Re: head -r320458 (e.g.) amd64 -> powerpc (32-bit) cross-buildworld fails for time libc++ static_asserts and overflow/underflow of long long (system clang/clang++ 4 based build)

From: Mark Millard <markmi_at_dsl-only.net>
Date: Thu, 29 Jun 2017 03:04:19 -0700
[The libc++ code in question appears to not be ready for
32-bit contexts with 64 bit times. Disable
experimental/filesystem for now? I've submitted
llvm bugzilla 33638 for the issue and have
added it to llvm's 25780, the FreeBSD META for
clang.]

On 2017-Jun-29, at 2:21 AM, Mark Millard <markmi_at_dsl-only.net> wrote:

> [TARGET_ARCH=powerpc64 fails similarly in its world32
> part of its build.]
> 
> On 2017-Jun-29, at 1:33 AM, Mark Millard <markmi_at_dsl-only.net> wrote:
> 
>> Beyond static_assert failures and overflow/underflow of long long
>> it also it complains in some cases about:
>> 
>> static_assert expression is not an integral constant expression
>> 
>> 
>> [I will note that attempting a gcc 4.2.1 build did not
>> stop and report such things for its libstdc++. The below
>> is somehow libc++ and/or clang 4 specific.]
>> 
>> 
>> Context:
>> 
>> # uname -apKU
>> FreeBSD FreeBSDx64OPC 12.0-CURRENT FreeBSD 12.0-CURRENT  r320458M  amd64 amd64 1200036 1200036
>> 
>> buildworld for TARGET_ARCH=powerpc resulted in:
>> 
>> --- filesystem/operations.o ---
>> /usr/src/contrib/libc++/src/experimental/filesystem/operations.cpp:579:1: error: static_assert failed ""
>> static_assert(is_representable({max_time_t, 999999999}), "");
>> ^             ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>> /usr/src/contrib/libc++/src/experimental/filesystem/operations.cpp:580:1: error: static_assert failed ""
>> static_assert(is_representable({max_time_t, 1000000000}), "");
>> ^             ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>> /usr/src/contrib/libc++/src/experimental/filesystem/operations.cpp:581:1: error: static_assert failed ""
>> static_assert(is_representable({min_time_t, 0}), "");
>> ^             ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>> /usr/src/contrib/libc++/src/experimental/filesystem/operations.cpp:603:1: error: static_assert failed ""
>> static_assert(!is_representable(file_time_type::max()), "");
>> ^             ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>> /usr/src/contrib/libc++/src/experimental/filesystem/operations.cpp:604:1: error: static_assert failed ""
>> static_assert(!is_representable(file_time_type::min()), "");
>> ^             ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>> /usr/src/contrib/libc++/src/experimental/filesystem/operations.cpp:605:15: error: static_assert expression is not an integral constant expression
>> static_assert(is_representable(file_time_type(seconds(max_time_t))), "");
>>             ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>> /usr/src/contrib/libc++/include/chrono:386:59: note: value 9223372036854775807000000 is outside the range of representable values of type 'long long'
>>                          static_cast<_Ct>(__fd.count()) * static_cast<_Ct>(_Period::num)));
>>                                                         ^
>> /usr/src/contrib/libc++/include/chrono:413:12: note: in call to '&__duration_cast<duration<long long, std::__1::ratio<1, 1> >, std::__1::chrono::duration<long long, std::__1::ratio<1, 1000000> > >()->operator()(seconds(max_time_t))'
>>   return __duration_cast<duration<_Rep, _Period>, _ToDuration>()(__fd);
>>          ^
>> /usr/src/contrib/libc++/include/chrono:560:26: note: in call to 'duration_cast(seconds(max_time_t))'
>>               : __rep_(_VSTD::chrono::duration_cast<duration>(__d).count()) {}
