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

docs/CommandGuide/lit.rst

@@ -316,6 +316,10 @@ executed, two important global variables are predefined:
  *on_clone* function will generally modify), and (3) the test path to the new
  directory being scanned.
 
+ **pipefail** Normally a test using a shell pipe fails if any of the commands
+ on the pipe fail. If this is not desired, setting this variable to false
+ makes the test fail only if the last command in the pipe fails.
+
 TEST DISCOVERY
 ~~~~~~~~~~~~~~
 

docs/ReleaseNotes.rst

@@ -41,6 +41,10 @@ Non-comprehensive list of changes in this release
    functionality, or simply have a lot to talk about), see the `NOTE` below
    for adding a new subsection.
 
+* The regression tests now fail if any command in a pipe fails. To disable it in
+  a directory, just add ``config.pipefail = False`` to its ``lit.local.cfg``.
+  See :doc:`Lit <CommandGuide/lit>` for the details.
+
 * Support for exception handling has been removed from the old JIT. Use MCJIT
   if you need EH support.
 

test/Other/pipefail.txt

@@ -0,0 +1,2 @@
+REQUIRES: shell
+RUN: ((false | true) && echo true || echo false) | grep false

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?