Hi Juan, Unfortunately we don't support configurations other than the bundled clang and libc++. Are you trying to use the system clang with the bundled libc++? A version mismatch there is likely to cause issues.
- Leszek On Mon, Aug 25, 2025 at 4:51 PM Juan dos Santos <[email protected]> wrote: > Hi everyone again! > > I found some problem with "use_custom_libcxx=false" this is the problem > with v8gen.py . > > v8gen.py makes the configuration with "use_custom_libcxx=false" so, with > this, the problem found is "std::bit_cast" not found. > I know I need the las clang with c++20, this is my version "clang version > 18.1.3 (1ubuntu1) Target: x86_64-pc-linux-gnu" > I think I have the right libc with this clang version (or I don't ?? ) > > My disto is Ubuntu 24.04 (docker image: > mcr.microsoft.com/vscode/devcontainers/cpp:1-ubuntu24.04) > > Then, I tried to complie with g++ but other errors appears (g++-14 > gcc-14): > > is_component_build = false > is_debug = false > target_cpu = "x64" > v8_enable_sandbox = true > v8_enable_backtrace = true > v8_enable_disassembler = true > v8_enable_object_print = true > v8_enable_verify_heap = true > dcheck_always_on = false > v8_monolithic = true > v8_use_external_startup_data = false > is_clang=false > use_sysroot=false > > Errors: > > In file included from > ../../third_party/libc++/src/include/__exception/exception_ptr.h:17, > from ../../third_party/libc++/src/include/exception:84, > from > ../../third_party/libc++abi/src/src/cxa_vector.cpp:16: > ../../third_party/libc++/src/include/__type_traits/decay.h:22:32: error: > expected type-specifier before ‘__decay’ > 22 | using type _LIBCPP_NODEBUG = __decay(_Tp); > | ^~~~~~~ > In file included from > ../../third_party/libc++/src/include/__exception/exception_ptr.h:18: > ../../third_party/libc++/src/include/__type_traits/is_pointer.h:22:62: > error: there are no arguments to ‘__is_pointer’ that depend on a template > parameter, so a declaration of ‘__is_pointer’ must be available > [-fpermissive] > 22 | struct _LIBCPP_NO_SPECIALIZATIONS is_pointer : > _BoolConstant<__is_pointer(_Tp)> {}; > | > ^~~~~~~~~~~~ > ../../third_party/libc++/src/include/__type_traits/is_pointer.h:22:62: > note: (if you use ‘-fpermissive’, G++ will accept your code, but allowing > the use of an undeclared name is deprecated) > ../../third_party/libc++/src/include/__type_traits/is_pointer.h:22:79: > error: template argument 1 is invalid > 22 | struct _LIBCPP_NO_SPECIALIZATIONS is_pointer : > _BoolConstant<__is_pointer(_Tp)> {}; > > ... > ....(more errors) > > > So, v8_monolith.a was not created, and I didn't find any way to do it. > > Please help > Juan dos Santos > > > El lunes, 25 de agosto de 2025 a las 8:03:43 UTC-3, Juan dos Santos > escribió: > >> Hi everyone >> >> When I run: >> >> tools/dev/gm.py x64.release >> >> Everything works fine but no libv8_monolith.a is created. >> So, I changed gm.py and add "v8_monolithic = true >> v8_use_external_startup_data = false" and run again. >> >> RELEASE_ARGS_TEMPLATE = f"""\ >> is_component_build = false >> is_debug = false >> %s{BUILD_DISTRIBUTION_LINE} >> v8_enable_backtrace = true >> v8_enable_disassembler = true >> v8_enable_object_print = true >> v8_enable_verify_heap = true >> dcheck_always_on = false >> v8_monolithic = true >> v8_use_external_startup_data = false >> """ >> >> and then run: >> >> autoninja -C out/x64.release >> >> finally I have libv8_monolith.a >> >> BUT.... >> >> if I run this command to make the configuration: >> >> tools/dev/v8gen.py x64.release.sample >> >> and then: >> >> autoninja -C out.gn/x64.release.sample/ v8_monolith >> >> the result is this error (basically std::bit_cast not found): >> >> offline mode >> ninja: Entering directory `out.gn/x64.release.sample/' >> 2.01s load siso config >> [1621/3672] 2m10.11s F CXX obj/torque_base/utils.o >> FAILED: 8b1561ec-f17b-4ae5-b401-647b0752f4f7 "./obj/torque_base/utils.o" >> CXX obj/torque_base/utils.o >> err: exit=1 >> ../../third_party/llvm-build/Release+Asserts/bin/clang++ -MMD -MF >> obj/torque_base/utils.o.d -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS >> -D_FORTIFY_SOURCE=2 -D_FILE_OFFSET_BITS=64 -D_LARGEFILE_SOURCE >> -D_LARGEFILE64_SOURCE -D_GNU_SOURCE >> -DCR_CLANG_REVISION=\"llvmorg-21-init-16348-gbd809ffb-17\" >> -D_LIBCPP_HARDENING_MODE=_LIBCPP_HARDENING_MODE_NONE >> -D_GLIBCXX_ASSERTIONS=1 -DCR_SYSROOT_KEY=20250129T203412Z-1 -DUSE_UDEV >> -DUSE_AURA=1 -DUSE_GLIB=1 -DUSE_OZONE=1 -DNDEBUG -DNVALGRIND >> -DDYNAMIC_ANNOTATIONS_ENABLED=0 -DV8_TYPED_ARRAY_MAX_SIZE_IN_HEAP=64 >> -DENABLE_GDB_JIT_INTERFACE -DV8_INTL_SUPPORT -DV8_TEMPORAL_SUPPORT >> -DV8_ATOMIC_OBJECT_FIELD_WRITES -DV8_ENABLE_LAZY_SOURCE_POSITIONS >> -DV8_WIN64_UNWINDING_INFO -DV8_ENABLE_REGEXP_INTERPRETER_THREADED_DISPATCH >> -DV8_ENABLE_FUZZTEST -DV8_SHORT_BUILTIN_CALLS -DV8_EXTERNAL_CODE_SPACE >> -DV8_ENABLE_SPARKPLUG -DV8_ENABLE_MAGLEV -DV8_ENABLE_TURBOFAN >> -DV8_ENABLE_WEBASSEMBLY -DV8_ENABLE_CONTINUATION_PRESERVED_EMBEDDER_DATA >> -DV8_ALLOCATION_FOLDING -DV8_ALLOCATION_SITE_TRACKING >> -DV8_ADVANCED_BIGINT_ALGORITHMS -DV8_STATIC_ROOTS -DV8_USE_ZLIB >> -DV8_USE_LIBM_TRIG_FUNCTIONS -DV8_ENABLE_WASM_SIMD256_REVEC >> -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_USE_DEFAULT_HASHER_SECRET=true >> -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_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../../include -Igen/include -I../../third_party/abseil-cpp -Wall -Wextra >> -Wimplicit-fallthrough -Wextra-semi -Wunreachable-code-aggressive -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 -Wthread-safety -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-math-errno -fno-strict-aliasing -fstack-protector -funwind-tables >> -fPIC -pthread -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 >> -Wa,--crel,--allow-experimental-crel --target=x86_64-unknown-linux-gnu >> -msse3 -Wno-builtin-macro-redefined -D__DATE__= -D__TIME__= >> -D__TIMESTAMP__= -ffile-compilation-dir=. -no-canonical-prefixes -Xclang >> -fmodule-file-home-is-cwd -fno-omit-frame-pointer -g0 -Wheader-hygiene >> -Wstring-conversion -Wtautological-overlap-compare -Wunreachable-code >> -Wctad-maybe-unsupported -Xclang -add-plugin -Xclang blink-gc-plugin >> -Wno-invalid-offsetof -Wshorten-64-to-32 -Wmissing-field-initializers >> -Wunnecessary-virtual-specifier -O3 -fdata-sections -ffunction-sections >> -fno-unique-section-names -fvisibility=default -Wexit-time-destructors >> -Wno-invalid-offsetof -Wenum-compare-conditional >> -Wno-nullability-completeness -std=c++20 -Wno-trigraphs >> -gsimple-template-names >> --sysroot=../../build/linux/debian_bullseye_amd64-sysroot -fexceptions >> -frtti -c ../../src/torque/utils.cc -o obj/torque_base/utils.o >> build step: cxx "./obj/torque_base/utils.o" >> siso_rule: clang/cxx >> stderr: >> In file included from ../../src/torque/utils.cc:15: >> In file included from ../../src/torque/ast.h:17: >> In file included from ../../src/numbers/integer-literal.h:10: >> In file included from ../../src/common/globals.h:22: >> ../../src/base/numbers/double.h:18:10: error: no template named >> 'bit_cast' in namespace 'std'; did you mean simply 'bit_cast'? >> 18 | return std::bit_cast<uint64_t>(d); >> | ^~~~~~~~~~~~~ >> | bit_cast >> ../../src/base/macros.h:137:16: note: 'bit_cast' declared here >> 137 | V8_INLINE Dest bit_cast(Source const& source) { >> | ^ >> In file included from ../../src/torque/utils.cc:15: >> In file included from ../../src/torque/ast.h:17: >> In file included from ../../src/numbers/integer-literal.h:10: >> In file included from ../../src/common/globals.h:22: >> ../../src/base/numbers/double.h:18:10: error: no template named >> 'bit_cast' in namespace 'std'; did you mean simply 'bit_cast'? >> 18 | return std::bit_cast<uint64_t>(d); >> | ^~~~~~~~~~~~~ >> | bit_cast >> ../../src/base/macros.h:137:16: note: 'bit_cast' declared here >> 137 | V8_INLINE