neovim: expose sideloadInitLua option to control the generation of init.lua

modules/programs/neovim.nix

@@ -245,6 +245,14 @@ in
         '';
       };
 
+      sideloadInitLua = mkOption {
+        type = types.bool;
+        default = false;
+        description = ''
+          Whether to sideload the content of {var}`initLua` without generating a {file}`init.lua`.
+        '';
+      };
+
       initLua = mkOption {
         type = types.lines;
         default = "";
@@ -495,13 +503,6 @@ in
               opt = [ ];
             };
           };
-
-      # This is a hack to avoid breaking config for users that dont want an init.lua to get generated
-      # See https://github.com/nix-community/home-manager/pull/8734
-      # we basically check if the generated wrapper lua config has any user-set config
-      # if not HM avoids creating an init.lua
-      # this makes the logic harder to understand and maintain so hopefully we can find a way out
-      wrapperHasUserConfig = wrappedNeovim'.luaRcContent != wrappedNeovim'.providerLuaRc;
     in
     {
       programs.neovim = {
@@ -530,9 +531,9 @@ in
 
       programs.neovim.extraPackages = mkIf cfg.autowrapRuntimeDeps vimPackageInfo.runtimeDeps;
 
-      programs.neovim.extraWrapperArgs = mkIf (!wrapperHasUserConfig) [
+      programs.neovim.extraWrapperArgs = mkIf (cfg.sideloadInitLua && cfg.initLua != "") [
         "--add-flags"
-        ''--cmd 'lua dofile("${pkgs.writeText "wrapper-init-lua" wrappedNeovim'.luaRcContent}")' ''
+        ''--cmd 'lua dofile("${pkgs.writeText "wrapper-init-lua" cfg.initLua}")' ''
       ];
 
       programs.neovim.initLua =
@@ -550,7 +551,7 @@ in
               null;
         in
         lib.mkMerge [
-          (lib.mkIf wrapperHasUserConfig (
+          (lib.mkIf (wrappedNeovim'.luaRcContent != "") (
             # we want it to appear rather early
             lib.mkOrder 200 wrappedNeovim'.luaRcContent
           ))
@@ -577,6 +578,7 @@ in
         ++ [
           {
             "nvim/init.lua" = mkIf (cfg.initLua != "") {
+              enable = !cfg.sideloadInitLua;
               text = cfg.initLua;
             };
 

tests/modules/programs/neovim/default.nix

@@ -4,9 +4,10 @@
   neovim-runtime = ./runtime.nix;
   neovim-wrapper-args = ./wrapper-args.nix;
 
-  # waiting for a nixpkgs patch
-  neovim-no-init-vim = ./no-init.nix;
+  neovim-no-init-vim = ./no-init-vim.nix;
   neovim-extra-lua-init = ./extra-lua-init.nix;
   neovim-extra-lua-default = ./extra-lua-default.nix;
   neovim-extra-lua-empty-plugin = ./extra-lua-empty-plugin.nix;
+
+  neovim-sideload-init-lua = ./sideload-init-lua.nix;
 }

tests/modules/programs/neovim/extra-lua-default.nix

@@ -1,10 +1,18 @@
+{ lib, ... }:
 {
   imports = [ ./stubs.nix ];
 
   programs.neovim.enable = true;
 
   nmt.script = ''
     nvimFolder="home-files/.config/nvim"
-    assertPathNotExists "$nvimFolder/init.lua"
+    initLua="home-files/.config/nvim/init.lua"
+    initLuaNormalized="$(normalizeStorePaths "$initLua")"
+
+    assertFileContent "$initLuaNormalized" ${builtins.toFile "init.lua-expected" (
+      lib.trim ''
+        vim.g.loaded_node_provider=0;vim.g.loaded_perl_provider=0;vim.g.ruby_host_prog='/nix/store/00000000000000000000000000000000-neovim-ruby-env/bin/neovim-ruby-host';vim.g.python3_host_prog='/nix/store/00000000000000000000000000000000-nvim-host-python3/bin/nvim-python3'
+      ''
+    )}
   '';
 }

tests/modules/programs/neovim/extra-lua-empty-plugin.nix

@@ -1,4 +1,4 @@
-{ pkgs, ... }:
+{ pkgs, lib, ... }:
 {
   imports = [ ./stubs.nix ];
 
@@ -13,7 +13,14 @@
   };
 
   nmt.script = ''
+    nvimFolder="home-files/.config/nvim"
     initLua="home-files/.config/nvim/init.lua"
-    assertPathNotExists "$initLua"
+    initLuaNormalized="$(normalizeStorePaths "$initLua")"
+
+    assertFileContent "$initLuaNormalized" ${builtins.toFile "init.lua-expected" (
+      lib.trim ''
+        vim.g.loaded_node_provider=0;vim.g.loaded_perl_provider=0;vim.g.ruby_host_prog='/nix/store/00000000000000000000000000000000-neovim-ruby-env/bin/neovim-ruby-host';vim.g.python3_host_prog='/nix/store/00000000000000000000000000000000-nvim-host-python3/bin/nvim-python3'
+      ''
+    )}
   '';
 }

tests/modules/programs/neovim/extra-lua-init.nix

@@ -14,6 +14,7 @@
     initLuaNormalized="$(normalizeStorePaths "$initLua")"
 
     assertFileContent "$initLuaNormalized" ${builtins.toFile "init.lua-expected" ''
+      vim.g.loaded_node_provider=0;vim.g.loaded_perl_provider=0;vim.g.ruby_host_prog='/nix/store/00000000000000000000000000000000-neovim-ruby-env/bin/neovim-ruby-host';vim.g.python3_host_prog='/nix/store/00000000000000000000000000000000-nvim-host-python3/bin/nvim-python3'
       -- initLua
     ''}
   '';

tests/modules/programs/neovim/no-init.nix → tests/modules/programs/neovim/no-init-vim.nix

