1.9.0 compile error with gcc-16: `encode_toon.hpp: error: 'exponent' may be used uninitialized [-Werror=maybe-uninitialized]`

[barracuda156]

Describe the bug

:info:build [ 98%] Building CXX object test/CMakeFiles/unit_tests.dir/toon/src/encode_toon_tests.cpp.o
:info:build cd /opt/local/var/macports/build/jsoncons-c9d1b342/work/build/test && /opt/local/bin/g++-mp-16  -I/opt/local/var/macports/build/jsoncons-c9d1b342/work/jsoncons-1.9.0/include -I/opt/local/var/macports/build/jsoncons-c9d1b342/work/jsoncons-1.9.0/test -I/opt/local/var/macports/build/jsoncons-c9d1b342/work/jsoncons-1.9.0/test/thirdparty -I/opt/local/var/macports/build/jsoncons-c9d1b342/work/jsoncons-1.9.0/test/thirdparty/catch -pipe -Os -DNDEBUG -I/opt/local/include -DJSONCONS_HAS_STATEFUL_ALLOCATOR=0 -DJSONCONS_HAS_POLYMORPHIC_ALLOCATOR=0 -D_GLIBCXX_USE_CXX11_ABI=0 -std=gnu++17 -mmacosx-version-min=10.6 -Werror=maybe-uninitialized -Wnon-virtual-dtor -Werror=free-nonheap-object -Werror=stringop-overflow -Werror -Wall -Wextra -Wcast-align -Wcast-qual -Wimplicit-fallthrough -Wsign-compare -pedantic -Wnonnull -Wnull-dereference -Werror=nonnull -MD -MT test/CMakeFiles/unit_tests.dir/toon/src/encode_toon_tests.cpp.o -MF CMakeFiles/unit_tests.dir/toon/src/encode_toon_tests.cpp.o.d -o CMakeFiles/unit_tests.dir/toon/src/encode_toon_tests.cpp.o -c /opt/local/var/macports/build/jsoncons-c9d1b342/work/jsoncons-1.9.0/test/toon/src/encode_toon_tests.cpp
:info:build [ 99%] Building CXX object test/CMakeFiles/unit_tests.dir/corelib/src/testmain.cpp.o
:info:build cd /opt/local/var/macports/build/jsoncons-c9d1b342/work/build/test && /opt/local/bin/g++-mp-16  -I/opt/local/var/macports/build/jsoncons-c9d1b342/work/jsoncons-1.9.0/include -I/opt/local/var/macports/build/jsoncons-c9d1b342/work/jsoncons-1.9.0/test -I/opt/local/var/macports/build/jsoncons-c9d1b342/work/jsoncons-1.9.0/test/thirdparty -I/opt/local/var/macports/build/jsoncons-c9d1b342/work/jsoncons-1.9.0/test/thirdparty/catch -pipe -Os -DNDEBUG -I/opt/local/include -DJSONCONS_HAS_STATEFUL_ALLOCATOR=0 -DJSONCONS_HAS_POLYMORPHIC_ALLOCATOR=0 -D_GLIBCXX_USE_CXX11_ABI=0 -std=gnu++17 -mmacosx-version-min=10.6 -Werror=maybe-uninitialized -Wnon-virtual-dtor -Werror=free-nonheap-object -Werror=stringop-overflow -Werror -Wall -Wextra -Wcast-align -Wcast-qual -Wimplicit-fallthrough -Wsign-compare -pedantic -Wnonnull -Wnull-dereference -Werror=nonnull -MD -MT test/CMakeFiles/unit_tests.dir/corelib/src/testmain.cpp.o -MF CMakeFiles/unit_tests.dir/corelib/src/testmain.cpp.o.d -o CMakeFiles/unit_tests.dir/corelib/src/testmain.cpp.o -c /opt/local/var/macports/build/jsoncons-c9d1b342/work/jsoncons-1.9.0/test/corelib/src/testmain.cpp
:info:build In file included from /opt/local/var/macports/build/jsoncons-c9d1b342/work/jsoncons-1.9.0/test/toon/src/encode_toon_tests.cpp:5:
:info:build /opt/local/var/macports/build/jsoncons-c9d1b342/work/jsoncons-1.9.0/include/jsoncons_ext/toon/encode_toon.hpp: In function 'std::string jsoncons::toon::detail::exponential_to_decimal_notation(std::string_view)':
:info:build /opt/local/var/macports/build/jsoncons-c9d1b342/work/jsoncons-1.9.0/include/jsoncons_ext/toon/encode_toon.hpp:144:9: error: 'exponent' may be used uninitialized [-Werror=maybe-uninitialized]
:info:build   144 |         if (exponent > decimal_places)
:info:build       |         ^~
:info:build /opt/local/var/macports/build/jsoncons-c9d1b342/work/jsoncons-1.9.0/include/jsoncons_ext/toon/encode_toon.hpp:120:17: note: 'exponent' was declared here
:info:build   120 |     std::size_t exponent;
:info:build       |                 ^~~~~~~~
:info:build cc1plus: all warnings being treated as errors
:info:build make[2]: *** [test/CMakeFiles/unit_tests.dir/toon/src/encode_toon_tests.cpp.o] Error 1
:info:build make[2]: *** Waiting for unfinished jobs....

Enumerate the steps to reproduce the bug

Run the build.

Include a small, self-contained example if possible

What compiler, architecture, and operating system?

• Compiler: gcc 16.1.0
• Architecture: ppc
• Operating system: MacOS 10.6.8

What jsoncons library version?

• Latest release 1.9.0
• Other release ______
• master

@danielaparker Could you please take a look?

[danielaparker]

This should be addressed on master.

[danielaparker]

@barracuda156, if you're still following this issue, please verify that this issue is resolved on master, thanks.