neovim-unwrapped: add optional wasmtime support

Add a wasmSupport override that enables Neovim's wasmtime integration and uses wasm-enabled tree-sitter while keeping defaults aligned with upstream.

pkgs/by-name/ne/neovim-unwrapped/package.nix

@@ -11,6 +11,7 @@
   unibilium,
   utf8proc,
   tree-sitter,
+  wasmtime_36,
   fetchurl,
   buildPackages,
   treesitter-parsers ? import ./treesitter-parsers.nix { inherit fetchurl; },
@@ -20,6 +21,7 @@
   versionCheckHook,
   nix-update-script,
   writableTmpDirAsHomeHook,
+  wasmSupport ? false,
 
   # now defaults to false because some tests can be flaky (clipboard etc), see
   # also: https://github.com/neovim/neovim/issues/16233
@@ -30,6 +32,9 @@
 
 let
   lua = if lib.meta.availableOn stdenv.hostPlatform luajit then luajit else lua5_1;
+  treeSitterForNeovim = tree-sitter.override {
+    inherit wasmSupport;
+  };
 in
 
 stdenv.mkDerivation (
@@ -161,10 +166,13 @@ stdenv.mkDerivation (
       # and it's definition at: pkgs/development/lua-modules/overrides.nix
       lua.pkgs.libluv
       neovimLuaEnv
-      tree-sitter
+      treeSitterForNeovim
       unibilium
       utf8proc
     ]
+    ++ lib.optionals wasmSupport [
+      wasmtime_36
+    ]
     ++ lib.optionals (stdenv.hostPlatform.libc != "glibc") [
       # Provide libintl for non-glibc platforms
       gettext
@@ -202,13 +210,20 @@ stdenv.mkDerivation (
         pyEnv # for src/clint.py
       ];
 
-    # nvim --version output retains compilation flags and references to build tools
-    postPatch = lib.optionalString (!stdenv.buildPlatform.canExecute stdenv.hostPlatform) ''
-      sed -i runtime/CMakeLists.txt \
-        -e "s|\".*/bin/nvim|\${stdenv.hostPlatform.emulator buildPackages} &|g"
-      sed -i src/nvim/po/CMakeLists.txt \
-        -e "s|\$<TARGET_FILE:nvim|\${stdenv.hostPlatform.emulator buildPackages} &|g"
-    '';
+    postPatch =
+      lib.optionalString wasmSupport ''
+        substituteInPlace src/nvim/CMakeLists.txt \
+          --replace-fail \
+            'find_package(Wasmtime 36.0.6 EXACT REQUIRED)' \
+            'find_package(Wasmtime REQUIRED)'
+      ''
+      # nvim --version output retains compilation flags and references to build tools
+      + lib.optionalString (!stdenv.buildPlatform.canExecute stdenv.hostPlatform) ''
+        sed -i runtime/CMakeLists.txt \
+          -e "s|\".*/bin/nvim|\${stdenv.hostPlatform.emulator buildPackages} &|g"
+        sed -i src/nvim/po/CMakeLists.txt \
+          -e "s|\$<TARGET_FILE:nvim|\${stdenv.hostPlatform.emulator buildPackages} &|g"
+      '';
     # check that the above patching actually works
     disallowedRequisites = [
       stdenv.cc
@@ -229,6 +244,12 @@ stdenv.mkDerivation (
       (lib.cmakeBool "ENABLE_TRANSLATIONS" true)
       (lib.cmakeBool "USE_BUNDLED_BUSTED" false)
     ]
+    ++ lib.optionals wasmSupport [
+      # FindWasmtime has no pkg-config fallback.
+      (lib.cmakeBool "ENABLE_WASMTIME" true)
+      (lib.cmakeFeature "WASMTIME_INCLUDE_DIR" "${lib.getDev wasmtime_36}/include")
+      (lib.cmakeFeature "WASMTIME_LIBRARY" "${lib.getLib wasmtime_36}/lib/libwasmtime${stdenv.hostPlatform.extensions.sharedLibrary}")
+    ]
     ++ (
       if lua.pkgs.isLuaJIT then
         [