https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90835
--- Comment #26 from ro at CeBiTec dot Uni-Bielefeld.DE <ro at CeBiTec dot Uni-Bielefeld.DE> --- > --- Comment #25 from Iain Sandoe <iains at gcc dot gnu.org> --- > (In reply to r...@cebitec.uni-bielefeld.de from comment #24) >> > --- Comment #23 from Iain Sandoe <iains at gcc dot gnu.org> --- >> > unpatched GCC master, gcc-9.x, gcc-8.x and gcc-7.5 work for me with any >> > SDK >= >> > Xcode commandline tools 11.3b. >> >> I've recently tried both building gcc 8.3.0 (build only) and master >> (full bootstrap and test) on macOS 10.14.6 and 10.15.3, each with Xcode >> 11.3.1. Both worked *provided the build and target compilers were >> configured with the approriate --with-sysroot to account for the lack of >> /usr/include and startup objects in /usr/lib*. > > That's not going to change, I think (at least, the underlying behaviour). Indeed, we'll have to live with that. > We could entertain and implement a change to Darwin's configuration that > automatically discovers the /Library/Developer/CommandLineTools .. or > /Applications/Xcode... for Darwin versions >= X and complains of fails to > configure if those can't be seen (asking for a --with-sysroot=). That's one option, certainly easier for the users. At the least, the issue should be documented in install.texi so they can add --with-sysroot manually if need be. I just noticed that the install docs only have a small section on PowerPC Darwin, nothing else... > We can already invoke GCC like "xcrun /path/to/gcc-exe" provided that is not > called "gcc" or "g++" it will work to set the SDKROOT which gcc honours from > 7.5+. > > The only irritation is that we can't use 'gcc' or 'g++' in that position, > because xcrun places the clang/++ aliases ahead of the GCC in the PATH (even > if > the GCC install is first) [last time I tried]. Sounds like a bad mess and totally unexpected. Besides, the additional exec will have some cost. No idea how measurable it would be for a bootstrap, though. > There's also an API to obtain the info - but only on 10.15+ and it forces one > to install XCode I suspect to use it, I'm not keen on making new dependencies > on things outside our control - I'd rather make use of OSS equivalents. Understood. In particular when Xcode.app can be installed anywhere, not just in /Applications. Maybe something to talk about with Jeremy Sequoia, perhaps it can be provided from some stable location?