clang update.py: When running tests on Windows, make sure DIA works.

tools/clang/scripts/update.py

Index: tools/clang/scripts/update.py
diff --git a/tools/clang/scripts/update.py b/tools/clang/scripts/update.py
index 0abb42af0586bd7085e805720d9d15c2fec5a2c2..dc54f511f8f94edc865cb312e03c3ba09a5c620d 100755
--- a/tools/clang/scripts/update.py
+++ b/tools/clang/scripts/update.py
@@ -220,8 +220,8 @@ def RunCommand(command, msvc_arch=None, env=None, fail_hard=True):
 
 def CopyFile(src, dst):
   """Copy a file from src to dst."""
-  shutil.copy(src, dst)
   print "Copying %s to %s" % (src, dst)
+  shutil.copy(src, dst)
 
 
 def CopyDirectoryContents(src, dst, filename_filter=None):
@@ -351,6 +351,13 @@ def GetVSVersion():
   return vs_version
 
 
+def CopyDiaDllTo(target_dir):
+  # This script always wants to use the 64-bit msdia*.dll.
+  dia_path = os.path.join(GetVSVersion().Path(), 'DIA SDK', 'bin', 'amd64')
+  dia_dll = os.path.join(dia_path, 'msdia140.dll')  # Bump after VC updates.
+  CopyFile(dia_dll, target_dir)
+
+
 def UpdateClang(args):
   print 'Updating Clang to %s...' % PACKAGE_VERSION
 
@@ -384,6 +391,8 @@ def UpdateClang(args):
     try:
       DownloadAndUnpack(cds_full_url, LLVM_BUILD_DIR)
       print 'clang %s unpacked' % PACKAGE_VERSION
+      if sys.platform == 'win32':
+        CopyDiaDllTo(os.path.join(LLVM_BUILD_DIR, 'bin'))
       # Download the gold plugin if requested to by an environment variable.
       # This is used by the CFI ClusterFuzz bot, and it's required for official
       # builds on linux.
@@ -476,6 +485,8 @@ def UpdateClang(args):
     RunCommand(['cmake'] + bootstrap_args + [LLVM_DIR], msvc_arch='x64')
     RunCommand(['ninja'], msvc_arch='x64')
     if args.run_tests:
+      if sys.platform == 'win32':
+        CopyDiaDllTo(os.path.join(LLVM_BOOTSTRAP_DIR, 'bin'))
       RunCommand(['ninja', 'check-all'], msvc_arch='x64')
     RunCommand(['ninja', 'install'], msvc_arch='x64')
     if args.gcc_toolchain:
@@ -760,6 +771,8 @@ def UpdateClang(args):
     os.chdir(LLVM_BUILD_DIR)
     RunCommand(['ninja', 'cr-check-all'], msvc_arch='x64')
   if args.run_tests:
+    if sys.platform == 'win32':
+      CopyDiaDllTo(os.path.join(LLVM_BUILD_DIR, 'bin'))
     os.chdir(LLVM_BUILD_DIR)
     RunCommand(['ninja', 'check-all'], msvc_arch='x64')