Setting resource.RLIMIT_STACK not working on MacOS

Bug report

Bug description:

Running

python3.14 -c "import resource; resource.setrlimit(resource.RLIMIT_STACK, resource.getrlimit(resource.RLIMIT_STACK))"

On MacOS 15.7.2 on my M4 Macbook produces the following error:

Traceback (most recent call last):
  File "<string>", line 1, in <module>
    import resource; resource.setrlimit(resource.RLIMIT_STACK, resource.getrlimit(resource.RLIMIT_STACK))
                     ~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
ValueError: current limit exceeds maximum limit

Given we are setting the limit to what it was previously, I would not expect this to exceed the maximum limit, because we are not actually changing any limits. The following c program works without issue

#include <stdio.h>
#include <errno.h>
#include <sys/resource.h>

int main(void)
{
    struct rlimit limits = {
        8372224,
        60792480
    };
    int r = setrlimit(RLIMIT_STACK, &limits);
    if (r == -1) {
        perror("setrlimit");
        return 1;
    }
    return 0;
}

(The limits I am setting there are the defaults that python reports).

This seems to be related to #78783.

CPython versions tested on:

3.14

Operating systems tested on:

macOS

Linked PRs

• gh-150170

從報告的、在 macOS 上使用 resource.setrlimit 和 resource.getrlimit 的 Python 命令開始，然後檢視相關的 issue #78783 和連結的 PR gh-150170。在報告的 macOS 設定中，將 RLIMIT_STACK 設為 getrlimit 傳回的值不再引發 ValueError，即表示完成。