0_Rootfs: Add GCC 15

[fxcoudert]

I doubt that I might be able to carry this alone, but let's try :)

@giordano I've used your GCC 14 PR (#10132) as inspiration, what I'm not sure I understand is how that GCC version can build on aarch64-darwin? I mean, it does not seem to carry the branch from Iain Sandoe (either as patch or as branch)

[giordano]

Thanks for starting this! I'll try to have a look when I get more time, but the compilers are complicated because they aren't built in CI like all other packages, we need to build them manually locally 😞 (hopefully this will be solved by https://github.com/JuliaPackaging/BinaryBuilder2.jl, which makes compiler toolchains regular packages)

what I'm not sure I understand is how that GCC version can build on aarch64-darwin? I mean, it does not seem to carry the branch from Iain Sandoe (either as patch or as branch)

Yeah, for aarch64-darwin...we're actually stuck at gcc 12 for no good reason:

Yggdrasil/0_RootFS/gcc_sources.jl

Lines 157 to 168 in c7bd137

	gcc_version_sources[v"12.0.1-iains"] = [
	GitSource("https://github.com/iains/gcc-darwin-arm64.git",
	"af646bebaceed617775b5465cf06cb5d270a16f4"),
	ArchiveSource("https://mirrors.kernel.org/gnu/mpfr/mpfr-4.0.2.tar.xz",
	"1d3be708604eae0e42d578ba93b390c2a145f17743a744d8f3f8c2ad5855a38a"),
	ArchiveSource("https://mirrors.kernel.org/gnu/mpc/mpc-1.1.0.tar.gz",
	"6985c538143c1208dcb1ac42cedad6ff52e267b47e5f970183a3e75125b43c2e"),
	ArchiveSource("https://gcc.gnu.org/pub/gcc/infrastructure/isl-0.18.tar.bz2",
	"6b8b0fd7f81d0a957beb3679c81bbb34ccc7568d5682844d8924424a0dadcb1b"),
	ArchiveSource("https://mirrors.kernel.org/gnu/gmp/gmp-6.2.0.tar.xz",
	"258e6cd51b3fbdfc185c716d55f82c08aff57df0c6fbd143cf6ed561267a1526"),
	]

The directory where the build happens is https://github.com/JuliaPackaging/Yggdrasil/tree/256221ab8825603bb143b6d9877a9de32905797d/0_RootFS/GCCBootstrap%4012-IainS, which is separate from all other GCCs of the same version

[fxcoudert]

Yeah, for aarch64-darwin...we're actually stuck at gcc 12 for no good reason

OK I've added a GCC 15 for macOS

[giordano]

We probably want to ship the patch for iains/gcc-darwin-arm64#148 when it'll be available (or wait for a new minor version with the patch included?)