fix: remove deprecated operator"" syntax usage

[lidavidm]

Clang warns about this. Apparently GCC 4.9 may warn about the fixed syntax, though!

Spotted in the ADBC CI:

 /adbc/c/vendor/nanoarrow/nanoarrow.hpp:94:35: error: identifier '_asv' preceded by whitespace in a literal operator declaration is deprecated [-Werror,-Wdeprecated-literal-operator]
   94 | inline ArrowStringView operator"" _asv(const char* data, std::size_t size_bytes) {
      |                        ~~~~~~~~~~~^~~~
      |                        operator""_asv

[WillAyd]

lgtm. Meson coverage error seems unrelated

[paleolimbot]

Yes, I think this happened because it fails to compile on GCC 4.8 this way:

# export NANOARROW_ARCH=arm64      
# export NANOARROW_PLATFORM=centos7
# docker compose run --rm verify   
[ 14%] Building CXX object CMakeFiles/nanoarrow_testing.dir/src/nanoarrow/testing/testing.cc.o
In file included from /nanoarrow/src/nanoarrow/nanoarrow_testing.hpp:25:0,
                 from /nanoarrow/src/nanoarrow/testing/testing.cc:20:
/nanoarrow/src/nanoarrow/nanoarrow.hpp:95:24: error: missing space between ‘""’ and suffix identifier
 inline ArrowStringView operator""_asv(const char* data, std::size_t size_bytes) {
                        ^
/nanoarrow/src/nanoarrow/testing/testing.cc:2312:1: error: expected ‘}’ at end of input
 }  // namespace nanoarrow
 ^
/nanoarrow/src/nanoarrow/testing/testing.cc:2312:1: error: expected ‘}’ at end of input
cc1plus: warning: unrecognized command line option "-Wno-misleading-indentation" [enabled by default]
gmake[2]: *** [CMakeFiles/nanoarrow_testing.dir/src/nanoarrow/testing/testing.cc.o] Error 1
gmake[1]: *** [CMakeFiles/nanoarrow_testing.dir/all] Error 2
gmake: *** [all] Error 2
Failed to verify release candidate. See /tmp/nanoarrow-HEAD.qjyj8h for details.

Because we still check that the tests pass when compiled on gcc 4.8 and we use _asv in the tests, we probably need this to be something like:

#if !defined(__clang__) && (defined(__GNUC__) && __GNUC__ < 6)
inline ArrowStringView operator"" _asv(const char* data, std::size_t size_bytes) {
#else
inline ArrowStringView operator""_asv(const char* data, std::size_t size_bytes) {
#endif

...Or we could move that to the gtest_util header where it is less likely to cause problems for downstream projects. That would be a breaking change but I think that is OK.

[lidavidm]

Ah, bleh. I'll try with the ifdef in a bit

[paleolimbot]

Thank you!

I opened an issue for the Meson coverage build failure: #663