Re: PATCH: Add STB_SECONDARY support

[Alan Modra <amodra at gmail dot com>]

On Mon, Jul 02, 2012 at 06:31:34AM -0700, H.J. Lu wrote:
> The main usage is
> 
> 1. ISV defines a secondary symbol in a library.
> 2. The library with a secondary symbol is used by programmers.
> 
> #1 and #2 are different people. ISV has no control over
> the command line used by programmers.  We need
> a reliable solution which is transparent to programmers,

It sounds to me that the best solution would be to define a way of
marking an archive that instructs the linker to link it last
regardless of where it is placed on the command line, then just use
weak symbols.  This has the added benefit that your backup
implementations will be included on an object file granularity, which
is likely to be the simplest and most useful model.  Also, this should
work with PE and other object formats rather than being ELF only.

Options for marking the archive are
- A new magic string to replace "!<arch>\012", as we did for thin
  archives. 
- A special file name in the archive, similar to the way extended file
  names are recognized.
- A magic symbol in the armap.

I'm not sure which is best.

-- 
Alan Modra
Australia Development Lab, IBM