Re: Libs ordering in LDADD

[Eric Siegerman]

On Sun, Oct 19, 2003 at 12:07:37PM -0400, Earnie Boyd wrote:
> the line order.  If I have object foo that has dependency to libbar.a 
> then I must have object foo before -lbar.

To explain why that is:  when the linker searches a library, it
only links in the modules that it knows to be needed.  Suppose
foo.o needs function bazzle(), which is found in -lbar.  If you
give:
        ld .... -lbar foo.o
Then at the time the "bar" library is searched, the linker
doesn't yet know that bazzle() is needed, and so doesn't link it
in.  Then foo.o comes along with a reference to undefined
function bazzle(), but nothing *following* foo.o on the command
line can satisfy that reference.  You get an "undefined" error.
But with:
        ld .... foo.o -lbar
the linker knows, while searching -lbar, that it needs bazzle().

The situation with two libraries is similar.

--

|  | /\
|-_|/  >   Eric Siegerman, Toronto, Ont.        address@hidden
|  |  /
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