better runtime error msg qhen running a program with metalua

diff --git a/src/compiler/metalua.mlua b/src/compiler/metalua.mlua
index 265f06b8e79f37c80bccea964c2a397a89a44955..9e1fdc38a9a1886cae2203715cecc05eb61191b4 100644 (file)
--- a/src/compiler/metalua.mlua
+++ b/src/compiler/metalua.mlua
@@ -233,7 +233,10 @@ local function main (...)
       -- FIXME: check for failures
 
       runargs = table.icat(cfg.params or { }, runargs)
-      local st, msg = pcall(f, unpack (runargs))
+      local function print_traceback (errmsg)
+         return errmsg .. '\n' .. debug.traceback ('',2) .. '\n'
+      end
+      local st, msg = xpcall(|| f(unpack (runargs)), print_traceback)
       if not st then
          io.stderr:write(msg)
          os.exit(RUNTIME_ERROR_NUMBER)