c++ - g++如何在忽略函数返回值时获得警告

Question

lint 会产生一些警告，例如:

foo.c XXX Warning 534: Ignoring return value of function bar()

来自 lint manual

534 Ignoring return value of function

'Symbol' (compare with Location) A function that returns a value is called just for side effects as, for example, in a statement by itself or the left-hand side of a comma operator. Try: (void) function(); to call a function and ignore its return value. See also the fvr, fvo and fdr flags in §5.5 "Flag Options".

我想在编译期间收到此警告(如果存在)。 gcc/g++ 中是否有任何选项可以实现这一点？我打开了 -Wall 但显然没有检测到这一点。

Answer 1

从 C++17 开始，您可以使用 [[nodiscard]] attribute .

例子:

[[nodiscard]] int bar() {
  return 42;
}