I think it is just CXX. The PCC business is the thing that magically changes from CC to CXX depending on --with-clanguage being set. But CXX is always the C++ linker.
Barry > On Dec 31, 2017, at 6:18 PM, Jed Brown <[email protected]> wrote: > > "Smith, Barry F." <[email protected]> writes: > >> There is always a C++ linker available so long as PETSc was built without >> --with-cxx=0 so just use it, why make a big deal out of it? > > What is it called? I would like to just use CXX, but we have PCC_LINKER > written out independently. I don't know any circumstance in which > PCC_LINKER is different from PCC, but maybe there is. We should get rid > of this duplication unless there is a specific circumstance in which > they are different. > > $ grep mpicxx ompi/lib/petsc/conf/petscvariables > > > CXX = /home/jed/usr/ccache/ompi/bin/mpicxx > > > CXXCPP = /home/jed/usr/ccache/ompi/bin/mpicxx -E > > $ grep mpicc ompi/lib/petsc/conf/petscvariables > > > SL_LINKER = /home/jed/usr/ccache/ompi/bin/mpicc > > > PCC = /home/jed/usr/ccache/ompi/bin/mpicc > PCC_LINKER = /home/jed/usr/ccache/ompi/bin/mpicc > CC = /home/jed/usr/ccache/ompi/bin/mpicc > DYNAMICLINKER = /home/jed/usr/ccache/ompi/bin/mpicc > CPP = /home/jed/usr/ccache/ompi/bin/mpicc -E > LD_SHARED = /home/jed/usr/ccache/ompi/bin/mpicc > > >> Barry >> >>> On Dec 31, 2017, at 5:58 PM, Jed Brown <[email protected]> wrote: >>> >>> "Smith, Barry F." <[email protected]> writes: >>> >>>>> On Dec 31, 2017, at 2:14 PM, Jed Brown <[email protected]> wrote: >>>>> >>>>> Matthew Knepley <[email protected]> writes: >>>>> >>>>>> On Sun, Dec 31, 2017 at 2:35 PM, Jed Brown <[email protected]> wrote: >>>>>> >>>>>>> Matthew Knepley <[email protected]> writes: >>>>>>> >>>>>>>> On Sun, Dec 31, 2017 at 1:55 PM, Jed Brown <[email protected]> wrote: >>>>>>>> >>>>>>>>> These look like linker errors and that build uses >>>>>>>>> --with-cxxlib-autodetect=0. We either need a rule to *link* C++ using >>>>>>>>> CXX (i.e., mpicxx) or add LIBS=-lstdc++. >>>>>>>>> >>>>>>>> >>>>>>>> I thought we were doing this (linking C++ mains with CXX). >>>>>>> >>>>>>> After compiling to the object file (ex3.o) we don't know what language >>>>>>> main was written in, and this doesn't solve the actual problem that C++ >>>>>>> linking is required if any object (not just main) depends on C++. >>>>>>> >>>>>> >>>>>> My thinking here was the following: >>>>>> >>>>>> 1) No C++ is allowed in PETSc, unless --with-clanguage=cxx, in which case >>>>>> the linker is C++ >>>>>> 2) If C++ is in an external library, then that configure requires the C++ >>>>>> library >>>>>> 3) The executable itself could be C++, in which case I proposed using the >>>>>> C++ linker explicitly >>>>>> >>>>>> About not knowing which objects come with C++ main: I thought we did. >>>>>> Don't >>>>>> they go into a separate set? >>>>> >>>>> Right, we do have that information for tests. Note that a single test >>>>> executable can depend on multiple source files, and the one containing >>>>> main might not be C++ while another is. I don't know if there are any >>>>> such instances in PETSc. >>>>> >>>>> I can change the build rules for tests with C++ sources later today. >>>> >>>> Jed, are you indicating that you will resolve the original problem I >>>> reported? Where will you resolve it? The problem may come up in one of my >>>> branches. >>> >>> I was going to put it in a new branch from 'master'. There is >>> disgusting duplication in 'maint' that has since been fixed so I'd >>> rather not do it there. >>> >>> Under what conditions is PCC_LINKER different from CC (or CXX when >>> clanguage=C++)? I need to find a C++ linker and would prefer to use >>> $(CXX) rather than adding a new configure test. I feel like the >>> generated petscvariables has an inordinate amount of duplication all >>> with non-standard names and no documentation. >>> >>> The cheap way to fix your issue is to add LIBS=-lstdc++ to your >>> configure.
