From 22ba111e661879978b990645d6267fc4180ea1da Mon Sep 17 00:00:00 2001
From: Andy Hanson <anhans@microsoft.com>
Date: Thu, 1 Sep 2016 09:25:20 -0700
Subject: [PATCH 1/4] Search for `node_modules` in parent directories when
 getting type roots.

---
 src/compiler/program.ts                       | 33 +++++++++++++---
 ...peRootsFromNodeModulesInParentDirectory.js | 17 ++++++++
 ...tsFromNodeModulesInParentDirectory.symbols | 14 +++++++
 ...romNodeModulesInParentDirectory.trace.json | 39 +++++++++++++++++++
 ...ootsFromNodeModulesInParentDirectory.types | 14 +++++++
 ...peRootsFromNodeModulesInParentDirectory.ts | 15 +++++++
 6 files changed, 126 insertions(+), 6 deletions(-)
 create mode 100644 tests/baselines/reference/typeRootsFromNodeModulesInParentDirectory.js
 create mode 100644 tests/baselines/reference/typeRootsFromNodeModulesInParentDirectory.symbols
 create mode 100644 tests/baselines/reference/typeRootsFromNodeModulesInParentDirectory.trace.json
 create mode 100644 tests/baselines/reference/typeRootsFromNodeModulesInParentDirectory.types
 create mode 100644 tests/cases/compiler/typeRootsFromNodeModulesInParentDirectory.ts

diff --git a/src/compiler/program.ts b/src/compiler/program.ts
index 49f61981d7260..7a4adf9ff0815 100644
--- a/src/compiler/program.ts
+++ b/src/compiler/program.ts
@@ -8,8 +8,6 @@ namespace ts {
 
     const emptyArray: any[] = [];
 
-    const defaultTypeRoots = ["node_modules/@types"];
-
     export function findConfigFile(searchPath: string, fileExists: (fileName: string) => boolean): string {
         while (true) {
             const fileName = combinePaths(searchPath, "tsconfig.json");
@@ -168,7 +166,7 @@ namespace ts {
 
     const typeReferenceExtensions = [".d.ts"];
 
-    function getEffectiveTypeRoots(options: CompilerOptions, host: ModuleResolutionHost) {
+    function getEffectiveTypeRoots(options: CompilerOptions, host: ModuleResolutionHost): string[] | undefined {
         if (options.typeRoots) {
             return options.typeRoots;
         }
@@ -181,10 +179,33 @@ namespace ts {
             currentDirectory = host.getCurrentDirectory();
         }
 
-        if (!currentDirectory) {
-            return undefined;
+        return currentDirectory && getDefaultTypeRoots(currentDirectory, host);
+    }
+
+    function getDefaultTypeRoots(currentDirectory: string, host: ModuleResolutionHost): string[] | undefined {
+        const nodeModules = getNearestNodeModules(currentDirectory, host);
+        return nodeModules && [combinePaths(nodeModules, "@types")];
+    }
+
+    function getNearestNodeModules(currentDirectory: string, host: ModuleResolutionHost): string | undefined {
+        if (!host.directoryExists) {
+            return combinePaths(currentDirectory, "node_modules");
+            // And if it doesn't exist, tough.
+        }
+
+        while (true) {
+            const nodeModules = combinePaths(currentDirectory, "node_modules");
+            if (host.directoryExists(nodeModules)) {
+                return nodeModules;
+            }
+            else {
+                const parent = getDirectoryPath(currentDirectory);
+                if (parent === currentDirectory) {
+                    return undefined;
+                }
+                currentDirectory = parent;
+            }
         }
-        return map(defaultTypeRoots, d => combinePaths(currentDirectory, d));
     }
 
