I have the same issue. But since Google is dropping support for use_custom_libcxx=false, I think it would be better to compile V8 with the custom std lib they supply because this issue will only get worse over time until we need a complex custom patch. We should create a dynamic library in our Android projects that links against v8_monolith.a and is also compiled with the same custom standard library, then this dynamic library is loaded by our code, which can just use whatever standard library we want to use as long as the interface doesn't require ABI compatibility, but at least this is in our control and easy to keep in mind.
The part I'm struggling with is configuring CMake in Android to build a dynamic library with the custom std lib from V8. Anyone has an idea? On Thursday, 18 September 2025 at 18:49:26 UTC+2 Mati Cohen wrote: > Hey guys, I am just facing the same issue, did you manage to get a > successful build? > > On Wednesday, September 3, 2025 at 8:45:43 AM UTC-4 [email protected] > wrote: > >> I am also struggling with the same issue. I believe the problem related >> to temporal_rs can be resolved with the following gn flags. >> enable_rust=false >> enable_rust_cxx=false >> v8_enable_temporal_support=false >> 2025년 7월 30일 수요일 오전 11시 53분 24초 UTC+9에 sw l님이 작성: >> >>> *"However, after successfully compiling, I encountered the following >>> undefined symbol issue when integrating it into the Android project."* >>> >>> [image: error.png] >>> 在2025年7月30日星期三 UTC+8 10:51:24<sw l> 写道： >>> >>>> *"Currently, I am still using the configuration use_custom_libcxx = >>>> false, and I applied the following patch to modify the code and make it >>>> compile successfully."* >>>> >>>> >>>> *builtins-typed-array.cc* >>>> diff --git a/src/builtins/builtins-typed-array.cc >>>> b/src/builtins/builtins-typed-array.cc >>>> index abc1234..def5678 100644 >>>> --- a/src/builtins/builtins-typed-array.cc >>>> +++ b/src/builtins/builtins-typed-array.cc >>>> @@ -506,10 +506,15 @@ simdutf::result ArrayBufferSetFromBase64( >>>> simdutf::last_chunk_handling_options last_chunk_handling, >>>> DirectHandle<JSTypedArray> typed_array, size_t& output_length) { >>>> output_length = array_length; >>>> - simdutf::result simd_result; >>>> + simdutf::result simd_result = {simdutf::error_code::SUCCESS, 0}; >>>> if (typed_array->buffer()->is_shared()) { >>>> - simd_result = simdutf::atomic_base64_to_binary_safe( >>>> - reinterpret_cast<const T>(input_vector), input_length, >>>> + // For shared buffers, we need to copy to a temporary buffer first >>>> + std::unique_ptr<char[]> temp_input = >>>> std::make_unique<char[]>(input_length); >>>> + std::memcpy(temp_input.get(), reinterpret_cast<const >>>> char*>(input_vector), >>>> + input_length); >>>> + >>>> + simd_result = simdutf::base64_to_binary_safe( >>>> + temp_input.get(), input_length, >>>> reinterpret_cast<char*>(typed_array->DataPtr()), output_length, >>>> alphabet, last_chunk_handling, /*decode_up_to_bad_char*/ true); >>>> } else { >>>> @@ -836,8 +841,13 @@ BUILTIN(Uint8ArrayPrototypeToBase64) { >>>> size_t simd_result_size; >>>> if (uint8array->buffer()->is_shared()) { >>>> - simd_result_size = simdutf::atomic_binary_to_base64( >>>> - std::bit_cast<const char*>(uint8array->DataPtr()), length, >>>> + // For