On Jan 22 16:47, Christian Franke via Cygwin wrote:
> Busybox does not build OOTB on Cygwin due to the addition of itoa/utoa() to
> newlib in 2014:
> https://cygwin.com/git/?p=newlib-cygwin.git;a=commit;h=32c96dd
>
> This is because Busybox use local functions with same name but different
> signature. This does not affect build on FreeBSD, Linux (glibc, musl libc),
> ... because these functions simply do not exits there. For the busybox
> Cygwin package, I use an ugly local hack to fix this.
>
> itoa() is mentioned as a non-standard extension here:
> https://en.wikibooks.org/wiki/C_Programming/stdlib.h/itoa
> https://cplusplus.com/reference/cstdlib/itoa/
>
> MSVC provides itoa() as a "POSIX version" of _itoa():
> https://learn.microsoft.com/cpp/c-runtime-library/reference/itoa-itow
>
> But SUS-1997... POSIX-2018 do not mention these functions:
> https://pubs.opengroup.org/onlinepubs/7908799/
> https://pubs.opengroup.org/onlinepubs/9699919799/
>
> Newlib guards the prototypes with __MISC_VISIBLE in stdlib.h and
> sys/features.h says:
>
> * __MISC_VISIBLE
> * Extensions found in both BSD and SVr4 (shorthand for
> * (__BSD_VISIBLE || __SVID_VISIBLE)), or newlib-specific
> * extensions; enabled by default.
>
> __MISC_VISIBLE is set if and only if _DEFAULT_SOURCE is set, so the comment
> below should also include "... or newlib-specific extensions":
>
> * _DEFAULT_SOURCE (or none of the above)
> * POSIX-1.2008 with BSD and SVr4 extensions
>
>
> The above is not suitable to disable only the non-standard functions for
> such use cases. Using -D_GNU_SOURCE should IMO not enable functions
> unavailable on Linux. This is not the case because _GNU_SOURCE implies
> _DEFAULT_SOURCE.
>
> No patch provided for now, as I'm not yet sure how to handle this. Possibly:
>
> - Use __MISC_VISIBLE only for (__BSD_VISIBLE || __SVID_VISIBLE) - under the
> assumption that this is applicable for most cases.
> - Introduce __NONSTD_VISIBLE for non-standard functions like itoa().
> - Introduce _NONSTD_SOURCE to set __NONSTD_VISIBLE independent from other
> _*_SOURCE defines.
Counter proposal:
First of all, Cygwin does NOT export itoa/utoa! Only the prototypes
exist from the Cygwin POV.
As Cygwin is usually the only newlib project with backward compat
issues, we have two simple choices:
- Drop itoa/utoa entirely, or
- just guard them with
#if __MISC_VISIBLE && !defined (__CYGWIN__)
You can make a proposal like that on the newlib list and then we can
discuss it there, ok?
Corinna
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