Re: Does g++ really need to compile main, if c++ code is involved?

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On 20/03/14 13:10, Eric Wolf wrote:
> On 3/20/2014 7:29 AM, Tim Prince wrote:
>> On 3/20/2014 4:27 AM, Eric Wolf wrote:
>>>
>>> We have a big bunch of C and C++ code in our product and compile
>>> main with g++, because I read in
>>>
>>> http://www.parashift.com/c++-faq/overview-mixing-langs.html
>>>
>>> that this is needed.
>>
>> The proper compile mode will be selected regardless of whether you
>> invoke gcc, g++, gfortran, ... e.g. according to the file name. As
>> your reference pointed out, that is not true of many other compilers.
> 
> That's not the point.
> 
> I can easily move the main function into a file ending with .c. Linking
> will still succeed, but I assume, that things will start to go terribly
> wrong, when the c++ code throws an exception, which is caught nowhere,
> or if one tries to use a global non pod object.

Why do you /assume/ this?  Just try it and see.  It should be a simple
matter to write a few test files.

> 
> Here I need a catalog of things, I am not allowed to do in the c++
> portion of the code, so that nothing goes wrong.
> 
>> The second point in that reference is valid: g++ includes -lstdc++
>> implicitly, which the other languages do not, so that g++ references
>> can be satisfied during linking.
> 
> That's useful. So I can use ld to link again, as long as I include
> -lstdc++ Option. That's all?

It is normal practice to use gcc (or g++) to run the linker, rather than
calling it explicitly.  It makes it easier to get the write options
passed on, and makes everything a little more consistent.

> 
> Please excuse the missing References header. I subscribed the digest
> version of the mailing list and my mail programm is defective. I can't
> set the References header by hand.
> 
> Yours sincerely,
> 
> Eric Wolf
> 
> 

Have you tried googling for "difference between gcc and g++"?  There are
plenty of good answers here.

<http://stackoverflow.com/questions/172587/what-is-the-difference-between-g-and-gcc>

The key points are that "-lstdc++" is included by g++ when you use it
for the linker - you need to add it explicitly if using gcc to link.
And it seems that g++ will treat .c files as C++, while gcc treats them
as C files.


So the key issue is not whether you will use g++ or gcc, but whether you
can compile main() in a language other than C++ and still get features
such as static constructors and full exception handling.  I don't know
the answer to that one.







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