services.emacs: add option extraOptions

This is to allow adding command-line arguments to the Emacs daemon.
Previously only the Emacs client could be started with custom
arguments.

modules/services/emacs.nix

@@ -54,6 +54,15 @@ in {
       description = "The Emacs package to use.";
     };
 
+    extraOptions = mkOption {
+      type = with types; listOf str;
+      default = [ ];
+      example = [ "-f" "exwm-enable" ];
+      description = ''
+        Extra command-line arguments to pass to <command>emacs</command>.
+      '';
+    };
+
     client = {
       enable = mkEnableOption "generation of Emacs client desktop file";
       arguments = mkOption {
@@ -111,7 +120,7 @@ in {
             # when using socket activation.
               optionalString cfg.socketActivation.enable
               "=${escapeShellArg socketPath}"
-            }"'';
+            } ${escapeShellArgs cfg.extraOptions}"'';
 
           # Emacs will exit with status 15 after having received SIGTERM, which
           # is the default "KillSignal" value systemd uses to stop services.

tests/modules/services/emacs/emacs-service-27.nix

@@ -17,6 +17,7 @@ with lib;
     programs.emacs.enable = true;
     services.emacs.enable = true;
     services.emacs.client.enable = true;
+    services.emacs.extraOptions = [ "-f" "exwm-enable" ];
 
     nmt.script = ''
       assertPathNotExists home-files/.config/systemd/user/emacs.socket

tests/modules/services/emacs/emacs-service-28.nix

@@ -17,6 +17,7 @@ with lib;
     programs.emacs.enable = true;
     services.emacs.enable = true;
     services.emacs.client.enable = true;
+    services.emacs.extraOptions = [ "-f" "exwm-enable" ];
 
     nmt.script = ''
       assertPathNotExists home-files/.config/systemd/user/emacs.socket

tests/modules/services/emacs/emacs-service-emacs.service

@@ -2,7 +2,7 @@
 WantedBy=default.target
 
 [Service]
-ExecStart=@runtimeShell@ -l -c "@emacs@/bin/emacs --fg-daemon"
+ExecStart=@runtimeShell@ -l -c "@emacs@/bin/emacs --fg-daemon '-f' 'exwm-enable'"
 Restart=on-failure
 SuccessExitStatus=15
 Type=notify

tests/modules/services/emacs/emacs-socket-27.nix

@@ -19,6 +19,7 @@ in {
     programs.emacs.enable = true;
     services.emacs.enable = true;
     services.emacs.client.enable = true;
+    services.emacs.extraOptions = [ "-f" "exwm-enable" ];
     services.emacs.socketActivation.enable = true;
 
     nmt.script = ''

tests/modules/services/emacs/emacs-socket-28.nix

@@ -19,6 +19,7 @@ in {
     programs.emacs.enable = true;
     services.emacs.enable = true;
     services.emacs.client.enable = true;
+    services.emacs.extraOptions = [ "-f" "exwm-enable" ];
     services.emacs.socketActivation.enable = true;
 
     nmt.script = ''

tests/modules/services/emacs/emacs-socket-emacs.service

@@ -1,5 +1,5 @@
 [Service]
-ExecStart=@runtimeShell@ -l -c "@emacs@/bin/emacs --fg-daemon='%t/emacs/server'"
+ExecStart=@runtimeShell@ -l -c "@emacs@/bin/emacs --fg-daemon='%t/emacs/server' '-f' 'exwm-enable'"
 ExecStartPost=@coreutils@/bin/chmod --changes -w %t/emacs
 ExecStopPost=@coreutils@/bin/chmod --changes +w %t/emacs
 Restart=on-failure