[petsc-dev] need C++ expert help

[Barry Smith]

   I need help from someone who knows the subtleties of c++.  We have a PETSc example that always compiles fine with C but generates annoying warnings with C++. I've tried many different variants to eliminate the warnings with no luck

   Any help is appreciated.

    Barry


mpicxx -o ex45.o -c -Wall -Wwrite-strings -Wno-strict-aliasing -Wno-unknown-pragmas -fvisibility=hidden -g -O   -fPIC    -I/sandbox/petsc/petsc.clone-3/include -I/sandbox/petsc/petsc.clone-3/arch-linux-opt-cxx-quad/include -I/usr/include/mpich2    `pwd`/ex45.c
/sandbox/petsc/petsc.clone-3/src/mat/examples/tests/ex45.c: In function ‘void Store2DArray(int, int, double*, const char*, int*)’:
/sandbox/petsc/petsc.clone-3/src/mat/examples/tests/ex45.c:75:41: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   if (write(fd,vals,m*n*sizeof(double)) != ((unsigned int) (m*n))*sizeof(double)) abort();
                                         ^
/sandbox/petsc/petsc.clone-3/src/mat/examples/tests/ex45.c: In function ‘void Store1DArray(int, double*, const char*, int*)’:
/sandbox/petsc/petsc.clone-3/src/mat/examples/tests/ex45.c:97:36: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   if (write(fd,a,m*sizeof(double)) != ((unsigned int)m)*sizeof(double)) abort();


It can be found here ftp://ftp.mcs.anl.gov/pub/petsc/nightlylogs/archive/2016/09/13/examples_next_arch-linux-opt-cxx-quad_grind.log