CXX-Modules: import std does still not work on Linux with clang++

/root/cmake/cmake-4.0.4-linux-x86_64/share/cmake-4.0/Modules/CMakeDetermineCompilerId.cmake(357):  if(xCXX STREQUAL xCXX AND EXISTS /root/cmake/cmake-4.0.4-linux-x86_64/share/cmake-4.0/Modules/CXX-DetectStdlib.h AND ( xClang STREQUAL xClang AND xGNU STREQUAL xGNU ) OR ( xClang STREQUAL xGNU ) )
/root/cmake/cmake-4.0.4-linux-x86_64/share/cmake-4.0/Modules/CMakeDetermineCompilerId.cmake(363):  execute_process(COMMAND /root/llvm/bin/clang++  -U_FORTIFY_SOURCE;-D_FORTIFY_SOURCE=3;-fstack-protector-strong;-fcf-protection=full;-fstack-clash-protection;-Wall;-Wextra;-Wpedantic;-Wconversion;-Wsign-conversion;-Wcast-qual;-Wformat=2;-Wno-undef;-Werror=float-equal;-Wshadow;-Wcast-align;-Wunused;-Wnull-dereference;-Wdouble-promotion;-Wimplicit-fallthrough;-Wextra-semi;-Woverloaded-virtual;-Wnon-virtual-dtor;-Wold-style-cast -E -x c++-header /root/cmake/cmake-4.0.4-linux-x86_64/share/cmake-4.0/Modules/CXX-DetectStdlib.h -o - OUTPUT_VARIABLE _lang_stdlib_out ERROR_VARIABLE _lang_stdlib_err RESULT_VARIABLE _lang_stdlib_res ERROR_STRIP_TRAILING_WHITESPACE )
/root/cmake/cmake-4.0.4-linux-x86_64/share/cmake-4.0/Modules/CMakeDetermineCompilerId.cmake(375):  if(_lang_stdlib_res EQUAL 0 )
/root/cmake/cmake-4.0.4-linux-x86_64/share/cmake-4.0/Modules/CMakeDetermineCompilerId.cmake(376):  string(REGEX REPLACE .*CMAKE-STDLIB-DETECT: (.+)
.* \1 CMAKE_CXX_STANDARD_LIBRARY # 1 "/root/cmake/cmake-4.0.4-linux-x86_64/share/cmake-4.0/Modules/CXX-DetectStdlib.h"
# 1 "<built-in>" 1
# 1 "<built-in>" 3
# 480 "<built-in>" 3
# 1 "<command line>" 1
# 1 "<built-in>" 2
# 1 "/root/cmake/cmake-4.0.4-linux-x86_64/share/cmake-4.0/Modules/CXX-DetectStdlib.h" 2
# 1 "/usr/lib/gcc/x86_64-linux-gnu/14/../../../../include/c++/14/version" 1 3
# 34 "/usr/lib/gcc/x86_64-linux-gnu/14/../../../../include/c++/14/version" 3


# 1 "/usr/lib/gcc/x86_64-linux-gnu/14/../../../../include/c++/14/bits/version.h" 1 3
# 48 "/usr/lib/gcc/x86_64-linux-gnu/14/../../../../include/c++/14/bits/version.h" 3

# 1 "/usr/lib/gcc/x86_64-linux-gnu/14/../../../../include/x86_64-linux-gnu/c++/14/bits/c++config.h" 1 3
# 34 "/usr/lib/gcc/x86_64-linux-gnu/14/../../../../include/x86_64-linux-gnu/c++/14/bits/c++config.h" 3
# 308 "/usr/lib/gcc/x86_64-linux-gnu/14/../../../../include/x86_64-linux-gnu/c++/14/bits/c++config.h" 3
namespace std
{
  typedef long unsigned int size_t;
  typedef long int ptrdiff_t;


  typedef decltype(nullptr) nullptr_t;


#pragma GCC visibility push(default)


  extern "C++" __attribute__ ((__noreturn__, __always_inline__))
  inline void __terminate() noexcept
  {
    void terminate() noexcept __attribute__ ((__noreturn__,__cold__));
    terminate();
  }
#pragma GCC visibility pop
}
# 341 "/usr/lib/gcc/x86_64-linux-gnu/14/../../../../include/x86_64-linux-gnu/c++/14/bits/c++config.h" 3
namespace std
{
  inline namespace __cxx11 __attribute__((__abi_tag__ ("cxx11"))) { }
}
namespace __gnu_cxx
{
  inline namespace __cxx11 __attribute__((__abi_tag__ ("cxx11"))) { }
}
# 534 "/usr/lib/gcc/x86_64-linux-gnu/14/../../../../include/x86_64-linux-gnu/c++/14/bits/c++config.h" 3
namespace std
{
#pragma GCC visibility push(default)




  __attribute__((__always_inline__))
  constexpr inline bool
  __is_constant_evaluated() noexcept
  {





    return __builtin_is_constant_evaluated();



  }
#pragma GCC visibility pop
}
# 573 "/usr/lib/gcc/x86_64-linux-gnu/14/../../../../include/x86_64-linux-gnu/c++/14/bits/c++config.h" 3
namespace std
{
#pragma GCC visibility push(default)