shared buffers, we need to copy to a temporary buffer first >>>> + std::unique_ptr<char[]> temp_input = std::make_unique<char[]>(length); >>>> + std::memcpy(temp_input.get(), >>>> + std::bit_cast<const char*>(uint8array->DataPtr()), length); >>>> + >>>> + simd_result_size = simdutf::binary_to_base64( >>>> + temp_input.get(), length, >>>> reinterpret_cast<char*>(output->GetChars(no_gc)), alphabet); >>>> } else { >>>> simd_result_size = simdutf::binary_to_base64( >>>> >>>> >>>> simd.cc >>>> diff --git a/src/objects/simd.cc b/src/objects/simd.cc >>>> index ef2b8118eec..c595f955efe 100644 >>>> --- a/src/objects/simd.cc >>>> +++ b/src/objects/simd.cc >>>> @@ -484,11 +484,23 @@ void AtomicUint8ArrayToHexSlow(const char* bytes, >>>> size_t length, >>>> // https://cplusplus.github.io/LWG/issue3508 >>>> // we instead provide a mutable input, which is ok since we are only >>>> reading >>>> // from it. >>>> - char* mutable_bytes = const_cast<char*>(bytes); >>>> + // char* mutable_bytes = const_cast<char*>(bytes); >>>> for (size_t i = 0; i < length; i++) { >>>> - uint8_t byte = >>>> - >>>> std::atomic_ref<char>(mutable_bytes[i]).load(std::memory_order_relaxed); >>>> - PerformNibbleToHexAndWriteIntoStringOutPut(byte, index, >>>> string_output); >>>> + // uint8_t byte = >>>> + // >>>> std::atomic_ref<char>(mutable_bytes[i]).load(std::memory_order_relaxed); >>>> + // PerformNibbleToHexAndWriteIntoStringOutPut(byte, index, >>>> string_output); >>>> + >>>> + // Use compiler built-in atomic load for shared memory >>>> + char byte; >>>> + __atomic_load( >>>> + const_cast<char*>(bytes) + i, >>>> + &byte, >>>> + __ATOMIC_RELAXED >>>> + ); >>>> + PerformNibbleToHexAndWriteIntoStringOutPut( >>>> + static_cast<uint8_t>(byte), >>>> + index, string_output); >>>> + >>>> index += 2; >>>> } >>>> } >>>> @@ -1081,14 +1093,23 @@ bool ArrayBufferFromHex(const base::Vector<T>& >>>> input_vector, bool is_shared, >>>> size_t index = 0; >>>> std::optional<uint8_t> result = 0; >>>> - for (uint32_t i = 0; i < output_length * 2; i += 2) { >>>> + for (size_t i = 0; i < output_length * 2; i += 2) { >>>> result = HandleRemainingHexValues(input_vector, i); >>>> if (result.has_value()) { >>>> + uint8_t value = result.value(); >>>> if (is_shared) { >>>> - std::atomic_ref<uint8_t>(buffer[index++]) >>>> - .store(result.value(), std::memory_order_relaxed); >>>> + // std::atomic_ref<uint8_t>(buffer[index++]) >>>> + // .store(result.value(), std::memory_order_relaxed); >>>> + // Use compiler built-in atomic store for shared memory >>>> + __atomic_store( >>>> + buffer + index, >>>> + &value, >>>> + __ATOMIC_RELAXED >>>> + ); >>>> + index++; >>>> } else { >>>> - buffer[index++] = result.value(); >>>> + // buffer[index++] = result.value(); >>>> + buffer[index++] = value; >>>> } >>>> } else { >>>> return false; >>>> >>>> 在2025年7月29日星期二 UTC+8 20:13:45<[email protected]> 写道： >>>> >>>>> “Did you solve this issue? I’m currently facing the same problem and >>>>> at the time I didn’t have a good solution. I’m using a configuration >>>>> similar to yours and am encountering the exact same issue.” >>>>> 在2025年7月28日星期一 UTC+8 21:16:30<[email protected]> 写道： >>>>> >>>>>> *"When building the V8 static library for the Android platform >>>>>> (arm64-v8a), the following error occurred in simdutf."