Need a version of flycheck-define-checker and flycheck-define-command-checker that doesn't have to have the checker executable be hard-coded to a string but rather looked up dynamically

[nordlow]

I want a version of

flycheck-define-checker and flycheck-define-command-checker

that doesn't have to have the checker executable be hard-coded to a string.

This is needed for source files for the D programming language (.d .di) that have the prefix

#!/usr/bin/env dub

at the top of its contents. Such a .d FILE is called as a script via dub --single FILE.d instead of the D compiler typically being dmd.

I guess I can use flycheck-define-generic-checker but that API is so different from flycheck-define-command-checker.

So instead of my current

(flycheck-define-checker d-dmd-all
  "A D syntax checker using the DMD (or LDC) compiler."
  :command ("dmd"
            (eval (flycheck-d-compiler-args default-directory "dmd"))
            source) ;(source ".d") makes ‘flycheck-compile’ output refer to temporary files which is worthless
  :error-patterns   ;TODO merge with ‘d-dmd-compilation-error-rx’
  ((error line-start (file-name) "(" line "," column "): Error: " (message) line-end)
   (warning line-start (file-name) "(" line "," column "): "
            (or "Warning" "Deprecation") ": " (message) line-end) ;TODO `compilation-deprecation-face'
   (info line-start (file-name) "(" line "," column "): "
         (or "Info" "Debug") ": " (message) line-end) ;TODO `compilation-debug-face'
   (info line-start (file-name) "(" line "," column "):" space (message) line-end) ;unclassified
   (info line-start
         (file-name) "(" line "," column "): " (or "Info" "Remark" "vgc" "vtemplate") ": " (message) ;TODO `compilation-info-face'
         line-end))
  :modes (d-mode d-ts-mode)
  ;; currently no way of seeing the resource requirements for individual checkers in the mode-line:
  ;; :next-checkers ((warning . d-dscanner-style))
  )

I would like to be able to write

(flycheck-define-checker d-dmd-or-dub-all
  :command (eval (flycheck-d-compiler-command default-directory))
  ;; ...
  )

. I can of course duplicate the checker but that needs to copy all the :error-patterns and use two passing of :predicate one to d-dmd-all and the inversion to d-dub-all which is not adhere to the DRY-pattern. Can't you just relax the requirement that the first element of the :command property must be known at evaluation time to be a string?

[bbatsov]

I'll have to think about this, as your use-case is quite peculiar and I don't recall anyone else asking for something similar.