  extern "C++" __attribute__ ((__noreturn__))
  void
  __glibcxx_assert_fail
    (const char* __file, int __line, const char* __function,
     const char* __condition)
  noexcept;
#pragma GCC visibility pop
}
# 601 "/usr/lib/gcc/x86_64-linux-gnu/14/../../../../include/x86_64-linux-gnu/c++/14/bits/c++config.h" 3
namespace std
{
  __attribute__((__always_inline__,__visibility__("default")))
  inline void
  __glibcxx_assert_fail()
  { }
}
# 680 "/usr/lib/gcc/x86_64-linux-gnu/14/../../../../include/x86_64-linux-gnu/c++/14/bits/c++config.h" 3
# 1 "/usr/lib/gcc/x86_64-linux-gnu/14/../../../../include/x86_64-linux-gnu/c++/14/bits/os_defines.h" 1 3
# 39 "/usr/lib/gcc/x86_64-linux-gnu/14/../../../../include/x86_64-linux-gnu/c++/14/bits/os_defines.h" 3
# 1 "/usr/include/features.h" 1 3 4
# 394 "/usr/include/features.h" 3 4
# 1 "/usr/include/features-time64.h" 1 3 4
# 20 "/usr/include/features-time64.h" 3 4
# 1 "/usr/include/x86_64-linux-gnu/bits/wordsize.h" 1 3 4
# 21 "/usr/include/features-time64.h" 2 3 4
# 1 "/usr/include/x86_64-linux-gnu/bits/timesize.h" 1 3 4
# 19 "/usr/include/x86_64-linux-gnu/bits/timesize.h" 3 4
# 1 "/usr/include/x86_64-linux-gnu/bits/wordsize.h" 1 3 4
# 20 "/usr/include/x86_64-linux-gnu/bits/timesize.h" 2 3 4
# 22 "/usr/include/features-time64.h" 2 3 4
# 395 "/usr/include/features.h" 2 3 4
# 480 "/usr/include/features.h" 3 4
# 1 "/usr/include/stdc-predef.h" 1 3 4
# 481 "/usr/include/features.h" 2 3 4
# 502 "/usr/include/features.h" 3 4
# 1 "/usr/include/x86_64-linux-gnu/sys/cdefs.h" 1 3 4
# 576 "/usr/include/x86_64-linux-gnu/sys/cdefs.h" 3 4
# 1 "/usr/include/x86_64-linux-gnu/bits/wordsize.h" 1 3 4
# 577 "/usr/include/x86_64-linux-gnu/sys/cdefs.h" 2 3 4
# 1 "/usr/include/x86_64-linux-gnu/bits/long-double.h" 1 3 4
# 578 "/usr/include/x86_64-linux-gnu/sys/cdefs.h" 2 3 4
# 503 "/usr/include/features.h" 2 3 4
# 526 "/usr/include/features.h" 3 4
# 1 "/usr/include/x86_64-linux-gnu/gnu/stubs.h" 1 3 4
# 10 "/usr/include/x86_64-linux-gnu/gnu/stubs.h" 3 4
# 1 "/usr/include/x86_64-linux-gnu/gnu/stubs-64.h" 1 3 4
# 11 "/usr/include/x86_64-linux-gnu/gnu/stubs.h" 2 3 4
# 527 "/usr/include/features.h" 2 3 4
# 40 "/usr/lib/gcc/x86_64-linux-gnu/14/../../../../include/x86_64-linux-gnu/c++/14/bits/os_defines.h" 2 3
# 681 "/usr/lib/gcc/x86_64-linux-gnu/14/../../../../include/x86_64-linux-gnu/c++/14/bits/c++config.h" 2 3


# 1 "/usr/lib/gcc/x86_64-linux-gnu/14/../../../../include/x86_64-linux-gnu/c++/14/bits/cpu_defines.h" 1 3
# 684 "/usr/lib/gcc/x86_64-linux-gnu/14/../../../../include/x86_64-linux-gnu/c++/14/bits/c++config.h" 2 3
# 887 "/usr/lib/gcc/x86_64-linux-gnu/14/../../../../include/x86_64-linux-gnu/c++/14/bits/c++config.h" 3
# 1 "/usr/lib/gcc/x86_64-linux-gnu/14/../../../../include/c++/14/pstl/pstl_config.h" 1 3
# 888 "/usr/lib/gcc/x86_64-linux-gnu/14/../../../../include/x86_64-linux-gnu/c++/14/bits/c++config.h" 2 3
# 50 "/usr/lib/gcc/x86_64-linux-gnu/14/../../../../include/c++/14/bits/version.h" 2 3
# 37 "/usr/lib/gcc/x86_64-linux-gnu/14/../../../../include/c++/14/version" 2 3
# 2 "/root/cmake/cmake-4.0.4-linux-x86_64/share/cmake-4.0/Modules/CXX-DetectStdlib.h" 2




