Debug build fails with clang-11 compiler.

[shariar-rajib]

Hi,

We are trying to compile this library using clang-11. The runtime version builds without any issues however the debug build fails with the following error:

[ 36%] Building CXX object libuavcan/CMakeFiles/libuavcan_test.dir/test/marshal/integer_spec.cpp.o
[ 37%] Building CXX object libuavcan/CMakeFiles/libuavcan_test_optim.dir/test/dsdl_test/dsdl_const_2.cpp.o
1 warning generated.
[ 38%] Building CXX object libuavcan/CMakeFiles/libuavcan_test.dir/test/marshal/scalar_codec.cpp.o
[ 38%] Building CXX object libuavcan/CMakeFiles/libuavcan_test.dir/test/marshal/type_util.cpp.o
/home/raj/dasa_cheri/libuavcan/libuavcan/test/marshal/array.cpp:353:20: error: use of overloaded operator '==' is ambiguous (with operand types 'A' (aka 'Array<IntegerSpec<1, SignednessUnsigned, CastModeSaturate>, ArrayModeDynamic, 5>') and 'B' (aka 'Array<IntegerSpec<8, SignednessSigned, CastModeSaturate>, ArrayModeDynamic, 255>'))
    ASSERT_FALSE(a == b);
                 ~ ^  ~
/home/raj/dasa_cheri/libuavcan/build/googletest-src/googletest/include/gtest/gtest.h:1905:25: note: expanded from macro 'ASSERT_FALSE'
  GTEST_TEST_BOOLEAN_(!(condition), #condition, true, false, \
                        ^~~~~~~~~
/home/raj/dasa_cheri/libuavcan/build/googletest-src/googletest/include/gtest/internal/gtest-internal.h:1229:34: note: expanded from macro 'GTEST_TEST_BOOLEAN_'
      ::testing::AssertionResult(expression)) \
                                 ^~~~~~~~~~
/home/raj/dasa_cheri/libuavcan/./libuavcan/include/uavcan/marshal/array.hpp:766:5: note: candidate function [with R = uavcan::Array<uavcan::IntegerSpec<8, uavcan::SignednessSigned, uavcan::CastModeSaturate>, uavcan::ArrayModeDynamic, 255>]
    operator==(const R& rhs) const
    ^
/home/raj/dasa_cheri/libuavcan/./libuavcan/include/uavcan/marshal/array.hpp:1101:1: note: candidate function [with R = uavcan::Array<uavcan::IntegerSpec<1, uavcan::SignednessUnsigned, uavcan::CastModeSaturate>, uavcan::ArrayModeDynamic, 5>, T = uavcan::IntegerSpec<8, uavcan::SignednessSigned, uavcan::CastModeSaturate>, ArrayMode = uavcan::ArrayModeDynamic, MaxSize = 255]
operator==(const R& rhs, const Array<T, ArrayMode, MaxSize>& lhs)

The commands used to build the library:

git clone https://github.com/DroneCAN/libuavcan
cd libuavcan
git submodule update --init
mkdir build
cd build
cmake .. -DCMAKE_BUILD_TYPE=Debug -DCMAKE_C_COMPILER="clang-11" -DCMAKE_CXX_COMPILER="clang++-11"
make -j8

Output of cmake:

-- The C compiler identification is Clang 11.1.0
-- The CXX compiler identification is Clang 11.1.0
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Check for working C compiler: /usr/bin/clang-11 - skipped
-- Detecting C compile features
-- Detecting C compile features - done
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Check for working CXX compiler: /usr/bin/clang++-11 - skipped
-- Detecting CXX compile features
-- Detecting CXX compile features - done

-- Configuring done
-- Generating done
-- Build files have been written to: /home/raj/dasa_cheri/libuavcan/build/googletest-download
[ 11%] Creating directories for 'googletest'
[ 22%] Performing download step (git clone) for 'googletest'
Cloning into 'googletest-src'...
HEAD is now at ba96d0b1 Merge pull request #1622 from rohanjoyce/bazel_test_filter
[ 33%] Performing update step for 'googletest'
[ 44%] No patch step for 'googletest'
[ 55%] No configure step for 'googletest'
[ 66%] No build step for 'googletest'
[ 77%] No install step for 'googletest'
[ 88%] No test step for 'googletest'
[100%] Completed 'googletest'
[100%] Built target googletest
CMake Deprecation Warning at build/googletest-src/CMakeLists.txt:1 (cmake_minimum_required):
  Compatibility with CMake < 2.8.12 will be removed from a future version of
  CMake.

-- Found PythonInterp: /usr/bin/python (found version "2.7.17") 
-- Performing Test CMAKE_HAVE_LIBC_PTHREAD
-- Performing Test CMAKE_HAVE_LIBC_PTHREAD - Failed
-- Check if compiler accepts -pthread
-- Check if compiler accepts -pthread - yes
-- Found Threads: TRUE  
-- Debug build
-- Using Compiler ID: Clang
-- Using C++11
-- Debug build (note: requires gtest)
-- GTest found, tests will be built and run.
-- Looking for pthread_create in pthreads
-- Looking for pthread_create in pthreads - not found
-- Looking for pthread_create in pthread
-- Looking for pthread_create in pthread - found
-- Configuring done
-- Generating done
-- Build files have been written to: /home/raj/dasa_cheri/libuavcan/build

Compiler info:

Ubuntu clang version 11.1.0-++20211011094159+1fdec59bffc1-1~exp1~20211011214614.8
Target: x86_64-pc-linux-gnu
Thread model: posix
InstalledDir: /usr/bin

Operating system info:

Linux 5.4.0-146-generic #163~18.04.1-Ubuntu SMP Mon Mar 20 15:02:59 UTC 2023 x86_64 x86_64 x86_64 GNU/Linux