In preparation for the deprecation of `stdenv.isX`.
These shorthands are not conducive to cross-compilation because they
hide the platforms.
Darwin might get cross-compilation for which the continued usage of `stdenv.isDarwin` will get in the way
One example of why this is bad and especially affects compiler packages
https://www.github.com/NixOS/nixpkgs/pull/343059
There are too many files to go through manually but a treewide should
get users thinking when they see a `hostPlatform.isX` in a place where it
doesn't make sense.
```
fd --type f "\.nix" | xargs sd --fixed-strings "stdenv.is" "stdenv.hostPlatform.is"
fd --type f "\.nix" | xargs sd --fixed-strings "stdenv'.is" "stdenv'.hostPlatform.is"
fd --type f "\.nix" | xargs sd --fixed-strings "clangStdenv.is" "clangStdenv.hostPlatform.is"
fd --type f "\.nix" | xargs sd --fixed-strings "gccStdenv.is" "gccStdenv.hostPlatform.is"
fd --type f "\.nix" | xargs sd --fixed-strings "stdenvNoCC.is" "stdenvNoCC.hostPlatform.is"
fd --type f "\.nix" | xargs sd --fixed-strings "inherit (stdenv) is" "inherit (stdenv.hostPlatform) is"
fd --type f "\.nix" | xargs sd --fixed-strings "buildStdenv.is" "buildStdenv.hostPlatform.is"
fd --type f "\.nix" | xargs sd --fixed-strings "effectiveStdenv.is" "effectiveStdenv.hostPlatform.is"
fd --type f "\.nix" | xargs sd --fixed-strings "originalStdenv.is" "originalStdenv.hostPlatform.is"
```
Key test case: nixpkgs#pkgsStatic.pkgsLLVM.ncurses
Prior to this patch, this fails with errors such as:
```
error: undefined symbol: __cxa_throw
```
I think this is a reasonable solution because in #292043, libcxxabi was
'merged into libcxx', however, the commit message suggests that only
dynamic linking was accounted for, because it says:
```
* linux/freebsd `libc++.so` is a linker script `LINK(libc++.so.1, -lc++abi)` making `-lc++` sufficient.
```
Whereas, I found that if I tried linking a "hello world" C++ program
with a static hostPlatform, it failed unless -lc++abi was passed.
Signed-off-by: Peter Waller <p@pwaller.net>
Currently we set dynamic-linker unconditionally. This breaks
however some static binaries i.e. rust binaries linked against musl.
There is no reason we should set an elf interpreter for static binaries
hence this is skipped if `-static` or `-static-pie` is either passed to
our cc or ld wrapper.
fc9644d4c9 accidentally enabled the
sanitizer tests for GCC on Darwin, when fixing that case was never
attempted. Also inverted the condition from broken to working for
clarity.
We already did them on non-mass-rebuild llvm 6. Also, this allows
simplifying the stdenv booting.
We were missing the libcxxabi dep in compile-rt in llvm 6, so fixed that
too.
