* Dmitry V. Levin: > Let's make clear what's going on here. First of all, dwfl-proc-attach.c > does not use dlopen so it doesn't pull it in and doesn't need -ldl. > In regular builds, dwfl-proc-attach.o is linked with ../libdw/libdw.so > which in turn uses dlopen and is already linked with -ldl. > When elfutils is configured with --enable-gprof or --enable-gcov, > BUILD_STATIC is enabled and dwfl-proc-attach.o is linked with > ../libdw/libdw.a -lz $(zip_LIBS) $(libelf) $(libebl) -ldl -lpthread > which already contains -ldl. > In any case, I fail to understand why dwfl-proc-attach might need > an extra -ldl, especially in LDFLAGS which goes before LDADD > in the linking command.
It may have to do with --as-needed that some builds use. If there are no pending undefined references, some linkers drop earlier shared object references with --as-needed (similar to what happens with static archives). The GCC LTO plugin results in ld looking at more objects in greater detail for some reason. Without LTO and --as-needed, you probably don't get a dlopen export (if you do not link with -E) because indirect dependencies are not consulted, breaking the valgrind workaround because there is no interposition. Thanks, Florian