     /**
diff --git a/tests/baselines/reference/typeRootsFromNodeModulesInParentDirectory.js b/tests/baselines/reference/typeRootsFromNodeModulesInParentDirectory.js
new file mode 100644
index 0000000000000..9e93755d1f096
--- /dev/null
+++ b/tests/baselines/reference/typeRootsFromNodeModulesInParentDirectory.js
@@ -0,0 +1,17 @@
+//// [tests/cases/compiler/typeRootsFromNodeModulesInParentDirectory.ts] ////
+
+//// [index.d.ts]
+
+declare module "xyz" {
+    export const x: number;
+}
+
+//// [a.ts]
+import { x } from "xyz";
+x;
+
+
+//// [a.js]
+"use strict";
+var xyz_1 = require("xyz");
+xyz_1.x;
diff --git a/tests/baselines/reference/typeRootsFromNodeModulesInParentDirectory.symbols b/tests/baselines/reference/typeRootsFromNodeModulesInParentDirectory.symbols
new file mode 100644
index 0000000000000..10cbdaa3c5321
--- /dev/null
+++ b/tests/baselines/reference/typeRootsFromNodeModulesInParentDirectory.symbols
@@ -0,0 +1,14 @@
+=== /src/a.ts ===
+import { x } from "xyz";
+>x : Symbol(x, Decl(a.ts, 0, 8))
+
+x;
+>x : Symbol(x, Decl(a.ts, 0, 8))
+
+=== /node_modules/@types/foo/index.d.ts ===
+
+declare module "xyz" {
+    export const x: number;
+>x : Symbol(x, Decl(index.d.ts, 2, 16))
+}
+
diff --git a/tests/baselines/reference/typeRootsFromNodeModulesInParentDirectory.trace.json b/tests/baselines/reference/typeRootsFromNodeModulesInParentDirectory.trace.json
new file mode 100644
index 0000000000000..7782ffc4ebf86
--- /dev/null
+++ b/tests/baselines/reference/typeRootsFromNodeModulesInParentDirectory.trace.json
@@ -0,0 +1,39 @@
+[
+    "======== Resolving module 'xyz' from '/src/a.ts'. ========",
+    "Module resolution kind is not specified, using 'NodeJs'.",
+    "Loading module 'xyz' from 'node_modules' folder.",
+    "File '/src/node_modules/xyz.ts' does not exist.",
+    "File '/src/node_modules/xyz.tsx' does not exist.",
+    "File '/src/node_modules/xyz.d.ts' does not exist.",
+    "File '/src/node_modules/xyz/package.json' does not exist.",
+    "File '/src/node_modules/xyz/index.ts' does not exist.",
+    "File '/src/node_modules/xyz/index.tsx' does not exist.",
+    "File '/src/node_modules/xyz/index.d.ts' does not exist.",
+    "File '/src/node_modules/@types/xyz.ts' does not exist.",
+    "File '/src/node_modules/@types/xyz.tsx' does not exist.",
+    "File '/src/node_modules/@types/xyz.d.ts' does not exist.",
+    "File '/src/node_modules/@types/xyz/package.json' does not exist.",
+    "File '/src/node_modules/@types/xyz/index.ts' does not exist.",
+    "File '/src/node_modules/@types/xyz/index.tsx' does not exist.",
+    "File '/src/node_modules/@types/xyz/index.d.ts' does not exist.",
+    "File '/node_modules/xyz.ts' does not exist.",
+    "File '/node_modules/xyz.tsx' does not exist.",
+    "File '/node_modules/xyz.d.ts' does not exist.",
+    "File '/node_modules/xyz/package.json' does not exist.",
+    "File '/node_modules/xyz/index.ts' does not exist.",
+    "File '/node_modules/xyz/index.tsx' does not exist.",
+    "File '/node_modules/xyz/index.d.ts' does not exist.",
+    "File '/node_modules/@types/xyz.ts' does not exist.",
+    "File '/node_modules/@types/xyz.tsx' does not exist.",
+    "File '/node_modules/@types/xyz.d.ts' does not exist.",
+    "File '/node_modules/@types/xyz/package.json' does not exist.",
+    "File '/node_modules/@types/xyz/index.ts' does not exist.",
+    "File '/node_modules/@types/xyz/index.tsx' does not exist.",
+    "File '/node_modules/@types/xyz/index.d.ts' does not exist.",
+    "======== Module name 'xyz' was not resolved. ========",
+    "======== Resolving type reference directive 'foo', containing file '/src/__inferred type names__.ts', root directory '/node_modules/@types'. ========",
+    "Resolving with primary search path '/node_modules/@types'",
+    "File '/node_modules/@types/foo/package.json' does not exist.",
+    "File '/node_modules/@types/foo/index.d.ts' exist - use it as a name resolution result.",
+    "======== Type reference directive 'foo' was successfully resolved to '/node_modules/@types/foo/index.d.ts', primary: true. ========"
+]
\ No newline at end of file
diff --git a/tests/baselines/reference/typeRootsFromNodeModulesInParentDirectory.types b/tests/baselines/reference/typeRootsFromNodeModulesInParentDirectory.types
new file mode 100644
index 0000000000000..532a05fcb87c4
--- /dev/null
+++ b/tests/baselines/reference/typeRootsFromNodeModulesInParentDirectory.types
@@ -0,0 +1,14 @@
+=== /src/a.ts ===
+import { x } from "xyz";
+>x : number
+
+x;
+>x : number
+
+=== /node_modules/@types/foo/index.d.ts ===
+
+declare module "xyz" {
+    export const x: number;
+>x : number
+}
+
diff --git a/tests/cases/compiler/typeRootsFromNodeModulesInParentDirectory.ts b/tests/cases/compiler/typeRootsFromNodeModulesInParentDirectory.ts
new file mode 100644
index 0000000000000..59b7d6a3188cb
--- /dev/null
+++ b/tests/cases/compiler/typeRootsFromNodeModulesInParentDirectory.ts
@@ -0,0 +1,15 @@
+// @noImplicitReferences: true
+// @traceResolution: true
+// @currentDirectory: /src
+
+// @Filename: /node_modules/@types/foo/index.d.ts
+declare module "xyz" {
+    export const x: number;
+}
+
+// @Filename: /src/a.ts
+import { x } from "xyz";
+x;
+
+// @Filename: /src/tsconfig.json
+{}

From c5c6acf8831f6fdf866c95880df889223addb579 Mon Sep 17 00:00:00 2001
From: Andy Hanson <anhans@microsoft.com>
Date: Thu, 1 Sep 2016 10:42:32 -0700
Subject: [PATCH 2/4] Update test baselines: We no longer search in
 node_modules/@types if it does not exist.

