Won't compile with GCC 15 (with default options)

[rostislav-nikitin]

Problem
GCC versions before GCC 15 defaulted to the GNU C89 standard (-std=gnu89 or similar), which still allowed the old-style syntax for backward compatibility. With GCC 15, the default has changed to C23 (-std=gnu23), where the old syntax is no longer valid. Code using this style will now cause a compilation error.

/* Old-style function definition */
int max(a, b)
int a, b;
{
return a > b ? a : b;
}

Fix
Use compiler option: -std=gnu89