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<format>: Reject dynamic width or precision of non-integral type #4155

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merged 2 commits into from
Nov 17, 2023
Merged

<format>: Reject dynamic width or precision of non-integral type #4155

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099c7bf
Reject dynamic width or precision of non-integral type
cpplearner Nov 10, 2023
9abb93c
Remove redundant check
cpplearner Nov 10, 2023
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10 changes: 8 additions & 2 deletions stl/inc/chrono
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Original file line number Diff line number Diff line change
Expand Up @@ -4766,20 +4766,26 @@ public:

constexpr void _On_dynamic_width(const size_t _Arg_id) {
_Parse_ctx.check_arg_id(_Arg_id);
_Parse_ctx._Check_dynamic_spec_integral(_Arg_id);
_Specs._Dynamic_width_index = _Verify_dynamic_arg_index_in_range(_Arg_id);
}

constexpr void _On_dynamic_width(_Auto_id_tag) {
_Specs._Dynamic_width_index = _Verify_dynamic_arg_index_in_range(_Parse_ctx.next_arg_id());
const size_t _Arg_id = _Parse_ctx.next_arg_id();
_Parse_ctx._Check_dynamic_spec_integral(_Arg_id);
_Specs._Dynamic_width_index = _Verify_dynamic_arg_index_in_range(_Arg_id);
}

constexpr void _On_dynamic_precision(const size_t _Arg_id) {
_Parse_ctx.check_arg_id(_Arg_id);
_Parse_ctx._Check_dynamic_spec_integral(_Arg_id);
_Specs._Dynamic_precision_index = _Verify_dynamic_arg_index_in_range(_Arg_id);
}

constexpr void _On_dynamic_precision(_Auto_id_tag) {
_Specs._Dynamic_precision_index = _Verify_dynamic_arg_index_in_range(_Parse_ctx.next_arg_id());
const size_t _Arg_id = _Parse_ctx.next_arg_id();
_Parse_ctx._Check_dynamic_spec_integral(_Arg_id);
_Specs._Dynamic_precision_index = _Verify_dynamic_arg_index_in_range(_Arg_id);
}

constexpr void _On_localized() {
Expand Down
127 changes: 89 additions & 38 deletions stl/inc/format
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Original file line number Diff line number Diff line change
Expand Up @@ -578,6 +578,10 @@ _EXPORT_STD template <class _Ty, class _CharT = char>
struct formatter;

inline void _You_see_this_error_because_arg_id_is_out_of_range() noexcept {}
inline void _Invalid_arg_type_for_dynamic_width_or_precision() noexcept {}

template <class _CharT>
class _Compile_time_parse_context;

_EXPORT_STD template <class _CharT>
class basic_format_parse_context {
Expand Down Expand Up @@ -645,6 +649,19 @@ public:
_Next_arg_id = -1;
}

constexpr void _Check_dynamic_spec_integral(const size_t _Idx) noexcept {
if (_STD is_constant_evaluated()) {
// This downcast might seem UB-prone, but since it only happens at compile-time,
// the compiler will produce an error if it is invalid.
auto& _Ctx = static_cast<_Compile_time_parse_context<_CharT>&>(*this);

_STL_INTERNAL_CHECK(_Ctx._Arg_type[_Idx] != _Basic_format_arg_type::_None);
if (_Ctx._Arg_type[_Idx] > _Basic_format_arg_type::_ULong_long_type) {
_Invalid_arg_type_for_dynamic_width_or_precision();
}
}
}

private:
basic_string_view<_CharT> _Format_string;
size_t _Num_args;
Expand All @@ -657,6 +674,19 @@ private:
_EXPORT_STD using format_parse_context = basic_format_parse_context<char>;
_EXPORT_STD using wformat_parse_context = basic_format_parse_context<wchar_t>;

template <class _CharT>
class _Compile_time_parse_context : public basic_format_parse_context<_CharT> {
friend basic_format_parse_context<_CharT>;

public:
constexpr _Compile_time_parse_context(const basic_string_view<_CharT> _Fmt, const size_t _Num_args,
const _Basic_format_arg_type* const _Arg_type_) noexcept
: basic_format_parse_context<_CharT>(_Fmt, _Num_args), _Arg_type(_Arg_type_) {}

private:
const _Basic_format_arg_type* const _Arg_type;
};

template <class _Ty, class _Context, class _Formatter = _Context::template formatter_type<remove_const_t<_Ty>>>
concept _Formattable_with = semiregular<_Formatter>
&& requires(_Formatter& __f, const _Formatter& __cf, _Ty&& __t, _Context __fc,
Expand Down Expand Up @@ -880,6 +910,41 @@ auto _Format_arg_traits<_Context>::_Type_eraser() {
}
}

