[Bug gold/17458] New: Symbol that normally exported from a binary reported as PREVAILING_DEF_IRONLY to a plugin

[rafael.espindola at gmail dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=17458

            Bug ID: 17458
           Summary: Symbol that normally exported from a binary reported
                    as PREVAILING_DEF_IRONLY to a plugin
           Product: binutils
           Version: unspecified
            Status: NEW
          Severity: normal
          Priority: P2
         Component: gold
          Assignee: ccoutant at google dot com
          Reporter: rafael.espindola at gmail dot com
                CC: ian at airs dot com

Created attachment 7814
  --> https://sourceware.org/bugzilla/attachment.cgi?id=7814&action=edit
testcase

The attached testcase has a run.sh script. Running it on my machine prints

     9: 0000000000400508     0 FUNC    GLOBAL DEFAULT   11 _init
    11: 00000000004006d4     0 FUNC    GLOBAL DEFAULT   14 _fini

     6: 000000000040064d     6 FUNC    GLOBAL DEFAULT   13 bar
     9: 0000000000400508     0 FUNC    GLOBAL DEFAULT   11 _init
    11: 00000000004006d4     0 FUNC    GLOBAL DEFAULT   14 _fini

The first run is using lto and the symbol bar is reported as
PREVAILING_DEF_IRONLY which causes the plugin to drop it.

On the second run -flto is not used and the linker keeps it in the main binary.
When the program is executed, that is the symbol the dynamic linker will use.

The testcase is sensitive to the versions used. If the commented line in the
script is removed, the main binary symbol will have the same version as the one
in the shared library and it is kept.

It looks like all symbols of a given name are kept in the symbol table even if
one with a preferred version is found. It is not clear if this is a bug or if
the bug is telling the plugin the symbol is IRONLY.

This is a reduced testcase from trying to override operator delete in the main
binary.

The same issue is present with gnu ld.

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