console compiler: revamp exit codes

Don't use -1 since that is turned into 255 on unix systems. Small non-negative
integers should work on all platforms.

0 = success
1 = unexpected error
2 = usage error
3 = serious warnings (controlled by flag)

Author: cgay

sources/environment/commands/build.dylan

@@ -265,13 +265,13 @@ define method do-execute-command
       end;
       message(context, "Build of '%s' completed", project.project-name);
       if (serious-warnings? & ~command.%allow-serious-warnings?)
-        $error-exit-code
+        $serious-warnings-exit-code
       else
         $success-exit-code
       end
     else
       message(context, "Build of '%s' aborted",   project.project-name);
-      $error-exit-code
+      $unexpected-error-exit-code
     end
   exception (error :: <file-system-error>)
     command-error("%s", error)

sources/environment/commands/command-line.dylan

@@ -8,8 +8,10 @@ Warranty:  Distributed WITHOUT WARRANTY OF ANY KIND
 
 /// Useful constants
 
-define constant $success-exit-code = 0;
-define constant $error-exit-code   = -1;
+define constant $success-exit-code          = 0;
+define constant $unexpected-error-exit-code = 1;
+define constant $usage-error-exit-code      = 2;
+define constant $serious-warnings-exit-code = 3;
 
 define constant $whitespace                 = #[' ', '\t', '\n'];
 define constant $quote-characters           = #['\'', '"'];

sources/environment/commands/module.dylan

@@ -87,8 +87,10 @@ define module command-lines
          display-command-prompt,
          execute-command-line,
          execute-server-command,
-         $error-exit-code,
-         $success-exit-code;
+         $success-exit-code,
+         $unexpected-error-exit-code,
+         $serious-warnings-exit-code,
+         $usage-error-exit-code;
 
   // Command line user interface
   export command-line-choose-file,

sources/environment/console/command-line.dylan

@@ -160,8 +160,9 @@ define method do-execute-command
             next-handler()
           else
             display-condition(context, condition);
-            message(context, "Exiting with return code %d", $error-exit-code);
-            return($error-exit-code)
+            message(context, "Exiting with return code %d",
+                    $unexpected-error-exit-code);
+            return($unexpected-error-exit-code)
           end
         end;
     local method run

sources/environment/console/start.dylan

@@ -21,7 +21,7 @@ define function main
         parse-command-line(server, arguments, class: class)
       exception (error :: <parse-error>)
         format(output-stream, "%s\n", error);
-        exit-application($error-exit-code)
+        exit-application($usage-error-exit-code)
       end;
   let status-code :: <integer> = execute-command(command);
   exit-application(status-code)