languages/rust: fix rustaceanvim DAP adapter

Align codelldb adapter setup with rustaceanvim’s built-in logic.
Add languages.rust.dap.backend option to choose between codelldb
and lldb-dap adapters.

docs/manual/release-notes/rl-0.8.md

@@ -621,3 +621,9 @@
 [JudahZF](https://github.com/JudahZF):
 
 - Added gitFiles mapping option to telescope
+
+[Ring-A-Ding-Ding-Baby](https://github.com/Ring-A-Ding-Ding-Baby)
+
+- Aligned `codelldb` adapter setup with [rustaceanvim]’s built-in logic.
+- Added `languages.rust.dap.backend` option to choose between `codelldb` and
+  `lldb-dap` adapters.

modules/plugins/languages/rust.nix

@@ -87,6 +87,19 @@ in {
         type = package;
         default = pkgs.lldb;
       };
+
+      adapter = mkOption {
+        type = enum ["lldb-dap" "codelldb"];
+        default = "codelldb";
+        description = ''
+          Select which LLDB-based debug adapter to use:
+
+          - "codelldb": use the CodeLLDB adapter from the vadimcn.vscode-lldb extension.
+          - "lldb-dap": use the LLDB DAP implementation shipped with LLVM (lldb-dap).
+
+          The default "codelldb" backend generally provides a better debugging experience for Rust.
+        '';
+      };
     };
 
     extensions = {
@@ -191,11 +204,20 @@ in {
 
             ${optionalString cfg.dap.enable ''
             dap = {
-              adapter = {
-                type = "executable",
-                command = "${cfg.dap.package}/bin/lldb-dap",
-                name = "rustacean_lldb",
-              },
+              adapter = ${
+              if cfg.dap.adapter == "lldb-dap"
+              then ''
+                {
+                  type = "executable",
+                  command = "${cfg.dap.package}/bin/lldb-dap",
+                  name = "rustacean_lldb",
+                }''
+              else let
+                codelldb = pkgs.vscode-extensions.vadimcn.vscode-lldb.adapter;
+                codelldbPath = "${codelldb}/bin/codelldb";
+                liblldbPath = "${codelldb}/share/lldb/lib/liblldb.so";
+              in ''require("rustaceanvim.config").get_codelldb_adapter("${codelldbPath}", "${liblldbPath}")''
+            },
             },
           ''}
           }