Re: [BUG] ld behavior varies for C++ static initializer depending on .a or .o input

[Hal Black <black@ieee.org>]

Ian Lance Taylor wrote:

> Hal Black <black@ieee.org> writes:
> 
> 
>>>It means that including any class with a static initializer in a .a
>>>file would mean that that class would be included in all programs
>>>linked with that .a file.
>>
>>Yes.  That's the desired behavior.  If a developer were to develop a
>>library with a static initializer with side-effects, it would be
>>something that should be called whenever that library was used.
> 
> 
> No Unix linker has ever worked that way.

Well, for most of the lifetime of Unix, there were no static 
initializers, since there was no C++, so this is not surprising.

> Also, while this is not the reason for not making the change, it turns
> out that it is not an efficient change to make.  It would require the
> linker to examine every object in every archive, which obviates the
> entire point of having archives in the first place.  Again, this
> inefficiency, while severe, is not the reason for not making the
> change; the reason for not making the change is that ld and ar
> implement behaviour which has not changed for decades, and should not
> be changed now.

For the C code that ld has been linking for decades, I agree with you 100%.

But, C++ has additional requirements.  Either the tool needs to change 
to meet these requirements, or a different tool needs to be used to meet 
them.

If .a is meant only for what it has been used for decades without 
changing to accomodate the full C++ specification, you're right, I 
misunderstood the usage for it.  That is definately not what I want. 
Based on the other replies, I guess that .so can be used to acheive the 
desired behavior even though it includes too much.

Anyway, thank you for responding and for your time, Ian.