Merge pull request #9396 from zhengbli/fix9186

Check getCurrentDirectory availability in getEffectiveTypeRoots

src/compiler/program.ts

@@ -187,8 +187,22 @@ namespace ts {
     const typeReferenceExtensions = [".d.ts"];
 
     function getEffectiveTypeRoots(options: CompilerOptions, host: ModuleResolutionHost) {
-        return options.typeRoots ||
-            map(defaultTypeRoots, d => combinePaths(options.configFilePath ? getDirectoryPath(options.configFilePath) : host.getCurrentDirectory(), d));
+        if (options.typeRoots) {
+            return options.typeRoots;
+        }
+
+        let currentDirectory: string;
+        if (options.configFilePath) {
+            currentDirectory = getDirectoryPath(options.configFilePath);
+        }
+        else if (host.getCurrentDirectory) {
+            currentDirectory = host.getCurrentDirectory();
+        }
+
+        if (!currentDirectory) {
+            return undefined;
+        }
+        return map(defaultTypeRoots, d => combinePaths(currentDirectory, d));
     }
 
     /**
@@ -228,7 +242,7 @@ namespace ts {
         const failedLookupLocations: string[] = [];
 
         // Check primary library paths
-        if (typeRoots.length) {
+        if (typeRoots && typeRoots.length) {
             if (traceEnabled) {
                 trace(host, Diagnostics.Resolving_with_primary_search_path_0, typeRoots.join(", "));
             }
@@ -1046,9 +1060,11 @@ namespace ts {
         let result: string[] = [];
         if (host.directoryExists && host.getDirectories) {
             const typeRoots = getEffectiveTypeRoots(options, host);
-            for (const root of typeRoots) {
-                if (host.directoryExists(root)) {
-                    result = result.concat(host.getDirectories(root));
+            if (typeRoots) {
+                for (const root of typeRoots) {
+                    if (host.directoryExists(root)) {
+                        result = result.concat(host.getDirectories(root));
+                    }
                 }
             }
         }

tests/cases/fourslash/server/typeReferenceOnServer.ts

@@ -0,0 +1,9 @@
+/// <reference path='../fourslash.ts' />
+
+/////// <reference types="foo" />
+////var x: number;
+////x./*1*/
+
+goTo.marker("1");
+verify.not.completionListIsEmpty();
+