CMAKE-STDLIB-DETECT: libstdc++
 )
/root/cmake/cmake-4.0.4-linux-x86_64/share/cmake-4.0/Modules/CMakeDetermineCompilerId.cmake(381):  if(CMAKE_CXX_COMPILER_ID )
/root/cmake/cmake-4.0.4-linux-x86_64/share/cmake-4.0/Modules/CMakeDetermineCompilerId.cmake(382):  if(CMAKE_CXX_COMPILER_VERSION )
/root/cmake/cmake-4.0.4-linux-x86_64/share/cmake-4.0/Modules/CMakeDetermineCompilerId.cmake(383):  set(_version  20.1.6 )
/root/cmake/cmake-4.0.4-linux-x86_64/share/cmake-4.0/Modules/CMakeDetermineCompilerId.cmake(387):  if(CMAKE_CXX_COMPILER_ARCHITECTURE_ID AND xClang STREQUAL xIAR )
/root/cmake/cmake-4.0.4-linux-x86_64/share/cmake-4.0/Modules/CMakeDetermineCompilerId.cmake(389):  else()
/root/cmake/cmake-4.0.4-linux-x86_64/share/cmake-4.0/Modules/CMakeDetermineCompilerId.cmake(390):  set(_archid  )
/root/cmake/cmake-4.0.4-linux-x86_64/share/cmake-4.0/Modules/CMakeDetermineCompilerId.cmake(392):  if(CMAKE_CXX_HOST_COMPILER_ID )
/root/cmake/cmake-4.0.4-linux-x86_64/share/cmake-4.0/Modules/CMakeDetermineCompilerId.cmake(397):  else()
/root/cmake/cmake-4.0.4-linux-x86_64/share/cmake-4.0/Modules/CMakeDetermineCompilerId.cmake(398):  set(_hostcc  )
/root/cmake/cmake-4.0.4-linux-x86_64/share/cmake-4.0/Modules/CMakeDetermineCompilerId.cmake(400):  message(STATUS The CXX compiler identification is  Clang 20.1.6 )
-- The CXX compiler identification is Clang 20.1.6
/root/cmake/cmake-4.0.4-linux-x86_64/share/cmake-4.0/Modules/CMakeDetermineCompilerId.cmake(402):  unset(_hostcc )
/root/cmake/cmake-4.0.4-linux-x86_64/share/cmake-4.0/Modules/CMakeDetermineCompilerId.cmake(403):  unset(_archid )
/root/cmake/cmake-4.0.4-linux-x86_64/share/cmake-4.0/Modules/CMakeDetermineCompilerId.cmake(404):  unset(_version )
/root/cmake/cmake-4.0.4-linux-x86_64/share/cmake-4.0/Modules/CMakeDetermineCompilerId.cmake(405):  unset(_variant )
/root/cmake/cmake-4.0.4-linux-x86_64/share/cmake-4.0/Modules/CMakeDetermineCompilerId.cmake(410):  if(lang STREQUAL Fortran AND CMAKE_CXX_COMPILER_ID STREQUAL XL )
/root/cmake/cmake-4.0.4-linux-x86_64/share/cmake-4.0/Modules/CMakeDetermineCompilerId.cmake(414):  set(CMAKE_CXX_COMPILER_ID Clang PARENT_SCOPE )
/root/cmake/cmake-4.0.4-linux-x86_64/share/cmake-4.0/Modules/CMakeDetermineCompilerId.cmake(415):  set(CMAKE_CXX_PLATFORM_ID Linux PARENT_SCOPE )
/root/cmake/cmake-4.0.4-linux-x86_64/share/cmake-4.0/Modules/CMakeDetermineCompilerId.cmake(416):  set(CMAKE_CXX_COMPILER_ARCHITECTURE_ID  PARENT_SCOPE )
/root/cmake/cmake-4.0.4-linux-x86_64/share/cmake-4.0/Modules/CMakeDetermineCompilerId.cmake(417):  set(MSVC_CXX_ARCHITECTURE_ID  PARENT_SCOPE )
/root/cmake/cmake-4.0.4-linux-x86_64/share/cmake-4.0/Modules/CMakeDetermineCompilerId.cmake(419):  set(CMAKE_CXX_XCODE_ARCHS  PARENT_SCOPE )
/root/cmake/cmake-4.0.4-linux-x86_64/share/cmake-4.0/Modules/CMakeDetermineCompilerId.cmake(420):  set(CMAKE_CXX_CL_SHOWINCLUDES_PREFIX  PARENT_SCOPE )
/root/cmake/cmake-4.0.4-linux-x86_64/share/cmake-4.0/Modules/CMakeDetermineCompilerId.cmake(421):  set(CMAKE_CXX_COMPILER_FRONTEND_VARIANT GNU PARENT_SCOPE )
/root/cmake/cmake-4.0.4-linux-x86_64/share/cmake-4.0/Modules/CMakeDetermineCompilerId.cmake(422):  set(CMAKE_CXX_COMPILER_VERSION 20.1.6 PARENT_SCOPE )
/root/cmake/cmake-4.0.4-linux-x86_64/share/cmake-4.0/Modules/CMakeDetermineCompilerId.cmake(423):  set(CMAKE_CXX_COMPILER_VERSION_INTERNAL  PARENT_SCOPE )
/root/cmake/cmake-4.0.4-linux-x86_64/share/cmake-4.0/Modules/CMakeDetermineCompilerId.cmake(424):  set(CMAKE_CXX_COMPILER_WRAPPER  PARENT_SCOPE )
/root/cmake/cmake-4.0.4-linux-x86_64/share/cmake-4.0/Modules/CMakeDetermineCompilerId.cmake(425):  set(CMAKE_CXX_SIMULATE_ID  PARENT_SCOPE )
/root/cmake/cmake-4.0.4-linux-x86_64/share/cmake-4.0/Modules/CMakeDetermineCompilerId.cmake(426):  set(CMAKE_CXX_SIMULATE_VERSION  PARENT_SCOPE )
/root/cmake/cmake-4.0.4-linux-x86_64/share/cmake-4.0/Modules/CMakeDetermineCompilerId.cmake(427):  set(CMAKE_CXX_HOST_COMPILER_ID  PARENT_SCOPE )
/root/cmake/cmake-4.0.4-linux-x86_64/share/cmake-4.0/Modules/CMakeDetermineCompilerId.cmake(428):  set(CMAKE_CXX_HOST_COMPILER_VERSION  PARENT_SCOPE )
/root/cmake/cmake-4.0.4-linux-x86_64/share/cmake-4.0/Modules/CMakeDetermineCompilerId.cmake(429):  set(CMAKE_CXX_STANDARD_COMPUTED_DEFAULT 17 PARENT_SCOPE )
/root/cmake/cmake-4.0.4-linux-x86_64/share/cmake-4.0/Modules/CMakeDetermineCompilerId.cmake(430):  set(CMAKE_CXX_EXTENSIONS_COMPUTED_DEFAULT ON PARENT_SCOPE )
/root/cmake/cmake-4.0.4-linux-x86_64/share/cmake-4.0/Modules/CMakeDetermineCompilerId.cmake(431):  set(CMAKE_CXX_COMPILER_PRODUCED_OUTPUT  PARENT_SCOPE )
/root/cmake/cmake-4.0.4-linux-x86_64/share/cmake-4.0/Modules/CMakeDetermineCompilerId.cmake(432):  set(CMAKE_CXX_COMPILER_PRODUCED_FILES a.out PARENT_SCOPE )
/root/cmake/cmake-4.0.4-linux-x86_64/share/cmake-4.0/Modules/CMakeDetermineCompilerId.cmake(433):  set(CMAKE_CXX_COMPILER_CLANG_RESOURCE_DIR /root/llvm/lib/clang/20 PARENT_SCOPE )
/root/cmake/cmake-4.0.4-linux-x86_64/share/cmake-4.0/Modules/CMakeDetermineCompilerId.cmake(434):  set(CMAKE_CXX_STANDARD_LIBRARY libstdc++ PARENT_SCOPE )
/root/cmake/cmake-4.0.4-linux-x86_64/share/cmake-4.0/Modules/CMakeDetermineCompilerId.cmake(435):  set(CMAKE_CXX_COMPILER_APPLE_SYSROOT  PARENT_SCOPE )
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Check for working CXX compiler: /root/llvm/bin/clang++ - skipped
/root/cmake/cmake-4.0.4-linux-x86_64/share/cmake-4.0/Modules/CMakeDetermineCompilerSupport.cmake(5):  function(cmake_determine_compiler_support lang )
/root/cmake/cmake-4.0.4-linux-x86_64/share/cmake-4.0/Modules/CMakeDetermineCompilerSupport.cmake(7):  if(xCXX STREQUAL xC AND COMMAND cmake_record_c_compile_features )
/root/cmake/cmake-4.0.4-linux-x86_64/share/cmake-4.0/Modules/CMakeDetermineCompilerSupport.cmake(57):  elseif(xCXX STREQUAL xCXX AND COMMAND cmake_record_cxx_compile_features )
/root/cmake/cmake-4.0.4-linux-x86_64/share/cmake-4.0/Modules/CMakeDetermineCompilerSupport.cmake(58):  message(CHECK_START Detecting CXX compile features )
-- Detecting CXX compile features
/root/cmake/cmake-4.0.4-linux-x86_64/share/cmake-4.0/Modules/CMakeDetermineCompilerSupport.cmake(60):  set(CMAKE_CXX98_COMPILE_FEATURES )
/root/cmake/cmake-4.0.4-linux-x86_64/share/cmake-4.0/Modules/CMakeDetermineCompilerSupport.cmake(61):  set(CMAKE_CXX11_COMPILE_FEATURES )
/root/cmake/cmake-4.0.4-linux-x86_64/share/cmake-4.0/Modules/CMakeDetermineCompilerSupport.cmake(62):  set(CMAKE_CXX14_COMPILE_FEATURES )
/root/cmake/cmake-4.0.4-linux-x86_64/share/cmake-4.0/Modules/CMakeDetermineCompilerSupport.cmake(63):  set(CMAKE_CXX17_COMPILE_FEATURES )
/root/cmake/cmake-4.0.4-linux-x86_64/share/cmake-4.0/Modules/CMakeDetermineCompilerSupport.cmake(64):  set(CMAKE_CXX20_COMPILE_FEATURES )
/root/cmake/cmake-4.0.4-linux-x86_64/share/cmake-4.0/Modules/CMakeDetermineCompilerSupport.cmake(65):  set(CMAKE_CXX23_COMPILE_FEATURES )
/root/cmake/cmake-4.0.4-linux-x86_64/share/cmake-4.0/Modules/CMakeDetermineCompilerSupport.cmake(66):  set(CMAKE_CXX26_COMPILE_FEATURES )
/root/cmake/cmake-4.0.4-linux-x86_64/share/cmake-4.0/Modules/CMakeDetermineCompilerSupport.cmake(68):  include(/root/cmake/cmake-4.0.4-linux-x86_64/share/cmake-4.0/Modules/Internal/FeatureTesting.cmake )
/root/cmake/cmake-4.0.4-linux-x86_64/share/cmake-4.0/Modules/CMakeDetermineCompilerSupport.cmake(70):  cmake_record_cxx_compile_features()
/root/cmake/cmake-4.0.4-linux-x86_64/share/cmake-4.0/Modules/CMakeDetermineCompilerSupport.cmake(72):  if(NOT _result EQUAL 0 )
/root/cmake/cmake-4.0.4-linux-x86_64/share/cmake-4.0/Modules/CMakeDetermineCompilerSupport.cmake(77):  if(CMAKE_CXX23_COMPILE_FEATURES AND CMAKE_CXX26_COMPILE_FEATURES )
/root/cmake/cmake-4.0.4-linux-x86_64/share/cmake-4.0/Modules/CMakeDetermineCompilerSupport.cmake(78):  list(REMOVE_ITEM CMAKE_CXX26_COMPILE_FEATURES cxx_std_23 )
/root/cmake/cmake-4.0.4-linux-x86_64/share/cmake-4.0/Modules/CMakeDetermineCompilerSupport.cmake(80):  if(CMAKE_CXX20_COMPILE_FEATURES AND CMAKE_CXX23_COMPILE_FEATURES )
/root/cmake/cmake-4.0.4-linux-x86_64/share/cmake-4.0/Modules/CMakeDetermineCompilerSupport.cmake(81):  list(REMOVE_ITEM CMAKE_CXX23_COMPILE_FEATURES cxx_std_20 )
/root/cmake/cmake-4.0.4-linux-x86_64/share/cmake-4.0/Modules/CMakeDetermineCompilerSupport.cmake(83):  if(CMAKE_CXX17_COMPILE_FEATURES AND CMAKE_CXX20_COMPILE_FEATURES )
/root/cmake/cmake-4.0.4-linux-x86_64/share/cmake-4.0/Modules/CMakeDetermineCompilerSupport.cmake(84):  list(REMOVE_ITEM CMAKE_CXX20_COMPILE_FEATURES cxx_std_17 )
/root/cmake/cmake-4.0.4-linux-x86_64/share/cmake-4.0/Modules/CMakeDetermineCompilerSupport.cmake(86):  if(CMAKE_CXX14_COMPILE_FEATURES AND CMAKE_CXX17_COMPILE_FEATURES )
/root/cmake/cmake-4.0.4-linux-x86_64/share/cmake-4.0/Modules/CMakeDetermineCompilerSupport.cmake(87):  list(REMOVE_ITEM CMAKE_CXX17_COMPILE_FEATURES cxx_std_14;cxx_aggregate_default_initializers;cxx_attribute_deprecated;cxx_binary_literals;cxx_contextual_conversions;cxx_decltype_auto;cxx_digit_separators;cxx_generic_lambdas;cxx_lambda_init_captures;cxx_relaxed_constexpr;cxx_return_type_deduction;cxx_variable_templates )
/root/cmake/cmake-4.0.4-linux-x86_64/share/cmake-4.0/Modules/CMakeDetermineCompilerSupport.cmake(89):  if(CMAKE_CXX11_COMPILE_FEATURES AND CMAKE_CXX14_COMPILE_FEATURES )
/root/cmake/cmake-4.0.4-linux-x86_64/share/cmake-4.0/Modules/CMakeDetermineCompilerSupport.cmake(90):  list(REMOVE_ITEM CMAKE_CXX14_COMPILE_FEATURES cxx_std_11;cxx_alias_templates;cxx_alignas;cxx_alignof;cxx_attributes;cxx_auto_type;cxx_constexpr;cxx_decltype;cxx_decltype_incomplete_return_types;cxx_default_function_template_args;cxx_defaulted_functions;cxx_defaulted_move_initializers;cxx_delegating_constructors;cxx_deleted_functions;cxx_enum_forward_declarations;cxx_explicit_conversions;cxx_extended_friend_declarations;cxx_extern_templates;cxx_final;cxx_func_identifier;cxx_generalized_initializers;cxx_inheriting_constructors;cxx_inline_namespaces;cxx_lambdas;cxx_local_type_template_args;cxx_long_long_type;cxx_noexcept;cxx_nonstatic_member_init;cxx_nullptr;cxx_override;cxx_range_for;cxx_raw_string_literals;cxx_reference_qualified_functions;cxx_right_angle_brackets;cxx_rvalue_references;cxx_sizeof_member;cxx_static_assert;cxx_strong_enums;cxx_thread_local;cxx_trailing_return_types;cxx_unicode_literals;cxx_uniform_initialization;cxx_unrestricted_unions;cxx_user_literals;cxx_variadic_macros;cxx_variadic_templates )
/root/cmake/cmake-4.0.4-linux-x86_64/share/cmake-4.0/Modules/CMakeDetermineCompilerSupport.cmake(92):  if(CMAKE_CXX98_COMPILE_FEATURES AND CMAKE_CXX11_COMPILE_FEATURES )
/root/cmake/cmake-4.0.4-linux-x86_64/share/cmake-4.0/Modules/CMakeDetermineCompilerSupport.cmake(93):  list(REMOVE_ITEM CMAKE_CXX11_COMPILE_FEATURES cxx_std_98;cxx_template_template_parameters )
/root/cmake/cmake-4.0.4-linux-x86_64/share/cmake-4.0/Modules/CMakeDetermineCompilerSupport.cmake(96):  if(NOT CMAKE_CXX_COMPILE_FEATURES )
/root/cmake/cmake-4.0.4-linux-x86_64/share/cmake-4.0/Modules/CMakeDetermineCompilerSupport.cmake(97):  set(CMAKE_CXX_COMPILE_FEATURES cxx_std_98;cxx_template_template_parameters cxx_std_11;cxx_alias_templates;cxx_alignas;cxx_alignof;cxx_attributes;cxx_auto_type;cxx_constexpr;cxx_decltype;cxx_decltype_incomplete_return_types;cxx_default_function_template_args;cxx_defaulted_functions;cxx_defaulted_move_initializers;cxx_delegating_constructors;cxx_deleted_functions;cxx_enum_forward_declarations;cxx_explicit_conversions;cxx_extended_friend_declarations;cxx_extern_templates;cxx_final;cxx_func_identifier;cxx_generalized_initializers;cxx_inheriting_constructors;cxx_inline_namespaces;cxx_lambdas;cxx_local_type_template_args;cxx_long_long_type;cxx_noexcept;cxx_nonstatic_member_init;cxx_nullptr;cxx_override;cxx_range_for;cxx_raw_string_literals;cxx_reference_qualified_functions;cxx_right_angle_brackets;cxx_rvalue_references;cxx_sizeof_member;cxx_static_assert;cxx_strong_enums;cxx_thread_local;cxx_trailing_return_types;cxx_unicode_literals;cxx_uniform_initialization;cxx_unrestricted_unions;cxx_user_literals;cxx_variadic_macros;cxx_variadic_templates cxx_std_14;cxx_aggregate_default_initializers;cxx_attribute_deprecated;cxx_binary_literals;cxx_contextual_conversions;cxx_decltype_auto;cxx_digit_separators;cxx_generic_lambdas;cxx_lambda_init_captures;cxx_relaxed_constexpr;cxx_return_type_deduction;cxx_variable_templates cxx_std_17 cxx_std_20 cxx_std_23 cxx_std_26 )
/root/cmake/cmake-4.0.4-linux-x86_64/share/cmake-4.0/Modules/CMakeDetermineCompilerSupport.cmake(109):  set(CMAKE_CXX_IMPORT_STD  )
/root/cmake/cmake-4.0.4-linux-x86_64/share/cmake-4.0/Modules/CMakeDetermineCompilerSupport.cmake(110):  foreach(_cmake_import_std_version IN ITEMS 23 26 )
/root/cmake/cmake-4.0.4-linux-x86_64/share/cmake-4.0/Modules/CMakeDetermineCompilerSupport.cmake(111):  if(CMAKE_CXX23_COMPILE_FEATURES )
/root/cmake/cmake-4.0.4-linux-x86_64/share/cmake-4.0/Modules/CMakeDetermineCompilerSupport.cmake(112):  set(_cmake_cxx_import_std  )
/root/cmake/cmake-4.0.4-linux-x86_64/share/cmake-4.0/Modules/CMakeDetermineCompilerSupport.cmake(113):  cmake_create_cxx_import_std(23 _cmake_cxx_import_std )
/root/cmake/cmake-4.0.4-linux-x86_64/share/cmake-4.0/Modules/Compiler/Clang-CXX-CXXImportStd.cmake(1):  function(_cmake_cxx_import_std std variable )
CMake Warning (dev) at /root/cmake/cmake-4.0.4-linux-x86_64/share/cmake-4.0/Modules/Compiler/CMakeCommonCompilerMacros.cmake:248 (cmake_language):
  CMake's support for `import std;` in C++23 and newer is experimental.  It
  is meant only for experimentation and feedback to CMake developers.
Call Stack (most recent call first):
  /root/cmake/cmake-4.0.4-linux-x86_64/share/cmake-4.0/Modules/CMakeDetermineCompilerSupport.cmake:113 (cmake_create_cxx_import_std)
  /root/cmake/cmake-4.0.4-linux-x86_64/share/cmake-4.0/Modules/CMakeTestCXXCompiler.cmake:83 (CMAKE_DETERMINE_COMPILER_SUPPORT)
  CMakeLists.txt:5 (project)
This warning is for project developers.  Use -Wno-dev to suppress it.

