[gold patch] PR 22868: Fix case where IR file provides symbol visibility but replacement file does not

[Cary Coutant <ccoutant at gmail dot com>]

In PR 22868, two IR files provide conflicting visibility for a symbol.
When a def with PROTECTED visibility is seen after a def with DEFAULT
visibility, gold does not override the visibility. Later, if the
replacement object define the symbol with DEFAULT visibility, the symbol
remains DEFAULT. This was caused by a recent change to allow multiply-defined
absolute symbols, combined with the fact that the plugin framework was using
SHN_ABS as the section index for placeholder symbols. The solution is to
use a real (but arbitrary) section index.

-cary

2018-03-26  Cary Coutant  <ccoutant@gmail.com>

gold/
        PR gold/22868
        * plugin.cc (Sized_pluginobj::do_add_symbols): Use a real section
        index instead of SHN_ABS for defined symbols.
        * testsuite/Makefile.am (plugin_pr22868): New test case.
        * testsuite/Makefile.in: Regenerate
        * testsuite/plugin_pr22868.sh: New test script.
        * testsuite/plugin_pr22868_a.c: New source file.
        * testsuite/plugin_pr22868_b.c: New source file.

Attachment: pr22868.patch
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