Update merge_pgc_files.py in preparation for VS2017

build/vs_toolchain.py

Index: build/vs_toolchain.py
diff --git a/build/vs_toolchain.py b/build/vs_toolchain.py
index 0ff51815212da7198fc521eedaf1f45ffefe5cd6..61a3559859f7d38e0d5d21ea2c27eaaef3eab1f7 100755
--- a/build/vs_toolchain.py
+++ b/build/vs_toolchain.py
@@ -218,6 +218,28 @@ def _CopyUCRTRuntime(target_dir, source_dir, target_cpu, dll_pattern, suffix):
                     os.path.join(source_dir, 'ucrtbase' + suffix))
 
 
+def FindVCToolsRoot():
+  """In VS2017 the PGO runtime dependencies are located in
+  {toolchain_root}/VC/Tools/MSVC/{x.y.z}/bin/Host{target_cpu}/{target_cpu}/, the
+  {version_number} part is likely to change in case of a minor update of the
+  toolchain so we don't hardcode this value here (except for the major number).
+
+  This returns the '{toolchain_root}/VC/Tools/MSVC/{x.y.z}/bin/' path.
+
+  This function should only be called when using VS2017.
+  """
+  assert GetVisualStudioVersion() == '2017'
+  assert ('GYP_MSVS_OVERRIDE_PATH' in os.environ)
+  vc_tools_msvc_root = os.path.join(os.environ['GYP_MSVS_OVERRIDE_PATH'],
+      'VC', 'Tools', 'MSVC')
+  for directory in os.listdir(vc_tools_msvc_root):
+    if not os.path.isdir(os.path.join(vc_tools_msvc_root, directory)):
+      continue
+    if re.match('14\.\d+\.\d+', directory):
+      return os.path.join(vc_tools_msvc_root, directory, 'bin')
+  raise Exception('Unable to find the VC tools directory.')
+
+
 def _CopyPGORuntime(target_dir, target_cpu):
   """Copy the runtime dependencies required during a PGO build.
   """
@@ -229,20 +251,7 @@ def _CopyPGORuntime(target_dir, target_cpu):
                                        'VC', 'bin')
     pgo_x64_runtime_dir = os.path.join(pgo_x86_runtime_dir, 'amd64')
   elif env_version == '2017':
-    # In VS2017 the PGO runtime dependencies are located in
-    # {toolchain_root}/VC/Tools/MSVC/{x.y.z}/bin/Host{target_cpu}/{target_cpu}/,
-    # the {version_number} part is likely to change in case of a minor update of
-    # the toolchain so we don't hardcode this value here (except for the major
-    # number).
-    vc_tools_msvc_root = os.path.join(os.environ.get('GYP_MSVS_OVERRIDE_PATH'),
-        'VC', 'Tools', 'MSVC')
-    pgo_runtime_root = None
-    for directory in os.listdir(vc_tools_msvc_root):
-      if not os.path.isdir(os.path.join(vc_tools_msvc_root, directory)):
-        continue
-      if re.match('14\.\d+\.\d+', directory):
-        pgo_runtime_root = os.path.join(vc_tools_msvc_root, directory, 'bin')
-        break
+    pgo_runtime_root = FindVCToolsRoot()
     assert pgo_runtime_root
     # There's no version of pgosweep.exe in HostX64/x86, so we use the copy
     # from HostX86/x86.