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Reactivate Clang UBSan test coverage #5746

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Merged
StephanTLavavej merged 5 commits into from
Oct 4, 2025
Merged

Reactivate Clang UBSan test coverage #5746

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9bb35f1
Activate UBSan.
StephanTLavavej Sep 14, 2025
a348a47
Avoid duration_cast() UB, tracked by LWG-3921.
StephanTLavavej Sep 14, 2025
0c1d28b
Avoid UB caused by deliberate misalignment with `#pragma pack`.
StephanTLavavej Sep 14, 2025
1446cb9
Permanently avoid wmemcmp() UB, reported as VSO-2583476 "wmemcmp() tr…
StephanTLavavej Sep 14, 2025
e9f2d73
Properly detect UBSan in test code.
StephanTLavavej Sep 29, 2025
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21 changes: 13 additions & 8 deletions stl/inc/__msvc_string_view.hpp
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Expand Up @@ -360,18 +360,23 @@ struct _WChar_traits : private _Char_traits<_Elem, unsigned short> {
_NODISCARD static _CONSTEXPR17 int compare(_In_reads_(_Count) const _Elem* const _First1,
_In_reads_(_Count) const _Elem* const _First2, const size_t _Count) noexcept /* strengthened */ {
// compare [_First1, _First1 + _Count) with [_First2, ...)
#if _HAS_CXX17
if (_STD _Is_constant_evaluated()) {
if constexpr (is_same_v<_Elem, wchar_t>) {
return __builtin_wmemcmp(_First1, _First2, _Count);
#if _USE_STD_VECTOR_ALGORITHMS
if (!_STD _Is_constant_evaluated()) {
// TRANSITION, GH-2289: Use vectorized algorithms for better performance than __builtin_wmemcmp.
const size_t _Pos = _Mismatch_vectorized<sizeof(_Elem)>(_First1, _First2, _Count);
if (_Pos == _Count) {
return 0;
} else {
return _Primary_char_traits::compare(_First1, _First2, _Count);
return _First1[_Pos] < _First2[_Pos] ? -1 : +1;
}
}
#endif // _HAS_CXX17
#endif // ^^^ _USE_STD_VECTOR_ALGORITHMS ^^^

return _CSTD wmemcmp(
reinterpret_cast<const wchar_t*>(_First1), reinterpret_cast<const wchar_t*>(_First2), _Count);
if constexpr (is_same_v<_Elem, wchar_t>) {
return __builtin_wmemcmp(_First1, _First2, _Count);
} else {
return _Primary_char_traits::compare(_First1, _First2, _Count);
}
}

_NODISCARD static _CONSTEXPR17 size_t length(_In_z_ const _Elem* _First) noexcept /* strengthened */ {
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11 changes: 6 additions & 5 deletions tests/std/tests/P0355R7_calendars_and_time_zones_formatting/test.cpp
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Expand Up @@ -23,8 +23,6 @@
using namespace std;
using namespace chrono;

constexpr auto intmax_max = numeric_limits<intmax_t>::max();

template <typename CharT>
[[nodiscard]] constexpr const CharT* choose_literal(const char* const str, const wchar_t* const wstr) noexcept {
if constexpr (is_same_v<CharT, char>) {
Expand Down Expand Up @@ -252,8 +250,6 @@ void empty_braces_helper(

template <typename CharT>
void test_duration_formatter() {
using LongRatio = ratio<intmax_max - 1, intmax_max>;

empty_braces_helper(seconds{5}, STR("5s"));
empty_braces_helper(minutes{7}, STR("7min"));
empty_braces_helper(hours{9}, STR("9h"));
Expand All @@ -266,8 +262,13 @@ void test_duration_formatter() {
empty_braces_helper(duration<int, ratio<22, 7>>{40}, STR("40[22/7]s"));
empty_braces_helper(duration<int, ratio<53, 101>>{40}, STR("40[53/101]s"));
empty_braces_helper(duration<int, ratio<201, 2147483647>>{40}, STR("40[201/2147483647]s"));
// TRANSITION, LWG-3921: duration_cast used in formatting may raise UB

#if 0 // TRANSITION, LWG-3921: Our duration formatting constructs an hh_mm_ss, which calls duration_cast,
// which triggers signed integer overflow when a duration has a pathological ratio, like this:
constexpr auto intmax_max = numeric_limits<intmax_t>::max();
using LongRatio = ratio<intmax_max - 1, intmax_max>;
empty_braces_helper(duration<int, LongRatio>{1}, STR("1[9223372036854775806/9223372036854775807]s"));
#endif // ^^^ disabled test due to undefined behavior ^^^

