Config help: setting environment variables with :env (general suggestions welcome)

[nickbanderson]

Hi, firstly, thank you very much for developing an alternative to dap-mode for those of us who prefer to use eglot over lsp-mode.

Here is my use-package for dape with setup for a work project, super-program:

(use-package dape
  :custom
  (dape-buffer-window-arrangement 'right)
  (dape-debug t)
  :config
  (add-to-list 'dape-configs
               `(super-program
                 ensure dape-ensure-command
                 command "lldb-vscode"
                 command-cwd dape-cwd-fn
                 :type "lldb-vscode"
                 :cwd (lambda () (s-concat (funcall dape-cwd-fn) "bin"))
                 :program (lambda () (s-concat (funcall dape-cwd-fn) "bin/super-program-binary"))
                 :args ["blah", "bleh"]
                 :env (
                       ;; needed at runtime to prevent dynamic linking error to a .so used by super-program
                       :LD_LIBRARY_PATH "/usr/local/some_proprietary_install/lib64"
                       ;; used by super-program itself
                       :BLAH_ENV "100"
                       )
                 ))
  )

The project layout:

super-program/
    .git/
    bin/
        super-program-binary
    src/
        *.C
        include/
            *.H
    ...other dirs

It took a lot of trial and error to find the correct combo of command-cwd, :cwd, and program to convey the meaning of "the project root is at (project-current), but the binary to debug is in ./bin and it must be ran from ./bin or else the relative paths it uses will break". The above config works, but I am not proud of it lol :P

I can't get the environment vars defined with :env to be seen by super-program-binary - confirmed by linker error and it complaining about undefined BLAH_ENV. I can work around this by manually setting these two env vars with #'setenv such that they are well defined in 'process-environment before I call #'dape, but I would much prefer to encapsulate them within the 'dape-config entry. I am starting to suspect that :env is for the adapter, and maybe they are not inherited in or shared with the debugged program itself...IDK.

I'd appreciate any help with the environment var issue or any general suggestions!

[svaante]

#include <stdio.h>
#include <stdlib.h>

int main(int argc, char *argv[]) {
    char *blah_env = getenv("BLAH_ENV");
    printf("%s\n", blah_env);
    return 0;
}

/* Local Variables: */
/* dape-command: (lldb-vscode compile "gcc -g env.c" :program "a.out" :env ["BLAH_ENV=100"]) */
/* End: */

Had to go digging, https://llvm.googlesource.com/lldb/+/master/tools/lldb-vscode/ for lldb-vscode the :env property has it's own unique signature.

[nickbanderson]

Thank you so much! Works great. I ended up using the following in order to inherit the environment of a nix develop shell:

(defun nick/env-array-from-shell (command)
  "When COMMAND runs the shell command `env`, processes that output into an array of envs.
Useful for `nix develop` or `nix shell` commands.

E.g. `[\"A=1\", \"B=asdf\"]`"
  (seq-filter
   (lambda (str) (s-contains-p "=" str))
   (s-lines (shell-command-to-string command))))

;; a dape config entry:
(...
 :env (lambda () (nick/env-array-from-shell "nix develop ~/code/personal-flake#specific-dev-shell-output -c env")))

Edit: I couldn't make nix-ld happy with the above despite setting NIX_LD and NIX_LD_LIBRARY_PATH appropriately, so I now omit :env from my dape config entirely, instead using the below file in my project's root dir in combination with emacs-direnv.

# .envrc in project root enabled with `direnv allow`
use flake ~/code/personal-flake#specific-dev-shell-output

With this final setup, the environment is set before I run any dape commands, but things work out. Not sure what I'm missing with the previous :env setup, but this works!