util, refactor: Switch to value-initialization

[hebasto]

This PR allows to avoid false positive -Wmaybe-uninitialized warnings when cross-compiling for Windows.

[DrahtBot]

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Conflicts

Reviewers, this pull request conflicts with the following ones:

• #30005 ([PoC, nomerge] PCP IPv4 portmap+IPv6 pinhole test by laanwj)

If you consider this pull request important, please also help to review the conflicting pull requests. Ideally, start with the one that should be merged first.

[DrahtBot]

🚧 At least one of the CI tasks failed. Make sure to run all tests locally, according to the
documentation.

Possibly this is due to a silent merge conflict (the changes in this pull request being
incompatible with the current code in the target branch). If so, make sure to rebase on the latest
commit of the target branch.

Leave a comment here, if you need help tracking down a confusing failure.

_{Debug: https://github.com/bitcoin/bitcoin/runs/24591151932}

[fanquake]

CI still failing:

In file included from ./hash.h:13,
                 from ./pubkey.h:10,
                 from ./addresstype.h:9,
                 from ./outputtype.h:9,
                 from outputtype.cpp:6:
In member function ‘bool prevector<N, T, Size, Diff>::is_direct() const [with unsigned int N = 28; T = unsigned char; Size = unsigned int; Diff = int]’,
    inlined from ‘prevector<N, T, Size, Diff>::~prevector() [with unsigned int N = 28; T = unsigned char; Size = unsigned int; Diff = int]’ at ./prevector.h:474:23,
    inlined from ‘CScript::~CScript()’ at ./script/script.h:413:7,
    inlined from ‘CNoDestination::~CNoDestination()’ at ./addresstype.h:18:7,
    inlined from ‘constexpr void std::destroy_at(_Tp*) [with _Tp = CNoDestination]’ at /usr/lib/gcc/x86_64-w64-mingw32/12-posix/include/c++/bits/stl_construct.h:88:18,
    inlined from ‘constexpr void std::_Destroy(_Tp*) [with _Tp = CNoDestination]’ at /usr/lib/gcc/x86_64-w64-mingw32/12-posix/include/c++/bits/stl_construct.h:149:22,
    inlined from ‘std::__detail::__variant::_Variant_storage<false, CNoDestination, PubKeyDestination, PKHash, ScriptHash, WitnessV0ScriptHash, WitnessV0KeyHash, WitnessV1Taproot, WitnessUnknown>::_M_reset()::<lambda(auto:19&&)> mutable [with auto:19 = CNoDestination&]’ at /usr/lib/gcc/x86_64-w64-mingw32/12-posix/include/c++/variant:472:19,
    inlined from ‘constexpr _Res std::__invoke_impl(__invoke_other, _Fn&&, _Args&& ...) [with _Res = void; _Fn = __detail::__variant::_Variant_storage<false, CNoDestination, PubKeyDestination, PKHash, ScriptHash, WitnessV0ScriptHash, WitnessV0KeyHash, WitnessV1Taproot, WitnessUnknown>::_M_reset()::<lambda(auto:19&&)>; _Args = {CNoDestination&}]’ at /usr/lib/gcc/x86_64-w64-mingw32/12-posix/include/c++/bits/invoke.h:61:36,
    inlined from ‘constexpr std::enable_if_t<is_invocable_r_v<_Res, _Callable, _Args ...>, _Res> std::__invoke_r(_Callable&&, _Args&& ...) [with _Res = void; _Callable = __detail::__variant::_Variant_storage<false, CNoDestination, PubKeyDestination, PKHash, ScriptHash, WitnessV0ScriptHash, WitnessV0KeyHash, WitnessV1Taproot, WitnessUnknown>::_M_reset()::<lambda(auto:19&&)>; _Args = {CNoDestination&}]’ at /usr/lib/gcc/x86_64-w64-mingw32/12-posix/include/c++/bits/invoke.h:111:28,