---
 tests/baselines/reference/library-reference-11.trace.json | 6 ++----
 tests/baselines/reference/library-reference-12.trace.json | 6 ++----
 tests/baselines/reference/library-reference-7.trace.json  | 6 ++----
 3 files changed, 6 insertions(+), 12 deletions(-)

diff --git a/tests/baselines/reference/library-reference-11.trace.json b/tests/baselines/reference/library-reference-11.trace.json
index 365fe3ce72d2c..e0af1e39c5ac8 100644
--- a/tests/baselines/reference/library-reference-11.trace.json
+++ b/tests/baselines/reference/library-reference-11.trace.json
@@ -1,8 +1,6 @@
 [
-    "======== Resolving type reference directive 'jquery', containing file '/a/b/consumer.ts', root directory '/node_modules/@types'. ========",
-    "Resolving with primary search path '/node_modules/@types'",
-    "File '/node_modules/@types/jquery/package.json' does not exist.",
-    "File '/node_modules/@types/jquery/index.d.ts' does not exist.",
+    "======== Resolving type reference directive 'jquery', containing file '/a/b/consumer.ts', root directory not set. ========",
+    "Root directory cannot be determined, skipping primary search paths.",
     "Looking up in 'node_modules' folder, initial location '/a/b'",
     "File '/a/b/node_modules/jquery.ts' does not exist.",
     "File '/a/b/node_modules/jquery.d.ts' does not exist.",
diff --git a/tests/baselines/reference/library-reference-12.trace.json b/tests/baselines/reference/library-reference-12.trace.json
index 84144f82729c6..2cdf1f5f20ace 100644
--- a/tests/baselines/reference/library-reference-12.trace.json
+++ b/tests/baselines/reference/library-reference-12.trace.json
@@ -1,8 +1,6 @@
 [
-    "======== Resolving type reference directive 'jquery', containing file '/a/b/consumer.ts', root directory '/node_modules/@types'. ========",
-    "Resolving with primary search path '/node_modules/@types'",
-    "File '/node_modules/@types/jquery/package.json' does not exist.",
-    "File '/node_modules/@types/jquery/index.d.ts' does not exist.",
+    "======== Resolving type reference directive 'jquery', containing file '/a/b/consumer.ts', root directory not set. ========",
+    "Root directory cannot be determined, skipping primary search paths.",
     "Looking up in 'node_modules' folder, initial location '/a/b'",
     "File '/a/b/node_modules/jquery.ts' does not exist.",
     "File '/a/b/node_modules/jquery.d.ts' does not exist.",
diff --git a/tests/baselines/reference/library-reference-7.trace.json b/tests/baselines/reference/library-reference-7.trace.json
index b681ea312a8bb..419fe6d055d72 100644
--- a/tests/baselines/reference/library-reference-7.trace.json
+++ b/tests/baselines/reference/library-reference-7.trace.json
@@ -1,8 +1,6 @@
 [
-    "======== Resolving type reference directive 'jquery', containing file '/src/consumer.ts', root directory '/node_modules/@types'. ========",
-    "Resolving with primary search path '/node_modules/@types'",
-    "File '/node_modules/@types/jquery/package.json' does not exist.",
-    "File '/node_modules/@types/jquery/index.d.ts' does not exist.",
+    "======== Resolving type reference directive 'jquery', containing file '/src/consumer.ts', root directory not set. ========",
+    "Root directory cannot be determined, skipping primary search paths.",
     "Looking up in 'node_modules' folder, initial location '/src'",
     "File '/src/node_modules/jquery.ts' does not exist.",
     "File '/src/node_modules/jquery.d.ts' does not exist.",

From 0e8e5ec3e5c2b97180bae83ef62ffa4646fa2e06 Mon Sep 17 00:00:00 2001
From: Andy Hanson <anhans@microsoft.com>
Date: Fri, 2 Sep 2016 07:06:13 -0700
Subject: [PATCH 3/4] Search up for all node_modules directories available

