Re: io.popen binary write compatibility

[Roberto Ierusalimschy <roberto@...>]

> I know that Lua's touchstone is C89, and I think this type of issue
> discussed was before and it was mentioned that the existing behavior is
> preferable to passing through platform-specific flags. But I don't think it
> involved the "x" flag in particular, which has a uniquely important purpose.

In the past we did meet systems that literally crashed when given an
invalid mode to 'fopen'; that is why we added the checks. Any way,
you can define your own 'l_checkmode' in 'luaconf.h' to accept "x".
(We have optional support for some features in C99, like the '%a'
format specifier; but C11 is still not in our horizon.)

-- Roberto