>>                        ^
>> /usr/src/contrib/libc++/include/__config:390:15: note: expanded from macro '_VSTD'
>> #define _VSTD std::_LIBCPP_NAMESPACE
>>             ^
>> /usr/src/contrib/libc++/src/experimental/filesystem/operations.cpp:605:47: note: in call to 'duration(seconds(max_time_t), 0)'
>> static_assert(is_representable(file_time_type(seconds(max_time_t))), "");
>>                                             ^
>> /usr/src/contrib/libc++/src/experimental/filesystem/operations.cpp:606:15: error: static_assert expression is not an integral constant expression
>> static_assert(is_representable(file_time_type(seconds(min_time_t))), "");
>>             ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>> /usr/src/contrib/libc++/include/chrono:386:59: note: value -9223372036854775808000000 is outside the range of representable values of type 'long long'
>>                          static_cast<_Ct>(__fd.count()) * static_cast<_Ct>(_Period::num)));
>>                                                         ^
>> /usr/src/contrib/libc++/include/chrono:413:12: note: in call to '&__duration_cast<duration<long long, std::__1::ratio<1, 1> >, std::__1::chrono::duration<long long, std::__1::ratio<1, 1000000> > >()->operator()(seconds(min_time_t))'
>>   return __duration_cast<duration<_Rep, _Period>, _ToDuration>()(__fd);
>>          ^
>> /usr/src/contrib/libc++/include/chrono:560:26: note: in call to 'duration_cast(seconds(min_time_t))'
>>               : __rep_(_VSTD::chrono::duration_cast<duration>(__d).count()) {}
>>                        ^
>> /usr/src/contrib/libc++/include/__config:390:15: note: expanded from macro '_VSTD'
>> #define _VSTD std::_LIBCPP_NAMESPACE
>>             ^
>> /usr/src/contrib/libc++/src/experimental/filesystem/operations.cpp:606:47: note: in call to 'duration(seconds(min_time_t), 0)'
>> static_assert(is_representable(file_time_type(seconds(min_time_t))), "");
>>                                             ^
>> . . .
>> --- lib__L ---
>> 7 errors generated.
>> *** [filesystem/operations.o] Error code 1
>> 
>> make[5]: stopped in /usr/src/lib/libc++experimental
>> .ERROR_TARGET='filesystem/operations.o'
>> .ERROR_META_FILE='/usr/obj/powerpcvtsc_clang/powerpc.powerpc/usr/src/lib/libc++experimental/_usr_obj_powerpcvtsc_clang_powerpc.powerpc_usr_src_lib_libc++experimental_filesystem_operations.o.meta'
>> .MAKE.LEVEL='5'
>> MAKEFILE=''
>> .MAKE.MODE='meta missing-filemon=yes missing-meta=yes silent=yes verbose'
>> _ERROR_CMD='c++  -target powerpc-unknown-freebsd12.0 --sysroot=/usr/obj/powerpcvtsc_clang/powerpc.powerpc/usr/src/tmp -B/usr/obj/powerpcvtsc_clang/powerpc.powerpc/usr/src/tmp/usr/bin  -O2 -pipe -fstack-protector-strong -Wno-empty-body -Wno-string-plus-int -Wno-unused-const-variable -Wno-tautological-compare -Wno-unused-value -Wno-parentheses-equality -Wno-unused-function -Wno-enum-conversion -Wno-unused-local-typedef -Wno-address-of-packed-member -Wno-switch -Wno-switch-enum -Wno-knr-promoted-parameter -Wno-parentheses -Qunused-arguments  -fpic -isystem /usr/src/contrib/libc++/include -nostdinc++ -nostdlib -D_LIBCPP_BUILDING_LIBRARY -DLIBCXXRT -std=c++14 -Wno-c++11-extensions  -c /usr/src/contrib/libc++/src/experimental/filesystem/operations.cpp -o filesystem/operations.o;'
>> .CURDIR='/usr/src/lib/libc++experimental'
>> 
>> 
>> # more /usr/obj/powerpcvtsc_clang/powerpc.powerpc/usr/src/lib/libc++experimental/_usr_obj_powerpcvtsc_clang_powerpc.powerpc_usr_src_lib_libc++experimental_filesystem_operations.o.meta