    inlined from ‘static constexpr decltype(auto) std::__detail::__variant::__gen_vtable_impl<std::__detail::__variant::_Multi_array<_Result_type (*)(_Visitor, _Variants ...)>, std::integer_sequence<long long unsigned int, __indices ...> >::__visit_invoke(_Visitor&&, _Variants ...) [with _Result_type = void; _Visitor = std::__detail::__variant::_Variant_storage<false, CNoDestination, PubKeyDestination, PKHash, ScriptHash, WitnessV0ScriptHash, WitnessV0KeyHash, WitnessV1Taproot, WitnessUnknown>::_M_reset()::<lambda(auto:19&&)>&&; _Variants = {std::variant<CNoDestination, PubKeyDestination, PKHash, ScriptHash, WitnessV0ScriptHash, WitnessV0KeyHash, WitnessV1Taproot, WitnessUnknown>&}; long long unsigned int ...__indices = {0}]’ at /usr/lib/gcc/x86_64-w64-mingw32/12-posix/include/c++/variant:1035:40,
    inlined from ‘constexpr decltype(auto) std::__do_visit(_Visitor&&, _Variants&& ...) [with _Result_type = void; _Visitor = __detail::__variant::_Variant_storage<false, CNoDestination, PubKeyDestination, PKHash, ScriptHash, WitnessV0ScriptHash, WitnessV0KeyHash, WitnessV1Taproot, WitnessUnknown>::_M_reset()::<lambda(auto:19&&)>; _Variants = {variant<CNoDestination, PubKeyDestination, PKHash, ScriptHash, WitnessV0ScriptHash, WitnessV0KeyHash, WitnessV1Taproot, WitnessUnknown>&}]’ at /usr/lib/gcc/x86_64-w64-mingw32/12-posix/include/c++/variant:1783:5,
    inlined from ‘constexpr decltype(auto) std::__do_visit(_Visitor&&, _Variants&& ...) [with _Result_type = void; _Visitor = __detail::__variant::_Variant_storage<false, CNoDestination, PubKeyDestination, PKHash, ScriptHash, WitnessV0ScriptHash, WitnessV0KeyHash, WitnessV1Taproot, WitnessUnknown>::_M_reset()::<lambda(auto:19&&)>; _Variants = {variant<CNoDestination, PubKeyDestination, PKHash, ScriptHash, WitnessV0ScriptHash, WitnessV0KeyHash, WitnessV1Taproot, WitnessUnknown>&}]’ at /usr/lib/gcc/x86_64-w64-mingw32/12-posix/include/c++/variant:1729:5,
    inlined from ‘constexpr void std::__detail::__variant::_Variant_storage<false, _Types ...>::_M_reset() [with _Types = {CNoDestination, PubKeyDestination, PKHash, ScriptHash, WitnessV0ScriptHash, WitnessV0KeyHash, WitnessV1Taproot, WitnessUnknown}]’ at /usr/lib/gcc/x86_64-w64-mingw32/12-posix/include/c++/variant:470:23,
    inlined from ‘constexpr std::__detail::__variant::_Variant_storage<false, _Types ...>::~_Variant_storage() [with _Types = {CNoDestination, PubKeyDestination, PKHash, ScriptHash, WitnessV0ScriptHash, WitnessV0KeyHash, WitnessV1Taproot, WitnessUnknown}]’ at /usr/lib/gcc/x86_64-w64-mingw32/12-posix/include/c++/variant:480:17,
    inlined from ‘constexpr std::__detail::__variant::_Copy_ctor_base<false, CNoDestination, PubKeyDestination, PKHash, ScriptHash, WitnessV0ScriptHash, WitnessV0KeyHash, WitnessV1Taproot, WitnessUnknown>::~_Copy_ctor_base()’ at /usr/lib/gcc/x86_64-w64-mingw32/12-posix/include/c++/variant:554:12,
