[ros-users] Linker --as-needed

[Daniel Stonier]

On 10 August 2010 02:32, Josh Faust <jfaust at willowgarage.com> wrote:

>
>> Happy to hear that it works in general (would be pretty bad if it
>> didn't...).  I'm more concerned about whether we're currently
>> specifying everything completely, or unknowingly exploiting
>> overlinkage.
>>
>> I guess the only way to find out is to build and test everything with
>> that option included.
>>
>>
> I just did two quick tests:
>  1) .so that overrides a global symbol (strstr in this case)
>  2) .so with a global object that has a constructor/destructor
>
> #1 worked, #2 failed (the .so was removed).
>
> If #1 failed I'd say we can't default to it.  Not sure how important #2 is,
> but it's something that could definitely cause problems that would be
> difficult to track down.
>
> Josh
>

Josh, how did you produce result 2)? I just tested it here to be aware of
when it might break and couldn't reproduce the failure. It correctly
excludes/includes the library when I comment/uncomment the relevant usage of
the variable. Snippets below:

LIBRARY HPP:

namespace ecl {

class A {
public:
A() : i(3) {}
~A() {}
int i;
};
extern const A a;

}

LIBRARY CPP:

namespace ecl {

const A a;

}

MAIN CPP

int main() {
    std::cout << "i: " << ecl::a.i << std::endl;
    return 0;
}






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