// formatting small types needs to work as iostreams << VSO-1521926
empty_braces_helper(duration<long long, atto>{123}, STR("123as"));
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3 changes: 1 addition & 2 deletions tests/std/tests/VSO_0000000_vector_algorithms_floats/env.lst
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Expand Up @@ -46,8 +46,7 @@ PM_COMPILER="clang-cl" PM_CL="-fno-ms-compatibility -fno-delayed-template-parsin
PM_COMPILER="clang-cl" PM_CL="-fno-ms-compatibility -fno-delayed-template-parsing -Wno-unqualified-std-cast-call /EHsc /MDd /std:c++17 /w14640 /Zc:threadSafeInit- --start-no-unused-arguments"
PM_COMPILER="clang-cl" PM_CL="-fno-ms-compatibility -fno-delayed-template-parsing -Wno-unqualified-std-cast-call /EHsc /MT /std:c++20 /permissive- /w14640 /Zc:threadSafeInit- --start-no-unused-arguments"
PM_COMPILER="clang-cl" PM_CL="-fno-ms-compatibility -fno-delayed-template-parsing -Wno-unqualified-std-cast-call /EHsc /MTd /std:c++latest /permissive- /w14640 /Zc:threadSafeInit- --start-no-unused-arguments"
# TRANSITION, GH-3568
# PM_COMPILER="clang-cl" PM_CL="-fno-ms-compatibility -fno-delayed-template-parsing -Wno-unqualified-std-cast-call /EHsc /MT /std:c++latest /permissive- /w14640 /Zc:threadSafeInit- -fsanitize=undefined -fno-sanitize-recover=undefined --start-no-unused-arguments"
PM_COMPILER="clang-cl" PM_CL="-fno-ms-compatibility -fno-delayed-template-parsing -Wno-unqualified-std-cast-call /EHsc /MT /std:c++latest /permissive- /w14640 /Zc:threadSafeInit- -fsanitize=undefined -fno-sanitize-recover=undefined --start-no-unused-arguments"
RUNALL_CROSSLIST
* PM_CL="/fp:strict"
* PM_CL="/fp:precise"
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10 changes: 10 additions & 0 deletions tests/std/tests/VSO_0000000_vector_algorithms_mismatch_and_lex_compare/test.cpp
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Expand Up @@ -172,9 +172,19 @@ namespace test_mismatch_sizes_and_alignments {

template <class T, size_t Size, size_t PadSize>
char stack_array_various_alignments_impl() {
#ifdef __clang__
#if __has_feature(undefined_behavior_sanitizer)
#define TESTING_UBSAN
#endif
#endif

#ifdef TESTING_UBSAN
// Avoid testing misaligned inputs, which UBSan would reject.
#else // ^^^ UBSan / no UBSan vvv
with_pad<T, Size + 1, PadSize + 1> a = {};
with_pad<T, Size + 1, PadSize + 1> b = {};
assert(mismatch(begin(a.v), end(a.v), begin(b.v), end(b.v)) == make_pair(end(a.v), end(b.v)));
#endif // ^^^ no UBSan ^^^
return 0;
}

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3 changes: 1 addition & 2 deletions tests/std/tests/usual_matrix.lst
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Expand Up @@ -53,5 +53,4 @@ PM_COMPILER="clang-cl" PM_CL="-fno-ms-compatibility -fno-delayed-template-parsin
PM_COMPILER="clang-cl" PM_CL="-fno-ms-compatibility -fno-delayed-template-parsing -Wno-unqualified-std-cast-call /EHsc /MDd /std:c++17 /w14640 /Zc:threadSafeInit- --start-no-unused-arguments"
PM_COMPILER="clang-cl" PM_CL="-fno-ms-compatibility -fno-delayed-template-parsing -Wno-unqualified-std-cast-call /EHsc /MT /std:c++20 /permissive- /w14640 /Zc:threadSafeInit- --start-no-unused-arguments"
PM_COMPILER="clang-cl" PM_CL="-fno-ms-compatibility -fno-delayed-template-parsing -Wno-unqualified-std-cast-call /EHsc /MTd /std:c++latest /permissive- /fp:strict /w14640 /Zc:threadSafeInit- --start-no-unused-arguments"
# TRANSITION, GH-3568
# PM_COMPILER="clang-cl" PM_CL="-fno-ms-compatibility -fno-delayed-template-parsing -Wno-unqualified-std-cast-call /EHsc /MT /std:c++latest /permissive- /fp:strict /w14640 /Zc:threadSafeInit- -fsanitize=undefined -fno-sanitize-recover=undefined --start-no-unused-arguments"
PM_COMPILER="clang-cl" PM_CL="-fno-ms-compatibility -fno-delayed-template-parsing -Wno-unqualified-std-cast-call /EHsc /MT /std:c++latest /permissive- /fp:strict /w14640 /Zc:threadSafeInit- -fsanitize=undefined -fno-sanitize-recover=undefined --start-no-unused-arguments"
3 changes: 1 addition & 2 deletions tests/utils/stl/test/features.py
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Expand Up @@ -52,8 +52,7 @@ def getDefaultFeatures(config, litConfig):
DEFAULT_FEATURES.append(Feature(name='x86'))

elif litConfig.target_arch.casefold() == 'x64'.casefold():
# TRANSITION, GH-3568
# DEFAULT_FEATURES.append(Feature(name='ubsan'))
DEFAULT_FEATURES.append(Feature(name='ubsan'))
DEFAULT_FEATURES.append(Feature(name='edg'))
DEFAULT_FEATURES.append(Feature(name='arch_avx2'))
DEFAULT_FEATURES.append(Feature(name='x64'))
Expand Down