Re: Integrating libraries or exe's complied on different compilers
On Nov 15, 6:04 pm, Paavo Helde <nob...@ebi.ee> wrote:
shyam.lingego...@gmail.com kirjutas:
[...]
all. Is there any alternative for the same. What about
libraries compiled with two different compilers. If someone
can give some
You probably mean whether you can link together C++ libraries
compiled by different compilers. This is undefined by the
standard, meaning that you cannot do this portably.
It is only possible if both compilers follow the same ABI
(application binary interface). The ABI is typically defined
for a certain combination of a language platform, e.g. C++ ABI
for Linux on x86_64. I believe there are some platforms with
standardized C++ ABI, so if both compilers follow this, they
should be able to talk to each other.
However, this is not enough. For example, if one library uses
small- string optimization for std::string and the other does
not, then any attempt to pass a std::string from one library
to another will most probably fail miserably. This is where
the one-definition-rule of C++ kicks in, I guess - if the
libraries are using different std::string definitions, the
result is undefined.
The physical layout of std::string is part of a C++ ABI, so if
their is a C++ ABI, there should be no problem. (On the
platforms I work on, there isn't, and this doesn't work. In
fact, the C++ ABI even depends on compiler options, and you
can't necessarily link two libraries compiled with the same
compiler. From what I understand, this is more or less
general.)
Using only C types and extern "C" functions may be helpful,
because C ABI is standardized for more platforms. I am not too
sure what the C ABI says about things like struct
padding/packing, I would probably avoid them for any case and
use arrays instead.
A C ABI must define how struct's are laid out. All that I know
do. (In particular, both Windows and Posix do, since both use
struct's in their system ABI.) Of course, a compiler still
might have options, or pragmas, to break this compatibility.
--
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