---
 src/compiler/program.ts                       |  26 +--
 ...RootsFromMultipleNodeModulesDirectories.js |  31 ++++
 ...FromMultipleNodeModulesDirectories.symbols |  34 ++++
 ...mMultipleNodeModulesDirectories.trace.json | 157 ++++++++++++++++++
 ...tsFromMultipleNodeModulesDirectories.types |  36 ++++
 ...RootsFromMultipleNodeModulesDirectories.ts |  27 +++
 6 files changed, 299 insertions(+), 12 deletions(-)
 create mode 100644 tests/baselines/reference/typeRootsFromMultipleNodeModulesDirectories.js
 create mode 100644 tests/baselines/reference/typeRootsFromMultipleNodeModulesDirectories.symbols
 create mode 100644 tests/baselines/reference/typeRootsFromMultipleNodeModulesDirectories.trace.json
 create mode 100644 tests/baselines/reference/typeRootsFromMultipleNodeModulesDirectories.types
 create mode 100644 tests/cases/compiler/typeRootsFromMultipleNodeModulesDirectories.ts

diff --git a/src/compiler/program.ts b/src/compiler/program.ts
index 7a4adf9ff0815..3cddeb03f38bb 100644
--- a/src/compiler/program.ts
+++ b/src/compiler/program.ts
@@ -183,31 +183,33 @@ namespace ts {
     }
 
     function getDefaultTypeRoots(currentDirectory: string, host: ModuleResolutionHost): string[] | undefined {
-        const nodeModules = getNearestNodeModules(currentDirectory, host);
-        return nodeModules && [combinePaths(nodeModules, "@types")];
+        return map(getAllNodeModulesDirectories(currentDirectory, host), nodeModules => combinePaths(nodeModules, "@types"));
     }
 
-    function getNearestNodeModules(currentDirectory: string, host: ModuleResolutionHost): string | undefined {
+    /** Returns the path to every node_modules directory from some ancestor directory. */
+    function getAllNodeModulesDirectories(currentDirectory: string, host: ModuleResolutionHost): string[] | undefined {
         if (!host.directoryExists) {
-            return combinePaths(currentDirectory, "node_modules");
+            return [combinePaths(currentDirectory, "node_modules")];
             // And if it doesn't exist, tough.
         }
 
+        const all: string[] = [];
+
         while (true) {
             const nodeModules = combinePaths(currentDirectory, "node_modules");
             if (host.directoryExists(nodeModules)) {
-                return nodeModules;
+                all.push(nodeModules);
             }
-            else {
-                const parent = getDirectoryPath(currentDirectory);
-                if (parent === currentDirectory) {
-                    return undefined;
-                }
-                currentDirectory = parent;
+
+            const parent = getDirectoryPath(currentDirectory);
+            if (parent === currentDirectory) {
+                break;
             }
+            currentDirectory = parent;
         }
-    }
 