/root/cmake/cmake-4.0.4-linux-x86_64/share/cmake-4.0/Modules/Compiler/Clang-CXX-CXXImportStd.cmake(2):  if(CMAKE_CXX_STANDARD_LIBRARY STREQUAL libc++ )
/root/cmake/cmake-4.0.4-linux-x86_64/share/cmake-4.0/Modules/Compiler/Clang-CXX-CXXImportStd.cmake(4):  elseif(CMAKE_CXX_STANDARD_LIBRARY STREQUAL libstdc++ )
/root/cmake/cmake-4.0.4-linux-x86_64/share/cmake-4.0/Modules/Compiler/Clang-CXX-CXXImportStd.cmake(5):  set(_clang_modules_json_impl libstdc++ )
/root/cmake/cmake-4.0.4-linux-x86_64/share/cmake-4.0/Modules/Compiler/Clang-CXX-CXXImportStd.cmake(13):  execute_process(COMMAND /root/llvm/bin/clang++  -print-file-name=libstdc++.modules.json OUTPUT_VARIABLE _clang_libcxx_modules_json_file ERROR_VARIABLE _clang_libcxx_modules_json_file_err RESULT_VARIABLE _clang_libcxx_modules_json_file_res OUTPUT_STRIP_TRAILING_WHITESPACE ERROR_STRIP_TRAILING_WHITESPACE )
/root/cmake/cmake-4.0.4-linux-x86_64/share/cmake-4.0/Modules/Compiler/Clang-CXX-CXXImportStd.cmake(23):  if(_clang_libcxx_modules_json_file_res )
/root/cmake/cmake-4.0.4-linux-x86_64/share/cmake-4.0/Modules/Compiler/Clang-CXX-CXXImportStd.cmake(31):  if(NOT EXISTS libstdc++.modules.json )
/root/cmake/cmake-4.0.4-linux-x86_64/share/cmake-4.0/Modules/Compiler/Clang-CXX-CXXImportStd.cmake(32):  set(target_definition set(CMAKE_CXX23_COMPILER_IMPORT_STD_NOT_FOUND_MESSAGE "`libstdc++.modules.json` resource does not exist")
 PARENT_SCOPE )
/root/cmake/cmake-4.0.4-linux-x86_64/share/cmake-4.0/Modules/Compiler/Clang-CXX-CXXImportStd.cmake(35):  return()
/root/cmake/cmake-4.0.4-linux-x86_64/share/cmake-4.0/Modules/CMakeDetermineCompilerSupport.cmake(114):  if(_cmake_cxx_import_std )
/root/cmake/cmake-4.0.4-linux-x86_64/share/cmake-4.0/Modules/CMakeDetermineCompilerSupport.cmake(115):  string(APPEND CMAKE_CXX_IMPORT_STD ### Imported target for C++23 standard library
 )
/root/cmake/cmake-4.0.4-linux-x86_64/share/cmake-4.0/Modules/CMakeDetermineCompilerSupport.cmake(116):  string(APPEND CMAKE_CXX_IMPORT_STD if (NOT TARGET "__CMAKE::CXX23")
set(CMAKE_CXX23_COMPILER_IMPORT_STD_NOT_FOUND_MESSAGE "`libstdc++.modules.json` resource does not exist")
endif ()
if (TARGET "__CMAKE::CXX23")
  list(APPEND CMAKE_CXX_COMPILER_IMPORT_STD "23")
endif ()


