Use pipefail when available.

This change makes test with RUN lines like
RUN: opt ... | FileCheck

fail if opt fails, even if it prints what FileCheck wants. Enabling this
found some interesting cases of broken tests that were not being noticed
because opt (or some other tool) was crashing late.

Pipefail is used when the shell supports it or when using the internal
python based tester.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@187261 91177308-0d34-0410-b5e6-96231b3b80d8

utils/lit/lit/ShUtil.py

@@ -166,8 +166,9 @@ class ShLexer:
 ###
  
 class ShParser:
-    def __init__(self, data, win32Escapes = False):
+    def __init__(self, data, win32Escapes = False, pipefail = False):
         self.data = data
+        self.pipefail = pipefail
         self.tokens = ShLexer(data, win32Escapes = win32Escapes).lex()
     
     def lex(self):
@@ -224,7 +225,7 @@ class ShParser:
         while self.look() == ('|',):
             self.lex()
             commands.append(self.parse_command())
-        return Pipeline(commands, negate)
+        return Pipeline(commands, negate, self.pipefail)
             
     def parse(self):
         lhs = self.parse_pipeline()

utils/lit/lit/TestRunner.py

@@ -245,7 +245,8 @@ def executeScriptInternal(test, litConfig, tmpBase, commands, cwd):
     cmds = []
     for ln in commands:
         try:
-            cmds.append(ShUtil.ShParser(ln, litConfig.isWindows).parse())
+            cmds.append(ShUtil.ShParser(ln, litConfig.isWindows,
+                                        test.config.pipefail).parse())
         except:
             return (Test.FAIL, "shell parser error on: %r" % ln)
 
@@ -284,6 +285,8 @@ def executeScript(test, litConfig, tmpBase, commands, cwd):
     if isWin32CMDEXE:
         f.write('\nif %ERRORLEVEL% NEQ 0 EXIT\n'.join(commands))
     else:
+        if test.config.pipefail:
+            f.write('set -o pipefail;')
         f.write('{ ' + '; } &&\n{ '.join(commands) + '; }')
     f.write('\n')
     f.close()

utils/lit/lit/TestingConfig.py

@@ -92,6 +92,7 @@ class TestingConfig:
         self.test_source_root = test_source_root
         self.excludes = set(excludes)
         self.available_features = set(available_features)
+        self.pipefail = True
 
     def clone(self, path):
         # FIXME: Chain implementations?