template <class _Context, class _Ty>
_NODISCARD consteval _Basic_format_arg_type _Get_format_arg_type() noexcept {
using _CharType = _Context::char_type;
using _Erased_type = _Format_arg_traits<_Context>::template _Storage_type<_Ty>;

if constexpr (is_same_v<_Erased_type, bool>) {
return _Basic_format_arg_type::_Bool_type;
} else if constexpr (is_same_v<_Erased_type, _CharType>) {
return _Basic_format_arg_type::_Char_type;
} else if constexpr (is_same_v<_Erased_type, int>) {
return _Basic_format_arg_type::_Int_type;
} else if constexpr (is_same_v<_Erased_type, unsigned int>) {
return _Basic_format_arg_type::_UInt_type;
} else if constexpr (is_same_v<_Erased_type, long long>) {
return _Basic_format_arg_type::_Long_long_type;
} else if constexpr (is_same_v<_Erased_type, unsigned long long>) {
return _Basic_format_arg_type::_ULong_long_type;
} else if constexpr (is_same_v<_Erased_type, float>) {
return _Basic_format_arg_type::_Float_type;
} else if constexpr (is_same_v<_Erased_type, double>) {
return _Basic_format_arg_type::_Double_type;
} else if constexpr (is_same_v<_Erased_type, long double>) {
return _Basic_format_arg_type::_Long_double_type;
} else if constexpr (is_same_v<_Erased_type, const void*>) {
return _Basic_format_arg_type::_Pointer_type;
} else if constexpr (is_same_v<_Erased_type, const _CharType*>) {
return _Basic_format_arg_type::_CString_type;
} else if constexpr (is_same_v<_Erased_type, basic_string_view<_CharType>>) {
return _Basic_format_arg_type::_String_type;
} else {
_STL_INTERNAL_STATIC_ASSERT(is_same_v<_Erased_type, typename basic_format_arg<_Context>::handle>);
return _Basic_format_arg_type::_Custom_type;
}
}

_EXPORT_STD template <class _Visitor, class _Context>
decltype(auto) visit_format_arg(_Visitor&& _Vis, basic_format_arg<_Context> _Arg) {
return _Arg._Visit(_STD forward<_Visitor>(_Vis));
Expand Down Expand Up @@ -1716,20 +1781,26 @@ public:

constexpr void _On_dynamic_width(const size_t _Arg_id) {
_Parse_ctx.check_arg_id(_Arg_id);
_Parse_ctx._Check_dynamic_spec_integral(_Arg_id);
_Dynamic_specs._Dynamic_width_index = _Verify_dynamic_arg_index_in_range(_Arg_id);
}

constexpr void _On_dynamic_width(_Auto_id_tag) {
_Dynamic_specs._Dynamic_width_index = _Verify_dynamic_arg_index_in_range(_Parse_ctx.next_arg_id());
const size_t _Arg_id = _Parse_ctx.next_arg_id();
_Parse_ctx._Check_dynamic_spec_integral(_Arg_id);
_Dynamic_specs._Dynamic_width_index = _Verify_dynamic_arg_index_in_range(_Arg_id);
}

constexpr void _On_dynamic_precision(const size_t _Arg_id) {
_Parse_ctx.check_arg_id(_Arg_id);
_Parse_ctx._Check_dynamic_spec_integral(_Arg_id);
_Dynamic_specs._Dynamic_precision_index = _Verify_dynamic_arg_index_in_range(_Arg_id);
}

constexpr void _On_dynamic_precision(_Auto_id_tag) {
_Dynamic_specs._Dynamic_precision_index = _Verify_dynamic_arg_index_in_range(_Parse_ctx.next_arg_id());
const size_t _Arg_id = _Parse_ctx.next_arg_id();
_Parse_ctx._Check_dynamic_spec_integral(_Arg_id);
_Dynamic_specs._Dynamic_precision_index = _Verify_dynamic_arg_index_in_range(_Arg_id);
}

private:
Expand Down Expand Up @@ -2015,37 +2086,8 @@ private:

template <class _Ty>
void _Store(const size_t _Arg_index, _Ty&& _Val) noexcept {
using _Erased_type = _Traits::template _Storage_type<_Ty>;

