Re: [libvirt] [PATCH] Put libraries in $LIBS, not $LDFLAGS, during configure tests.

On 25 Nov 2009, Daniel P. Berrange spake thusly: Autoconf has always sorted $LDFLAGS before object files. When -Wl,--as-needed is turned on by default (as a number of distros do), such libraries are silently dropped because nothing needs symbols from them at that point in the link, just as if they were static libraries. Without -Wl,--as-needed, every single library named in the link is added to DT_NEEDED, so this works. Nonetheless, it is plainly obvious to any Unix hand that cc -L/usr/lib -lfoo -o test thing-that-uses-foo.o is less likely to work than cc -L/usr/lib -o test thing-that-uses-foo.o -lfoo and if you put libraries in LDFLAGS, the former's often what you get. It'll probably fail for you, too, if HAL (say) is statically linked, because the -Wl,--as-needed behaviour for shared libraries is exactly how static libraries have always worked. The GNU Autoconf manual has long stated -- Variable: LDFLAGS [...] Don't use this variable to pass library names (`-l') to the linker; use `LIBS' instead. (I'm surprised that no Gentooers, for instance, have reported this already. A *lot* of distros turn on -Wl,--as-needed by default these days, often by modifying the built-in GCC specs and providing a fallback specs file that specifies -Wl,--no-as-needed for those very rare things, such as glibc's testsuite, that actually *require* linkage with shared libraries from which no symbols are required.)