 )
/root/cmake/cmake-4.0.4-linux-x86_64/share/cmake-4.0/Modules/CMakeDetermineCompilerSupport.cmake(111):  if(CMAKE_CXX26_COMPILE_FEATURES )
/root/cmake/cmake-4.0.4-linux-x86_64/share/cmake-4.0/Modules/CMakeDetermineCompilerSupport.cmake(112):  set(_cmake_cxx_import_std  )
/root/cmake/cmake-4.0.4-linux-x86_64/share/cmake-4.0/Modules/CMakeDetermineCompilerSupport.cmake(113):  cmake_create_cxx_import_std(26 _cmake_cxx_import_std )
/root/cmake/cmake-4.0.4-linux-x86_64/share/cmake-4.0/Modules/Compiler/Clang-CXX-CXXImportStd.cmake(1):  function(_cmake_cxx_import_std std variable )
/root/cmake/cmake-4.0.4-linux-x86_64/share/cmake-4.0/Modules/Compiler/Clang-CXX-CXXImportStd.cmake(2):  if(CMAKE_CXX_STANDARD_LIBRARY STREQUAL libc++ )
/root/cmake/cmake-4.0.4-linux-x86_64/share/cmake-4.0/Modules/Compiler/Clang-CXX-CXXImportStd.cmake(4):  elseif(CMAKE_CXX_STANDARD_LIBRARY STREQUAL libstdc++ )
/root/cmake/cmake-4.0.4-linux-x86_64/share/cmake-4.0/Modules/Compiler/Clang-CXX-CXXImportStd.cmake(5):  set(_clang_modules_json_impl libstdc++ )
/root/cmake/cmake-4.0.4-linux-x86_64/share/cmake-4.0/Modules/Compiler/Clang-CXX-CXXImportStd.cmake(13):  execute_process(COMMAND /root/llvm/bin/clang++  -print-file-name=libstdc++.modules.json OUTPUT_VARIABLE _clang_libcxx_modules_json_file ERROR_VARIABLE _clang_libcxx_modules_json_file_err RESULT_VARIABLE _clang_libcxx_modules_json_file_res OUTPUT_STRIP_TRAILING_WHITESPACE ERROR_STRIP_TRAILING_WHITESPACE )
/root/cmake/cmake-4.0.4-linux-x86_64/share/cmake-4.0/Modules/Compiler/Clang-CXX-CXXImportStd.cmake(23):  if(_clang_libcxx_modules_json_file_res )
/root/cmake/cmake-4.0.4-linux-x86_64/share/cmake-4.0/Modules/Compiler/Clang-CXX-CXXImportStd.cmake(31):  if(NOT EXISTS libstdc++.modules.json )
/root/cmake/cmake-4.0.4-linux-x86_64/share/cmake-4.0/Modules/Compiler/Clang-CXX-CXXImportStd.cmake(32):  set(target_definition set(CMAKE_CXX26_COMPILER_IMPORT_STD_NOT_FOUND_MESSAGE "`libstdc++.modules.json` resource does not exist")
 PARENT_SCOPE )
/root/cmake/cmake-4.0.4-linux-x86_64/share/cmake-4.0/Modules/Compiler/Clang-CXX-CXXImportStd.cmake(35):  return()
/root/cmake/cmake-4.0.4-linux-x86_64/share/cmake-4.0/Modules/CMakeDetermineCompilerSupport.cmake(114):  if(_cmake_cxx_import_std )
/root/cmake/cmake-4.0.4-linux-x86_64/share/cmake-4.0/Modules/CMakeDetermineCompilerSupport.cmake(115):  string(APPEND CMAKE_CXX_IMPORT_STD ### Imported target for C++26 standard library
 )
/root/cmake/cmake-4.0.4-linux-x86_64/share/cmake-4.0/Modules/CMakeDetermineCompilerSupport.cmake(116):  string(APPEND CMAKE_CXX_IMPORT_STD if (NOT TARGET "__CMAKE::CXX26")
set(CMAKE_CXX26_COMPILER_IMPORT_STD_NOT_FOUND_MESSAGE "`libstdc++.modules.json` resource does not exist")
endif ()
if (TARGET "__CMAKE::CXX26")
  list(APPEND CMAKE_CXX_COMPILER_IMPORT_STD "26")
endif ()


