[Bug gold/16693] "exclude-libs" drops symbols that are exported through "dynamic-list" or "export-dynamic-symbol"

[ccoutant at google dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=16693

--- Comment #9 from Cary Coutant <ccoutant at google dot com> ---
> --dynamic-list isn't used to control which symbols are exported or
> not.  From ld manual:
>
> '--dynamic-list=DYNAMIC-LIST-FILE'
>      Specify the name of a dynamic list file to the linker.  This is
>      typically used when creating shared libraries to specify a list of
>      global symbols whose references shouldn't be bound to the
>      definition within the shared library, or creating dynamically
>      linked executables to specify a list of symbols which should be
>      added to the symbol table in the executable.  This option is only
>      meaningful on ELF platforms which support shared libraries.

True, but a necessary side effect of not binding a symbol within the
library is exporting it via the dynamic symbol table. This option is
commonly used to ensure specific symbols are exported (it's basically
-Bsymbolic with a list of exceptions), but it doesn't *remove* any of
the locally-bound symbols from the dynamic symbol table. The
--exclude-libs option does that for symbols defined in the named
libraries, but also prevents symbols in the dynamic list from being
added. That, I think, is a bug.

A version script ought to also work (and is probably more appropriate
for Viatcheslav's application), but I still think --dynamic-list ought
to export a symbol even if it comes from an excluded library.

   --exclude-libs lib,lib,...
      Specifies a list of archive libraries from which symbols should
      not be automatically exported. The library names may be
      delimited by commas or colons. Specifying --exclude-libs
      ALL excludes symbols in all archive libraries from automatic
      export.

Note that it says *automatic* export. To me that implies that symbols
explicitly exported should still be exported.

-cary

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