On a fully updated Rasperry Pi OS using Raspberry Pi OS 2023-05-03 Drogon built fine, but a project linking to/including drogon would fail to build with `/usr/local/include/drogon/orm/SqlBinder.h:70:1: error: body of ‘constexpr’ function ‘constexpr T htonT(T) [with T = long unsigned int]’ not a return-statement 70 | }`.
Compiler details:
$ gcc -v
Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/usr/lib/gcc/aarch64-linux-gnu/10/lto-wrapper
Target: aarch64-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Debian 10.2.1-6' --with-bugurl=file:///usr/share/doc/gcc-10/README.Bugs --enable-languages=c,ada,c++,go,d,fortran,objc,obj-c++,m2 --prefix=/usr --with-gcc-major-version-only --program-suffix=-10 --program-prefix=aarch64-linux-gnu- --enable-shared --enable-linker-build-id --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix --libdir=/usr/lib --enable-nls --enable-bootstrap --enable-clocale=gnu --enable-libstdcxx-debug --enable-libstdcxx-time=yes --with-default-libstdcxx-abi=new --enable-gnu-unique-object --disable-libquadmath --disable-libquadmath-support --enable-plugin --enable-default-pie --with-system-zlib --enable-libphobos-checking=release --with-target-system-zlib=auto --enable-objc-gc=auto --enable-multiarch --enable-fix-cortex-a53-843419 --disable-werror --enable-checking=release --build=aarch64-linux-gnu --host=aarch64-linux-gnu --target=aarch64-linux-gnu --with-build-config=bootstrap-lto-lean --enable-link-mutex
Thread model: posix
Supported LTO compression algorithms: zlib zstd
gcc version 10.2.1 20210110 (Debian 10.2.1-6)
This is a proposed fix for this issue that adjusts this function to be a pair of IFDEFed return statements based on network byte order as the original function appeared to intend. This makes it so the function body is entirely a single return statement on each platform.
The error message from the C++17 compiler (which is the latest version supported on Raspberry Pi OS currently) indicates that constexpr functions must be entirely single return statements.