>> # Meta data file /usr/obj/powerpcvtsc_clang/powerpc.powerpc/usr/src/lib/libc++experimental/_usr_obj_powerpcvtsc_clang_powerpc.powerpc_usr_src_lib_libc++experimental_filesystem_operations.o.meta
>> CMD c++  -target powerpc-unknown-freebsd12.0 --sysroot=/usr/obj/powerpcvtsc_clang/powerpc.powerpc/usr/src/tmp -B/usr/obj/powerpcvtsc_clang/powerpc.powerpc/usr/src/tmp/usr/bin  -O2 -pipe -fstack-protector-strong -Wno-empty-body -Wno-string-plus-int -Wno-unused-const-variable -Wno-tautological-compare -Wno-unused-value -Wno-parentheses-equality -Wno-unused-function -Wno-enum-conversion -Wno-unused-local-typedef -Wno-address-of-packed-member -Wno-switch -Wno-switch-enum -Wno-knr-promoted-parameter -Wno-parentheses -Qunused-arguments  -fpic -isystem /usr/src/contrib/libc++/include -nostdinc++ -nostdlib -D_LIBCPP_BUILDING_LIBRARY -DLIBCXXRT -std=c++14 -Wno-c++11-extensions  -c /usr/src/contrib/libc++/src/experimental/filesystem/operations.cpp -o filesystem/operations.o
>> CWD /usr/obj/powerpcvtsc_clang/powerpc.powerpc/usr/src/lib/libc++experimental
>> TARGET filesystem/operations.o
>> -- command output --
>> /usr/src/contrib/libc++/src/experimental/filesystem/operations.cpp:579:1: error: static_assert failed ""
>> static_assert(is_representable({max_time_t, 999999999}), "");
>> ^             ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>> /usr/src/contrib/libc++/src/experimental/filesystem/operations.cpp:580:1: error: static_assert failed ""
>> static_assert(is_representable({max_time_t, 1000000000}), "");
>> ^             ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>> /usr/src/contrib/libc++/src/experimental/filesystem/operations.cpp:581:1: error: static_assert failed ""
>> static_assert(is_representable({min_time_t, 0}), "");
>> ^             ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>> /usr/src/contrib/libc++/src/experimental/filesystem/operations.cpp:603:1: error: static_assert failed ""
>> static_assert(!is_representable(file_time_type::max()), "");
>> ^             ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>> /usr/src/contrib/libc++/src/experimental/filesystem/operations.cpp:604:1: error: static_assert failed ""
>> static_assert(!is_representable(file_time_type::min()), "");
>> ^             ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>> /usr/src/contrib/libc++/src/experimental/filesystem/operations.cpp:605:15: error: static_assert expression is not an integral constant expression
>> static_assert(is_representable(file_time_type(seconds(max_time_t))), "");
>>             ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>> /usr/src/contrib/libc++/include/chrono:386:59: note: value 9223372036854775807000000 is outside the range of representable values of type 'long long'
>>                          static_cast<_Ct>(__fd.count()) * static_cast<_Ct>(_Period::num)));
>>                                                         ^
>> /usr/src/contrib/libc++/include/chrono:413:12: note: in call to '&__duration_cast<duration<long long, std::__1::ratio<1, 1> >, std::__1::chrono::duration<long long, std::__1::ratio<1, 1000000> > >()->operator()(seconds(max_time_t))'
>>   return __duration_cast<duration<_Rep, _Period>, _ToDuration>()(__fd);
>>          ^
>> /usr/src/contrib/libc++/include/chrono:560:26: note: in call to 'duration_cast(seconds(max_time_t))'
>>               : __rep_(_VSTD::chrono::duration_cast<duration>(__d).count()) {}
>>                        ^
>> /usr/src/contrib/libc++/include/__config:390:15: note: expanded from macro '_VSTD'
>> #define _VSTD std::_LIBCPP_NAMESPACE
>>             ^
>> /usr/src/contrib/libc++/src/experimental/filesystem/operations.cpp:605:47: note: in call to 'duration(seconds(max_time_t), 0)'
