Linker plugins should be aware of --defsym during symbol resolution

[Sriraman Tallam via binutils]

On Tue, Feb 13, 2018 at 4:08 PM, Sriraman Tallam <tmsriram@google.com> wrote:
> On Tue, Feb 13, 2018 at 3:53 PM, Cary Coutant <ccoutant@gmail.com> wrote:
>>> This is a nice idea and I am able to make this work for defsym uses.
>>> Anything I could do for definitions too?  I could add a defined_ field
>>> in Symbol which is set to Defined::DEFSYM.  That would avoid
>>> is_defsym_def too.
>>
>> I'd think Symbol::source() = Symbol::IS_CONSTANT would be the test you
>> need. That would also catch symbols defined in scripts, too.

It is too late for plugins before this gets done actually.
define_script_symbols gets called in gold.cc much after deferred
objects are processed.


>
> I was looking at this.  This doesn't work when bar is declared in
> foo.cc and then defined using defsym.  For example:
>
> extern "C" {
> int foo() {
>   return 27;
> }
> extern int bar();
> int main() {
>   return bar();
> }
> }
>
> $ gcc  -Wl,--defsym,bar=foo -Wl,--plugin,gold/testsuite/plugin_test.so
>  foo.o.syms
>
> bar is FROM_OBJECT.
>
>
>>
>> -cary