+        return all;
+    }
     /**
      * @param {string | undefined} containingFile - file that contains type reference directive, can be undefined if containing file is unknown.
      * This is possible in case if resolution is performed for directives specified via 'types' parameter. In this case initial path for secondary lookups
diff --git a/tests/baselines/reference/typeRootsFromMultipleNodeModulesDirectories.js b/tests/baselines/reference/typeRootsFromMultipleNodeModulesDirectories.js
new file mode 100644
index 0000000000000..a2542ca9cc099
--- /dev/null
+++ b/tests/baselines/reference/typeRootsFromMultipleNodeModulesDirectories.js
@@ -0,0 +1,31 @@
+//// [tests/cases/compiler/typeRootsFromMultipleNodeModulesDirectories.ts] ////
+
+//// [index.d.ts]
+
+declare module "xyz" {
+    export const x: number;
+}
+
+//// [index.d.ts]
+declare module "pdq" {
+    export const y: number; 
+}
+
+//// [index.d.ts]
+declare module "abc" {
+    export const z: number;
+}
+
+//// [a.ts]
+import { x } from "xyz";
+import { y } from "pdq";
+import { z } from "abc";
+x + y + z;
+
+
+//// [a.js]
+"use strict";
+var xyz_1 = require("xyz");
+var pdq_1 = require("pdq");
+var abc_1 = require("abc");
+xyz_1.x + pdq_1.y + abc_1.z;
diff --git a/tests/baselines/reference/typeRootsFromMultipleNodeModulesDirectories.symbols b/tests/baselines/reference/typeRootsFromMultipleNodeModulesDirectories.symbols
new file mode 100644
index 0000000000000..67fd371f8ee25
--- /dev/null
+++ b/tests/baselines/reference/typeRootsFromMultipleNodeModulesDirectories.symbols
@@ -0,0 +1,34 @@
+=== /foo/bar/a.ts ===
+import { x } from "xyz";
+>x : Symbol(x, Decl(a.ts, 0, 8))
+
+import { y } from "pdq";
+>y : Symbol(y, Decl(a.ts, 1, 8))
+
+import { z } from "abc";
+>z : Symbol(z, Decl(a.ts, 2, 8))
+
+x + y + z;
+>x : Symbol(x, Decl(a.ts, 0, 8))
+>y : Symbol(y, Decl(a.ts, 1, 8))
+>z : Symbol(z, Decl(a.ts, 2, 8))
+
+=== /node_modules/@types/dopey/index.d.ts ===
+
+declare module "xyz" {
+    export const x: number;
+>x : Symbol(x, Decl(index.d.ts, 2, 16))
+}
+
+=== /foo/node_modules/@types/grumpy/index.d.ts ===
+declare module "pdq" {
+    export const y: number; 
+>y : Symbol(y, Decl(index.d.ts, 1, 16))
+}
+
+=== /foo/node_modules/@types/sneezy/index.d.ts ===
+declare module "abc" {
+    export const z: number;
+>z : Symbol(z, Decl(index.d.ts, 1, 16))
+}
+
diff --git a/tests/baselines/reference/typeRootsFromMultipleNodeModulesDirectories.trace.json b/tests/baselines/reference/typeRootsFromMultipleNodeModulesDirectories.trace.json
new file mode 100644
index 0000000000000..c734e57cda24f
--- /dev/null
+++ b/tests/baselines/reference/typeRootsFromMultipleNodeModulesDirectories.trace.json
@@ -0,0 +1,157 @@
+[
+    "======== Resolving module 'xyz' from '/foo/bar/a.ts'. ========",
+    "Module resolution kind is not specified, using 'NodeJs'.",
+    "Loading module 'xyz' from 'node_modules' folder.",
+    "File '/foo/bar/node_modules/xyz.ts' does not exist.",
+    "File '/foo/bar/node_modules/xyz.tsx' does not exist.",
+    "File '/foo/bar/node_modules/xyz.d.ts' does not exist.",
+    "File '/foo/bar/node_modules/xyz/package.json' does not exist.",
+    "File '/foo/bar/node_modules/xyz/index.ts' does not exist.",
+    "File '/foo/bar/node_modules/xyz/index.tsx' does not exist.",
+    "File '/foo/bar/node_modules/xyz/index.d.ts' does not exist.",
+    "File '/foo/bar/node_modules/@types/xyz.ts' does not exist.",
+    "File '/foo/bar/node_modules/@types/xyz.tsx' does not exist.",
+    "File '/foo/bar/node_modules/@types/xyz.d.ts' does not exist.",
+    "File '/foo/bar/node_modules/@types/xyz/package.json' does not exist.",
+    "File '/foo/bar/node_modules/@types/xyz/index.ts' does not exist.",
+    "File '/foo/bar/node_modules/@types/xyz/index.tsx' does not exist.",
+    "File '/foo/bar/node_modules/@types/xyz/index.d.ts' does not exist.",
+    "File '/foo/node_modules/xyz.ts' does not exist.",
+    "File '/foo/node_modules/xyz.tsx' does not exist.",
+    "File '/foo/node_modules/xyz.d.ts' does not exist.",
+    "File '/foo/node_modules/xyz/package.json' does not exist.",
+    "File '/foo/node_modules/xyz/index.ts' does not exist.",
+    "File '/foo/node_modules/xyz/index.tsx' does not exist.",
+    "File '/foo/node_modules/xyz/index.d.ts' does not exist.",
+    "File '/foo/node_modules/@types/xyz.ts' does not exist.",
+    "File '/foo/node_modules/@types/xyz.tsx' does not exist.",
+    "File '/foo/node_modules/@types/xyz.d.ts' does not exist.",
+    "File '/foo/node_modules/@types/xyz/package.json' does not exist.",
+    "File '/foo/node_modules/@types/xyz/index.ts' does not exist.",
+    "File '/foo/node_modules/@types/xyz/index.tsx' does not exist.",
+    "File '/foo/node_modules/@types/xyz/index.d.ts' does not exist.",
+    "File '/node_modules/xyz.ts' does not exist.",
+    "File '/node_modules/xyz.tsx' does not exist.",
+    "File '/node_modules/xyz.d.ts' does not exist.",
+    "File '/node_modules/xyz/package.json' does not exist.",
+    "File '/node_modules/xyz/index.ts' does not exist.",
+    "File '/node_modules/xyz/index.tsx' does not exist.",
+    "File '/node_modules/xyz/index.d.ts' does not exist.",
