fopen是否可能返回stdout？是否需要调用fclose关闭它？

我写了一段实现输出文件选项的C代码，简化后的最小示例如下：

#define _XOPEN_SOURCE
#include <stdio.h>
#include <string.h>

static void output(const char *output_path) {
    FILE *output_file = stdout;

    if (output_path == NULL || *output_path == '\0' || strcmp(output_path, "-") == 0) {
        output_path = "stdout";
    }
    else {
        output_file = fopen(output_path, "w");
        if (output_file == NULL)
            return;
    }

    fprintf(stderr, "Output path: %s\n", output_path);
    fputs("Hello there\n", output_file);

    if (output_file != stdout)
        fclose(output_file);
}

int main(int argc, char *argv[]) {
    /* ... */
    output(argc > 1 ? argv[1] : NULL);
    /* ... */
    puts("Done");
    return 0;
}

这段代码的逻辑是：只有当传入非-的路径时才打开并关闭文件，否则直接使用stdout且不关闭（后续还要用它做其他输出）。即便之后不再使用stdout，我也遵循POSIX的建议不关闭它：

由于调用fclose()后对流的任何使用都会导致未定义行为，因此不应在stdin、stdout或stderr上调用fclose()，除非是在进程终止前立即调用（参见XBD进程终止），以避免在依赖这些流的其他标准接口中触发未定义行为。

但最近用gcc静态分析器检查时，它给出了文件泄漏的警告：

$ gcc --version
gcc (Debian 13.3.0-1) 13.3.0
Copyright (C) 2023 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

$ gcc -fanalyzer main.c
main.c: In function ‘output’:
main.c:20:12: warning: leak of FILE ‘output_file’ [CWE-775] [-Wanalyzer-file-leak]
   20 |         if (output_file != stdout)
      |            ^
  ‘output’: events 1-7
    |
    |    8 |         if (output_path == NULL || *output_path == '\0' || strcmp(output_path, "-") == 0) {
    |      |            ^
    |      |            |
    |      |            (1) following ‘false’ branch...
    |......
    |   12 |                 output_file = fopen(output_path, "w");
    |      |                               ~~~~~~~~~~~~~~~~~~~~~~~
    |      |                               |
    |      |                               (2) ...to here
    |      |                               (3) opened here
    |   13 |                 if (output_file == NULL)
    |      |                    ~
    |      |                    |
    |      |                    (4) assuming ‘output_file’ is non-NULL
    |      |                    (5) following ‘false’ branch (when ‘output_file’ is non-NULL)...
    |......
    |   17 |         fprintf(stderr, "Output path: %s\n", output_path);
    |      |         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    |      |         |
    |      |         (6) ...to here
    |......
    |   20 |         if (output_file != stdout)
    |      |            ~
    |      |            |
    |      |            (7) following ‘false’ branch...
    |
  ‘output’: event 8
    |
    |cc1:
    | (8): ...to here
    |
  ‘output’: event 9
    |
    |   20 |         if (output_file != stdout)
    |      |            ^
    |      |            |
    |      |            (9) ‘output_file’ leaks here; was opened at (3)
    |
main.c:20:12: warning: leak of ‘output_file’ [CWE-401] [-Wanalyzer-malloc-leak]
  ‘output’: events 1-7
    |
    |    8 |         if (output_path == NULL || *output_path == '\0' || strcmp(output_path, "-") == 0) {
    |      |            ^
    |      |            |
    |      |            (1) following ‘false’ branch...
    |......
    |   12 |                 output_file = fopen(output_path, "w");
    |      |                               ~~~~~~~~~~~~~~~~~~~~~~~
    |      |                               |
    |      |                               (2) ...to here
    |      |                               (3) allocated here
    |   13 |                 if (output_file == NULL)
    |      |                    ~
    |      |                    |
    |      |                    (4) assuming ‘output_file’ is non-NULL
    |      |                    (5) following ‘false’ branch (when ‘output_file’ is non-NULL)...
    |......
    |   17 |         fprintf(stderr, "Output path: %s\n", output_path);
    |      |         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    |      |         |
    |      |         (6) ...to here
    |......
    |   20 |         if (output_file != stdout)
    |      |            ~
    |      |            |
    |      |            (7) following ‘false’ branch...
    |
  ‘output’: event 8
    |
    |cc1:
    | (8): ...to here
    |
  ‘output’: event 9
    |
    |   20 |         if (output_file != stdout)
    |      |            ^
    |      |            |
    |      |            (9) ‘output_file’ leaks here; was allocated at (3)
    |

我认为分析器应该能理解fopen/fclose的行为，但它的警告似乎暗示fopen可能返回stdout，这种情况下需要调用fclose关闭它。事实真的是这样吗？还是我误解了分析器的输出？

内容的提问来源于stack exchange，提问作者Josh Brobst