    inlined from ‘constexpr std::__detail::__variant::_Move_ctor_base<false, CNoDestination, PubKeyDestination, PKHash, ScriptHash, WitnessV0ScriptHash, WitnessV0KeyHash, WitnessV1Taproot, WitnessUnknown>::~_Move_ctor_base()’ at /usr/lib/gcc/x86_64-w64-mingw32/12-posix/include/c++/variant:591:12,
    inlined from ‘constexpr std::__detail::__variant::_Copy_assign_base<false, CNoDestination, PubKeyDestination, PKHash, ScriptHash, WitnessV0ScriptHash, WitnessV0KeyHash, WitnessV1Taproot, WitnessUnknown>::~_Copy_assign_base()’ at /usr/lib/gcc/x86_64-w64-mingw32/12-posix/include/c++/variant:629:12,
    inlined from ‘constexpr std::__detail::__variant::_Move_assign_base<false, CNoDestination, PubKeyDestination, PKHash, ScriptHash, WitnessV0ScriptHash, WitnessV0KeyHash, WitnessV1Taproot, WitnessUnknown>::~_Move_assign_base()’ at /usr/lib/gcc/x86_64-w64-mingw32/12-posix/include/c++/variant:681:12,
    inlined from ‘constexpr std::__detail::__variant::_Variant_base<CNoDestination, PubKeyDestination, PKHash, ScriptHash, WitnessV0ScriptHash, WitnessV0KeyHash, WitnessV1Taproot, WitnessUnknown>::~_Variant_base()’ at /usr/lib/gcc/x86_64-w64-mingw32/12-posix/include/c++/variant:735:12,
    inlined from ‘constexpr std::variant<_Types>::~variant() [with _Types = {CNoDestination, PubKeyDestination, PKHash, ScriptHash, WitnessV0ScriptHash, WitnessV0KeyHash, WitnessV1Taproot, WitnessUnknown}]’ at /usr/lib/gcc/x86_64-w64-mingw32/12-posix/include/c++/variant:1407:28,
    inlined from ‘std::vector<std::variant<CNoDestination, PubKeyDestination, PKHash, ScriptHash, WitnessV0ScriptHash, WitnessV0KeyHash, WitnessV1Taproot, WitnessUnknown> > GetAllDestinationsForKey(const CPubKey&)’ at outputtype.cpp:79:5:
./prevector.h:175:37: error: ‘*(const prevector<28, unsigned char, unsigned int, int>*)((char*)&p2sh + offsetof(std::CTxDestination, std::variant<CNoDestination, PubKeyDestination, PKHash, ScriptHash, WitnessV0ScriptHash, WitnessV0KeyHash, WitnessV1Taproot, WitnessUnknown>::<unnamed>.std::__detail::__variant::_Variant_base<CNoDestination, PubKeyDestination, PKHash, ScriptHash, WitnessV0ScriptHash, WitnessV0KeyHash, WitnessV1Taproot, WitnessUnknown>::<unnamed>.std::__detail::__variant::_Move_assign_base<false, CNoDestination, PubKeyDestination, PKHash, ScriptHash, WitnessV0ScriptHash, WitnessV0KeyHash, WitnessV1Taproot, WitnessUnknown>::<unnamed>.std::__detail::__variant::_Copy_assign_base<false, CNoDestination, PubKeyDestination, PKHash, ScriptHash, WitnessV0ScriptHash, WitnessV0KeyHash, WitnessV1Taproot, WitnessUnknown>::<unnamed>.std::__detail::__variant::_Move_ctor_base<false, CNoDestination, PubKeyDestination, PKHash, ScriptHash, WitnessV0ScriptHash, WitnessV0KeyHash, WitnessV1Taproot, WitnessUnknown>::<unnamed>.std::__detail::__variant::_Copy_ctor_base<false, CNoDestination, PubKeyDestination, PKHash, ScriptHash, WitnessV0ScriptHash, WitnessV0KeyHash, WitnessV1Taproot, WitnessUnknown>::<unnamed>.std::__detail::__variant::_Variant_storage<false, CNoDestination, PubKeyDestination, PKHash, ScriptHash, WitnessV0ScriptHash, WitnessV0KeyHash, WitnessV1Taproot, WitnessUnknown>::_M_u)).prevector<28, unsigned char>::_size’ may be used uninitialized [-Werror=maybe-uninitialized]
