[llvm] r215127 - FileCheck: Add a flag to allow checking empty input

[Justin Bogner]

Author: bogner
Date: Thu Aug  7 13:40:37 2014
New Revision: 215127

URL: http://llvm.org/viewvc/llvm-project?rev=215127&view=rev
Log:
FileCheck: Add a flag to allow checking empty input

Currently FileCheck errors out on empty input. This is usually the
right thing to do, but makes testing things like "this command does
not emit some error message" hard to test. This usually leads to
people using "command 2>&1 | count 0" instead, and then the bots that
use guard malloc fail a few hours later.

By adding a flag to FileCheck that allows empty inputs, we can make
tests that consist entirely of "CHECK-NOT" lines feasible.

Added:
    llvm/trunk/test/FileCheck/check-empty.txt
Modified:
    llvm/trunk/utils/FileCheck/FileCheck.cpp

Added: llvm/trunk/test/FileCheck/check-empty.txt
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/FileCheck/check-empty.txt?rev=215127&view=auto
==============================================================================
--- llvm/trunk/test/FileCheck/check-empty.txt (added)
+++ llvm/trunk/test/FileCheck/check-empty.txt Thu Aug  7 13:40:37 2014
@@ -0,0 +1,11 @@
+// RUN: not FileCheck -check-prefix=FOO %s </dev/null 2>&1 | FileCheck -check-prefix=EMPTY-ERR %s
+// RUN: not FileCheck -check-prefix=NOFOO %s </dev/null 2>&1 | FileCheck -check-prefix=EMPTY-ERR %s
+// RUN: not FileCheck -check-prefix=FOO -allow-empty %s </dev/null 2>&1 | FileCheck -check-prefix=NO-EMPTY-ERR -check-prefix=NOT-FOUND %s
+// RUN: FileCheck -check-prefix=NOFOO -allow-empty %s </dev/null 2>&1 | FileCheck -allow-empty -check-prefix=NO-EMPTY-ERR %s
+
+; FOO: foo
+; NOFOO-NOT: foo
+
+; EMPTY-ERR: FileCheck error: '-' is empty.
+; NO-EMPTY-ERR-NOT: FileCheck error: '-' is empty.
+; NOT-FOUND: error: expected string not found in input

Modified: llvm/trunk/utils/FileCheck/FileCheck.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/utils/FileCheck/FileCheck.cpp?rev=215127&r1=215126&r2=215127&view=diff
==============================================================================
--- llvm/trunk/utils/FileCheck/FileCheck.cpp (original)
+++ llvm/trunk/utils/FileCheck/FileCheck.cpp Thu Aug  7 13:40:37 2014
@@ -57,6 +57,11 @@ static cl::list<std::string> ImplicitChe
              "this pattern occur which are not matched by a positive pattern"),
     cl::value_desc("pattern"));
 
+static cl::opt<bool> AllowEmptyInput(
+    "allow-empty", cl::init(false),
+    cl::desc("Allow the input file to be empty. This is useful when making\n"
+             "checks that some error message does not occur, for example."));
+
 typedef cl::list<std::string>::const_iterator prefix_iterator;
 
 //===----------------------------------------------------------------------===//
@@ -1260,7 +1265,7 @@ int main(int argc, char **argv) {
   }
   std::unique_ptr<MemoryBuffer> &File = FileOrErr.get();
 
-  if (File->getBufferSize() == 0) {
+  if (File->getBufferSize() == 0 && !AllowEmptyInput) {
     errs() << "FileCheck error: '" << InputFilename << "' is empty.\n";
     return 2;
   }