Function checkExtendPosition

packages/pug-linker/index.js:191–206

(ast, hasExtends)

}

function checkExtendPosition(ast, hasExtends) {
  var legitExtendsReached = false;
  walk(ast, function(node) {
    if (node.type === 'Extends') {
      if (hasExtends && !legitExtendsReached) {
        legitExtendsReached = true;
      } else {
        error(
          'EXTENDS_NOT_FIRST',
          'Declaration of template inheritance ("extends") should be the first thing in the file. There can only be one extends statement per file.',
          node
        );
      }
    }
  });
}