Re: [PATCH, libstdc++/61166] overflow when parse number in std::duration operator
On 15/05/14 22:54 -0400, Ed Smith-Rowland wrote:
On 05/15/2014 03:03 PM, Jonathan Wakely wrote:
Here's a finished patch to simplify bits/parse_numbers.h
Tested x86_64-linux. Ed, any objection to this version?
This looks great, thanks!
I committed that to trunk, I'll put it on the 4.9 branch too.
Having done that should we actually stop using it as suggested in the
bug trail? ;-)
I was going to do that, then realised that there's a defect in the
standard where it requires overflow in duration integer literals to be
diagnosed. That's only possible with literal operator templates, so I
think we should keep your _Parse_int code, but apply the attached
change to detect overflow.
As the TODO comment says, it should be sufficient to simply
instantiate integral_constant_Rep, _Val::value to give a diagnostic
when _Rep{_Value::value} is narrowing, but GCC only gives a warning
for it, and that's suppressed in a system header, so I do an explicit
static_assert. That could be replaced with ...
#pragma GCC diagnostic push
#pragma GCC diagnostic error -Woverflow
#pragma GCC diagnostic error -Wsystem-headers
templatetypename _Dur, char... _Digits
constexpr _Dur __check_overflow()
{
using _Val = __parse_int::_Parse_int_Digits...;
using _Rep = typename _Dur::rep;
return _Dur{integral_constant_Rep, _Val::value::value};
}
#pragma GCC diagnostic pop
... but I have plans to do that sort of thing more widely, which I'll
deal with another time as part of https://gcc.gnu.org/PR50871 and/or
https://gcc.gnu.org/PR58876 (what do other people think about using
diagnostic pragmas to locally re-enable diagnostics in our headers?)
Tested x86_64-linux, committed to trunk.
commit 361c9b79e0b1c7f2435f5b0b369a139b216dee90
Author: Jonathan Wakely jwak...@redhat.com
Date: Fri May 16 10:31:38 2014 +0100
* include/bits/parse_numbers.h (__parse_int::_Number_help): Check for
overflow.
* include/std/chrono (chrono_literals::__select_type::_Select_type):
Remove.
(chrono_literals::_Checked_integral_constant): Define.
Simplify UDL operator templates and check for overflow.
* testsuite/20_util/duration/literals/range.cc: New.
diff --git a/libstdc++-v3/include/bits/parse_numbers.h b/libstdc++-v3/include/bits/parse_numbers.h
index 0a42381a..a29d127 100644
--- a/libstdc++-v3/include/bits/parse_numbers.h
+++ b/libstdc++-v3/include/bits/parse_numbers.h
@@ -193,6 +193,7 @@ namespace __parse_int
_Pow / (_Base * __valid_digit::value),
_Digs...;
using type = __ull_constant_Pow * __digit::value + __next::type::value;
+ static_assert((type::value / _Pow) == __digit::value, overflow);
};
templateunsigned _Base, unsigned long long _Pow, char _Dig
diff --git a/libstdc++-v3/include/std/chrono b/libstdc++-v3/include/std/chrono
index b114e02..39ad5e3 100644
--- a/libstdc++-v3/include/std/chrono
+++ b/libstdc++-v3/include/std/chrono
@@ -787,117 +787,79 @@ _GLIBCXX_END_NAMESPACE_VERSION
inline namespace chrono_literals
{
-namespace __select_type
-{
-
- using namespace __parse_int;
-
- templateunsigned long long _Val, typename _Dur
- struct _Select_type
- : conditional
- _Val = static_castunsigned long long
- (numeric_limitstypename _Dur::rep::max()),
- _Dur, void
- {
- static constexpr typename _Select_type::type
- value{static_casttypename _Select_type::type(_Val)};
- };
-
- templateunsigned long long _Val, typename _Dur
- constexpr typename _Select_type_Val, _Dur::type
- _Select_type_Val, _Dur::value;
+templatetypename _Rep, unsigned long long _Val
+ struct _Checked_integral_constant
+ : integral_constant_Rep, static_cast_Rep(_Val)
+ {
+ static_assert(_Checked_integral_constant::value 0
+ _Checked_integral_constant::value == _Val,
+ literal value cannot be represented by duration type);
+ };
-} // __select_type
+templatetypename _Dur, char... _Digits
+ constexpr _Dur __check_overflow()
+ {
+ using _Val = __parse_int::_Parse_int_Digits...;
+ using _Rep = typename _Dur::rep;
+ // TODO: should be simply integral_constant_Rep, _Val::value
+ // but GCC doesn't reject narrowing conversions to _Rep.
+ using _CheckedVal = _Checked_integral_constant_Rep, _Val::value;
+ return _Dur{_CheckedVal::value};
+ }
constexpr chrono::durationlong double, ratio3600,1
operatorh(long double __hours)
{ return chrono::durationlong double, ratio3600,1{__hours}; }
template char... _Digits
- constexpr typename
- __select_type::_Select_type__select_int::_Select_int_Digits...::value,
- chrono::hours::type
+ constexpr chrono::hours
operatorh()
- {
- return __select_type::_Select_type
- __select_int::_Select_int_Digits...::value,
- chrono::hours::value;
- }
+ { return __check_overflowchrono::hours, _Digits...(); }
constexpr chrono::durationlong double, ratio60,1
Re: [PATCH, libstdc++/61166] overflow when parse number in std::duration operator
Here's a finished patch to simplify bits/parse_numbers.h
Tested x86_64-linux. Ed, any objection to this version?
commit 87d26af2fc07f0c45a0a6676161ae1db1d7541b7
Author: Jonathan Wakely jwak...@redhat.com
Date: Wed May 14 16:35:20 2014 +0100
2014-05-15 Ed Smith-Rowland 3dw...@verizon.net
Jonathan Wakely jwak...@redhat.com
PR libstdc++/61166
* include/bits/parse_numbers.h: Use integral_constant to remove
duplication and simplify.
