Musl x64 V8: static assertion failed

[bblanchon]

The build is failing since chromium/7019 (was okay in chromium/7009).
https://github.com/bblanchon/pdfium-binaries/actions/runs/13362632237/job/37315040982

x86_64-linux-musl-g++ -MMD -MF obj/v8/torque_generated_definitions/factory.o.d -DUSE_UDEV -DUSE_AURA=1 -DUSE_GLIB=1 -DUSE_OZONE=1 -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -D_FORTIFY_SOURCE=2 -D_FILE_OFFSET_BITS=64 -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_LIBCPP_HARDENING_MODE=_LIBCPP_HARDENING_MODE_NONE -D_GLIBCXX_ASSERTIONS=1 -DCR_SYSROOT_KEY=20250129T203412Z-1 -DNDEBUG -DNVALGRIND -DDYNAMIC_ANNOTATIONS_ENABLED=0 -DV8_TYPED_ARRAY_MAX_SIZE_IN_HEAP=64 -DV8_TLS_USED_IN_LIBRARY -DENABLE_GDB_JIT_INTERFACE -DV8_ATOMIC_OBJECT_FIELD_WRITES -DV8_ENABLE_LAZY_SOURCE_POSITIONS -DV8_WIN64_UNWINDING_INFO -DV8_ENABLE_REGEXP_INTERPRETER_THREADED_DISPATCH -DV8_SHORT_BUILTIN_CALLS -DV8_EXTERNAL_CODE_SPACE -DV8_ENABLE_SPARKPLUG -DV8_ENABLE_MAGLEV -DV8_ENABLE_TURBOFAN -DV8_ENABLE_CONTINUATION_PRESERVED_EMBEDDER_DATA -DV8_ALLOCATION_FOLDING -DV8_ALLOCATION_SITE_TRACKING -DV8_ADVANCED_BIGINT_ALGORITHMS -DV8_USE_ZLIB -DV8_ENABLE_MAGLEV_GRAPH_PRINTER -DV8_ENABLE_BUILTIN_JUMP_TABLE_SWITCH -DV8_ENABLE_EXTENSIBLE_RO_SNAPSHOT -DV8_ENABLE_BLACK_ALLOCATED_PAGES -DV8_ENABLE_LEAPTIERING -DV8_WASM_RANDOM_FUZZERS -DV8_ARRAY_BUFFER_INTERNAL_FIELD_COUNT=0 -DV8_ARRAY_BUFFER_VIEW_INTERNAL_FIELD_COUNT=0 -DV8_PROMISE_INTERNAL_FIELD_COUNT=0 -DV8_COMPRESS_POINTERS -DV8_COMPRESS_POINTERS_IN_SHARED_CAGE -DV8_31BIT_SMIS_ON_64BIT_ARCH -DV8_DEPRECATION_WARNINGS -DV8_HAVE_TARGET_OS -DV8_TARGET_OS_LINUX -DCPPGC_CAGED_HEAP -DCPPGC_YOUNG_GENERATION -DCPPGC_POINTER_COMPRESSION -DCPPGC_ENABLE_LARGER_CAGE -DCPPGC_SLIM_WRITE_BARRIER -DV8_TARGET_ARCH_X64 -DV8_RUNTIME_CALL_STATS -DABSL_ALLOCATOR_NOTHROW=1 -I.. -Igen -I../v8 -I../v8/include -Igen/v8 -I../third_party/abseil-cpp -Igen/v8/include -I../third_party/fp16/src/include -Wall -Wno-unused-local-typedefs -Wno-maybe-uninitialized -Wno-deprecated-declarations -Wno-comments -Wno-packed-not-aligned -Wno-missing-field-initializers -Wno-unused-parameter -Wno-psabi -fno-strict-overflow -fno-ident -fno-strict-aliasing -funwind-tables -fPIC -pipe -pthread -m64 -msse3 -Wno-builtin-macro-redefined -D__DATE__= -D__TIME__= -D__TIMESTAMP__= -fno-omit-frame-pointer -g0 -fvisibility=hidden -Wno-invalid-offsetof -Wno-strict-overflow -Wno-return-type -Wno-int-in-bool-context -Wno-deprecated -Wno-stringop-overflow -Wno-stringop-overread -Wno-restrict -Wno-array-bounds -Wno-nonnull -Wno-dangling-pointer -O3 -fdata-sections -ffunction-sections -fno-math-errno -Wno-narrowing -Wno-class-memaccess -Wno-invalid-offsetof -std=gnu++2a -fno-exceptions -fno-rtti --sysroot=../build/linux/debian_bullseye_amd64-sysroot -fvisibility-inlines-hidden  -c gen/v8/torque-generated/factory.cc -o obj/v8/torque_generated_definitions/factory.o
In file included from ../v8/src/objects/string-inl.h:28,
                 from ../v8/src/objects/script-inl.h:13,
                 from ../v8/src/objects/shared-function-info-inl.h:24,
                 from ../v8/src/objects/js-function-inl.h:24,
                 from ../v8/src/objects/map-inl.h:17,
                 from ../v8/src/objects/name-inl.h:11,
                 from ../v8/src/objects/lookup-cache-inl.h:10,
                 from ../v8/src/objects/descriptor-array-inl.h:16,
                 from ../v8/src/objects/field-index-inl.h:9,
                 from ../v8/src/objects/js-objects-inl.h:17,
                 from ../v8/src/objects/js-proxy-inl.h:9,
                 from ../v8/src/objects/objects-inl.h:35,
                 from ../v8/src/heap/paged-spaces-inl.h:13,
                 from ../v8/src/heap/new-spaces-inl.h:12,
                 from ../v8/src/heap/heap-inl.h:28,
                 from ../v8/src/heap/main-allocator-inl.h:9,
                 from ../v8/src/heap/local-heap-inl.h:15,
                 from ../v8/src/heap/factory-base-inl.h:9,
                 from gen/v8/torque-generated/factory.cc:2:
../v8/src/strings/string-hasher-inl.h: In function ‘v8::internal::detail::IndexParseResult v8::internal::detail::TryParseArrayIndex(const uchar*, uint32_t, uint32_t&, v8::internal::detail::ArrayIndexT&)’:
../v8/src/strings/string-hasher-inl.h:160:33: error: static assertion failed
  160 |     static_assert(sizeof(index) == sizeof(uint32_t));
      |                   ~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~
../v8/src/strings/string-hasher-inl.h:176:50: error: static assertion failed
  176 |         static_assert(String::kMaxArrayIndexSize ==
      |                       ~~~~~~~~~~~~~~~~~~~~~~~~~~~^~
  177 |                       String::kMaxIntegerIndexSize);
      |                       ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
At global scope:
cc1plus: note: unrecognized command-line option ‘-Wno-dangling-pointer’ may have been intended to silence earlier diagnostics

These static asserts were added in commit 63cb5b3519339bb90a50f5d2150c527d1a6ab96f of v8:
https://chromium-review.googlesource.com/c/v8/v8/+/6253748

The commit message says:

Fix build with older gcc and clang compilers

static_assert may fail even on 64-bit platforms
which might be related to this bug (Change in 9.1):
https://cplusplus.github.io/CWG/issues/2518.html

Running x86_64-linux-musl-gcc --version shows

x86_64-linux-musl-gcc (GCC) 11.2.1 20211120