ssh: switch type of matchBlocks to listOrDagOf

This switches the type of `matchBlocks` from `loaOf` to `listOrDagOf`.
The former has been deprecated in Nixpkgs. The latter allows
dependencies between entries to be expressed using the DAG functions.

modules/programs/ssh.nix

@@ -56,7 +56,7 @@ let
     };
   };
 
-  matchBlockModule = types.submodule ({ name, ... }: {
+  matchBlockModule = types.submodule ({ dagName, ... }: {
     options = {
       host = mkOption {
         type = types.str;
@@ -266,7 +266,7 @@ let
       };
     };
 
-    config.host = mkDefault name;
+    config.host = mkDefault dagName;
   });
 
   matchBlockStr = cf: concatStringsSep "\n" (
@@ -392,7 +392,7 @@ in
     };
 
     matchBlocks = mkOption {
-      type = types.loaOf matchBlockModule;
+      type = hm.types.listOrDagOf matchBlockModule;
       default = {};
       example = literalExample ''
         {
@@ -400,7 +400,7 @@ in
             hostname = "example.com";
             user = "john";
           };
-          foo = {
+          foo = lib.hm.dag.entryBefore ["john.example.com"] {
             hostname = "example.com";
             identityFile = "/home/john/.ssh/foo_rsa";
           };
@@ -408,11 +408,15 @@ in
       '';
       description = ''
         Specify per-host settings. Note, if the order of rules matter
-        then this must be a list. See
+        then use the DAG functions to express the dependencies as
+        shown in the example.
+        </para><para>
+        See
         <citerefentry>
           <refentrytitle>ssh_config</refentrytitle>
           <manvolnum>5</manvolnum>
-        </citerefentry>.
+        </citerefentry>
+        for more information.
       '';
     };
   };
@@ -432,18 +436,24 @@ in
             checkLocal = block: any' checkBindAndHost block.localForwards;
             checkRemote = block: any' checkBindAndHost block.remoteForwards;
             checkMatchBlock = block: all (fn: fn block) [ checkLocal checkRemote checkDynamic ];
-          in any' checkMatchBlock (builtins.attrValues cfg.matchBlocks);
+          in any' checkMatchBlock (map (block: block.data) (builtins.attrValues cfg.matchBlocks));
         message = "Forwarded paths cannot have ports.";
       }
     ];
 
-    home.file.".ssh/config".text = ''
+    home.file.".ssh/config".text =
+      let
+        sortedMatchBlocks = hm.dag.topoSort cfg.matchBlocks;
+        sortedMatchBlocksStr = builtins.toJSON sortedMatchBlocks;
+        matchBlocks =
+          if sortedMatchBlocks ? result
+          then sortedMatchBlocks.result
+          else abort "Dependency cycle in SSH match blocks: ${sortedMatchBlocksStr}";
+      in ''
       ${concatStringsSep "\n" (
         mapAttrsToList (n: v: "${n} ${v}") cfg.extraOptionOverrides)}
 
-      ${concatStringsSep "\n\n" (
-        map matchBlockStr (
-        builtins.attrValues cfg.matchBlocks))}
+      ${concatStringsSep "\n\n" (map (block: matchBlockStr block.data) matchBlocks)}
 
       Host *
         ForwardAgent ${yn cfg.forwardAgent}

tests/modules/programs/ssh/match-blocks-attrs-expected.conf

@@ -16,6 +16,9 @@ Host xyz
   RemoteForward /run/user/1000/gnupg/S.gpg-agent.extra /run/user/1000/gnupg/S.gpg-agent
   DynamicForward [localhost]:2839
 
+Host ordered
+  Port 1
+
 Host *
   ForwardAgent no
   Compression no

tests/modules/programs/ssh/match-blocks-attrs.nix

@@ -12,6 +12,8 @@ with lib;
           proxyJump = "jump-host";
         };
 
+        ordered = hm.dag.entryAfter [ "xyz" ] { port = 1; };
+
         xyz = {
           identityFile = "file";
           serverAliveInterval = 60;