  175 |     bool is_direct() const { return _size <= N; }
      |                                     ^~~~~
outputtype.cpp: In function ‘std::vector<std::variant<CNoDestination, PubKeyDestination, PKHash, ScriptHash, WitnessV0ScriptHash, WitnessV0KeyHash, WitnessV1Taproot, WitnessUnknown> > GetAllDestinationsForKey(const CPubKey&)’:
outputtype.cpp:77:24: note: ‘p2sh’ declared here
   77 |         CTxDestination p2sh = ScriptHash(GetScriptForDestination(segwit));
      |                        ^~~~
In file included from /usr/lib/gcc/x86_64-w64-mingw32/12-posix/include/c++/vector:64,
                 from ./serialize.h:26,
                 from ./hash.h:14:
In destructor ‘constexpr std::_Vector_base<_Tp, _Alloc>::~_Vector_base() [with _Tp = unsigned char; _Alloc = std::allocator<unsigned char>]’,
    inlined from ‘constexpr std::vector<_Tp, _Alloc>::~vector() [with _Tp = unsigned char; _Alloc = std::allocator<unsigned char>]’ at /usr/lib/gcc/x86_64-w64-mingw32/12-posix/include/c++/bits/stl_vector.h:733:7,
    inlined from ‘constexpr WitnessUnknown::~WitnessUnknown()’ at ./addresstype.h:94:8,
    inlined from ‘constexpr void std::destroy_at(_Tp*) [with _Tp = WitnessUnknown]’ at /usr/lib/gcc/x86_64-w64-mingw32/12-posix/include/c++/bits/stl_construct.h:88:18,
    inlined from ‘constexpr void std::_Destroy(_Tp*) [with _Tp = WitnessUnknown]’ at /usr/lib/gcc/x86_64-w64-mingw32/12-posix/include/c++/bits/stl_construct.h:149:22,
    inlined from ‘std::__detail::__variant::_Variant_storage<false, CNoDestination, PubKeyDestination, PKHash, ScriptHash, WitnessV0ScriptHash, WitnessV0KeyHash, WitnessV1Taproot, WitnessUnknown>::_M_reset()::<lambda(auto:19&&)> mutable [with auto:19 = WitnessUnknown&]’ at /usr/lib/gcc/x86_64-w64-mingw32/12-posix/include/c++/variant:472:19,
    inlined from ‘constexpr _Res std::__invoke_impl(__invoke_other, _Fn&&, _Args&& ...) [with _Res = void; _Fn = __detail::__variant::_Variant_storage<false, CNoDestination, PubKeyDestination, PKHash, ScriptHash, WitnessV0ScriptHash, WitnessV0KeyHash, WitnessV1Taproot, WitnessUnknown>::_M_reset()::<lambda(auto:19&&)>; _Args = {WitnessUnknown&}]’ at /usr/lib/gcc/x86_64-w64-mingw32/12-posix/include/c++/bits/invoke.h:61:36,
    inlined from ‘constexpr std::enable_if_t<is_invocable_r_v<_Res, _Callable, _Args ...>, _Res> std::__invoke_r(_Callable&&, _Args&& ...) [with _Res = void; _Callable = __detail::__variant::_Variant_storage<false, CNoDestination, PubKeyDestination, PKHash, ScriptHash, WitnessV0ScriptHash, WitnessV0KeyHash, WitnessV1Taproot, WitnessUnknown>::_M_reset()::<lambda(auto:19&&)>; _Args = {WitnessUnknown&}]’ at /usr/lib/gcc/x86_64-w64-mingw32/12-posix/include/c++/bits/invoke.h:111:28,