 )
/root/cmake/cmake-4.0.4-linux-x86_64/share/cmake-4.0/Modules/CMakeDetermineCompilerSupport.cmake(121):  set(CMAKE_CXX_COMPILE_FEATURES cxx_std_98;cxx_template_template_parameters;cxx_std_11;cxx_alias_templates;cxx_alignas;cxx_alignof;cxx_attributes;cxx_auto_type;cxx_constexpr;cxx_decltype;cxx_decltype_incomplete_return_types;cxx_default_function_template_args;cxx_defaulted_functions;cxx_defaulted_move_initializers;cxx_delegating_constructors;cxx_deleted_functions;cxx_enum_forward_declarations;cxx_explicit_conversions;cxx_extended_friend_declarations;cxx_extern_templates;cxx_final;cxx_func_identifier;cxx_generalized_initializers;cxx_inheriting_constructors;cxx_inline_namespaces;cxx_lambdas;cxx_local_type_template_args;cxx_long_long_type;cxx_noexcept;cxx_nonstatic_member_init;cxx_nullptr;cxx_override;cxx_range_for;cxx_raw_string_literals;cxx_reference_qualified_functions;cxx_right_angle_brackets;cxx_rvalue_references;cxx_sizeof_member;cxx_static_assert;cxx_strong_enums;cxx_thread_local;cxx_trailing_return_types;cxx_unicode_literals;cxx_uniform_initialization;cxx_unrestricted_unions;cxx_user_literals;cxx_variadic_macros;cxx_variadic_templates;cxx_std_14;cxx_aggregate_default_initializers;cxx_attribute_deprecated;cxx_binary_literals;cxx_contextual_conversions;cxx_decltype_auto;cxx_digit_separators;cxx_generic_lambdas;cxx_lambda_init_captures;cxx_relaxed_constexpr;cxx_return_type_deduction;cxx_variable_templates;cxx_std_17;cxx_std_20;cxx_std_23;cxx_std_26 PARENT_SCOPE )
/root/cmake/cmake-4.0.4-linux-x86_64/share/cmake-4.0/Modules/CMakeDetermineCompilerSupport.cmake(122):  set(CMAKE_CXX98_COMPILE_FEATURES cxx_std_98;cxx_template_template_parameters PARENT_SCOPE )
/root/cmake/cmake-4.0.4-linux-x86_64/share/cmake-4.0/Modules/CMakeDetermineCompilerSupport.cmake(123):  set(CMAKE_CXX11_COMPILE_FEATURES cxx_std_11;cxx_alias_templates;cxx_alignas;cxx_alignof;cxx_attributes;cxx_auto_type;cxx_constexpr;cxx_decltype;cxx_decltype_incomplete_return_types;cxx_default_function_template_args;cxx_defaulted_functions;cxx_defaulted_move_initializers;cxx_delegating_constructors;cxx_deleted_functions;cxx_enum_forward_declarations;cxx_explicit_conversions;cxx_extended_friend_declarations;cxx_extern_templates;cxx_final;cxx_func_identifier;cxx_generalized_initializers;cxx_inheriting_constructors;cxx_inline_namespaces;cxx_lambdas;cxx_local_type_template_args;cxx_long_long_type;cxx_noexcept;cxx_nonstatic_member_init;cxx_nullptr;cxx_override;cxx_range_for;cxx_raw_string_literals;cxx_reference_qualified_functions;cxx_right_angle_brackets;cxx_rvalue_references;cxx_sizeof_member;cxx_static_assert;cxx_strong_enums;cxx_thread_local;cxx_trailing_return_types;cxx_unicode_literals;cxx_uniform_initialization;cxx_unrestricted_unions;cxx_user_literals;cxx_variadic_macros;cxx_variadic_templates PARENT_SCOPE )
/root/cmake/cmake-4.0.4-linux-x86_64/share/cmake-4.0/Modules/CMakeDetermineCompilerSupport.cmake(124):  set(CMAKE_CXX14_COMPILE_FEATURES cxx_std_14;cxx_aggregate_default_initializers;cxx_attribute_deprecated;cxx_binary_literals;cxx_contextual_conversions;cxx_decltype_auto;cxx_digit_separators;cxx_generic_lambdas;cxx_lambda_init_captures;cxx_relaxed_constexpr;cxx_return_type_deduction;cxx_variable_templates PARENT_SCOPE )
/root/cmake/cmake-4.0.4-linux-x86_64/share/cmake-4.0/Modules/CMakeDetermineCompilerSupport.cmake(125):  set(CMAKE_CXX17_COMPILE_FEATURES cxx_std_17 PARENT_SCOPE )
/root/cmake/cmake-4.0.4-linux-x86_64/share/cmake-4.0/Modules/CMakeDetermineCompilerSupport.cmake(126):  set(CMAKE_CXX20_COMPILE_FEATURES cxx_std_20 PARENT_SCOPE )
/root/cmake/cmake-4.0.4-linux-x86_64/share/cmake-4.0/Modules/CMakeDetermineCompilerSupport.cmake(127):  set(CMAKE_CXX23_COMPILE_FEATURES cxx_std_23 PARENT_SCOPE )
/root/cmake/cmake-4.0.4-linux-x86_64/share/cmake-4.0/Modules/CMakeDetermineCompilerSupport.cmake(128):  set(CMAKE_CXX26_COMPILE_FEATURES cxx_std_26 PARENT_SCOPE )
/root/cmake/cmake-4.0.4-linux-x86_64/share/cmake-4.0/Modules/CMakeDetermineCompilerSupport.cmake(129):  set(CMAKE_CXX_IMPORT_STD ### Imported target for C++23 standard library
if (NOT TARGET "__CMAKE::CXX23")
set(CMAKE_CXX23_COMPILER_IMPORT_STD_NOT_FOUND_MESSAGE "`libstdc++.modules.json` resource does not exist")
endif ()
if (TARGET "__CMAKE::CXX23")
  list(APPEND CMAKE_CXX_COMPILER_IMPORT_STD "23")
endif ()


