Thread Subject: Mex error in 64-bit 2008a Mac OS X beta

I'm having trouble mex'ing some C++ code, which I have been able
to compile successfully both on 64-bit Windows, Linux, as well as 32-bit Mac
MATLAB versions. The problem is in the link loader (_mexFunction is
undefined).

The output of mex -v -g is given below. Any help would be much
appreciated!

Thanks.

- Sridhar

mex -g -v -largeArrayDims FastGSOGP.cpp
-> mexopts.sh sourced from directory (DIR = $MATLAB/bin)
   FILE = /Applications/MATLAB_R2008a/bin/mexopts.sh
-----------------------------------------------------------
-----
-> MATLAB = /Applications/MATLAB_R2008a
-> CC = gcc-4.0
-> CC flags:
         CFLAGS = -fno-common -no-cpp-precomp -arch x86_64 -
isysroot /Developer/SDKs/MacOSX10.5.sdk -mmacosx-version-min=10.5 -
fexceptions
         CDEBUGFLAGS = -g
         COPTIMFLAGS = -O2 -DNDEBUG
         CLIBS = -L/Applications/MATLAB_R2008a/bin/maci64 -lmx -
lmex -lmat -lstdc++
         arguments =
-> CXX = g++-4.0
-> CXX flags:
         CXXFLAGS = -fno-common -no-cpp-precomp -fexceptions -
arch x86_64 -isysroot /Developer/SDKs/MacOSX10.5.sdk -mmacosx-
version-min=10.5
         CXXDEBUGFLAGS = -g
         CXXOPTIMFLAGS = -O2 -DNDEBUG
         CXXLIBS = -L/Applications/MATLAB_R2008a/bin/maci64 -lmx -
lmex -lmat -lstdc++
         arguments =
-> FC = gfortran
-> FC flags:
         FFLAGS = -m64
         FDEBUGFLAGS = -g
         FOPTIMFLAGS = -O
         FLIBS = -L/Applications/MATLAB_R2008a/bin/maci64 -lmx -
lmex -lmat -L -lgfortran -L -lgfortranbegin
         arguments =
-> LD = gcc-4.0
-> Link flags:
         LDFLAGS = -Wl,-twolevel_namespace -undefined error -arch
x86_64 -Wl,-syslibroot,/Developer/SDKs/MacOSX10.5.sdk -mmacosx-
version-min=10.5 -bundle -Wl,-
exported_symbols_list,/Applications/MATLAB_R2008a/extern/lib/maci64/me
xFunction.map
         LDDEBUGFLAGS = -g
         LDOPTIMFLAGS = -O
         LDEXTENSION = .mexmaci64
         arguments =
-> LDCXX =
-> Link flags:
         LDCXXFLAGS =
         LDCXXDEBUGFLAGS =
         LDCXXOPTIMFLAGS =
         LDCXXEXTENSION =
         arguments =
-----------------------------------------------------------
-----

-> g++-4.0 -c -I/Applications/MATLAB_R2008a/extern/include -
DMATLAB_MEX_FILE -fno-common -no-cpp-precomp -fexceptions -arch
x86_64 -isysroot /Developer/SDKs/MacOSX10.5.sdk -mmacosx-version-
min=10.5 -g "FastGSOGP.cpp"

-> gcc-4.0 -c -I/Applications/MATLAB_R2008a/extern/include -
DMATLAB_MEX_FILE -fno-common -no-cpp-precomp -arch x86_64 -
isysroot /Developer/SDKs/MacOSX10.5.sdk -mmacosx-version-min=10.5 -
fexceptions -g "/Applications/MATLAB_R2008a/extern/src/mexversion.c"

-> gcc-4.0 -g -Wl,-twolevel_namespace -undefined error -arch x86_64 -
Wl,-syslibroot,/Developer/SDKs/MacOSX10.5.sdk -mmacosx-version-
min=10.5 -bundle -Wl,-
exported_symbols_list,/Applications/MATLAB_R2008a/extern/lib/maci64/me
xFunction.map -o "FastGSOGP.mexmaci64" FastGSOGP.o mexversion.o -
L/Applications/MATLAB_R2008a/bin/maci64 -lmx -lmex -lmat -lstdc++

Undefined symbols:
  "_mexFunction", referenced from:
     -exported_symbols_list command line option
ld: symbol(s) not found
collect2: ld returned 1 exit status

    mex: link of ' "FastGSOGP.mexmaci64"' failed.

Hi Sridhar,

Try the following to diagnose the root cause.

Run the first g++ command, with ! before the command to escape out to
the shell and run it, then run !nm FastGSOGP.o.

The output of nm should contain a line with "T _mexFunction". If it
does not show up, or if it shows up with lots of characters before and
after the name (for example, __Z11mexFunctionsPP11mxArray_tagsPPKS_),
then something may be wrong with how it is being declared in the source
file FastGSOGP.cpp.

The declaration in your source file should match the parameter types
exactly, like this:

void mexFunction( int nlhs, mxArray *plhs[],
int nrhs, const mxArray *prhs[] )

The integer arguments must be the intrinsic "int" type (without
qualifiers), for this signature to work on all platforms. Use of short
or long integer, or other derived types, will cause the signature to
fail to be an exact match for certain compilers.