Dest bit_cast(Source const& source) { >> | ^ >> In file included from ../../src/torque/utils.cc:15: >> In file included from ../../src/torque/ast.h:17: >> In file included from ../../src/numbers/integer-literal.h:10: >> In file included from ../../src/common/globals.h:22: >> ../../src/base/numbers/double.h:17:27: error: constexpr function never >> produces a constant expression [-Winvalid-constexpr] >> 17 | inline constexpr uint64_t double_to_uint64(double d) { >> | ^~~~~~~~~~~~~~~~ >> ../../src/base/numbers/double.h:18:10: note: non-constexpr function >> 'bit_cast<unsigned long, double>' cannot be used in a constant expression >> 18 | return std::bit_cast<uint64_t>(d); >> | ^ >> ../../src/base/macros.h:137:16: note: declared here >> 137 | V8_INLINE Dest bit_cast(Source const& source) { >> | ^ >> In file included from ../../src/torque/utils.cc:15: >> In file included from ../../src/torque/ast.h:17: >> In file included from ../../src/numbers/integer-literal.h:10: >> In file included from ../../src/common/globals.h:22: >> ../../src/base/numbers/double.h:21:10: error: no template named >> 'bit_cast' in namespace 'std'; did you mean simply 'bit_cast'? >> 21 | return std::bit_cast<double>(d64); >> | ^~~~~~~~~~~~~ >> | bit_cast >> ../../src/base/macros.h:137:16: note: 'bit_cast' declared here >> 137 | V8_INLINE Dest bit_cast(Source const& source) { >> | ^ >> In file included from ../../src/torque/utils.cc:15: >> In file included from ../../src/torque/ast.h:17: >> In file included from ../../src/numbers/integer-literal.h:10: >> In file included from ../../src/common/globals.h:22: >> ../../src/base/numbers/double.h:21:10: error: no template named >> 'bit_cast' in namespace 'std'; did you mean simply 'bit_cast'? >> 21 | return std::bit_cast<double>(d64); >> | ^~~~~~~~~~~~~ >> | bit_cast >> ../../src/base/macros.h:137:16: note: 'bit_cast' declared here >> 137 | V8_INLINE Dest bit_cast(Source const& source) { >> | ^ >> In file included from ../../src/torque/utils.cc:15: >> In file included from ../../src/torque/ast.h:17: >> In file included from ../../src/numbers/integer-literal.h:10: >> In file included from ../../src/common/globals.h:22: >> ../../src/base/numbers/double.h:20:25: error: constexpr function never >> produces a constant expression [-Winvalid-constexpr] >> 20 | inline constexpr double uint64_to_double(uint64_t d64) { >> | ^~~~~~~~~~~~~~~~ >> ../../src/base/numbers/double.h:21:10: note: non-constexpr function >> 'bit_cast<double, unsigned long>' cannot be used in a constant expression >> 21 | return std::bit_cast<double>(d64); >> | ^ >> ../../src/base/macros.h:137:16: note: declared here >> 137 | V8_INLINE Dest bit_cast(Source const& source) { >> | ^ >> 6 errors generated. >> >> build failed >> local:1622 remote:0 cache:0 cache-write:0(err:0) fallback:0 retry:0 >> skip:228 >> fs: ops: 79691(err:9091) / r:6974(err:0) 458.69MiB / w:1134(err:0) >> 124.94MiB >> resource/capa used(err) wait-avg | s m | serv-avg | s m | >> localexec/8 468(1) 1m04.64s |▂ ▂▂▆█ | 2.09s | ▂▂█ ▂ | >> >> 2m10.34s Build Failure: 1622 done 1 failed 2050 remaining - 12.44/s >> 1 steps failed: exit=1 >> see ./out.gn/x64.release.sample/siso_output for full command line and >> output >> or ./out.gn/x64.release.sample/siso.INFO >> >> use ./out.gn/x64.release.sample/siso_failed_commands.sh to re-run failed >> commands >> >> >> -- > -- > v8-dev mailing list > [email protected] > http://groups.google.com/group/v8-dev > --- > You received this message because you are subscribed to the Google Groups > "v8-dev" 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-dev/460f6235-4181-410c-a3e6-e783d32906ben%40googlegroups.com > <https://groups.google.com/d/msgid/v8-dev/460f6235-4181-410c-a3e6-e783d32906ben%40googlegroups.com?utm_medium=email&utm_source=footer> > . > -- -- v8-dev mailing list [email protected] http://groups.google.com/group/v8-dev --- You 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