[libc++] Support Newlib as libc++'s C library [cstdio part, part 2]

[jroelofs]

Summary

Shims for lib2l and logbl.
Wrappers for clearerr, feof, ferror (which newlib implements as macros).

Edit: fix title. This one isn't ARM specific.
Edit: fix title again. This one no longer has to do with cmath.

[jfb]

I looked at this again, and it seems like they should be in newlib because of C99. Should this be fixed in newlib instead?

There was a thread about this on the newlib mailing list:

https://sourceware.org/ml/newlib/2014/msg00349.html

These two functions are mentioned later.

[mclow.lists]

include/cstdio

175 ↗

(On Diff #13893)

I think that these will cause warnings/errors if clearerr is not defined as a macro.

Should they be wrapped in #ifdef xxx ??

cmath has a pattern for this; should that be used here?

#ifdef isunordered
template <class _A1, class _A2>
_LIBCPP_ALWAYS_INLINE
bool
__libcpp_isunordered(_A1 __lcpp_x, _A2 __lcpp_y) _NOEXCEPT
{
    return isunordered(__lcpp_x, __lcpp_y);
}

#undef isunordered
bool isunordered(_A1 __lcpp_x, _A2 __lcpp_y) _NOEXCEPT
{
    return __libcpp_isunordered(__lcpp_x, __lcpp_y);
}
#endif

[jroelofs]

Yes, it does make sense to use that pattern, for the case of REENT_SMALL.

@jfb do we lose anything by implementing these shims here, and then later pushing them into newlib?

[jfb]

In D5420#10, @jroelofs wrote:

@jfb do we lose anything by implementing these shims here, and then later pushing them into newlib?

There may be a combination of newlib + libc++ where the functions are defined twice, once in newlib and once in libc++. That seems like a bad idea.

[jroelofs]

include/support/newlib/math.h

26 ↗

(On Diff #13995)

Should be taken care of here: https://sourceware.org/ml/newlib/2014/msg00469.html

[jroelofs]

Updating the diff to reflect the parts of this that have already made it into newlib itself. Now the title is a little misleading, so renaming that at the same time.

[danalbert]

LGTM.

[jroelofs]

r225563

libcxx/include/cstdio

 #endif  // getc
 
 #ifdef putc
 inline _LIBCPP_INLINE_VISIBILITY int __libcpp_putc(int __c, FILE* __stream) {return putc(__c, __stream);}
 #undef putc
 inline _LIBCPP_INLINE_VISIBILITY int putc(int __c, FILE* __stream) {return __libcpp_putc(__c, __stream);}
 #endif  // putc
 
+#ifdef clearerr
+inline _LIBCPP_INLINE_VISIBILITY void __libcpp_clearerr(FILE* __stream) { return clearerr(__stream); }
+#undef clearerr
+inline _LIBCPP_INLINE_VISIBILITY void clearerr(FILE* __stream) { return __libcpp_clearerr(__stream); }
+#endif  // clearerr
+
+#ifdef feof
+inline _LIBCPP_INLINE_VISIBILITY int __libcpp_feof(FILE* __stream) { return feof(__stream); }
+#undef feof
+inline _LIBCPP_INLINE_VISIBILITY int feof(FILE* __stream) { return __libcpp_feof(__stream); }
+#endif  // feof
+
+#ifdef ferror
+inline _LIBCPP_INLINE_VISIBILITY int __libcpp_ferror(FILE* __stream) { return ferror(__stream); }
+#undef ferror
+inline _LIBCPP_INLINE_VISIBILITY int ferror(FILE* __stream) { return __libcpp_ferror(__stream); }
+#endif  // ferror
+
 _LIBCPP_BEGIN_NAMESPACE_STD
 
 using ::FILE;
 using ::fpos_t;
 using ::size_t;
 
 using ::remove;
 using ::rename;