Re: Why is main's system clang (12.0.1-rc2) using /usr/local/bin/aarch64-unknown-freebsd14.0-ld ? (such breaks things)

From: Mark Millard via freebsd-toolchain <freebsd-toolchain_at_freebsd.org>
Date: Fri, 16 Jul 2021 11:26:28 -0700
On 2021-Jul-16, at 04:15, Mark Millard <marklmi at yahoo.com> wrote:

> On 2021-Jul-16, at 03:23, Dimitry Andric <dim at FreeBSD.org> wrote:
> 
>> On 16 Jul 2021, at 02:21, Mark Millard via freebsd-toolchain <freebsd-toolchain_at_freebsd.org> wrote:
>>> # c++ -v -o trivial trivial.cpp
>>> FreeBSD clang version 12.0.1 (git_at_github.com:llvm/llvm-project.git llvmorg-12.0.1-rc2-0-ge7dac564cd0e)
>>> Target: aarch64-unknown-freebsd14.0
>>> Thread model: posix
>>> InstalledDir: /usr/bin
>>> "/usr/bin/c++" -cc1 -triple aarch64-unknown-freebsd14.0 -emit-obj -mrelax-all --mrelax-relocations -disable-free -disable-llvm-verifier -discard-value-names -main-file-name trivial.cpp -mrelocation-model static -mframe-pointer=non-leaf -fno-rounding-math -mconstructor-aliases -munwind-tables -target-cpu generic -target-feature +neon -target-abi aapcs -fallow-half-arguments-and-returns -fno-split-dwarf-inlining -debugger-tuning=gdb -v -resource-dir /usr/lib/clang/12.0.1 -internal-isystem /usr/include/c++/v1 -fdeprecated-macro -fdebug-compilation-dir /usr/home/root/c_tests -ferror-limit 19 -fno-signed-char -fgnuc-version=4.2.1 -fcxx-exceptions -fexceptions -faddrsig -o /tmp/trivial-5d90b5.o -x c++ trivial.cpp
>>> clang -cc1 version 12.0.1 based upon LLVM 12.0.1 default target aarch64-unknown-freebsd14.0
>>> #include "..." search starts here:
>>> #include <...> search starts here:
>>> /usr/include/c++/v1
>>> /usr/lib/clang/12.0.1/include
>>> /usr/include
>>> End of search list.
>>> "/usr/local/bin/aarch64-unknown-freebsd14.0-ld" --eh-frame-hdr -dynamic-linker /libexec/ld-elf.so.1 --enable-new-dtags -o trivial /usr/lib/crt1.o /usr/lib/crti.o /usr/lib/crtbegin.o -L/usr/lib /tmp/trivial-5d90b5.o -lc++ -lm -lgcc --as-needed -lgcc_s --no-as-needed -lc -lgcc --as-needed -lgcc_s --no-as-needed /usr/lib/crtend.o /usr/lib/crtn.o
>> 
>> Yes, this is an unfortunate (and sometimes unwanted) side effect of the
>> way the clang driver searches for its linker(s). It prefers "target
>> specific executables" (meaning, those beginning with the target triple)
>> above generic executables, when searching for linkers, assemblers and
>> other external tools.
> 
> As far as I know the /usr/bin/clang++ related FreeBSD
> toolchain never has a file aarch64-unknown-freebsd14.0-ld
> in FreeBSD. (And similarly fr other suffices than ld.)
> 
> In other words, why is aarch64-unknown-freebsd14.0-ld
> even listed in TargetSpecificExecutables for the system
> toolchain's clang++ ?
> 
> I would argue that the default FreeBSD system toolchain
> configuration/operation should be adjusted/patched to not
> have automatic defaults that cause parts of that toolchain
> to not be used even though they are present, just because
> some unrelated/independent port(s) have been installed that
> are a different toolchain. (Explicitly enabling/allowing
> alternate matches may well be reasonable.)
> 
> As far as I know, there is no guarantee of compatibility
> with the gcc/g++/gnu related toolchain, with the error
> message that I reported being an example for attempted
> -flto use.
> 
>> See the Driver::GetProgramPath() function:
>> https://github.com/llvm/llvm-project/blob/release/12.x/clang/lib/Driver/Driver.cpp#L4981
> 
> It looks like if there was an implcit/automatic -B /usr/bin
> when /usr/bin/clang++ is the native FreeBSD toolchain one,
> that the problem would be avoided.
> 
> But, as, stands, that has to be done explicitly on the
> command lines in order to tell clang++ to use its own
> related FreeBSD toolchain instead of using one from
> ports.
> 
>> In short, if it finds aarch64-unknown-freebsd14.0-$TOOL in your PATH, it
>> will prefer that over $TOOL, even if the 'naked' $TOOL would be found in
>> an earlier PATH component.
>> 
>> For programs like ld, as and such, these will be found if you install
>> the devel/binutils port with an arch-specific FLAVOR. In this case, I
>> assume this was because you installed a CROSS_TOOLCHAIN package such as
>> freebsd9-gcc, or directly installed the aarch64-binutils package?
> 
> # pkg which /usr/local/bin/aarch64-unknown-freebsd14.0-ld
> /usr/local/bin/aarch64-unknown-freebsd14.0-ld was installed by package aarch64-binutils-2.33.1_4,1
> 
> # pkg delete aarch64-binutils
> Checking integrity... done (0 conflicting)
> Deinstallation has been requested for the following 3 packages (of 0 packages in the universe):
> 
> Installed packages to be REMOVED:
>       aarch64-binutils: 2.33.1_4,1
>       aarch64-gcc6: 6.5.0_3
>       aarch64-gcc9: 9.3.0_1
> 
> Number of packages to be removed: 3
> 
> The operation will free 278 MiB.
> 
> Proceed with deinstalling packages? [y/N]: N
> 
> So /usr/local/bin/aarch64-unknown-freebsd14.0-ld
> exists because I built and installed:
> 
> devel/freebsd-gcc6_at_aarch64
> devel/freebsd-gcc9_at_aarch64
> devel/binutils_at_aarch64
> 
>> Note that the native binutils package does not cause these problems,
>> since it prefixes its tools with $arch-portbld-freebsd14.0. E.g., the
>> 'vendor' field of the triple is set to "portbld", not "unknown".
>> 
>> I guess the flavored binutils packages do use the "unknown" vendor field
>> to avoid installation conflicts. But at some point this should be
>> resolved: either all binutils ports should use the "portbld" vendor, or
>> all of them should use "unknown", but this mixing is causing trouble, in
>> my opinion.
> 
> It has been all portbld at times in the past. That mix is also a
> problem. 3 distinct naming structures are needed, not just 2, in
> order to prevent mixing from occurring without some form of
> explicit request for a mix.

Another command line way to potentially control this might be
use of: -fuse-ld=lld

That might change the name looked for to: aarch64-unknown-freebsd14.0-lld
and not match any existing toolchains.

===
Mark Millard
marklmi at yahoo.com
( dsl-only.net went
away in early 2018-Mar)
Received on Fri Jul 16 2021 - 18:26:28 UTC

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