### Imported target for C++26 standard library
if (NOT TARGET "__CMAKE::CXX26")
set(CMAKE_CXX26_COMPILER_IMPORT_STD_NOT_FOUND_MESSAGE "`libstdc++.modules.json` resource does not exist")
endif ()
if (TARGET "__CMAKE::CXX26")
  list(APPEND CMAKE_CXX_COMPILER_IMPORT_STD "26")
endif ()


 PARENT_SCOPE )
/root/cmake/cmake-4.0.4-linux-x86_64/share/cmake-4.0/Modules/CMakeDetermineCompilerSupport.cmake(131):  message(CHECK_PASS done )
-- Detecting CXX compile features - done
-- CMAKE_CXX_COMPILER_IMPORT_STD=
-- ALGO_USE_MODULES=ON
-- CMAKE_CXX_IMPLICIT_INCLUDE_DIRECTORIES=/usr/include/c++/14;/usr/include/x86_64-linux-gnu/c++/14;/usr/include/c++/14/backward;/root/llvm/lib/clang/20/include;/usr/local/include;/usr/include/x86_64-linux-gnu;/usr/include
CMake Error at CMakeLists.txt:52 (message):
  Missing support for CMAKE_CXX_MODULE_STD!


-- Configuring incomplete, errors occurred!
make: *** [GNUmakefile:30: all] Error 1
root ➜ /home/builder/workdir (feature/import-std-in-cmake-3-30) $

I can’t understand why libstdc++ is searched?