>> static_assert(is_representable(file_time_type(seconds(max_time_t))), "");
>>                                             ^
>> /usr/src/contrib/libc++/src/experimental/filesystem/operations.cpp:606:15: error: static_assert expression is not an integral constant expression
>> static_assert(is_representable(file_time_type(seconds(min_time_t))), "");
>>             ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>> /usr/src/contrib/libc++/include/chrono:386:59: note: value -9223372036854775808000000 is outside the range of representable values of type 'long long'
>>                          static_cast<_Ct>(__fd.count()) * static_cast<_Ct>(_Period::num)));
>>                                                         ^
>> /usr/src/contrib/libc++/include/chrono:413:12: note: in call to '&__duration_cast<duration<long long, std::__1::ratio<1, 1> >, std::__1::chrono::duration<long long, std::__1::ratio<1, 1000000> > >()->operator()(seconds(min_time_t))'
>>   return __duration_cast<duration<_Rep, _Period>, _ToDuration>()(__fd);
>>          ^
>> /usr/src/contrib/libc++/include/chrono:560:26: note: in call to 'duration_cast(seconds(min_time_t))'
>>               : __rep_(_VSTD::chrono::duration_cast<duration>(__d).count()) {}
>>                        ^
>> /usr/src/contrib/libc++/include/__config:390:15: note: expanded from macro '_VSTD'
>> #define _VSTD std::_LIBCPP_NAMESPACE
>>             ^
>> /usr/src/contrib/libc++/src/experimental/filesystem/operations.cpp:606:47: note: in call to 'duration(seconds(min_time_t), 0)'
>> static_assert(is_representable(file_time_type(seconds(min_time_t))), "");
>>                                             ^
>> 7 errors generated.
>> *** Error code 1
>> 
>> 
>> 
>> Build configuration:
>> 
>> 
>> # svnlite info /usr/src/ | grep "Re[plv]"
>> Relative URL: ^/head
>> Repository Root: svn://svn.freebsd.org/base
>> Repository UUID: ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f
>> Revision: 320458
>> Last Changed Rev: 320458
>> 
>> 
>> # more ~/sys_build_scripts.amd64-host/make_powerpcvtsc_nodebug_clang_bootstrap-amd64-host.sh 
>> kldload -n filemon && \
>> script ~/sys_typescripts/typescript_make_powerpcvtsc_nodebug_clang_bootstrap-amd64-host-$(date +%Y-%m-%d:%H:%M:%S) \
>> env __MAKE_CONF="/root/src.configs/make.conf" SRCCONF="/dev/null" SRC_ENV_CONF="/root/src.configs/src.conf.powerpc-clang-bootstrap.amd64-host" \
>> WITH_META_MODE=yes \
>> MAKEOBJDIRPREFIX="/usr/obj/powerpcvtsc_clang" \
>> make $*
>> 
>> 
>> # more /root/src.configs/src.conf.powerpc-clang-bootstrap.amd64-host
>> TO_TYPE=powerpc
>> #
>> KERNCONF=GENERICvtsc-NODBG
>> TARGET=${TO_TYPE}
>> .if ${.MAKE.LEVEL} == 0
>> TARGET_ARCH=${TO_TYPE}
>> .export TARGET_ARCH
>> .endif
>> #
>> WITH_CROSS_COMPILER=
>> WITHOUT_SYSTEM_COMPILER=
>> #
>> WITH_LIBCPLUSPLUS=
>> WITH_BINUTILS_BOOTSTRAP=
>> WITH_ELFTOOLCHAIN_BOOTSTRAP=
>> WITH_CLANG_BOOTSTRAP=
>> WITH_CLANG=
>> WITH_CLANG_IS_CC=
>> WITH_CLANG_FULL=
>> WITH_CLANG_EXTRAS=
>> WITH_LLD=
>> # lldb requires missing atomic 8-byte operations for powerpc (non-64)
>> WITHOUT_LLDB=
>> #
>> WITH_BOOT=
>> WITHOUT_LIB32=
>> #
>> WITHOUT_GCC_BOOTSTRAP=
>> WITHOUT_GCC=
>> WITHOUT_GCC_IS_CC=
>> WITHOUT_GNUCXX=
>> #
>> NO_WERROR=
>> #
>> # Use WERROR to avoid stopping at the likes of:
>> # error: implicit conversion from 'int' to 'int8_t' (aka 'signed char') changes value from 128 to -128 [-Werror,-Wconstant-conversion]
>> WERROR=
>> MALLOC_PRODUCTION=
>> #
>> WITH_REPRODUCIBLE_BUILD=
>> WITH_DEBUG_FILES=
> 
> 
> The world32 part of a TARGET_ARCH=powerpc64 cross-buildworld
> also gets the same errors.