_Basic_format_arg_type _Arg_type;
if constexpr (is_same_v<_Erased_type, bool>) {
_Arg_type = _Basic_format_arg_type::_Bool_type;
} else if constexpr (is_same_v<_Erased_type, _CharType>) {
_Arg_type = _Basic_format_arg_type::_Char_type;
} else if constexpr (is_same_v<_Erased_type, int>) {
_Arg_type = _Basic_format_arg_type::_Int_type;
} else if constexpr (is_same_v<_Erased_type, unsigned int>) {
_Arg_type = _Basic_format_arg_type::_UInt_type;
} else if constexpr (is_same_v<_Erased_type, long long>) {
_Arg_type = _Basic_format_arg_type::_Long_long_type;
} else if constexpr (is_same_v<_Erased_type, unsigned long long>) {
_Arg_type = _Basic_format_arg_type::_ULong_long_type;
} else if constexpr (is_same_v<_Erased_type, float>) {
_Arg_type = _Basic_format_arg_type::_Float_type;
} else if constexpr (is_same_v<_Erased_type, double>) {
_Arg_type = _Basic_format_arg_type::_Double_type;
} else if constexpr (is_same_v<_Erased_type, long double>) {
_Arg_type = _Basic_format_arg_type::_Long_double_type;
} else if constexpr (is_same_v<_Erased_type, const void*>) {
_Arg_type = _Basic_format_arg_type::_Pointer_type;
} else if constexpr (is_same_v<_Erased_type, const _CharType*>) {
_Arg_type = _Basic_format_arg_type::_CString_type;
} else if constexpr (is_same_v<_Erased_type, basic_string_view<_CharType>>) {
_Arg_type = _Basic_format_arg_type::_String_type;
} else {
_STL_INTERNAL_STATIC_ASSERT(is_same_v<_Erased_type, typename basic_format_arg<_Context>::handle>);
_Arg_type = _Basic_format_arg_type::_Custom_type;
}
constexpr _Basic_format_arg_type _Arg_type = _STD _Get_format_arg_type<_Context, _Ty>();
using _Erased_type = _Traits::template _Storage_type<_Ty>;

#if !_HAS_CXX23
// Workaround towards N4950 [format.arg]/6.8 in C++20
Expand Down Expand Up @@ -3573,11 +3615,12 @@ struct _Format_checker {
using _ParseFunc = _ParseContext::iterator (*)(_ParseContext&);

static constexpr size_t _Num_args = sizeof...(_Args);
_ParseContext _Parse_context;
_Compile_time_parse_context<_CharT> _Parse_context;
_ParseFunc _Parse_funcs[_Num_args > 0 ? _Num_args : 1];

consteval explicit _Format_checker(basic_string_view<_CharT> _Fmt) noexcept
: _Parse_context(_Fmt, _Num_args), _Parse_funcs{&_Compile_time_parse_format_specs<_Args, _ParseContext>...} {}
consteval explicit _Format_checker(basic_string_view<_CharT> _Fmt, const _Basic_format_arg_type* _Arg_type) noexcept
: _Parse_context(_Fmt, _Num_args, _Arg_type),
_Parse_funcs{&_Compile_time_parse_format_specs<_Args, _ParseContext>...} {}
constexpr void _On_text(const _CharT*, const _CharT*) const noexcept {}
constexpr void _On_replacement_field(const size_t _Id, const _CharT*) const {
_ParseContext _Parse_ctx({});
Expand Down Expand Up @@ -3802,7 +3845,12 @@ public:
requires convertible_to<const _Ty&, basic_string_view<_CharT>>
consteval basic_format_string(const _Ty& _Str_val) : _Str(_Str_val) {
if (_Is_execution_charset_self_synchronizing()) {
_Parse_format_string(_Str, _Format_checker<_CharT, remove_cvref_t<_Args>...>{_Str});
using _Context = basic_format_context<back_insert_iterator<_Fmt_buffer<_CharT>>, _CharT>;
constexpr size_t _Num_args = sizeof...(_Args);
constexpr _Basic_format_arg_type _Arg_types[_Num_args > 0 ? _Num_args : 1] = {
_STD _Get_format_arg_type<_Context, _Args>()...};

_Parse_format_string(_Str, _Format_checker<_CharT, remove_cvref_t<_Args>...>{_Str, _Arg_types});
}
}

Expand Down Expand Up @@ -4129,11 +4177,14 @@ public:

constexpr void _On_dynamic_width(const size_t _Arg_id) {
_Parse_ctx.check_arg_id(_Arg_id);
_Parse_ctx._Check_dynamic_spec_integral(_Arg_id);
_Specs._Dynamic_width_index = _Verify_dynamic_arg_index_in_range(_Arg_id);
}

constexpr void _On_dynamic_width(_Auto_id_tag) {
_Specs._Dynamic_width_index = _Verify_dynamic_arg_index_in_range(_Parse_ctx.next_arg_id());
const size_t _Arg_id = _Parse_ctx.next_arg_id();
_Parse_ctx._Check_dynamic_spec_integral(_Arg_id);
_Specs._Dynamic_width_index = _Verify_dynamic_arg_index_in_range(_Arg_id);
}

private:
Expand Down