@@ -26,6 +26,5 @@
   nmt.script = ''
     nvimFolder="home-files/.config/nvim"
     assertPathNotExists "$nvimFolder/init.vim"
-    assertPathNotExists "$nvimFolder/init.lua"
   '';
 }

tests/modules/programs/neovim/plugin-config.expected

@@ -1,7 +1,7 @@
 package.path = "/nix/store/00000000000000000000000000000000-luajit/share/lua/5.1/?.lua;/nix/store/00000000000000000000000000000000-luajit/share/lua/5.1/?/init.lua".. ";" .. package.path
 package.cpath = "/nix/store/00000000000000000000000000000000-luajit/lib/lua/5.1/?.so".. ";" .. package.cpath
 
-vim.g.loaded_node_provider=0;vim.g.loaded_perl_provider=0;vim.g.loaded_ruby_provider=0;vim.g.python3_host_prog='/nix/store/00000000000000000000000000000000-nvim-host-python3/bin/nvim-python3'
+vim.g.loaded_node_provider=0;vim.g.loaded_perl_provider=0;vim.g.ruby_host_prog='/nix/store/00000000000000000000000000000000-neovim-ruby-env/bin/neovim-ruby-host';vim.g.python3_host_prog='/nix/store/00000000000000000000000000000000-nvim-host-python3/bin/nvim-python3'
 vim.cmd.source "/nix/store/00000000000000000000000000000000-init.vim"
 
 vim.g.Unicode_data_directory="/nix/store/00000000000000000000000000000000-vimplugin-unicode.vim/autoload/unicode"

tests/modules/programs/neovim/sideload-init-lua.nix

@@ -0,0 +1,81 @@
+{ pkgs, realPkgs, ... }:
+
+{
+  tests.stubs.wl-clipboard = { };
+
+  programs.neovim = {
+    enable = true;
+    package = realPkgs.neovim-unwrapped;
+    vimAlias = true;
+    withNodeJs = false;
+    withPython3 = true;
+    withRuby = false;
+
+    sideloadInitLua = true;
+
+    extraPython3Packages = (
+      ps: with ps; [
+        jedi
+        pynvim
+      ]
+    );
+
+    # plugins without associated config should not trigger the creation of init.vim
+    plugins = with pkgs.vimPlugins; [
+      {
+        plugin = vim-fugitive;
+        type = "viml";
+        config = ''
+          let g:hmPluginVimlConfig = 'HM_PLUGIN_VIML_CONFIG'
+        '';
+      }
+      {
+        plugin = vim-sensible;
+        type = "lua";
+        config = ''
+          vim.g.hmPluginLuaConfig = 'HM_PLUGIN_LUA_CONFIG'
+        '';
+      }
+    ];
+
+    extraConfig = ''
+      let g:hmExtraConfig = 'HM_EXTRA_CONFIG'
+    '';
+
+    initLua = ''
+      vim.g.hmInitLua = 'HM_INIT_LUA'
+    '';
+  };
+  nmt.script = ''
+    nvimFolder="home-files/.config/nvim"
+    nvimBin="home-path/bin/nvim"
+    export PATH="$TESTED/home-path/bin:$PATH"
+    export HOME="$TMPDIR/hm-user"
+    export XDG_CONFIG_HOME="$TESTED/home-files/.config"
+
+    assertNeovimExpr() {
+        local expr="$1"
+        local expected_pattern="$2"
+        local output=$(nvim -i NONE --headless -c "$expr" +q! 2>&1)
+        local exit_code=$?
+
+        if [ $exit_code -ne 0 ]; then
+          echo "neovim command failed with code: $exit_code and output:"
+          fail "$output"
+        elif ! grep "$expected_pattern" <(echo -n "$output") ; then
+          echo "Expression '$expr' doesn't match expected pattern '$expected_pattern'"
+          echo "Output:"
+          fail "$output"
+
+          echo "'$output'"
+        fi
+    }
+
+    assertPathNotExists "$nvimFolder/init.lua"
+
+    assertNeovimExpr "echo g:hmPluginVimlConfig" "HM_PLUGIN_VIML_CONFIG"
+    assertNeovimExpr "echo g:hmExtraConfig" "HM_EXTRA_CONFIG"
+    assertNeovimExpr "echo g:hmExtraConfig" "HM_EXTRA_CONFIG"
+    assertNeovimExpr "echo g:hmInitLua" "HM_INIT_LUA"
+  '';
+}

tests/modules/programs/neovim/wrapper-args.nix

@@ -41,6 +41,8 @@ in
     nvimBin="home-path/bin/nvim"
     export PATH="$TESTED/home-path/bin:$PATH"
     export HOME="$TMPDIR/hm-user"
+    # Load init.lua from $XDG_CONFIG_HOME/nvim/init.lua
+    export XDG_CONFIG_HOME="$TESTED/home-files/.config"
 
     assertBinaryContains() {
         local file="$TESTED/$1"
@@ -55,7 +57,8 @@ in
     assertNeovimExpr() {
         local var_name="$1"
         local expected_pattern="$2"
-        local output=$(nvim -i NONE --headless --cmd "echo $var_name" +q! 2>&1)
+        # Use -c to evaluate the expression after init.lua is loaded
+        local output=$(nvim -i NONE --headless -c "echo $var_name" +q! 2>&1)
         local exit_code=$?
 
         if [ $exit_code -ne 0 ]; then