    inlined from ‘static constexpr decltype(auto) std::__detail::__variant::__gen_vtable_impl<std::__detail::__variant::_Multi_array<_Result_type (*)(_Visitor, _Variants ...)>, std::integer_sequence<long long unsigned int, __indices ...> >::__visit_invoke(_Visitor&&, _Variants ...) [with _Result_type = void; _Visitor = std::__detail::__variant::_Variant_storage<false, CNoDestination, PubKeyDestination, PKHash, ScriptHash, WitnessV0ScriptHash, WitnessV0KeyHash, WitnessV1Taproot, WitnessUnknown>::_M_reset()::<lambda(auto:19&&)>&&; _Variants = {std::variant<CNoDestination, PubKeyDestination, PKHash, ScriptHash, WitnessV0ScriptHash, WitnessV0KeyHash, WitnessV1Taproot, WitnessUnknown>&}; long long unsigned int ...__indices = {7}]’ at /usr/lib/gcc/x86_64-w64-mingw32/12-posix/include/c++/variant:1035:40,
    inlined from ‘constexpr decltype(auto) std::__do_visit(_Visitor&&, _Variants&& ...) [with _Result_type = void; _Visitor = __detail::__variant::_Variant_storage<false, CNoDestination, PubKeyDestination, PKHash, ScriptHash, WitnessV0ScriptHash, WitnessV0KeyHash, WitnessV1Taproot, WitnessUnknown>::_M_reset()::<lambda(auto:19&&)>; _Variants = {variant<CNoDestination, PubKeyDestination, PKHash, ScriptHash, WitnessV0ScriptHash, WitnessV0KeyHash, WitnessV1Taproot, WitnessUnknown>&}]’ at /usr/lib/gcc/x86_64-w64-mingw32/12-posix/include/c++/variant:1790:5,
    inlined from ‘constexpr void std::__detail::__variant::_Variant_storage<false, _Types ...>::_M_reset() [with _Types = {CNoDestination, PubKeyDestination, PKHash, ScriptHash, WitnessV0ScriptHash, WitnessV0KeyHash, WitnessV1Taproot, WitnessUnknown}]’ at /usr/lib/gcc/x86_64-w64-mingw32/12-posix/include/c++/variant:470:23,
    inlined from ‘constexpr std::__detail::__variant::_Variant_storage<false, _Types ...>::~_Variant_storage() [with _Types = {CNoDestination, PubKeyDestination, PKHash, ScriptHash, WitnessV0ScriptHash, WitnessV0KeyHash, WitnessV1Taproot, WitnessUnknown}]’ at /usr/lib/gcc/x86_64-w64-mingw32/12-posix/include/c++/variant:480:17,
    inlined from ‘constexpr std::__detail::__variant::_Copy_ctor_base<false, CNoDestination, PubKeyDestination, PKHash, ScriptHash, WitnessV0ScriptHash, WitnessV0KeyHash, WitnessV1Taproot, WitnessUnknown>::~_Copy_ctor_base()’ at /usr/lib/gcc/x86_64-w64-mingw32/12-posix/include/c++/variant:554:12,
    inlined from ‘constexpr std::__detail::__variant::_Move_ctor_base<false, CNoDestination, PubKeyDestination, PKHash, ScriptHash, WitnessV0ScriptHash, WitnessV0KeyHash, WitnessV1Taproot, WitnessUnknown>::~_Move_ctor_base()’ at /usr/lib/gcc/x86_64-w64-mingw32/12-posix/include/c++/variant:591:12,
    inlined from ‘constexpr std::__detail::__variant::_Copy_assign_base<false, CNoDestination, PubKeyDestination, PKHash, ScriptHash, WitnessV0ScriptHash, WitnessV0KeyHash, WitnessV1Taproot, WitnessUnknown>::~_Copy_assign_base()’ at /usr/lib/gcc/x86_64-w64-mingw32/12-posix/include/c++/variant:629:12,
    inlined from ‘constexpr std::__detail::__variant::_Move_assign_base<false, CNoDestination, PubKeyDestination, PKHash, ScriptHash, WitnessV0ScriptHash, WitnessV0KeyHash, WitnessV1Taproot, WitnessUnknown>::~_Move_assign_base()’ at /usr/lib/gcc/x86_64-w64-mingw32/12-posix/include/c++/variant:681:12,
    inlined from ‘constexpr std::__detail::__variant::_Variant_base<CNoDestination, PubKeyDestination, PKHash, ScriptHash, WitnessV0ScriptHash, WitnessV0KeyHash, WitnessV1Taproot, WitnessUnknown>::~_Variant_base()’ at /usr/lib/gcc/x86_64-w64-mingw32/12-posix/include/c++/variant:735:12,
