Re: extern "C" From command line

[Brian Dessent <brian@dessent.net>]

Seyran Avanesyan wrote:

> Hi,

Please don't hijack threads; start a new thread.  Changing the subject
line does not accomplish this.  The mailing list archives on the gcc
website and any threaded email client will show your message as a reply
in a completely unrelated thread.

> Is there any way to make exported function names unmangled without using
> extern "C"?
> 
> I'm compiling c++ file to a dll. Exported functions doesn't have extern
> "C" specified for them, so their names got mangled.
> The file cannot be edited.
> 
> gcc -x c++ source.cpp -o source.o
> gcc -shared -o source.dll other_source.o source.o
> 
> If I put required names into .def file but compile as c++ file, because
> of mangling I got errors: "Can not export ZZZZ: symbol not defined"

The mangling is there for a reason.  If you exported a function with C++
linkage but without its name mangled then it's very likely that you
could call it from a compiler with a different C++ ABI, such as MSVC,
and that would fail.  Mangling prevents this, because it requires that
to call the function you have a compiler with compatible ABI.

If your complaint is simply that you don't want to put mangled names in
the .def file, then I must ask: why use a .def file at all?  It's
usually not needed.  The GNU linker has auto-export enabled by default
which causes all symbols to be exported if __declspec(dllexport) is not
used anywhere.  And if __declspec(dllexport) is used, then the source
itself already controls what functions to be exported so the .def file
is extraneous.

Brian