默认下载完vscode什么都不做，会提示一下信息
Cannot validate since no PHP executable is set. Use the setting 'php.validate.executablePath' to configure the PHP executable.

打开文件->首选项->setting，把PHP的执行路径填进去，前提是本机已经安装了PHP程序
{
"workbench.sideBar.location": "left",
"php.suggest.basic": false,
"php.validate.executablePath":"/usr/bin/php"
}

"php.suggest.basic": false是禁用内置的PHP支持
要禁用内置的PHP智能完成功能，以支持来自已安装的PHP扩展名的建议，请取消选中“ PHP”>“ Suggest：Basic”（php.suggest.basic在settings.json文件中设置为false）。