[Fortran/gfortran] Add a simple not tool to the test suite

Add a tool very similar to LLVM's not utility which inverts the return code of a
command. The major difference is that the utility is not dependent on LLVM's
libraries and performs less error checking than LLVM's not. It does support the
 --crash option when the command is expected to crash.

The gfortran tests have been updated to use this.

Author: tarunprabhu

Fortran/gfortran/CMakeLists.txt

@@ -445,7 +445,7 @@ function(gfortran_add_compile_test expect_error main others fflags ldflags)
   if (expect_error)
     # Since we don't check for any particular error, we expect "some" error.
     # In that case, the compiler's diagnostic output will be non-empty.
-    llvm_test_verify(${TESTCMD} -s %S/${out})
+    llvm_test_verify(%b/not ${DIFFPROG} %S/${relpath}/${EMPTY_FILE} %S/${out})
   else ()
     llvm_test_verify(${DIFFPROG} %S/${relpath}/${EMPTY_FILE} %S/${out})
   endif ()
@@ -658,22 +658,10 @@ get_filename_component(ISO_FORTRAN_C_HEADER_DIR
 # otherwise.
 set(DIFFPROG)
 if (WIN32)
-  # Windows support has been disabled earlier anyway, but at some point, we
-  # should find a way to check if a file is non-empty on windows.
-  message(FATAL_ERROR "No way to check file size in Windows.")
   find_program(DIFFPROG
     NAMES fc.exe
     REQUIRED)
 else ()
-  # FIXME: For the moment, check if a file is not empty, by using the test
-  # command/shell built-in on *nix. But it is not clear that all systems will
-  # have this. What we really need is to invert the result of DIFFPROG. LLVM has
-  # a not utility that will do just this. But it needs LLVM's build directory
-  # to be present unless it is installed on the system already. It is not clear
-  # if we can depend on this.
-  find_program(TESTCMD
-    NAMES test
-    REQUIRED)
   find_program(DIFFPROG
     NAMES diff cmp
     REQUIRED)

tools/CMakeLists.txt

@@ -39,3 +39,5 @@ else()
   add_executable(build-timeit-target ALIAS timeit-target)
   llvm_add_host_executable(build-timeit timeit timeit.c)
 endif()
+
+add_executable(not ${CMAKE_CURRENT_SOURCE_DIR}/not.cpp)

tools/not.cpp

@@ -0,0 +1,76 @@
+//===- not.cpp - The 'not' testing tool -----------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+// Usage:
+//   not cmd
+//     Will return true if cmd doesn't crash and returns false.
+//   not --crash cmd
+//     Will return true if cmd crashes (e.g. for testing crash reporting).
+
+// This file is a stripped down version of not.cpp from llvm/utils. This does
+// not depend on any LLVM library.
+
+#include <cstdlib>
+#include <iostream>
+#include <sstream>
+
+#ifdef _WIN32
+#include <windows.h>
+#endif
+
+int main(int argc, const char **argv) {
+  bool expectCrash = false;
+
+  ++argv;
+  --argc;
+
+  if (argc > 0 && std::string(argv[0]) == "--crash") {
+    ++argv;
+    --argc;
+    expectCrash = true;
+
+    // Crash is expected, so disable crash report and symbolization to reduce
+    // output and avoid potentially slow symbolization.
+#ifdef _WIN32
+    SetEnvironmentVariableA("LLVM_DISABLE_CRASH_REPORT", "1");
+    SetEnvironmentVariableA("LLVM_DISABLE_SYMBOLIZATION", "1");
+#else
+    setenv("LLVM_DISABLE_CRASH_REPORT", "1", 0);
+    setenv("LLVM_DISABLE_SYMBOLIZATION", "1", 0);
+#endif
+  }
+
+  if (argc == 0)
+    return 1;
+
+  std::stringstream ss;
+  ss << argv[0];
+  for (int i = 1; i < argc; ++i)
+    ss << " " << argv[i];
+  std::string cmd = ss.str();
+  int result = system(cmd.c_str());
+
+#ifdef _WIN32
+  // Handle abort() in msvcrt -- It has exit code as 3.  abort(), aka
+  // unreachable, should be recognized as a crash.  However, some binaries use
+  // exit code 3 on non-crash failure paths, so only do this if we expect a
+  // crash.
+  if (expectCrash && result == 3)
+    result = -3;
+#endif
+
+  if (result < 0) {
+    if (expectCrash)
+      return 0;
+    return 1;
+  }
+
+  if (expectCrash)
+    return 1;
+
+  return result == 0;
+}