plugins/lsp: add omnisharp language server

Co-authored-by: garaiza-93 <57430880+garaiza-93@users.noreply.github.com>

Author: GaetanLepage

plugins/lsp/language-servers/default.nix

@@ -377,6 +377,60 @@ with lib; let
         };
       };
     }
+    {
+      name = "omnisharp";
+      description = "Enable omnisharp language server, for C#";
+      package = pkgs.omnisharp-roslyn;
+      cmd = cfg: ["${cfg.package}/bin/OmniSharp"];
+      settings = cfg: {omnisharp = cfg;};
+      settingsOptions = {
+        enableEditorConfigSupport = helpers.defaultNullOpts.mkBool true ''
+          Enables support for reading code style, naming convention and analyzer settings from
+          `.editorconfig`.
+        '';
+
+        enableMsBuildLoadProjectsOnDemand = helpers.defaultNullOpts.mkBool false ''
+          If true, MSBuild project system will only load projects for files that were opened in the
+          editor.
+          This setting is useful for big C# codebases and allows for faster initialization of code
+          navigation features only for projects that are relevant to code that is being edited.
+          With this setting enabled OmniSharp may load fewer projects and may thus display
+          incomplete reference lists for symbols.
+        '';
+
+        enableRoslynAnalyzers = helpers.defaultNullOpts.mkBool false ''
+          If true, MSBuild project system will only load projects for files that were opened in the
+          editor.
+          This setting is useful for big C# codebases and allows for faster initialization of code
+          navigation features only for projects that are relevant to code that is being edited.
+          With this setting enabled OmniSharp may load fewer projects and may thus display
+          incomplete reference lists for symbols.
+        '';
+
+        organizeImportsOnFormat = helpers.defaultNullOpts.mkBool false ''
+          Specifies whether 'using' directives should be grouped and sorted during document
+          formatting.
+        '';
+
+        enableImportCompletion = helpers.defaultNullOpts.mkBool false ''
+          Enables support for showing unimported types and unimported extension methods in
+          completion lists.
+          When committed, the appropriate using directive will be added at the top of the current
+          file.
+          This option can have a negative impact on initial completion responsiveness, particularly
+          for the first few completion sessions after opening a solution.
+        '';
+
+        sdkIncludePrereleases = helpers.defaultNullOpts.mkBool true ''
+          Specifies whether to include preview versions of the .NET SDK when determining which
+          version to use for project loading.
+        '';
+
+        analyzeOpenDocumentsOnly = helpers.defaultNullOpts.mkBool true ''
+          Only run analyzers against open files when 'enableRoslynAnalyzers' is true.
+        '';
+      };
+    }
     {
       name = "pylsp";
       description = "Enable pylsp, for Python.";

tests/test-sources/plugins/lsp/nixd.nix

@@ -1,4 +1,4 @@
-{pkgs}: {
+{
   example = {
     plugins.lsp = {
       enable = true;

tests/test-sources/plugins/lsp/nvim-lsp.nix

@@ -92,6 +92,7 @@
         metals.enable = true;
         nil_ls.enable = true;
         nixd.enable = true;
+        omnisharp.enable = true;
         pylsp.enable = true;
         pyright.enable = true;
         rnix-lsp.enable = true;

tests/test-sources/plugins/lsp/omnisharp.nix

@@ -0,0 +1,21 @@
+{
+  defaults = {
+    plugins.lsp = {
+      enable = true;
+
+      servers.omnisharp = {
+        enable = true;
+
+        settings = {
+          enableEditorConfigSupport = true;
+          enableMsBuildLoadProjectsOnDemand = false;
+          enableRoslynAnalyzers = false;
+          organizeImportsOnFormat = false;
+          enableImportCompletion = false;
+          sdkIncludePrereleases = true;
+          analyzeOpenDocumentsOnly = true;
+        };
+      };
+    };
+  };
+}