionChanged = oldResolution
+                                ? !newResolution || 
+                                  oldResolution.resolvedFileName !== newResolution.resolvedFileName ||
+                                  !!oldResolution.shouldBeProperExternalModule !== !!newResolution.shouldBeProperExternalModule
+                                : newResolution;
+                                
+                            if (resolutionChanged) {
                                 return false;
-                            }                            
+                            }
                         }
                     }
                     // pass the cache of module resolutions from the old source file
@@ -874,9 +857,23 @@ namespace ts {
                 let resolutions = resolveModuleNamesWorker(moduleNames, file.fileName);
                 for (let i = 0; i < file.imports.length; ++i) {
                     let resolution = resolutions[i];
-                    setResolvedModuleName(file, moduleNames[i], resolution);
+                    setResolvedModule(file, moduleNames[i], resolution);
                     if (resolution && !options.noResolve) {
-                        findModuleSourceFile(resolution, file.imports[i]);
+                        const importedFile = findModuleSourceFile(resolution.resolvedFileName, file.imports[i]);
+                        if (importedFile && resolution.shouldBeProperExternalModule) {
+                            if (!isExternalModule(importedFile)) {
+                                let start = getTokenPosOfNode(file.imports[i], file)
+                                diagnostics.add(createFileDiagnostic(file, start, file.imports[i].end - start, Diagnostics.File_0_is_not_a_module, importedFile.fileName));
+                            }
+                            else if (!fileExtensionIs(importedFile.fileName, ".d.ts")) {
+                                let start = getTokenPosOfNode(file.imports[i], file)
+                                diagnostics.add(createFileDiagnostic(file, start, file.imports[i].end - start, Diagnostics.Proper_external_module_that_carries_external_typings_should_be_d_ts_file));
+                            }
+                            else if (importedFile.referencedFiles.length) {
+                                let firstRef = importedFile.referencedFiles[0];
+                                diagnostics.add(createFileDiagnostic(importedFile, firstRef.pos, firstRef.end - firstRef.pos, Diagnostics.Proper_external_module_that_carries_external_typings_cannot_contain_tripleslash_references));
+                            }
+                        }
                     }
                 }
             }

src/compiler/types.ts

@@ -1284,7 +1284,7 @@ namespace ts {
         // Stores a mapping 'external module reference text' -> 'resolved file name' | undefined
         // It is used to resolve module names in the checker.
         // Content of this fiels should never be used directly - use getResolvedModuleFileName/setResolvedModuleFileName functions instead
-        /* @internal */ resolvedModules: Map<string>;
+        /* @internal */ resolvedModules: Map<ResolvedModule>;
         /* @internal */ imports: LiteralExpression[];
     }
 
@@ -2283,11 +2283,20 @@ namespace ts {
 
     export interface ResolvedModule {
         resolvedFileName: string;
+        /*
+         * Denotes if 'resolvedFileName' should be proper external module:
+         * - be a .d.ts file 
+         * - use top level imports\exports
+         * - don't use tripleslash references
+         */
+        shouldBeProperExternalModule?: boolean;
+    }
+    
+    export interface ResolvedModuleWithFailedLookupLocations {
+        resolvedModule: ResolvedModule;
         failedLookupLocations: string[];
     }
 
-    export type ModuleNameResolver = (moduleName: string, containingFile: string, options: CompilerOptions, host: ModuleResolutionHost) => ResolvedModule;
-
     export interface CompilerHost extends ModuleResolutionHost {
         getSourceFile(fileName: string, languageVersion: ScriptTarget, onError?: (message: string) => void): SourceFile;
         getCancellationToken?(): CancellationToken;
@@ -2305,7 +2314,7 @@ namespace ts {
          * If resolveModuleNames is implemented then implementation for members from ModuleResolutionHost can be just 
          * 'throw new Error("NotImplemented")'  
          */
-        resolveModuleNames?(moduleNames: string[], containingFile: string): string[];
+        resolveModuleNames?(moduleNames: string[], containingFile: string): ResolvedModule[];
     }
 
     export interface TextSpan {

src/compiler/utilities.ts

@@ -99,20 +99,20 @@ namespace ts {
         return true;
     }    
 
-    export function hasResolvedModuleName(sourceFile: SourceFile, moduleNameText: string): boolean {
+    export function hasResolvedModule(sourceFile: SourceFile, moduleNameText: string): boolean {
         return sourceFile.resolvedModules && hasProperty(sourceFile.resolvedModules, moduleNameText);
     }
 
-    export function getResolvedModuleFileName(sourceFile: SourceFile, moduleNameText: string): string {
-        return hasResolvedModuleName(sourceFile, moduleNameText) ? sourceFile.resolvedModules[moduleNameText] : undefined;
+    export function getResolvedModule(sourceFile: SourceFile, moduleNameText: string): ResolvedModule {
+        return hasResolvedModule(sourceFile, moduleNameText) ? sourceFile.resolvedModules[moduleNameText] : undefined;
     }
 
-    export function setResolvedModuleName(sourceFile: SourceFile, moduleNameText: string, resolvedFileName: string): void {
+    export function setResolvedModule(sourceFile: SourceFile, moduleNameText: string, resolvedModule: ResolvedModule): void {
         if (!sourceFile.resolvedModules) {
             sourceFile.resolvedModules = {};
         }
 
-        sourceFile.resolvedModules[moduleNameText] = resolvedFileName;
+        sourceFile.resolvedModules[moduleNameText] = resolvedModule;
     }
 
     // Returns true if this node contains a parse error anywhere underneath it.

src/harness/harnessLanguageService.ts

@@ -225,8 +225,8 @@ module Harness.LanguageService {
                     let imports: ts.Map<string> = {};
                     for (let module of preprocessInfo.importedFiles) {
                         let resolutionInfo = ts.resolveModuleName(module.fileName, fileName, compilerOptions, moduleResolutionHost);
-                        if (resolutionInfo.resolvedFileName) {
-                            imports[module.fileName] = resolutionInfo.resolvedFileName;
+                        if (resolutionInfo.resolvedModule) {
+                            imports[module.fileName] = resolutionInfo.resolvedModule.resolvedFileName;
                         }
                     }
                     return JSON.stringify(imports);