Turns out the libc++ code in question looks like:

_LIBCPP_CONSTEXPR_AFTER_CXX11
bool is_representable(TimeSpec const& tm) {
  if (tm.tv_sec >= 0) {
    return (tm.tv_sec < max_seconds) ||
        (tm.tv_sec == max_seconds && tm.tv_nsec <= max_nsec);
  } else if (tm.tv_sec == (min_seconds - 1)) {
     return tm.tv_nsec >= min_nsec_timespec;
  } else {
    return (tm.tv_sec >= min_seconds);
  }
}
#ifndef _LIBCPP_HAS_NO_CXX14_CONSTEXPR
#if defined(__LP64__)
. . .
#else
static_assert(is_representable({max_time_t, 999999999}), "");
static_assert(is_representable({max_time_t, 1000000000}), "");
static_assert(is_representable({min_time_t, 0}), "");
#endif
#endif
                               
_LIBCPP_CONSTEXPR_AFTER_CXX11
bool is_representable(file_time_type const& tm) {
  auto secs = duration_cast<seconds>(tm.time_since_epoch());
  auto nsecs = duration_cast<nanoseconds>(tm.time_since_epoch() - secs);
  if (nsecs.count() < 0) {
    secs = secs +  seconds(1);
    nsecs = nsecs + seconds(1);
  }
  using TLim = numeric_limits<time_t>;
  if (secs.count() >= 0)
    return secs.count() <= TLim::max();
  return secs.count() >= TLim::min();
}
#ifndef _LIBCPP_HAS_NO_CXX14_CONSTEXPR
#if defined(__LP64__)
. . .
#else
static_assert(!is_representable(file_time_type::max()), "");
static_assert(!is_representable(file_time_type::min()), "");
static_assert(is_representable(file_time_type(seconds(max_time_t))), "");
static_assert(is_representable(file_time_type(seconds(min_time_t))), "");
#endif
#endif

_LIBCPP_CONSTEXPR_AFTER_CXX11
file_time_type convert_timespec(TimeSpec const& tm) {
  auto adj_msec = duration_cast<microseconds>(nanoseconds(tm.tv_nsec));
  if (tm.tv_sec >= 0) {
    auto Dur = seconds(tm.tv_sec) + microseconds(adj_msec);
    return file_time_type(Dur);
  } else if (duration_cast<microseconds>(nanoseconds(tm.tv_nsec)).count() == 0) {
    return file_time_type(seconds(tm.tv_sec));
  } else { // tm.tv_sec < 0
    auto adj_subsec = duration_cast<microseconds>(seconds(1) - nanoseconds(tm.tv_nsec));
    auto Dur = seconds(tm.tv_sec + 1) - adj_subsec;
    return file_time_type(Dur);
  }
}
#ifndef _LIBCPP_HAS_NO_CXX14_CONSTEXPR
#if defined(__LP64__)
. . .
#else
// FIXME add tests for 32 bit builds
#endif
#endif

That "FIXME" likely gives a clue as to the status of
of the handling for ILP32 contexts.

There seems to be the expectation that IPL32 will not
have 64-bit time_t as well.


===
Mark Millard
markmi at dsl-only.net
Received on Thu Jun 29 2017 - 08:04:23 UTC

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