It is useful to make these dynamic and not bake them into gcc. This
means we don’t have to rebuild gcc to change these values. Instead, we
will pass cflags to gcc based on platform values. This was already
done hackily for android gcc (which is multi-target), but not for our
own gccs which are single target.
To accomplish this, we need to add a few things:
- add ‘arch’ to cpu
- add NIX_CFLAGS_COMPILE_BEFORE flag (goes before args)
- set -march everywhere
- set mcpu, mfpu, mmode, and mtune based on targetPlatform.gcc flags
cc-wrapper: only set -march when it is in the cpu type
Some architectures don’t have a good mapping of -march. For instance
POWER architecture doesn’t support the -march flag at all!
https://gcc.gnu.org/onlinedocs/gcc/RS_002f6000-and-PowerPC-Options.html#RS_002f6000-and-PowerPC-Options
gobject-introspection uses glib’s g_module_open function, which in turn relies
on dlopen. I also implemented openat, since I initially thought this function
was used but turns out dlopen uses the openat signal directly. We might as
well keep it, even thought I do not need it at the moment.
this adds libc++ to the LLVM cross, giving us access to the full
Nixpkgs set. This requires 4 stages of wrapped compilers:
- Clang with no libraries
- Clang with just compiler-rt
- Clang with Libc, and compiler-rt
- Clang with Libc++, Libc, and compiler-rt
This iteration was long, about five weeks (2fcb11a2), I think.
Darwin: it's missing a few thousand binaries and there's a make-netbsd
regression, but I suppose these aren't merge blockers.
buildRustCrate has a handy `include` helper, that only imports those whitelisted
files and folders to the store.
However, the function's matching logic is broken and includes all files,
regardless of whether or not they're whitelisted, as long as the whitelist
contains at least one name (regardless of whether that name exists). This is
because it doesn't take into account that
`lib.strings.removePrefix "foo" "bar" == "bar"` (that is, paths that don't match
the prefix are passed straight through).
