From: lynnmcguire5@gmail.com   
      
   On 1/7/2025 4:18 PM, Thomas Koenig wrote:   
   > Lynn McGuire  schrieb:   
   >> I just ran into a nasty problem with GFortran and G++ (C++).  Probably   
   >> not a bug ???  I am using GCC 14.1.   
   >>   
   >> I have a lot of code in C++ (over 100,000 lines).  I have 750,000 lines   
   >> of code in GFortran.  I have to extern "C" this code in C++ to make it   
   >> callable by GFortran code.   
   >>   
   >> I missed declaring a couple of C++ functions as extern "C" which means   
   >> that they kept their C++ mangled link names.  But these C++ functions   
   >> were declared as integer*8 and external in the GFortran code (old F77   
   >> code).   
   >>   
   >> So, the GCC linker did not report to me that it did not have a link for   
   >> the G++ functions.  This may be a bug, I am not sure.   
   >   
   > Without having looked at the source code, I suspect   
   > it is probably something that you are not describing.   
   >   
   > You can look into the object files with any number of utilities,   
   > for example "nm".  Here's an example:   
   >   
   > subroutine foo   
   >    external bar   
   >    integer *8 bar   
   >    print *,bar(1234)   
   > end subroutine foo   
   >   
   > Compiling to an object file and running nm on this will show you   
   >   
   >                   U bar_   
   > 0000000000000000 T foo_   
   >                   U _gfortran_st_write   
   >                   U _gfortran_st_write_done   
   >                   U _gfortran_transfer_integer_write   
   >   
   > which means you have a symbol "foo_" defined, it is a global (hence   
   > uppercase) symbol in the text section (hence T).  You also have   
   > several undefined symbols, among them bar_, plus some gfortran   
   > library routines, so all is fine.   
   >   
   > If you do not find your undefined   
   >> When I ran the program, the C++ functions were not called by the   
   >> GFortran code.  Instead, the GFortran code treated the C++ functions as   
   >> integer*8 scalar variables.   
   >   
   >>   
   >> If needful, I can probably put together a small code sample that   
   >> exhibits the problem.  Maybe.  It could be that the size of my code   
   >> affects the GCC linker.   
   >   
   > That I would consider highly unlikely.   
      
   I turn off the trailing underscores in the Fortran code.  I build Win32   
   DLLs that are Excel VBA, C++, and Fortran callable.   
      
   I will try to build a sample code on Wednesday that illustrates the problem.   
      
   Thanks,   
   Lynn   
      
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