Hi Jonathan, Thank you very much for your response.
Since the previous email I have had more correspondence with Marc at the OpenBSD misc mailing list. He clarified that the reason the -L/usr/lib prefix was added, was "because of ld.ldd, the linker from clang. see, that one does not link with /usr/lib by default, which tends to break everything.", apparently. I asked him if it would not be better if GCC (both OS-bundled and port) would locate the -L/usr/lib to the trailing position just like clang does on OpenBSD and GCC does on all other platforms, and he responded: > I have zero idea how to do that purely in specs. Have fun tinkering. > > This is probably something we'll adopt but low priority. (https://marc.info/?l=openbsd-misc&m=161479588215993&w=2) On my part, I have zero idea how to do this in GCC spec syntax too. On Wednesday, 3 March 2021 14:16, Jonathan Wakely <jwakely....@gmail.com> wrote: > On Wed, 3 Mar 2021 at 12:35, Bob via Gcc gcc@gcc.gnu.org wrote: .. > > Here is to trig the behavior on OpenBSD: .. > > As you see here my "-LMYDIRTEST" comes after -L/usr/lib . > > Normally on any Unix the -L/usr/lib is appended to the end of LD's > > arguments, is it not - can you please confirm? > > (This question affects why OpenBSD added a custom behavior.) > > Second, a GCC patching question, your help to figure would be much > > appreciated: OpenBSD's patchset to GCC v8 is in the patches > > subdirectory here: > > https://cvsweb.openbsd.org/ports/lang/gcc/8/ > > As I get it, GCC's default behavior is to put -L/usr/dir in the > > trailing position, so one of these patches must modify GCC to put > > it in the leading position instead. Can you tell me which line in which > > patch file it is that has this effect? > > It's done in several different files, one for each supported arch. > You've already found where it's done for x86: > https://cvsweb.openbsd.org/ports/lang/gcc/8/patches/patch-gcc_config_i386_openbsdelf_h > > The latest version has been fixed (as you say below) but the previous > version added -L/usr/lib unconditionally. That LINK_SPEC is the first > group of options passed to the linker. If -L/usr/lib is added to > LINK_SPEC then it comes before any other -L options. In other words, > there's no patch to say "put -L/usr/lib first instead of last" > there's just a patch that puts it first. > > That's not how other targets do it, which is why -L/usr/lib doesn't > come first for other targets, only for OpenBSD. Can you please clarify what needs to be changed exactly on OpenBSD, for the -L/usr/lib to come last instead of first? Per what Marc said above here, your clarification should be incorporated to become OpenBSD default configuration. > > Last for completeness a discussion of GCC's "-nostdlib" argument: .. > > -L/usr/lib . However, there is no TRAILING -L/usr/lib so that one needs > > to be added manually. > > Of course. Because when you use -nostdlib ALL libraries and library > paths need to be added manually. That's what it means. For my situation, -nostdlib is overkill is it not? > > And, especially, -nostdlib has a handful > > other effects which I don't understand and which are not really > > discussed anywhere, as I get it: > > They're discussed in the manual. (Unimportantly but anyhow, I see no complete list of GCC arguments that would need to be added, to reverse -nostdlib .) > > Grepping GCC's code for nostdlib gives me this: .. > > of special GCC-internal language with its own syntax. Is this called > > "GCC spec file" syntax? > > Yes, documented athttps://gcc.gnu.org/onlinedocs/gcc/Spec-Files.html > > > The patch I referenced above, modifies > > patches/patch-gcc_config_i386_openbsdelf_h 's line 11 > > from " + -L/usr/lib\"" to "%{!nostdlib:-L/usr/lib}\"", again the > > same syntax language. > > That means that -L/usr/lib is only added when -nostdlib is not used. Right. > > Someone's discussion on what -nostdlib actually does, would be great > > for the purpose of GCC documentation, the current description at > > https://gcc.gnu.org/onlinedocs/gcc/Link-Options.html is too brief. > > I don't see why it's too brief. It's quite accurate. > > The option means that GCC won't tell the linker to use any of the > default libraries and library paths (which you can see by adding -v to > the gcc command you use to link). That's accurate. -nostdlib has no more effect than that? So it's about linking back the C/C++ library and adding -L paths for GCC to find them. What about crtbegin/end.o such? Bob
