https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90330
--- Comment #22 from Matt Thompson <matthew.thompson at nasa dot gov> --- (In reply to Iain Sandoe from comment #19) > (In reply to Matt Thompson from comment #17) > > > > b) (remind me) what is the "--with-native-system-header-dir=/usr/include" > > > meant to provide? It seems like you are maybe mixing cross-configuration > > > options with native ones... > > > > This was my attempt to try to work around the fact that Apple no longer > > supplies a /usr/include: > > > > https://developer.apple.com/documentation/xcode_release_notes/ > > xcode_10_release_notes#3035624 > > > > Now, I'm not sure that gcc itself needs /usr/include, but many of the > > libraries and more I compile with gcc seem to assume it. And I've gotten to > > the point where I just couldn't figure out how to pass '-isysroot' down to > > code like f2py (gcc is called by f2py but f2py only passes down Fortran > > flags. And I just *cannot* get our CMake system to pass > > CFLAGS='-isysroot...' to the gcc call within f2py). > > > > So, I thought I'd look around and saw that Homebrew built a little > > differently: > > > > https://github.com/Homebrew/homebrew-core/blob/master/Formula/gcc.rb > > > > adding: > > elsif MacOS.version >= :mojave > > # System headers are no longer located in /usr/include > > args << "--with-native-system-header-dir=/usr/include" > > args << > > "--with-sysroot=/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk" > > I don't know what they intended to achieve with this. There *is* one > gremlin with the sysroot being > /Library/Developer/CommandLineTools/SDKs/MacOSX.sdk which is that > /usr/local/include is still a usable directory and needs to be searched > *without* prepending the sysroot. This is something I want to fix during > the next couple of months - but isn't necessary *unless* you've installed > packages into /usr/local that you want to use. > > (A workaround is to add -I... so it shouldn't be a show-stopper) Luckily (?) for me, there is nothing in my /usr/local/include save for Fuse headers. Since I can't install Homebrew in its default /usr/local (I do it in user space), it's pretty dang pure on my system! > > > > My hope was perhaps this would "embed" in gcc the fact that sysroot is not > > in /usr/include but was in > > /Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include and so f2py > > would work again. > > > > Is it just the --with-sysroot that I'd need to "hardcode" a gcc with that > > sysroot? > > the --with-sysroot=/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk > should "just work" (modulo the gotcha about /usr/local mentioned) with no > need for any additional magic. Ooh. Okay. I'll give that a shot. > > > I have tried the same configure line with gcc 8.2.0 loaded, but I get: > > > > checking whether we are cross compiling... configure: error: in > > `/Users/mathomp4/src/GCC/gcc-9.2.0-BUILD-820loaded': > > configure: error: cannot run C compiled programs. > > If you meant to cross compile, use `--host'. > > See `config.log' for more details > > If you want to use GCC as the bootstrap and it was built for a system with > /usr/include [and now that directory has been removed] then you need to > supply it with a sysroot explicitly as I do. > > CC="gcc-8-x --sysroot=/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk" > CXX="g++-8.x --sysroot=/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk" > (on the configure line) Hmm. Okay. I'll give this a shot. I suppose I want to use clang just because I'll have to keep bootstrapping with a previous version forever, right? And is this done at the configure stage? Make stage? My autotools-fu is a bit weak. > > > > Note, looking at Homebrew again, I do see they also build with: > > > > make BOOT_LDFLAGS=-Wl,-headerpad_max_install_names > > That is solving a different problem - where it would seem that they intend > to use install_name_tool to update the install paths and are allowing the > maximum space. > > > would that help? > > very unlikely. Huh. This might actually be something that we've hit in CMake on other codes, but if it's not needed, I won't do it for now.