    inlined from ‘constexpr std::variant<_Types>::~variant() [with _Types = {CNoDestination, PubKeyDestination, PKHash, ScriptHash, WitnessV0ScriptHash, WitnessV0KeyHash, WitnessV1Taproot, WitnessUnknown}]’ at /usr/lib/gcc/x86_64-w64-mingw32/12-posix/include/c++/variant:1407:28,
    inlined from ‘std::vector<std::variant<CNoDestination, PubKeyDestination, PKHash, ScriptHash, WitnessV0ScriptHash, WitnessV0KeyHash, WitnessV1Taproot, WitnessUnknown> > GetAllDestinationsForKey(const CPubKey&)’ at outputtype.cpp:79:5:
/usr/lib/gcc/x86_64-w64-mingw32/12-posix/include/c++/bits/stl_vector.h:367:31: error: ‘*(std::_Vector_base<unsigned char, std::allocator<unsigned char> >*)((char*)&p2sh + offsetof(std::CTxDestination, std::variant<CNoDestination, PubKeyDestination, PKHash, ScriptHash, WitnessV0ScriptHash, WitnessV0KeyHash, WitnessV1Taproot, WitnessUnknown>::<unnamed>.std::__detail::__variant::_Variant_base<CNoDestination, PubKeyDestination, PKHash, ScriptHash, WitnessV0ScriptHash, WitnessV0KeyHash, WitnessV1Taproot, WitnessUnknown>::<unnamed>.std::__detail::__variant::_Move_assign_base<false, CNoDestination, PubKeyDestination, PKHash, ScriptHash, WitnessV0ScriptHash, WitnessV0KeyHash, WitnessV1Taproot, WitnessUnknown>::<unnamed>.std::__detail::__variant::_Copy_assign_base<false, CNoDestination, PubKeyDestination, PKHash, ScriptHash, WitnessV0ScriptHash, WitnessV0KeyHash, WitnessV1Taproot, WitnessUnknown>::<unnamed>.std::__detail::__variant::_Move_ctor_base<false, CNoDestination, PubKeyDestination, PKHash, ScriptHash, WitnessV0ScriptHash, WitnessV0KeyHash, WitnessV1Taproot, WitnessUnknown>::<unnamed>.std::__detail::__variant::_Copy_ctor_base<false, CNoDestination, PubKeyDestination, PKHash, ScriptHash, WitnessV0ScriptHash, WitnessV0KeyHash, WitnessV1Taproot, WitnessUnknown>::<unnamed>.std::__detail::__variant::_Variant_storage<false, CNoDestination, PubKeyDestination, PKHash, ScriptHash, WitnessV0ScriptHash, WitnessV0KeyHash, WitnessV1Taproot, WitnessUnknown>::_M_u) + 8).std::_Vector_base<unsigned char, std::allocator<unsigned char> >::_M_impl.std::_Vector_base<unsigned char, std::allocator<unsigned char> >::_Vector_impl::<anonymous>.std::_Vector_base<unsigned char, std::allocator<unsigned char> >::_Vector_impl_data::_M_end_of_storage’ may be used uninitialized [-Werror=maybe-uninitialized]
  367 |                       _M_impl._M_end_of_storage - _M_impl._M_start);
      |                       ~~~~~~~~^~~~~~~~~~~~~~~~~
outputtype.cpp: In function ‘std::vector<std::variant<CNoDestination, PubKeyDestination, PKHash, ScriptHash, WitnessV0ScriptHash, WitnessV0KeyHash, WitnessV1Taproot, WitnessUnknown> > GetAllDestinationsForKey(const CPubKey&)’:
outputtype.cpp:77:24: note: ‘p2sh’ declared here
   77 |         CTxDestination p2sh = ScriptHash(GetScriptForDestination(segwit));
      |                        ^~~~

[hebasto]

Closing.

CI still failing:

FWIW, those false positive warnings are fixed in GCC 13.

[laanwj]

Concept ACK on adding value initialization here, seems like a good precaution in any case.