Brian



Sridhar Mahadevan wrote:
> I'm having trouble mex'ing some C++ code, which I have been able
> to compile successfully both on 64-bit Windows, Linux, as well as 32-bit Mac
> MATLAB versions. The problem is in the link loader (_mexFunction is
> undefined).
>
> The output of mex -v -g is given below. Any help would be much
> appreciated!
>
> Thanks.
>
> - Sridhar
>
> mex -g -v -largeArrayDims FastGSOGP.cpp
> -> mexopts.sh sourced from directory (DIR = $MATLAB/bin)
> FILE = /Applications/MATLAB_R2008a/bin/mexopts.sh
> -----------------------------------------------------------
> -----
> -> MATLAB = /Applications/MATLAB_R2008a
> -> CC = gcc-4.0
> -> CC flags:
> CFLAGS = -fno-common -no-cpp-precomp -arch x86_64 -
> isysroot /Developer/SDKs/MacOSX10.5.sdk -mmacosx-version-min=10.5 -
> fexceptions
> CDEBUGFLAGS = -g
> COPTIMFLAGS = -O2 -DNDEBUG
> CLIBS = -L/Applications/MATLAB_R2008a/bin/maci64 -lmx -
> lmex -lmat -lstdc++
> arguments =
> -> CXX = g++-4.0
> -> CXX flags:
> CXXFLAGS = -fno-common -no-cpp-precomp -fexceptions -
> arch x86_64 -isysroot /Developer/SDKs/MacOSX10.5.sdk -mmacosx-
> version-min=10.5
> CXXDEBUGFLAGS = -g
> CXXOPTIMFLAGS = -O2 -DNDEBUG
> CXXLIBS = -L/Applications/MATLAB_R2008a/bin/maci64 -lmx -
> lmex -lmat -lstdc++
> arguments =
> -> FC = gfortran
> -> FC flags:
> FFLAGS = -m64
> FDEBUGFLAGS = -g
> FOPTIMFLAGS = -O
> FLIBS = -L/Applications/MATLAB_R2008a/bin/maci64 -lmx -
> lmex -lmat -L -lgfortran -L -lgfortranbegin
> arguments =
> -> LD = gcc-4.0
> -> Link flags:
> LDFLAGS = -Wl,-twolevel_namespace -undefined error -arch
> x86_64 -Wl,-syslibroot,/Developer/SDKs/MacOSX10.5.sdk -mmacosx-
> version-min=10.5 -bundle -Wl,-
> exported_symbols_list,/Applications/MATLAB_R2008a/extern/lib/maci64/me
> xFunction.map
> LDDEBUGFLAGS = -g
> LDOPTIMFLAGS = -O
> LDEXTENSION = .mexmaci64
> arguments =
> -> LDCXX =
> -> Link flags:
> LDCXXFLAGS =
> LDCXXDEBUGFLAGS =
> LDCXXOPTIMFLAGS =
> LDCXXEXTENSION =
> arguments =
> -----------------------------------------------------------
> -----
>
> -> g++-4.0 -c -I/Applications/MATLAB_R2008a/extern/include -
> DMATLAB_MEX_FILE -fno-common -no-cpp-precomp -fexceptions -arch
> x86_64 -isysroot /Developer/SDKs/MacOSX10.5.sdk -mmacosx-version-
> min=10.5 -g "FastGSOGP.cpp"
>
> -> gcc-4.0 -c -I/Applications/MATLAB_R2008a/extern/include -
> DMATLAB_MEX_FILE -fno-common -no-cpp-precomp -arch x86_64 -
> isysroot /Developer/SDKs/MacOSX10.5.sdk -mmacosx-version-min=10.5 -
> fexceptions -g "/Applications/MATLAB_R2008a/extern/src/mexversion.c"
>
> -> gcc-4.0 -g -Wl,-twolevel_namespace -undefined error -arch x86_64 -
> Wl,-syslibroot,/Developer/SDKs/MacOSX10.5.sdk -mmacosx-version-
> min=10.5 -bundle -Wl,-
> exported_symbols_list,/Applications/MATLAB_R2008a/extern/lib/maci64/me
> xFunction.map -o "FastGSOGP.mexmaci64" FastGSOGP.o mexversion.o -
> L/Applications/MATLAB_R2008a/bin/maci64 -lmx -lmex -lmat -lstdc++
>
> Undefined symbols:
> "_mexFunction", referenced from:
> -exported_symbols_list command line option
> ld: symbol(s) not found
> collect2: ld returned 1 exit status
>
> mex: link of ' "FastGSOGP.mexmaci64"' failed.
>
>

Brian Arnold <Brian.Arnold@mathworks.com> wrote in message
<488880D4.9090606@mathworks.com>...
> Hi Sridhar,
>
> Try the following to diagnose the root cause.
>
> Run the first g++ command, with ! before the command to escape out to
> the shell and run it, then run !nm FastGSOGP.o.
>
> The output of nm should contain a line with "T _mexFunction". If it
> does not show up, or if it shows up with lots of characters before and
> after the name (for example, __Z11mexFunctionsPP11mxArray_tagsPPKS_),
> then something may be wrong with how it is being declared in the source
> file FastGSOGP.cpp.
>
> The declaration in your source file should match the parameter types
> exactly, like this:
>
> void mexFunction( int nlhs, mxArray *plhs[],
> int nrhs, const mxArray *prhs[] )
>
> The integer arguments must be the intrinsic "int" type (without
> qualifiers), for this signature to work on all platforms. Use of short
> or long integer, or other derived types, will cause the signature to
> fail to be an exact match for certain compilers.
>
> Brian


Brian,

Many thanks! You hit the nail on the head. I had to reformat the declaration
of mexFunction. This now works perfectly.