I have tried it with every available cmake version 4.x and llvm version 20, 21, and 22!

root ➜ /home/builder/workdir (feature/import-std-in-cmake-3-30) $ /root/llvm/bin/clang++  -print-file-name=libc++.modules.json
/root/llvm/bin/../lib/x86_64-unknown-linux-gnu/libc++.modules.json

root ➜ /home/builder/workdir (feature/import-std-in-cmake-3-30) $ cat /root/llvm/bin/../lib/x86_64-unknown-linux-gnu/libc++.modules.json
{
  "version": 1,
  "revision": 1,
  "modules": [
    {
      "logical-name": "std",
      "source-path": "../../share/libc++/v1/std.cppm",
      "is-std-library": true,
      "local-arguments": {
        "system-include-directories": [
          "../../share/libc++/v1"
        ]
      }
    },
    {
      "logical-name": "std.compat",
      "source-path": "../../share/libc++/v1/std.compat.cppm",
      "is-std-library": true,
      "local-arguments": {
        "system-include-directories": [
          "../../share/libc++/v1"
        ]
      }
    }
  ]
}
root ➜ /home/builder/workdir (feature/import-std-in-cmake-3-30) $ 

… and I can compile the libc++.modules.json contents:

root ➜ /home/builder/workdir (feature/use_cxx_module_std) $ ninja -C build/dev clean 
ninja: Entering directory `build/dev'
[1/1] Cleaning all built files...
Cleaning... 20 files.
root ➜ /home/builder/workdir (feature/use_cxx_module_std) $ ninja -C build/dev stdc++ -v
ninja: Entering directory `build/dev'
[1/6] "/usr/bin/clang-scan-deps-20" -format=p1689 -- /usr/lib/llvm-20/bin/clang++ -D_LIBCPP_HAS_NO_LOCALIZATION  -O3 -DNDEBUG -std=gnu++26 -fexperimental-library -stdlib=libc++ -Wno-reserved-module-identifier -x c++ /usr/lib/llvm-20/share/libc++/v1/std.compat.cppm -c -o module/tests/CMakeFiles/stdc++.dir/usr/lib/llvm-20/share/libc++/v1/std.compat.cppm.o -resource-dir "/usr/lib/llvm-20/lib/clang/20" -MT module/tests/CMakeFiles/stdc++.dir/usr/lib/llvm-20/share/libc++/v1/std.compat.cppm.o.ddi -MD -MF module/tests/CMakeFiles/stdc++.dir/usr/lib/llvm-20/share/libc++/v1/std.compat.cppm.o.ddi.d > module/tests/CMakeFiles/stdc++.dir/usr/lib/llvm-20/share/libc++/v1/std.compat.cppm.o.ddi.tmp && mv module/tests/CMakeFiles/stdc++.dir/usr/lib/llvm-20/share/libc++/v1/std.compat.cppm.o.ddi.tmp module/tests/CMakeFiles/stdc++.dir/usr/lib/llvm-20/share/libc++/v1/std.compat.cppm.o.ddi
[2/6] "/usr/bin/clang-scan-deps-20" -format=p1689 -- /usr/lib/llvm-20/bin/clang++ -D_LIBCPP_HAS_NO_LOCALIZATION  -O3 -DNDEBUG -std=gnu++26 -fexperimental-library -stdlib=libc++ -Wno-reserved-module-identifier -x c++ /usr/lib/llvm-20/share/libc++/v1/std.cppm -c -o module/tests/CMakeFiles/stdc++.dir/usr/lib/llvm-20/share/libc++/v1/std.cppm.o -resource-dir "/usr/lib/llvm-20/lib/clang/20" -MT module/tests/CMakeFiles/stdc++.dir/usr/lib/llvm-20/share/libc++/v1/std.cppm.o.ddi -MD -MF module/tests/CMakeFiles/stdc++.dir/usr/lib/llvm-20/share/libc++/v1/std.cppm.o.ddi.d > module/tests/CMakeFiles/stdc++.dir/usr/lib/llvm-20/share/libc++/v1/std.cppm.o.ddi.tmp && mv module/tests/CMakeFiles/stdc++.dir/usr/lib/llvm-20/share/libc++/v1/std.cppm.o.ddi.tmp module/tests/CMakeFiles/stdc++.dir/usr/lib/llvm-20/share/libc++/v1/std.cppm.o.ddi
[3/6] /root/cmake/cmake-4.0.4-linux-x86_64/bin/cmake -E cmake_ninja_dyndep --tdi=module/tests/CMakeFiles/stdc++.dir/CXXDependInfo.json --lang=CXX --modmapfmt=clang --dd=module/tests/CMakeFiles/stdc++.dir/CXX.dd @module/tests/CMakeFiles/stdc++.dir/CXX.dd.rsp
[4/6] /usr/bin/ccache /usr/lib/llvm-20/bin/clang++ -D_LIBCPP_HAS_NO_LOCALIZATION  -O3 -DNDEBUG -std=gnu++26 -fexperimental-library -stdlib=libc++ -Wno-reserved-module-identifier -MD -MT module/tests/CMakeFiles/stdc++.dir/usr/lib/llvm-20/share/libc++/v1/std.cppm.o -MF module/tests/CMakeFiles/stdc++.dir/usr/lib/llvm-20/share/libc++/v1/std.cppm.o.d @module/tests/CMakeFiles/stdc++.dir/usr/lib/llvm-20/share/libc++/v1/std.cppm.o.modmap -o module/tests/CMakeFiles/stdc++.dir/usr/lib/llvm-20/share/libc++/v1/std.cppm.o -c /usr/lib/llvm-20/share/libc++/v1/std.cppm
[5/6] /usr/bin/ccache /usr/lib/llvm-20/bin/clang++ -D_LIBCPP_HAS_NO_LOCALIZATION  -O3 -DNDEBUG -std=gnu++26 -fexperimental-library -stdlib=libc++ -Wno-reserved-module-identifier -MD -MT module/tests/CMakeFiles/stdc++.dir/usr/lib/llvm-20/share/libc++/v1/std.compat.cppm.o -MF module/tests/CMakeFiles/stdc++.dir/usr/lib/llvm-20/share/libc++/v1/std.compat.cppm.o.d @module/tests/CMakeFiles/stdc++.dir/usr/lib/llvm-20/share/libc++/v1/std.compat.cppm.o.modmap -o module/tests/CMakeFiles/stdc++.dir/usr/lib/llvm-20/share/libc++/v1/std.compat.cppm.o -c /usr/lib/llvm-20/share/libc++/v1/std.compat.cppm
[6/6] : && /root/cmake/cmake-4.0.4-linux-x86_64/bin/cmake -E rm -f module/tests/libstdc++.a && /usr/lib/llvm-20/bin/llvm-ar qc module/tests/libstdc++.a  module/tests/CMakeFiles/stdc++.dir/usr/lib/llvm-20/share/libc++/v1/std.cppm.o module/tests/CMakeFiles/stdc++.dir/usr/lib/llvm-20/share/libc++/v1/std.compat.cppm.o && /usr/lib/llvm-20/bin/llvm-ranlib module/tests/libstdc++.a && :
root ➜ /home/builder/workdir (feature/use_cxx_module_std) $ uname -a
Linux fe5675bfd498 6.10.14-linuxkit #1 SMP PREEMPT_DYNAMIC Tue Oct 14 07:34:37 UTC 2025 x86_64 x86_64 x86_64 GNU/Linux
root ➜ /home/builder/workdir (feature/use_cxx_module_std) $ cat /etc/issue
Ubuntu 24.04.2 LTS \n \l

root ➜ /home/builder/workdir (feature/use_cxx_module_std) $