[Bug ld/26198] Failure to merge read only data of machine code object file and LTO object file on MinGW

[nickc at redhat dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=26198

Nick Clifton <nickc at redhat dot com> changed:

           What    |Removed                     |Added
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                 CC|                            |nickc at redhat dot com

--- Comment #1 from Nick Clifton <nickc at redhat dot com> ---
(In reply to Markus Böck from comment #0)
Hi Markus,

> c:/gcc/bin/../lib/gcc/x86_64-w64-mingw32/10/../../../../x86_64-w64-mingw32/
> bin/ld.exe: test2.o (symbol from
> plugin):(.gnu.linkonce.t._ZNKSt9type_info4nameEv+0x0): multiple definition
> of `std::type_info::name() const';
> test1.o:test.cpp:(.

> Failed to reproduce this issue with a linux target

I think that this might be a compiler issue, rather than an assembler issue...

> nm output of test1.o:
> 0000000000000000 T _ZNKSt9type_info4nameEv                                  
> 0000000000000000 T _ZNKSt9type_info9hash_codeEv                             

> gcc-nm output of test2.o:
> 00000000 T _ZNKSt9type_info4nameEv                                          
> 00000000 T _ZNKSt9type_info9hash_codeEv                                     

Using gcc v9 on an x86_64 linux box to compile the test I found
that those symbols are declared as weak:

  % gcc-nm test1.o
  [...]
  0000000000000000 W _ZNKSt9type_info4nameEv
  0000000000000000 W _ZNKSt9type_info9hash_codeEv

  % gcc-nm test2.o
  [...]
  00000000 W _ZNKSt9type_info4nameEv
  00000000 W _ZNKSt9type_info9hash_codeEv

Which explains why it works for me.  My guess is that gcc thinks that
it cannot generate weak symbols for the COFF/PE environment of Mingw,
or something along those lines.  Perhaps you can investigate the output
from your gcc to see if this guess is correct ?

Cheers
  Nick

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