+    "File '/node_modules/@types/xyz.ts' does not exist.",
+    "File '/node_modules/@types/xyz.tsx' does not exist.",
+    "File '/node_modules/@types/xyz.d.ts' does not exist.",
+    "File '/node_modules/@types/xyz/package.json' does not exist.",
+    "File '/node_modules/@types/xyz/index.ts' does not exist.",
+    "File '/node_modules/@types/xyz/index.tsx' does not exist.",
+    "File '/node_modules/@types/xyz/index.d.ts' does not exist.",
+    "======== Module name 'xyz' was not resolved. ========",
+    "======== Resolving module 'pdq' from '/foo/bar/a.ts'. ========",
+    "Module resolution kind is not specified, using 'NodeJs'.",
+    "Loading module 'pdq' from 'node_modules' folder.",
+    "File '/foo/bar/node_modules/pdq.ts' does not exist.",
+    "File '/foo/bar/node_modules/pdq.tsx' does not exist.",
+    "File '/foo/bar/node_modules/pdq.d.ts' does not exist.",
+    "File '/foo/bar/node_modules/pdq/package.json' does not exist.",
+    "File '/foo/bar/node_modules/pdq/index.ts' does not exist.",
+    "File '/foo/bar/node_modules/pdq/index.tsx' does not exist.",
+    "File '/foo/bar/node_modules/pdq/index.d.ts' does not exist.",
+    "File '/foo/bar/node_modules/@types/pdq.ts' does not exist.",
+    "File '/foo/bar/node_modules/@types/pdq.tsx' does not exist.",
+    "File '/foo/bar/node_modules/@types/pdq.d.ts' does not exist.",
+    "File '/foo/bar/node_modules/@types/pdq/package.json' does not exist.",
+    "File '/foo/bar/node_modules/@types/pdq/index.ts' does not exist.",
+    "File '/foo/bar/node_modules/@types/pdq/index.tsx' does not exist.",
+    "File '/foo/bar/node_modules/@types/pdq/index.d.ts' does not exist.",
+    "File '/foo/node_modules/pdq.ts' does not exist.",
+    "File '/foo/node_modules/pdq.tsx' does not exist.",
+    "File '/foo/node_modules/pdq.d.ts' does not exist.",
+    "File '/foo/node_modules/pdq/package.json' does not exist.",
+    "File '/foo/node_modules/pdq/index.ts' does not exist.",
+    "File '/foo/node_modules/pdq/index.tsx' does not exist.",
+    "File '/foo/node_modules/pdq/index.d.ts' does not exist.",
+    "File '/foo/node_modules/@types/pdq.ts' does not exist.",
+    "File '/foo/node_modules/@types/pdq.tsx' does not exist.",
+    "File '/foo/node_modules/@types/pdq.d.ts' does not exist.",
+    "File '/foo/node_modules/@types/pdq/package.json' does not exist.",
+    "File '/foo/node_modules/@types/pdq/index.ts' does not exist.",
+    "File '/foo/node_modules/@types/pdq/index.tsx' does not exist.",
+    "File '/foo/node_modules/@types/pdq/index.d.ts' does not exist.",
+    "File '/node_modules/pdq.ts' does not exist.",
+    "File '/node_modules/pdq.tsx' does not exist.",
+    "File '/node_modules/pdq.d.ts' does not exist.",
+    "File '/node_modules/pdq/package.json' does not exist.",
+    "File '/node_modules/pdq/index.ts' does not exist.",
+    "File '/node_modules/pdq/index.tsx' does not exist.",
+    "File '/node_modules/pdq/index.d.ts' does not exist.",
+    "File '/node_modules/@types/pdq.ts' does not exist.",
+    "File '/node_modules/@types/pdq.tsx' does not exist.",
+    "File '/node_modules/@types/pdq.d.ts' does not exist.",
+    "File '/node_modules/@types/pdq/package.json' does not exist.",
+    "File '/node_modules/@types/pdq/index.ts' does not exist.",
+    "File '/node_modules/@types/pdq/index.tsx' does not exist.",
+    "File '/node_modules/@types/pdq/index.d.ts' does not exist.",
+    "======== Module name 'pdq' was not resolved. ========",
+    "======== Resolving module 'abc' from '/foo/bar/a.ts'. ========",
+    "Module resolution kind is not specified, using 'NodeJs'.",
+    "Loading module 'abc' from 'node_modules' folder.",
+    "File '/foo/bar/node_modules/abc.ts' does not exist.",
+    "File '/foo/bar/node_modules/abc.tsx' does not exist.",
+    "File '/foo/bar/node_modules/abc.d.ts' does not exist.",
+    "File '/foo/bar/node_modules/abc/package.json' does not exist.",
+    "File '/foo/bar/node_modules/abc/index.ts' does not exist.",
+    "File '/foo/bar/node_modules/abc/index.tsx' does not exist.",
+    "File '/foo/bar/node_modules/abc/index.d.ts' does not exist.",
+    "File '/foo/bar/node_modules/@types/abc.ts' does not exist.",
+    "File '/foo/bar/node_modules/@types/abc.tsx' does not exist.",
+    "File '/foo/bar/node_modules/@types/abc.d.ts' does not exist.",
+    "File '/foo/bar/node_modules/@types/abc/package.json' does not exist.",
+    "File '/foo/bar/node_modules/@types/abc/index.ts' does not exist.",
+    "File '/foo/bar/node_modules/@types/abc/index.tsx' does not exist.",
+    "File '/foo/bar/node_modules/@types/abc/index.d.ts' does not exist.",
+    "File '/foo/node_modules/abc.ts' does not exist.",
+    "File '/foo/node_modules/abc.tsx' does not exist.",
+    "File '/foo/node_modules/abc.d.ts' does not exist.",
+    "File '/foo/node_modules/abc/package.json' does not exist.",
+    "File '/foo/node_modules/abc/index.ts' does not exist.",
+    "File '/foo/node_modules/abc/index.tsx' does not exist.",
+    "File '/foo/node_modules/abc/index.d.ts' does not exist.",
+    "File '/foo/node_modules/@types/abc.ts' does not exist.",
