https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105420
--- Comment #2 from Liam White <byteslice at airmail dot cc> --- Created attachment 52906 --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=52906&action=edit Preprocessed source The first attachment is automatically and manually reduced from the following source: ResultCode KThread::Initialize(KThreadFunction func, uintptr_t arg, VAddr user_stack_top, s32 prio, s32 virt_core, KProcess* owner, ThreadType type) { // Assert parameters are valid. ASSERT((type == ThreadType::Main) || (type == ThreadType::Dummy) || (Svc::HighestThreadPriority <= prio && prio <= Svc::LowestThreadPriority)); ASSERT((owner != nullptr) || (type != ThreadType::User)); ASSERT(0 <= virt_core && virt_core < static_cast<s32>(Common::BitSize<u64>())); // Convert the virtual core to a physical core. const s32 phys_core = Core::Hardware::VirtualToPhysicalCoreMap[virt_core]; ASSERT(0 <= phys_core && phys_core < static_cast<s32>(Core::Hardware::NUM_CPU_CORES)); // ... } And it produces this compiler error (compile this preprocessed source with -O2 -Werror=array-bounds -std=gnu++20): In static member function ‘static constexpr _Tp& std::__array_traits<_Tp, _Nm>::_S_ref(const _Tp (&)[_Nm], std::size_t) [with _Tp = int; long unsigned int _Nm = 64]’, inlined from ‘constexpr const std::array<_Tp, _Nm>::value_type& std::array<_Tp, _Nm>::operator[](size_type) const [with _Tp = int; long unsigned int _Nm = 64]’ at k_thread.cpp:59748:25, inlined from ‘ResultCode Kernel::KThread::Initialize(Kernel::KThreadFunction, uintptr_t, VAddr, s32, s32, Kernel::KProcess*, Kernel::ThreadType)’ at k_thread.cpp:102280:77: k_thread.cpp:59638:36: error: array subscript 64 is above array bounds of ‘std::__array_traits<int, 64>::_Type’ {aka ‘const int [64]’} [-Werror=array-bounds] 59638 | { return const_cast<_Tp&>(__t[__n]); } | ~~~^ k_thread.cpp: In member function ‘ResultCode Kernel::KThread::Initialize(Kernel::KThreadFunction, uintptr_t, VAddr, s32, s32, Kernel::KProcess*, Kernel::ThreadType)’: k_thread.cpp:77557:51: note: while referencing ‘Core::Hardware::VirtualToPhysicalCoreMap’ 77557 | constexpr std::array<s32, Common::BitSize<u64>()> VirtualToPhysicalCoreMap{ | ^~~~~~~~~~~~~~~~~~~~~~~~ cc1plus: some warnings being treated as errors I generally believe that this is a bug in the compiler as the array is similarly never accessed with the constant value 64.
