Code:
  (lambda ()
    (c-ts-mode)
    (setq-local indent-tabs-mode nil)
    (setq-local c-ts-mode-indent-offset 2)
    (c-ts-mode-set-style 'gnu)
    (indent-region (point-min) (point-max)))

Point-Char: |

Name: Basic

=-=
int
main (void)
{
  return 0;
}
=-=-=

Name: Hanging Braces (GNU Style)

=-=
int
main (void)
{
  if (true)
    {
    }
}
=-=-=

Name: Labels (GNU Style)

=-=
int
main (void)
{
 label:
  return 0;
  if (true)
    {
    label:
      return 0;
    }
  else
    {
      if (true)
        {
        label:
          return 0;
        }
    }
}
=-=-=

Name: For Loop with Multi-line Condition (GNU Style)

=-=
int main()
{
  for (int i = 0;
       i < b;
       i++)
    {
      return 0;
    }
}
=-=-=

Name: If-Else (GNU Style)

=-=
int main()
{
  if (true)
    {
      return 0;
    }
  else
    {
      return 1;
    }
}
=-=-=

Name: Empty Line
=-=
int main()
{
  |
}
=-=-=

Name: Concecutive blocks (GNU Style) (bug#60873)

=-=
int
main (int   argc,
      char *argv[])
{
  {
    int i = 0;
  }
}
=-=-=

Name: Bracket-less Block-Statement (GNU Style) (bug#61026)

=-=
int main() {
  while (true)
    if (true)
      {
        puts ("Hello");
      }
  for (int i=0;
       i<5;
       i++)
    if (true)
      {
        puts ("Hello");
      }
  do
    if (true)
      {
        puts ("Hello");
      }
  while (true);
  if (true)
    if (true)
      {
        puts ("Hello");
      }
}
=-=-=

Name: Multiline Parameter List (bug#60398)

=-=
int f2(int x,
       int y) {
  return x + y;
};
=-=-=

Name: Multiline Block Comments 1 (bug#60270)

=-=
/**
 * @some_func:
 * @arg1:
 */
=-=-=

Name: Multiline Block Comments 2 (bug#60270)

=-=
/*
  some comment
 */
=-=-=

Name: Multiline Block Comments 3 (bug#60270)

=-=
/* some comment
 */
=-=-=

Name: Multiline Block Comments 4 (bug#60270)

=-=
/*
 * Some comment
 */
=-=-=

Name: Multiline Block Comments 5 (bug#60270)

=-=
/*
line one
line 2
 */
=-=
/*
  line one
  line 2
 */
=-=-=


Code:
  (lambda ()
    (c-ts-mode)
    (setq-local indent-tabs-mode nil)
    (setq-local c-ts-mode-indent-offset 8)
    (c-ts-mode-set-style 'linux)
    (indent-region (point-min) (point-max)))

Name: Labels (Linux Style)

=-=-=
int main (void)
{
label:
        return 0;
        if (true) {
label:
                return 0;
        }
        else {
                if (true) {
label:
                        return 0;
                }
        }
}
=-=-=

Name: Bracket-less Block-Statement (Linux Style) (bug#61026)

=-=-=
int main() {
  while (true)
    if (true) {
      puts ("Hello");
    }
  for (int i=0;
       i<5;
       i++)
    if (true) {
      puts ("Hello");
    }
  do
    if (true) {
      puts ("Hello");
    }
  while (true);
  if (true)
    if (true) {
      puts ("Hello");
    }
}
=-=-=

Name: Complicated mixed bracket matching indentation (bug#61142)

=-=
void foo(
         int foo) {
  for (;;)
    return 5;

  if (a == 0
      && b == 1
      && foo)
    {
      return 0;
    }
  else if (a == 1)
    {
      return 1;
    }
  else if (true)
    return 5;
  else
    {
      if (a == 0
          && b == 1
          && foo)
        for (
             int i = 0;
             i < 5;
             i++)
          if (true)
            do
              i = 5;
            while (true);
          else if (false)
            {
              return 6;
            }
          else
            if (true
                && false)
              return 6;
    }
}
=-=-=