Check for errno explicitly on Windows which can be set if the command

interpreter was not found. Otherwise, check for the WEXITSTATUS and WTERMSIG
macros which are only defined on POSIX-compliant systems. In all other cases,
prefer failing at compile-time rather than using the value returned by the call
to system().

Author: tarunprabhu

tools/not.cpp

@@ -67,16 +67,24 @@ int main(int argc, const char **argv) {
   if (expectCrash && result == 3) {
     retcode = 3;
     signal = 1;
+  } else if (errno) {
+    // If the command interpreter was not found, errno will be set and 0 will
+    // be returned. It is unlikely that this will happen in our use case, but
+    // check anyway.
+    retcode = 1;
+    signal = 1;
   } else {
     // On Windows, result is the exit code, except for the special case above.
     retcode = result;
     signal = 0;
   }
-#else
-  // On POSIX systems, result is a composite value of the exit code and,
-  // potentially, the signal that caused termination of the command.
+#elif defined(WEXITSTATUS) && defined(WTERMSIG)
+  // On POSIX systems and Solaris, result is a composite value of the exit code
+  // and, potentially, the signal that caused termination of the command.
   retcode = WEXITSTATUS(result);
   signal = WTERMSIG(result);
+#else
+#error "Unsupported system"
 #endif
 
   // If signal is non-zero, the command caused a crash, usually SIGABRT.