* >>>>>> >>>>>> root@ce59529b30aa:~/v8/v8# gn gen out/android.arm64.monolith --args=" >>>>>> >>>>>> > target_os = \"android\" >>>>>> >>>>>> > target_cpu = \"arm64\" >>>>>> >>>>>> > is_debug = false >>>>>> >>>>>> > optimize_for_size = true >>>>>> >>>>>> > v8_enable_31bit_smis_on_64bit_arch = true >>>>>> >>>>>> > symbol_level = 0 >>>>>> >>>>>> > v8_use_external_startup_data=false >>>>>> >>>>>> > >>>>>> >>>>>> > v8_monolithic = true >>>>>> >>>>>> > v8_static_library = true >>>>>> >>>>>> > is_component_build = false >>>>>> >>>>>> > >>>>>> >>>>>> > v8_enable_webassembly = false >>>>>> >>>>>> > v8_enable_i18n_support = false >>>>>> >>>>>> > #v8_enable_pointer_compression = true >>>>>> >>>>>> > >>>>>> >>>>>> > android_unstripped_runtime_outputs = false >>>>>> >>>>>> > dcheck_always_on = false >>>>>> >>>>>> > default_min_sdk_version = 21 >>>>>> >>>>>> > v8_android_log_stdout = true >>>>>> >>>>>> > >>>>>> >>>>>> > use_sysroot = false >>>>>> >>>>>> > use_custom_libcxx = false >>>>>> >>>>>> > use_glib = false >>>>>> >>>>>> > " >>>>>> >>>>>> Done. Made 1013 targets from 228 files in 454ms >>>>>> >>>>>> root@ce59529b30aa:~/v8/v8# autoninja -C out/android.arm64.monolith >>>>>> v8_monolith >>>>>> >>>>>> ninja: Entering directory `out/android.arm64.monolith' >>>>>> >>>>>> 1.06s load siso config >>>>>> >>>>>> [1227/3101] 25m00.40s F CXX >>>>>> obj/v8_base_without_compiler/builtins-typed-array.o >>>>>> >>>>>> *FAILED: 6a074098-7768-4ded-a7d8-da56e857aaa2 >>>>>> "./obj/v8_base_without_compiler/builtins-typed-array.o" CXX >>>>>> obj/v8_base_without_compiler/builtins-typed-array.o* >>>>>> >>>>>> err: exit=1 >>>>>> >>>>>> ../../third_party/llvm-build/Release+Asserts/bin/clang++ -MD -MF >>>>>> obj/v8_base_without_compiler/builtins-typed-array.o.d >>>>>> -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -D_FORTIFY_SOURCE=2 >>>>>> -D_GNU_SOURCE -D__ARM_NEON__=1 -DANDROID >>>>>> -D__ANDROID_UNAVAILABLE_SYMBOLS_ARE_WEAK__ -DHAVE_SYS_UIO_H >>>>>> -DANDROID_NDK_VERSION_ROLL=r28_1 >>>>>> -DCR_CLANG_REVISION=\"llvmorg-21-init-11777-gfd3fecfc-1\" >>>>>> -D_LIBCPP_HARDENING_MODE=_LIBCPP_HARDENING_MODE_NONE -DNDEBUG >>>>>> -DNVALGRIND >>>>>> -DDYNAMIC_ANNOTATIONS_ENABLED=0 -DV8_TYPED_ARRAY_MAX_SIZE_IN_HEAP=64 >>>>>> -DV8_TEMPORAL_SUPPORT -DV8_ATOMIC_OBJECT_FIELD_WRITES >>>>>> -DV8_ENABLE_LAZY_SOURCE_POSITIONS -DV8_WIN64_UNWINDING_INFO >>>>>> -DV8_ENABLE_REGEXP_INTERPRETER_THREADED_DISPATCH >>>>>> -DV8_SNAPSHOT_COMPRESSION >>>>>> -DV8_ENABLE_CONTROL_FLOW_INTEGRITY -DV8_ENABLE_FUZZTEST >>>>>> -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_USE_ZLIB -DV8_USE_LIBM_TRIG_FUNCTIONS >>>>>> -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_ENABLE_SANDBOX -DV8_DEPRECATION_WARNINGS >>>>>> -DV8_IMMINENT_DEPRECATION_WARNINGS -DV8_HAVE_TARGET_OS >>>>>> -DV8_TARGET_OS_ANDROID -DCPPGC_CAGED_HEAP -DCPPGC_YOUNG_GENERATION >>>>>> -DCPPGC_POINTER_COMPRESSION -DCPPGC_ENABLE_LARGER_CAGE >>>>>> -DCPPGC_SLIM_WRITE_BARRIER -DV8_TARGET_ARCH_ARM64 >>>>>> -DV8_ANDROID_LOG_STDOUT >>>>>> -DV8_RUNTIME_CALL_STATS -DABSL_ALLOCATOR_NOTHROW=1 >>>>>> -DTEMPORAL_CAPI_VERSION_0_0_9 -DHWY_BROKEN_TARGETS=HWY_ALL_SVE -I../.. >>>>>> -Igen -I../../include -Igen/include -I../../third_party/abseil-cpp >>>>>> -I../../third_party/fp16/src/include >>>>>> -I../../third_party/rust/chromium_crates_io/vendor/temporal_capi-v0_0_9/bindings/cpp >>>>>> >>>>>> -I../../third_party/dragonbox/src/include >>>>>> -I../../third_party/fast_float/src/include >>>>>> -I../../third_party/highway/src >>>>>> -I../../third_party/zlib -Wall -Wextra -Wimplicit-fallthrough >>>>>> -Wextra-semi >>>>>> -Wunreachable-code-aggressive -Wthread-safety -Wgnu >>>>>> -Wno-gnu-anonymous-struct -Wno-gnu-conditional-omitted-operand >>>>>> -Wno-gnu-include-next -Wno-gnu-label-as-value -Wno-gnu-redeclared-enum >>>>>> -Wno-gnu-statement-expression -Wno-gnu-zero-variadic-macro-arguments >>>>>> -Wno-zero-length-array -Wunguarded-availability >>>>>> -Wno-missing-field-initializers -Wno-unused-parameter -Wno-psabi >>>>>> -Wloop-analysis -Wno-unneeded-internal-declaration >>>>>> -Wno-cast-function-type >>>>>> -Wno-thread-safety-reference-return -Wno-nontrivial-memcall -Wshadow >>>>>> -Werror -fno-delete-null-pointer-checks -fno-strict-overflow -fno-ident >>>>>> -fno-strict-aliasing -fstack-protector -funwind-tables -fPIC >>>>>> -fcolor-diagnostics -fmerge-all-constants -fno-sized-deallocation >>>>>> -fcrash-diagnostics-dir=../../tools/clang/crashreports -mllvm >>>>>> -instcombine-lower-dbg-declare=0 -mllvm >>>>>> -split-threshold-for-reg-with-hint=0 -ffp-contract=off >>>>>> -ffunction-sections >>>>>> -fno-short-enums -mbranch-protection=standard >>>>>> --target=aarch64-linux-android21 -mno-outline >>>>>> -Wno-builtin-macro-redefined >>>>>> -D__DATE__= -D__TIME__= -D__TIMESTAMP__= -ffile-compilation-dir=. >>>>>> -no-canonical-prefixes -fno-omit-frame-pointer -g0 -Wheader-hygiene >>>>>> -Wstring-conversion -Wtautological-overlap-compare -Wunreachable-code >>>>>> -Wno-shadow -Wctad-maybe-unsupported -Xclang -add-plugin -Xclang >>>>>> blink-gc-plugin -Wno-invalid-offsetof -Wshorten-64-to-32 >>>>>> -Wmissing-field-initializers -O2 -fdata-sections -ffunction-sections >>>>>> -fno-unique-section-names -fno-math-errno -fvisibility=default >>>>>> -Wexit-time-destructors -Wno-invalid-offsetof -Wenum-compare-conditional >>>>>> -Wno-nullability-completeness -std=c++20 -Wno-trigraphs >>>>>> -gsimple-template-names -fno-exceptions -fno-rtti >>>>>> --sysroot=../../third_party/android_toolchain/ndk/toolchains/llvm/prebuilt/linux-x86_64/sysroot >>>>>> >>>>>> -c ../../src/builtins/builtins-typed-array.cc -o >>>>>> obj/v8_base_without_compiler/builtins-typed-array.o >>>>>> >>>>>> build step: cxx >>>>>> "./obj/v8_base_without_compiler/builtins-typed-array.o" >>>>>> >>>>>> siso_rule: clang/cxx >>>>>> >>>>>> stderr: >>>>>> >>>>>> *../../src/builtins/builtins-typed-array.cc:508:28: **error: **no >>>>>> member named 'atomic_base64_to_binary_safe' in namespace 'simdutf'; did >>>>>> you >>>>>> mean 'base64_to_binary_safe'?* >>>>>> >>>>>> 508 | simd_result = simdutf::atomic_base64_to_binary_safe( >>>>>> >>>>>> | * ^~~~~~~~~~~~~~~~~~~~~~~~~~~~* >>>>>> >>>>>> | base64_to_binary_safe >>>>>> >>>>>> *../../third_party/simdutf/simdutf.h:4369:1: **note: >>>>>> *'base64_to_binary_safe' >>>>>> declared here >>>>>> >>>>>> 4369 | base64_to_binary_safe(const char *input, size_t length, char >>>>>> *output, >>>>>> >>>>>> | *^* >>>>>> >>>>>> *../../src/builtins/builtins-typed-array.cc:829:35: **error: **no >>>>>> member named 'atomic_binary_to_base64' in namespace 'simdutf'; did you >>>>>> mean >>>>>> 'binary_to_base64'?