fix sysroot on macos with esp clang

internal/crosscompile/crosscompile.go

@@ -5,6 +5,7 @@ import (
 	"fmt"
 	"io/fs"
 	"os"
+	"os/exec"
 	"path/filepath"
 	"runtime"
 	"strings"
@@ -44,6 +45,16 @@ func cacheDir() string {
 	return filepath.Join(env.LLGoCacheDir(), "crosscompile")
 }
 
+// getMacOSSysroot returns the macOS SDK path using xcrun
+func getMacOSSysroot() (string, error) {
+	cmd := exec.Command("xcrun", "--sdk", "macosx", "--show-sdk-path")
+	output, err := cmd.Output()
+	if err != nil {
+		return "", err
+	}
+	return strings.TrimSpace(string(output)), nil
+}
+
 // getESPClangRoot returns the ESP Clang root directory, checking LLGoROOT first,
 // then downloading if needed and platform is supported
 func getESPClangRoot() (clangRoot string, err error) {
@@ -118,6 +129,16 @@ func use(goos, goarch string, wasiThreads bool) (export Export, err error) {
 			"-fuse-ld=lld",
 		}
 
+		// Add sysroot for macOS only
+		if goos == "darwin" {
+			sysrootPath, sysrootErr := getMacOSSysroot()
+			if sysrootErr != nil {
+				err = fmt.Errorf("failed to get macOS SDK path: %w", sysrootErr)
+				return
+			}
+			export.LDFLAGS = append([]string{"--sysroot=" + sysrootPath}, export.LDFLAGS...)
+		}
+
 		// Add OS-specific flags
 		switch goos {
 		case "darwin": // ld64.lld (macOS)