this allows a compiler derivation to provide a
hardeningUnsupportedFlagsByTargetPlatform passthru attr
that will be called with the targetPlatform to determine
the unsupported hardening flags for that platform.
we can do this because even though a clang compiler is
multi-target by nature, cc-wrapper effectively fixes the
target platform at wrapping time. otherwise we'd have to
sniff the intended target at runtime, which wouldn't
be fun at all.
the advantage of using a new attribute instead of
allowing hardeningUnsupportedFlags to optionally be a
function is that hardeningUnsupportedFlags retains its
simple overriding pattern for simple cases (i.e.
`(prev.hardeningUnsupportedFlags or []) ++ [ "foo" ]`
) which will continue to work as long as the bottom-most
function of hardeningUnsupportedFlagsByTargetPlatform
falls back to hardeningUnsupportedFlags.
c33c7c3d5f ("clang_11: Fix RISC-V builds for compiler-rt. (#135718)")
already marked tihs as broken for LLVM 11, but didn't apply the same
change to other affected LLVM versions.
This change applies the upstream PR
https://github.com/llvm/llvm-project/pull/77218 so the same link flags
on darwin are used as when LIBCXX_CXX_ABI=libcxxabi. Specifically, this
adds
"-Wl,-force_symbols_not_weak_list,${CMAKE_CURRENT_SOURCE_DIR}/../lib/notweak.exp"
which prevents libcxx from segfaulting on darwin
compiler-rt includes <linux/unistd.h> on RISC-V. This only seems to
be necessary for useLLVM, but looking at the source code I can't
see any reason for that, so probably in the non-useLLVM case it just
gets propagated in.
for hygiene
Run `deadnix . --edit`
`gccForLibs` is an argument used by multi.nix but it's an argument to
cc-wrapper, not to llvmPackages.
`@args` in `llvm/default.nix` was accidentally added in 4badff49fd
There are no uses of `@` therefore these changes are safe.
What changed:
* Fixed crtbeginS.o and crtendS.o missing
(they may or may not be called crt{begin_end},{,_shared}.
* Fixed implicit function declaration causing build errors for various
builds by supplying -Wno-implicit-function-declaration.
* Fixed __cxxabi_config.h missing, by adding -I${cxxabi}/include/c++/v1
in the wrapper.
* Fixed libcxx failing to build due to missing libunwind symbols by
including libunwind as a buildInput, and setting
-DLIBCXX_ADDITIONAL_LIBRARIES=unwind for stdenv.hostPlatform.useLLVM == true.
* libcxxabi wants to find libunwind at libunwind_shared.so, so symlink
it there in libunwind.
* llvmPackages_16.libcxxabi: Pass -nostdlib via CMAKE_*_LINKER_FLAGS
Without this flag, the link of libcxxabi.so tries to pull in libgcc and
friends, from the clang compiler driver.
* Drop unneeded musl hack patch from libcxx.
* Pass -Wno-error=implicit-function-declaration only to compiler-rt
See LLVM forum discussion:
https://discourse.llvm.org/t/configure-script-breakage-with-the-new-werror-implicit-function-declaration/65213
In summary, LLVM 16 made implicit function declaration an error. This
happens a lot in configure scripts which can break things.
* llvmPackages_16: !isDarwin: Supply -DLIBCXX_ABI_USE_LLVM_UNWINDER=On
Otherwise it fails with various undefined references to _Unwind_*
functions: (full list: _Unwind_DeleteException _Unwind_GetIP
_Unwind_GetLanguageSpecificData _Unwind_GetRegionStart
_Unwind_RaiseException _Unwind_Resume _Unwind_SetGR _Unwind_SetIP).
* 16.libcxxabi: Only pass -nostdlib for useLLVM and Darwin builds
What was tested:
* x86_64-linux, aarch64-linux, the stdenv builds.
* Additionally I was able to get nix to build, with an overlay to fix
a couple of minor issues in downstream packages (overlay supplied in
PR #246577.
* aarch64-darwin fails spuriously in a single LLVM test
strip-preserve-atime.test checking atime timestamps.
* The same for pkgsLLVM with llvmPackages = llvmPackages_15.
Signed-off-by: Peter Waller <p@pwaller.net>
clang_15 appears to not cross compile in the build!=(host==target)
case due to two problems, which this commit fixes:
- It trips -Wmaybe-uninitialized on recent gcc, but only in the
build!=host case (likely due to #ifdefs)
- Two more buildPlatform tools have been added:
clang-tidy-confusable-chars-gen and clang-pseudo-gen
Co-authored-by: Rahul Butani <rrbutani@users.noreply.github.com>