* >>>>>> >>>>>> 829 | simd_result_size = simdutf::atomic_binary_to_base64( >>>>>> >>>>>> | * ^~~~~~~~~~~~~~~~~~~~~~~* >>>>>> >>>>>> | binary_to_base64 >>>>>> >>>>>> *../../third_party/simdutf/simdutf.h:4110:8: **note: *'binary_to_base64' >>>>>> declared here >>>>>> >>>>>> 4110 | size_t binary_to_base64(const char *input, size_t length, >>>>>> char *output, >>>>>> >>>>>> | * ^* >>>>>> >>>>>> *../../src/builtins/builtins-typed-array.cc:509:9: **error: **cannot >>>>>> initialize a parameter of type 'const char *' with an rvalue of type >>>>>> 'const >>>>>> char16_t *'* >>>>>> >>>>>> 509 | reinterpret_cast<const T>(input_vector), input_length, >>>>>> >>>>>> | * ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~* >>>>>> >>>>>> *../../src/builtins/builtins-typed-array.cc:687:21: **note: *in >>>>>> instantiation of function template specialization >>>>>> 'v8::internal::(anonymous >>>>>> namespace)::ArrayBufferSetFromBase64<const char16_t *>' requested here >>>>>> >>>>>> 687 | simd_result = ArrayBufferSetFromBase64( >>>>>> >>>>>> | * ^* >>>>>> >>>>>> *../../third_party/simdutf/simdutf.h:4369:35: **note: *passing >>>>>> argument to parameter 'input' here >>>>>> >>>>>> 4369 | base64_to_binary_safe(const char *input, size_t length, char >>>>>> *output, >>>>>> >>>>>> | * ^* >>>>>> >>>>>> 3 errors generated. >>>>>> >>>>>> >>>>>> build failed >>>>>> >>>>>> local:1228 remote:0 cache:0 fallback:0 retry:0 skip:478 >>>>>> >>>>>> fs: ops: 105378(err:21627) / r:13726(err:0) 1.09GiB / w:124(err:0) >>>>>> 113.85MiB >>>>>> >>>>>> resource/capa used(err) wait-avg | s m | serv-avg | s m | >>>>>> >>>>>> localexec/8 1135(1) 5m01.65s |▂▂▂▂▃█▄| 10.36s | ▃▃█▅▂ | >>>>>> >>>>>> pool=link/1 16(0) 13.35s |▆ ▇█▃ | 6.21s | ▃█▃ | >>>>>> >>>>>> >>>>>> *25m00.93s* Build Failure: 1228 done 1 failed 1873 remaining - 0.82/s >>>>>> >>>>>> 1 steps failed: exit=1 >>>>>> >>>>>> *see ./out/android.arm64.monolith/siso_output for full command line >>>>>> and output* >>>>>> >>>>>> * or ./out/android.arm64.monolith/siso.INFO* >>>>>> >>>>>> *use ./out/android.arm64.monolith/siso_failed_commands.sh to re-run >>>>>> failed commands* >>>>>> >>>>>> >>>>>> *------------------------------------------------------------------------------* >>>>>> >>>>>> *"If I remove the use_custom_libcxx, use_sysroot, and use_glib >>>>>> configurations, it can successfully compile libv8_monolith.a. However, >>>>>> when >>>>>> I integrate it into my Android project and use NDK version >>>>>> 28.1.13356709, >>>>>> it encounters unresolved symbol errors."* >>>>>> >>>>>> >>>>>> [image: error.png] >>>>>> >>>>>> *"I'm very confused right now and can't find any useful resources to >>>>>> help me solve the problem. Please tell me how to compile a static >>>>>> library >>>>>> that can be used on Android. The V8 tag I'm currently using is >>>>>> 13.9.210."* >>>>>> >>>>>> >>>>>> >>>>>> -- -- v8-users mailing list [email protected] http://groups.google.com/group/v8-users --- You received this message because you are subscribed to the Google Groups "v8-users" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion visit https://groups.google.com/d/msgid/v8-users/d4319cd7-eb4c-4888-a99f-1c686ab2b1ebn%40googlegroups.com.
