GCC-6.4 sys/select.h build failures with std=c++14

[Brian Inglis]

On 2017-09-25 19:41, Ian Fette wrote:
> I tried compiling a very simple program with curl using -std=c++14 under 
> 64-bit cygwin with gcc 6.4.0. When compiling with just g++ main.cpp -lcurl 
> everything is fine, however if I try to use c++14 as the dialect (g++ 
> main.cpp -lcurl -std=c++14) familiar problems creep up

> This is resolved by manually including <sys/select.h> before including 
> <curl/curl.h>

> This was discussed in the curl project in the past 
> (https://github.com/curl/curl/issues/749) where it was determined that it was
> caused by a cygwin bug which was addressed in 
> https://cygwin.com/git/gitweb.cgi?p=newlib-cygwin.git;a=blob;f=newlib/libc/include/sys/types.h;
> h=c9f0fc7f3a9ca420c2372c9af42ce2a0e63e3b1c;hb=ee97c4b22491b205fd3b7697e03c909e02b652d3
> If anyone has thoughts, I'd greatly appreciate it.

A lot of GNU and Cygwin package build problems are avoided by building either
without any -std=... option, or equivalently with -std=gnu++nn, which enables
many non-portable GCC extensions and Unix features, instead of -std=c++nn, which
disables GCC extensions and Unix features, and accepts only portable features
supported by GCC and C++ headers you specify.

In general, try replacing -std=c... with -std=gnu... or omitting -std=... and
see if your program builds without errors or warnings.
Adding -Wall -Wextra will let you know if anything appears questionable to the
compiler.

-- 
Take care. Thanks, Brian Inglis, Calgary, Alberta, Canada

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