Compilation failure with LLVM 17: explicitly defaulted three-way comparison operator is implicitly deleted

[herrhotzenplotz]

I cannot build contour at commit b610c52:

[ 49%] Building CXX object src/vtbackend/CMakeFiles/vtbackend.dir/RenderBufferBuilder.cpp.o
In file included from /usr/home/nico/src/contour/src/vtbackend/ColorPalette.cpp:3:
In file included from /usr/home/nico/src/contour/src/vtbackend/ColorPalette.h:5:
In file included from /usr/home/nico/src/contour/src/vtbackend/Image.h:5:
/usr/home/nico/src/contour/src/vtbackend/primitives.h:132:20: warning: explicitly defaulted three-way comparison operator is implicitly deleted [-Wdefaulted-function-deleted]
  132 |     constexpr auto operator<=>(CellLocation const&) const noexcept = default;
      |                    ^
/usr/home/nico/src/contour/src/vtbackend/primitives.h:111:16: note: defaulted 'operator<=>' is implicitly deleted because there is no viable three-way comparison function for member 'line'
  111 |     LineOffset line {};
      |                ^
/usr/home/nico/src/contour/src/vtbackend/primitives.h:132:70: note: replace 'default' with 'delete'
  132 |     constexpr auto operator<=>(CellLocation const&) const noexcept = default;
      |                                                                      ^~~~~~~
      |                                                                      delete
In file included from /usr/home/nico/src/contour/src/vtbackend/ColorPalette.cpp:3:
In file included from /usr/home/nico/src/contour/src/vtbackend/ColorPalette.h:5:
/usr/home/nico/src/contour/src/vtbackend/Image.h:221:30: error: object of type 'CellLocation' cannot be compared because its 'operator<=>' is implicitly deleted
  221 |                && a.offset() < b.offset());
      |                              ^
/usr/home/nico/src/contour/src/vtbackend/primitives.h:132:20: note: explicitly defaulted function was implicitly deleted here
  132 |     constexpr auto operator<=>(CellLocation const&) const noexcept = default;
      |                    ^
/usr/home/nico/src/contour/src/vtbackend/primitives.h:111:16: note: defaulted 'operator<=>' is implicitly deleted because there is no viable three-way comparison function for member 'line'
  111 |     LineOffset line {};
      |                ^
1 warning and 1 error generated.
--- src/vtbackend/CMakeFiles/vtbackend.dir/ColorPalette.cpp.o ---
*** [src/vtbackend/CMakeFiles/vtbackend.dir/ColorPalette.cpp.o] Error code 1

This issue applies to a few more files.

Operating system/pkg information:

$ uname -a
FreeBSD triton 14.0-RELEASE-p4 FreeBSD 14.0-RELEASE-p4 #4 fix/sennheiser-bt-headphones-n265405-ecf35d6c9761: Fri Dec 22 14:50:24 CET 2023     root@triton:/usr/obj/usr/src/amd64.amd64/sys/TRITON140 amd64
$
$ pkg info llvm17
llvm17-17.0.6_3
Name           : llvm17
Version        : 17.0.6_3
Installed on   : Fri Jan 19 15:46:11 2024 CET
Origin         : devel/llvm17
Architecture   : FreeBSD:14:amd64
Prefix         : /usr/local
Categories     : lang devel
Licenses       : REGEX and PD and MIT and LLVM2 and LLVM and BSD3CLAUSE
Maintainer     : brooks@FreeBSD.org
WWW            : https://llvm.org/
Comment        : LLVM and Clang
Options        :
    BE_AMDGPU      : on
    BE_FREEBSD     : off
    BE_NATIVE      : off
    BE_STANDARD    : on
    BE_WASM        : on
    CLANG          : on
    COMPILER_RT    : on
    DOCS           : on
    EXTRAS         : on
    FLANG          : off
    GOLD           : on
    LIT            : on
    LLD            : on
    LLDB           : on
    MLIR           : on
    OPENMP         : on
    POLLY          : on
    PYCLANG        : on
    STATIC_LIBS    : on
Shared Libs required:
    libzstd.so.1
    libpython3.9.so.1.0
    liblua-5.3.so
    libedit.so.0
Shared Libs provided:
    libomptarget.so.17
    libomp.so
    libmlir_runner_utils.so.17
    libmlir_float16_utils.so.17
    libmlir_c_runner_utils.so.17
    libmlir_async_runtime.so.17
    liblldb.so.17
    libclang_rt.ubsan_standalone.so
    libclang_rt.ubsan_minimal.so
    libclang_rt.tsan.so
    libclang_rt.dyndd.so
    libclang_rt.asan.so
    libclang.so.17
    libclang-cpp.so.17
    libarcher.so
    libRemarks.so.17
    libMLIR.so.17
    libLTO.so.17
    libLLVM-17.so
Annotations    :
    FreeBSD_version: 1400097
    build_timestamp: 2024-01-14T01:16:07+0000
    built_by       : poudriere-git-3.4.0
    cpe            : cpe:2.3:a:llvm:llvm:17.0.6:::::freebsd14:x64:3
    flavor         : default
    port_checkout_unclean: no
    port_git_hash  : c91d810f6
    ports_top_checkout_unclean: no
    ports_top_git_hash: b57ae9b9d
    repo_type      : binary
    repository     : FreeBSD
Flat size      : 1.57GiB
Description    :
The LLVM Project is a collection of modular and reusable compiler and
toolchain technologies.

This port includes Clang (a C/C++/Objective-C compiler), LLD (a linker),
LLDB (a debugger), an OpenMP runtime library, and the LLVM infrastructure
these are built on.
$ 

I've tried this with both the FreeBSD clang (which is llvm 16) and the version from ports. Both failed.

This bug should have been caught by CI. Maybe it's broken again?

[christianparpart]

Thanks @herrhotzenplotz. I noticed this already. I'll be fixing this. Thank you :)

[christianparpart]

Wait a second. You should not have it on boxed<> types. Did you recently run ./scripts/install-deps.sh? Because that'll update boxed-cpp that comes with operator<=> support.

What I was referring to is in the tests. That can be worked around by simply not building tests (for now). I'll fix that asap. :)

[herrhotzenplotz]

Aha, thank you. Cleaning the entire tree and re-running the install-deps.sh script fixed the issue.

Sorry for the noise.

[christianparpart]

But there is some truth in it, still. We must version-check libs like boxed-cpp to avoid such confusion.

[christianparpart]

p.s.: we've now added checks to our CMake files to ensure that libunicode as well as boxed-cpp is on its minimum version required for Contour. :)