(flycheck-define-checker vhdl-ghdl
  "A VHDL syntax checker using ghdl."
  :command ("ghdl" "-s" "--std=93" "--ieee=synopsys" "-fexplicit" source)
  :error-patterns
  ((error line-start (file-name) ":" line ":" column
	  ": " (message) line-end))
  :modes vhdl-mode)
(flycheck-set-checker-executable 'vhdl-ghdl)