Fix Windows build: link against node.lib for V8 symbols

On Windows/MSVC, V8 symbols must be resolved at link time via node.lib
(the import library). On Unix, they resolve at runtime when Node.js
loads the .node addon. The build script now finds node.lib from the
node-gyp cache or the Node.js install directory.

Author: semihalev

build.rs

@@ -17,6 +17,8 @@ extern crate napi_build;
 fn main() {
     napi_build::setup();
 
+    let target = std::env::var("TARGET").unwrap_or_default();
+
     // Compile v8_helpers.cpp — direct V8 bulk object creation
     let node_include = node_include_dir();
     let mut build = cc::Build::new();
@@ -25,7 +27,6 @@ fn main() {
         .file("src/v8_helpers.cpp")
         .include(&node_include);
 
-    let target = std::env::var("TARGET").unwrap_or_default();
     if target.contains("msvc") {
         // MSVC flags
         build.flag("/std:c++20").flag("/EHs-").flag("/GR-");
@@ -40,6 +41,52 @@ fn main() {
     }
 
     build.compile("v8_helpers");
+
+    // On Windows, link against node.lib for V8 symbols.
+    // On Unix, V8 symbols resolve at runtime when Node.js loads the .node addon.
+    if target.contains("windows") {
+        link_node_lib(&node_include);
+    }
+}
+
+/// Link against node.lib on Windows.
+///
+/// Searches for node.lib in:
+/// 1. node-gyp cache: <version_dir>/<arch>/node.lib
+/// 2. Node.js install directory (next to node.exe)
+fn link_node_lib(include_dir: &str) {
+    let include_path = std::path::Path::new(include_dir);
+
+    // node-gyp cache layout: .../Cache/<version>/include/node/
+    // node.lib is at:         .../Cache/<version>/x64/node.lib
+    if let Some(version_dir) = include_path.parent().and_then(|p| p.parent()) {
+        for arch in &["x64", "arm64", "x86"] {
+            let lib_dir = version_dir.join(arch);
+            if lib_dir.join("node.lib").exists() {
+                println!("cargo:rustc-link-search={}", lib_dir.display());
+                println!("cargo:rustc-link-lib=node");
+                return;
+            }
+        }
+    }
+
+    // Fallback: node.lib next to node.exe
+    let output = std::process::Command::new("node")
+        .args(["-e", "console.log(require('path').dirname(process.execPath))"])
+        .output()
+        .ok();
+    if let Some(out) = output {
+        if let Ok(dir) = String::from_utf8(out.stdout) {
+            let dir = dir.trim();
+            if std::path::Path::new(dir).join("node.lib").exists() {
+                println!("cargo:rustc-link-search={dir}");
+                println!("cargo:rustc-link-lib=node");
+                return;
+            }
+        }
+    }
+
+    panic!("node.lib not found. Required for Windows builds. Run: npx node-gyp install");
 }
 
 /// Get Node.js include directory for V8 headers.