How does linker choose library with same function export?

Thomas Wolff
Sun Oct 20 09:40:00 GMT 2019

Am 20.10.2019 um 11:15 schrieb Csaba Raduly:
> Hi,
> On Sat, Oct 19, 2019 at 2:57 PM Biswapriyo Nath  wrote:
>> I want to use socket() from ws2_32.dll file. But cygwin1.dll also has that
>> export. When I use `-lws2_32` option, will gcc **always** choose
>> ws2_32.lib? My query is somewhat similar with FAQ #5.11.
> I think the FAQ is pretty clear:
> "5.11.
> I don't want Unix sockets, how do I use normal Win32 winsock?
> You don't. "
I guess that should read "You don't, normally."
There may be reasons to look for special, Windows-supplied functionality 
variations, e.g. when interfacing to Windows (likely WSL, in this case).
Without the possibility to use a mix of POSIX and Windows APIs, the 
Cygwin Terminal (mintty) wouldn't exist.

For dedicated linking, I think the order of listing the libraries in the 
link command is essential.
If in doubt, you could also try to load the function dynamically from 
the desired library (using GetProcAddress for the Windows API or dlsym 
for POSIX).

> You shouldn't look at Cygwin programs as if they were Windows programs.
> Cygwin is a POSIX environment.
> You either create a Cygwin program and use the POSIX functions,
> or you create a Windows program (you can cross-compile Windows programs
> under Cygwin).
> Mixing the two is likely to run into problems, and you aren't going to
> get much help
> when you were told "don't do it" at the very beginning.
> Csaba

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