+    "File '/foo/node_modules/@types/abc.tsx' does not exist.",
+    "File '/foo/node_modules/@types/abc.d.ts' does not exist.",
+    "File '/foo/node_modules/@types/abc/package.json' does not exist.",
+    "File '/foo/node_modules/@types/abc/index.ts' does not exist.",
+    "File '/foo/node_modules/@types/abc/index.tsx' does not exist.",
+    "File '/foo/node_modules/@types/abc/index.d.ts' does not exist.",
+    "File '/node_modules/abc.ts' does not exist.",
+    "File '/node_modules/abc.tsx' does not exist.",
+    "File '/node_modules/abc.d.ts' does not exist.",
+    "File '/node_modules/abc/package.json' does not exist.",
+    "File '/node_modules/abc/index.ts' does not exist.",
+    "File '/node_modules/abc/index.tsx' does not exist.",
+    "File '/node_modules/abc/index.d.ts' does not exist.",
+    "File '/node_modules/@types/abc.ts' does not exist.",
+    "File '/node_modules/@types/abc.tsx' does not exist.",
+    "File '/node_modules/@types/abc.d.ts' does not exist.",
+    "File '/node_modules/@types/abc/package.json' does not exist.",
+    "File '/node_modules/@types/abc/index.ts' does not exist.",
+    "File '/node_modules/@types/abc/index.tsx' does not exist.",
+    "File '/node_modules/@types/abc/index.d.ts' does not exist.",
+    "======== Module name 'abc' was not resolved. ========",
+    "======== Resolving type reference directive 'grumpy', containing file '/src/__inferred type names__.ts', root directory '/foo/node_modules/@types,/node_modules/@types'. ========",
+    "Resolving with primary search path '/foo/node_modules/@types, /node_modules/@types'",
+    "File '/foo/node_modules/@types/grumpy/package.json' does not exist.",
+    "File '/foo/node_modules/@types/grumpy/index.d.ts' exist - use it as a name resolution result.",
+    "======== Type reference directive 'grumpy' was successfully resolved to '/foo/node_modules/@types/grumpy/index.d.ts', primary: true. ========",
+    "======== Resolving type reference directive 'sneezy', containing file '/src/__inferred type names__.ts', root directory '/foo/node_modules/@types,/node_modules/@types'. ========",
+    "Resolving with primary search path '/foo/node_modules/@types, /node_modules/@types'",
+    "File '/foo/node_modules/@types/sneezy/package.json' does not exist.",
+    "File '/foo/node_modules/@types/sneezy/index.d.ts' exist - use it as a name resolution result.",
+    "======== Type reference directive 'sneezy' was successfully resolved to '/foo/node_modules/@types/sneezy/index.d.ts', primary: true. ========",
+    "======== Resolving type reference directive 'dopey', containing file '/src/__inferred type names__.ts', root directory '/foo/node_modules/@types,/node_modules/@types'. ========",
+    "Resolving with primary search path '/foo/node_modules/@types, /node_modules/@types'",
+    "File '/foo/node_modules/@types/dopey/package.json' does not exist.",
+    "File '/foo/node_modules/@types/dopey/index.d.ts' does not exist.",
+    "File '/node_modules/@types/dopey/package.json' does not exist.",
+    "File '/node_modules/@types/dopey/index.d.ts' exist - use it as a name resolution result.",
+    "======== Type reference directive 'dopey' was successfully resolved to '/node_modules/@types/dopey/index.d.ts', primary: true. ========"
+]
\ No newline at end of file
diff --git a/tests/baselines/reference/typeRootsFromMultipleNodeModulesDirectories.types b/tests/baselines/reference/typeRootsFromMultipleNodeModulesDirectories.types
new file mode 100644
index 0000000000000..c47be9cdab3e2
--- /dev/null
+++ b/tests/baselines/reference/typeRootsFromMultipleNodeModulesDirectories.types
@@ -0,0 +1,36 @@
+=== /foo/bar/a.ts ===
+import { x } from "xyz";
+>x : number
+
+import { y } from "pdq";
+>y : number
+
+import { z } from "abc";
+>z : number
+
+x + y + z;
+>x + y + z : number
+>x + y : number
+>x : number
+>y : number
+>z : number
+
+=== /node_modules/@types/dopey/index.d.ts ===
+
+declare module "xyz" {
+    export const x: number;
+>x : number
+}
+
+=== /foo/node_modules/@types/grumpy/index.d.ts ===
+declare module "pdq" {
+    export const y: number; 
+>y : number
+}
+
+=== /foo/node_modules/@types/sneezy/index.d.ts ===
+declare module "abc" {
+    export const z: number;
+>z : number
+}
+
diff --git a/tests/cases/compiler/typeRootsFromMultipleNodeModulesDirectories.ts b/tests/cases/compiler/typeRootsFromMultipleNodeModulesDirectories.ts
new file mode 100644
index 0000000000000..b7f194706a8bd
--- /dev/null
+++ b/tests/cases/compiler/typeRootsFromMultipleNodeModulesDirectories.ts
@@ -0,0 +1,27 @@
+// @noImplicitReferences: true
+// @traceResolution: true
+// @currentDirectory: /src
+
+// @Filename: /node_modules/@types/dopey/index.d.ts
+declare module "xyz" {
+    export const x: number;
+}
+
+// @Filename: /foo/node_modules/@types/grumpy/index.d.ts
+declare module "pdq" {
+    export const y: number; 
+}
+
+// @Filename: /foo/node_modules/@types/sneezy/index.d.ts
+declare module "abc" {
+    export const z: number;
+}
+
+// @Filename: /foo/bar/a.ts
+import { x } from "xyz";
+import { y } from "pdq";
+import { z } from "abc";
+x + y + z;
+
+// @Filename: /foo/bar/tsconfig.json
+{}

