Source: coinor-cgl Version: 0.60.3+repack1-3 Tags: patch upstream User: debian-cr...@lists.debian.org Usertags: ftcbfs
coinor-cgl fails to cross build from source, because it doesn't build shared libraries and then dh_install fails. Now the reasons for that are ... a little involved. Please sit down and take a cup of coffee or tea or like that. Looking into the cross configure output, one can spot this: http://crossqa.debian.net/build/coinor-cgl_0.60.3+repack1-2_s390x_20200713232329.log > checking whether the s390x-linux-gnu-gcc linker (/usr/bin/ld -m elf64_s390) > supports shared libraries... /usr/bin/ld: unrecognised emulation mode: > elf64_s390 > Supported emulations: elf_x86_64 elf32_x86_64 elf_i386 elf_iamcu elf_l1om > elf_k1om i386pep i386pe > no Bummer. It's using the wrong ld. It should be using s390x-linux-gnu-ld. Why does it do that? It should be driving the ld name from gcc. However, it only does when working with a GNU compiler and as we can see: > checking whether we are using the GNU C compiler... no For some reason, it concludes that gcc is not a GNU C compiler. That's strange. You can also see this in native builds and it can have a range of misdetections as a consequence. Just why? The actual sequence of events is this: We start following inside AC_COIN_DEBUG_COMPILE. > checking whether we want to compile in debug mode... no Now we're moving inside AC_COIN_PROG_CC executing AC_REQUIREd code. > checking for s390x-linux-gnu-gcc... s390x-linux-gnu-gcc At this point $ac_objext is not yet computed, so it is empty. What we do next is use AC_TRY_COMPILE and that checks whether "conftest.$ac_objext" aka "conftest." is non-empty. It isn't, as the compiler chose to output to "conftest.o" instead, so we're not using a GNU compiler, right? > checking whether we are using the GNU C compiler... no > checking whether s390x-linux-gnu-gcc accepts -g... no > checking for s390x-linux-gnu-gcc option to accept ISO C89... unsupported > checking whether s390x-linux-gnu-gcc understands -c and -o together... yes Now we've completed the AC_REQUIREd stuff and proceed to the AC_PROG_CC inside AC_COIN_PROG_CC. > checking for s390x-linux-gnu-gcc... s390x-linux-gnu-gcc > checking whether the C compiler works... yes > checking for C compiler default output file name... a.out > checking for suffix of executables... > checking whether we are cross compiling... yes This time we compute $ac_cv_objext, which is propagated to $ac_objext. > checking for suffix of object files... o But we already checked that we're not using a GNU C compiler, so we don't check again. If we were checking again, we'd now see that it is a GNU C compiler as AC_TRY_COMPILE would now check for "conftest.o". > checking whether we are using the GNU C compiler... (cached) no The order of invocations is messed up. The basic structure of AC_COIN_PROG_CC is: AC_REQUIRE([AC_COIN_ENABLE_MSVC]) ... AC_PROG_CC([$comps]) ... AC_TRY_LINK(...) Unfortunately, the AC_TRY_LINK AC_REQUIREs AC_PROG_CC, so that gets executed before AC_COIN_PROG_CC gets a chance to compute $comps for AC_PROG_CC. The issue is that we're using AC_TRY_LINK in the same defun as we call AC_PROG_CC. That doesn't work. Once understood, the solution is quite simple. We must put the AC_PROG_CC and the AC_TRY_LINK in different defuns and ensure that our intended AC_PROG_CC is AC_REQUIREd before using AC_TRY_LINK. I'm attaching a patch to do that. Please consider applying it. I believe that this is worth fixing even if you don't care about cross builds. Helmut
--- coinor-cgl-0.60.3+repack1.orig/BuildTools/coin.m4 +++ coinor-cgl-0.60.3+repack1/BuildTools/coin.m4 @@ -665,9 +665,8 @@ AC_LANG_POP(C++) # given my the user), and find an appropriate value for CFLAGS. It is # possible to provide additional -D flags in the variable CDEFS. -AC_DEFUN([AC_COIN_PROG_CC], -[AC_REQUIRE([AC_COIN_ENABLE_MSVC]) -AC_LANG_PUSH(C) +AC_DEFUN([AC_COIN_PROG_CC_HEAD], +[ # For consistency, we set the C compiler to the same value of the C++ # compiler, if the C++ is set, but the C compiler isn't (only for CXX=cl) @@ -726,6 +725,13 @@ AC_PROG_CC([$comps]) if test -z "$CC" ; then AC_MSG_ERROR([Failed to find a C compiler!]) fi +]) +AC_DEFUN([AC_COIN_PROG_CC], +[AC_REQUIRE([AC_COIN_ENABLE_MSVC]) +dnl Separate the head of this macro to AC_COIN_PROG_CC_HEAD such that it +dnl controls the invocation of AC_PROG_CC instead of the AC_TRY_LINK below. +AC_REQUIRE([AC_COIN_PROG_CC_HEAD]) +AC_LANG_PUSH(C) # Autoconf incorrectly concludes that cl recognises -g. It doesn't. case "$CC" in clang* ) ;;
