r220177 - [modules] Add support for #include_next.

[Aaron Ballman]

On Tue, Oct 21, 2014 at 11:31 AM, JF Bastien <jfb at chromium.org> wrote:
>> The compiler has documented sizes for fundamental types which can be
>> used to define the types in this file. Eg)
>>
>> typedef signed char        int8_t;
>> typedef short              int16_t;
>> typedef int                int32_t;
>>
>> Nothing says we cannot provide this in similar fashion for our
>> stdint.h; though, as I pointed out, that could make this file *very*
>> ugly with a bunch of target-specific #ifs everywhere to ensure the
>> proper definitions of *int*_t and friends. I can understand not
>> wanting to do that (especially since the compiler already has this
>> information internally).
>
>
> The compiler guaranteeing something is different from that guarantee being
> in the language. C and C++ standard libraries like newlib target multiple
> compilers and can't rely on what LLVM guarantees, so they either have to use
> configure and ask the compiler by compiling a program, or just straight up
> ask the compiler when it provides nice macros.

Since others seem to be strongly in favor of (2), I will favor it as
well. I have made commit r220312 which implements (2), and brings the
MSVC compat bots back to being green.

~Aaron