[gold] extraneous warning message from Gold linker on hidden/internal symbol false match (bug 18596)

[Yiran Wang <yiran at google dot com>]

Hi All,

[ this message is posted at binutils-bugs before, and I heard this is
the right place ]

The bug is filed at
https://sourceware.org/bugzilla/show_bug.cgi?id=18596, and please
refer to it for a test case and some description there.

The related code is from fix of
https://sourceware.org/bugzilla/show_bug.cgi?id=10471

In short, Gold linker will issue a warning, when a hidden or internal
symbol "matches" a reference.
According to linker rule, the linker should ignore such "match" and do
not have to issue warning (this is what ld.bfd do), it might try to be
helpful, but some build script will do "-Werror" and there is
situation the hidden symbol false match cannot be removed from the
source, say, there is hidden and override of symbols.
The final resolve of the symbol may fall into the following category,
A. It will be resolved by a legal definition (this may happen before or after)
B. It will not be resolved, but it is allowed or intended for this link
(for these two cases, I wonder if how much is it helpful)
C. It will not be resolved and lead to a link error
(linker will say "undefined symbol", but a warning like "DSO can not
reference a hidden symbol" may be a bit plus here)

A simple fix is to remove the warning, while if it is actually helpful
to someone, there are options like, to create an option for it, to
only issue a warning when the symbol is not resolved at last, or
something else.

diff --git a/gold/resolve.cc b/gold/resolve.cc
index fdae0ba..af61096 100644
--- a/gold/resolve.cc
+++ b/gold/resolve.cc
@@ -286,15 +286,6 @@ Symbol_table::resolve(Sized_symbol<size>* to,
            && (to->visibility() == elfcpp::STV_HIDDEN
                || to->visibility() == elfcpp::STV_INTERNAL))
     {
-      // A dynamic object cannot reference a hidden or internal symbol
-      // defined in another object.
-      gold_warning(_("%s symbol '%s' in %s is referenced by DSO %s"),
-                   (to->visibility() == elfcpp::STV_HIDDEN
-                    ? "hidden"
-                    : "internal"),
-                   to->demangled_name().c_str(),
-                   to->object()->name().c_str(),
-                   object->name().c_str());
       return;
     }
   else

Best Regards,
Yiran Wang