Date: Mon, 27 Aug 2001 14:57:27 -0700 (PDT)
From: Will Robinson <wsr23 AT Stanford DOT EDU>
To: <djgpp AT delorie DOT com>
Subject: Re: linux->dos cross-compiler
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> > string.cpp: In function `int main()':
> > string.cpp:5: `string' undeclared (first use this function)
> > string.cpp:5: (Each undeclared identifier is reported only once for each
> >    function it appears in.)
> > string.cpp:5: parse error before `=' token
>
> string class is now namespace std.

Doh!  Please pardon my ignorance...adding
  using std::string
and such throughout the code has allowed me to compile all the source
files!

Now for (hopefully the last) hurdle...linking.  I've had to do some (I
think) odd things to get my code to even come close to linking:

-Explicitly included crt0.o in the list of object files to link.
-Put -lc -lstdc++ -lgcc at the end of the linker command line.

And I still get errors like these:

/opt/djgpp/i586-pc-msdosdjgpp/lib/libgcc.a(unwind-dw2-fde.o): In function
`read_encoded_value_with_base':
unwind-dw2-fde.c:211: multiple definition of `__register_frame_info'
/opt/djgpp/i586-pc-msdosdjgpp/lib/libc.a(rfinfo.o)(.text+0x0):rfinfo.c:
first defined here


/opt/djgpp/i586-pc-msdosdjgpp/lib/libgcc.a(unwind-dw2.o): In function
`read_encoded_value_with_base':
unwind-dw2.c:211: undefined reference to `strlen'
/opt/djgpp/i586-pc-msdosdjgpp/lib/libgcc.a(unwind-dw2-fde.o): In function
`base_from_object':
unwind-dw2-fde.c:231: undefined reference to `strlen'


/opt/djgpp/i586-pc-msdosdjgpp/lib/libstdc++.a(locale.o): In function
`std::locale::global(std::locale const&)':
locale.cc:717: undefined reference to `setlocale'
/opt/djgpp/i586-pc-msdosdjgpp/lib/libstdc++.a(locale.o): In function
`std::ctype<char>::do_toupper(char*, char const*) const':
locale.cc:55: undefined reference to `toupper'
/opt/djgpp/i586-pc-msdosdjgpp/lib/libstdc++.a(locale.o): In function
`std::ctype<char>::do_tolower(char*, char const*) const':
locale.cc:70: undefined reference to `tolower'


So it looks like __register_frame_info is defined both in libc.a and
libgcc.a, and that ld-dos isn't seeing the definitions of strlen,
setlocale, toupper, and tolower.  I don't know what to do about the first
problem , but the second is especially puzzling, since running
  nm-dos libc.a --print-file-name | grep strlen
gives:

libc.a:strlen.o:00000024 b .bss
libc.a:strlen.o:00000024 d .data
libc.a:strlen.o:00000000 t .text
libc.a:strlen.o:00000000 t ___gnu_compiled_c
libc.a:strlen.o:00000000 T _strlen
libc.a:strlen.o:00000000 t gcc2_compiled.
libc.a:c1args.o:0000004c t _far_strlen

And I get similar results for toupper, tolower, and setlocale.  When I add
a --verbose switch to my ld-dos command line, I find that it is indeed
using the right libc.a library, and is accessing a lot of files from it...

attempt to open /opt/djgpp/i586-pc-msdosdjgpp/lib/libc.a succeeded
(/opt/djgpp/i586-pc-msdosdjgpp/lib/libc.a)printf.o
(/opt/djgpp/i586-pc-msdosdjgpp/lib/libc.a)npxsetup.o
(/opt/djgpp/i586-pc-msdosdjgpp/lib/libc.a)fflush.o
.
.
.

...but that strlen.o, toupper.o, tolower.o, and setlocal.o are not in the
list of files loaded.  It's possible that other files are missing also,
but these 4 symbols are the only things turning up as unresolved in what
I'm currently trying to compile.  Any idea why they would show up in nm
but not be included during linking?

One thing's for sure...if I ever get this working correctly I'm going to
write up a nice long account of how it was done!

Thanks,
Will Robinson