LTO is disabled during bootstrap to keep the bootstrap tools small and
avoid unnecessary LLVM rebuilds, but is enabled in the final stdenv
stage and should be usable by normal packages.
This also updates the bootstrap tool builder to LLVM 5, but not the ones
we actually use for bootstrap. I'll make that change in a subsequent commit
so as to provide traceable provenance of the bootstrap tools.
Not every package that needs xcbuild will want to use its build phase.
I have moved the xcbuild setup hook to the new attribute xcbuildHook.
This means that dontUseXcbuild is no longer needed. If you just need
to call xcbuild on its own you can just refer to xcbuild.
toPath has confusing semantics and is never necessary; it can always
either just be omitted or replaced by pre-concatenating `/.`. It has
been marked as "!!! obsolete?" for more than 10 years in a C++
comment, hopefully removing it will let us properly deprecate and,
eventually, remove it.
I’m not going to fix all of them but this is the best way to do this
in Apple things. Just add ‘EXPORT_DSTDIR’ to the installFlags & set
‘DSTDIR’ to $(out). Please do this instead of the patching!
Following legacy packing conventions, `isArm` was defined just for
32-bit ARM instruction set. This is confusing to non packagers though,
because Aarch64 is an ARM instruction set.
The official ARM overview for ARMv8[1] is surprisingly not confusing,
given the overall state of affairs for ARM naming conventions, and
offers us a solution. It divides the nomenclature into three levels:
```
ISA: ARMv8 {-A, -R, -M}
/ \
Mode: Aarch32 Aarch64
| / \
Encoding: A64 A32 T32
```
At the top is the overall v8 instruction set archicture. Second are the
two modes, defined by bitwidth but differing in other semantics too, and
buttom are the encodings, (hopefully?) isomorphic if they encode the
same mode.
The 32 bit encodings are mostly backwards compatible with previous
non-Thumb and Thumb encodings, and if so we can pun the mode names to
instead mean "sets of compatable or isomorphic encodings", and then
voilà we have nice names for 32-bit and 64-bit arm instruction sets
which do not use the word ARM so as to not confused either laymen or
experienced ARM packages.
[1]: https://developer.arm.com/products/architecture/a-profile
