[test] Capture stderr from 'tar --version' call as well

Capture the stderr from 'tar --version' call as otherwise error messages
spill onto user's terminal unnecessarily (e.g. on NetBSD where tar does
not support long options).  While at it, refactor the code to use
communicate() instead of reinventing the wheel.

Differential Revision: https://reviews.llvm.org/D55443

llvm-svn: 349204

1 files changed, 6 insertions, 3 deletions

diff --git a/lld/test/lit.cfg.py b/lld/test/lit.cfg.py
index d4d9ea74efa..9989a1cc97a 100644
--- a/lld/test/lit.cfg.py
+++ b/lld/test/lit.cfg.py
@@ -94,7 +94,10 @@ if config.have_dia_sdk:
 tar_executable = lit.util.which('tar', config.environment['PATH'])
 if tar_executable:
     tar_version = subprocess.Popen(
-        [tar_executable, '--version'], stdout=subprocess.PIPE, env={'LANG': 'C'})
-    if 'GNU tar' in tar_version.stdout.read().decode():
+        [tar_executable, '--version'],
+        stdout=subprocess.PIPE,
+        stderr=subprocess.PIPE,
+        env={'LANG': 'C'})
+    sout, _ = tar_version.communicate()
+    if 'GNU tar' in sout.decode():
         config.available_features.add('gnutar')
-    tar_version.wait()