From cbd00b9a9260b2728e20d330b00f0c3257578068 Mon Sep 17 00:00:00 2001
From: Andy Hanson <anhans@microsoft.com>
Date: Fri, 2 Sep 2016 07:30:14 -0700
Subject: [PATCH 4/4] Use undefined instead of empty array, and check for
 existence of "node_modules/@types" instead of just for "node_modules".

---
 src/compiler/program.ts                       | 21 ++++++++++---------
 .../reference/library-reference-3.trace.json  |  6 ++----
 2 files changed, 13 insertions(+), 14 deletions(-)

diff --git a/src/compiler/program.ts b/src/compiler/program.ts
index 3cddeb03f38bb..6226d0d304b3b 100644
--- a/src/compiler/program.ts
+++ b/src/compiler/program.ts
@@ -182,23 +182,22 @@ namespace ts {
         return currentDirectory && getDefaultTypeRoots(currentDirectory, host);
     }
 
+    /**
+     * Returns the path to every node_modules/@types directory from some ancestor directory.
+     * Returns undefined if there are none.
+     */
     function getDefaultTypeRoots(currentDirectory: string, host: ModuleResolutionHost): string[] | undefined {
-        return map(getAllNodeModulesDirectories(currentDirectory, host), nodeModules => combinePaths(nodeModules, "@types"));
-    }
-
-    /** Returns the path to every node_modules directory from some ancestor directory. */
-    function getAllNodeModulesDirectories(currentDirectory: string, host: ModuleResolutionHost): string[] | undefined {
         if (!host.directoryExists) {
             return [combinePaths(currentDirectory, "node_modules")];
             // And if it doesn't exist, tough.
         }
 
-        const all: string[] = [];
+        let typeRoots: string[];
 
         while (true) {
-            const nodeModules = combinePaths(currentDirectory, "node_modules");
-            if (host.directoryExists(nodeModules)) {
-                all.push(nodeModules);
+            const atTypes = combinePaths(currentDirectory, nodeModulesAtTypes);
+            if (host.directoryExists(atTypes)) {
+                (typeRoots || (typeRoots = [])).push(atTypes);
             }
 
             const parent = getDirectoryPath(currentDirectory);
@@ -208,8 +207,10 @@ namespace ts {
             currentDirectory = parent;
         }
 
-        return all;
+        return typeRoots;
     }
+    const nodeModulesAtTypes = combinePaths("node_modules", "@types");
+
     /**
      * @param {string | undefined} containingFile - file that contains type reference directive, can be undefined if containing file is unknown.
      * This is possible in case if resolution is performed for directives specified via 'types' parameter. In this case initial path for secondary lookups
diff --git a/tests/baselines/reference/library-reference-3.trace.json b/tests/baselines/reference/library-reference-3.trace.json
index 730835c65e9ac..419fe6d055d72 100644
--- a/tests/baselines/reference/library-reference-3.trace.json
+++ b/tests/baselines/reference/library-reference-3.trace.json
@@ -1,8 +1,6 @@
 [
-    "======== Resolving type reference directive 'jquery', containing file '/src/consumer.ts', root directory '/src/node_modules/@types'. ========",
-    "Resolving with primary search path '/src/node_modules/@types'",
-    "File '/src/node_modules/@types/jquery/package.json' does not exist.",
-    "File '/src/node_modules/@types/jquery/index.d.ts' does not exist.",
+    "======== Resolving type reference directive 'jquery', containing file '/src/consumer.ts', root directory not set. ========",
+    "Root directory cannot be determined, skipping primary search paths.",
     "Looking up in 'node_modules' folder, initial location '/src'",
     "File '/src/node_modules/jquery.ts' does not exist.",
     "File '/src/node_modules/jquery.d.ts' does not exist.",