* testsuite/20_util/duration/literals/61166.cc: New.
diff --git a/libstdc++-v3/include/bits/parse_numbers.h b/libstdc++-v3/include/bits/parse_numbers.h
index 91a127c..0a42381a 100644
--- a/libstdc++-v3/include/bits/parse_numbers.h
+++ b/libstdc++-v3/include/bits/parse_numbers.h
@@ -27,8 +27,8 @@
* Do not attempt to use it directly. @headername{chrono}
*/
-#ifndef _PARSE_NUMBERS_H
-#define _PARSE_NUMBERS_H 1
+#ifndef _GLIBCXX_PARSE_NUMBERS_H
+#define _GLIBCXX_PARSE_NUMBERS_H 1
#pragma GCC system_header
@@ -36,289 +36,181 @@
#if __cplusplus 201103L
+#include limits
+
namespace std _GLIBCXX_VISIBILITY(default)
{
_GLIBCXX_BEGIN_NAMESPACE_VERSION
-namespace __parse_int {
-
+namespace __parse_int
+{
templateunsigned _Base, char _Dig
struct _Digit;
templateunsigned _Base
-struct _Digit_Base, '0'
+struct _Digit_Base, '0' : integral_constantunsigned, 0
{
- static constexpr bool valid{true};
- static constexpr unsigned value{0};
+ using __valid = true_type;
};
templateunsigned _Base
-struct _Digit_Base, '1'
+struct _Digit_Base, '1' : integral_constantunsigned, 1
{
- static constexpr bool valid{true};
- static constexpr unsigned value{1};
+ using __valid = true_type;
};
- templateunsigned _Base
-struct _Digit_Base, '2'
+ templateunsigned _Base, unsigned _Val
+struct _Digit_impl : integral_constantunsigned, _Val
{
- static_assert(_Base 2, invalid digit);
- static constexpr bool valid{true};
- static constexpr unsigned value{2};
+ static_assert(_Base _Val, invalid digit);
+ using __valid = true_type;
};
templateunsigned _Base
-struct _Digit_Base, '3'
-{
- static_assert(_Base 3, invalid digit);
- static constexpr bool valid{true};
- static constexpr unsigned value{3};
-};
+struct _Digit_Base, '2' : _Digit_impl_Base, 2
+{ };
templateunsigned _Base
-struct _Digit_Base, '4'
-{
- static_assert(_Base 4, invalid digit);
- static constexpr bool valid{true};
- static constexpr unsigned value{4};
-};
+struct _Digit_Base, '3' : _Digit_impl_Base, 3
+{ };
templateunsigned _Base
-struct _Digit_Base, '5'
-{
- static_assert(_Base 5, invalid digit);
- static constexpr bool valid{true};
- static constexpr unsigned value{5};
-};
+struct _Digit_Base, '4' : _Digit_impl_Base, 4
+{ };
templateunsigned _Base
-struct _Digit_Base, '6'
-{
- static_assert(_Base 6, invalid digit);
- static constexpr bool valid{true};
- static constexpr unsigned value{6};
-};
+struct _Digit_Base, '5' : _Digit_impl_Base, 5
+{ };
templateunsigned _Base
-struct _Digit_Base, '7'
-{
- static_assert(_Base 7, invalid digit);
- static constexpr bool valid{true};
- static constexpr unsigned value{7};
-};
+struct _Digit_Base, '6' : _Digit_impl_Base, 6
+{ };
templateunsigned _Base
-struct _Digit_Base, '8'
-{
- static_assert(_Base 8, invalid digit);
- static constexpr bool valid{true};
- static constexpr unsigned value{8};
-};
+struct _Digit_Base, '7' : _Digit_impl_Base, 7
+{ };
templateunsigned _Base
-struct _Digit_Base, '9'
-{
- static_assert(_Base 9, invalid digit);
- static constexpr bool valid{true};
- static constexpr unsigned value{9};
-};
+struct _Digit_Base, '8' : _Digit_impl_Base, 8
+{ };
templateunsigned _Base
-struct _Digit_Base, 'a'
-{
- static_assert(_Base 0xa, invalid digit);
- static constexpr bool valid{true};
- static constexpr unsigned value{0xa};
-};
+struct _Digit_Base, '9' : _Digit_impl_Base, 9
+{ };
templateunsigned _Base
-struct _Digit_Base, 'A'
-{
- static_assert(_Base 0xa, invalid digit);
- static constexpr bool valid{true};
- static constexpr unsigned value{0xa};
-};
+struct _Digit_Base, 'a' : _Digit_impl_Base, 0xa
+{ };
templateunsigned _Base
-struct _Digit_Base, 'b'
-{
- static_assert(_Base 0xb, invalid digit);
- static constexpr bool valid{true};
- static constexpr unsigned value{0xb};
-};
+struct _Digit_Base, 'A' : _Digit_impl_Base, 0xa
+{ };
templateunsigned _Base
-struct _Digit_Base, 'B'
-{
- static_assert(_Base 0xb, invalid digit);
- static constexpr bool valid{true};
- static constexpr
Re: [PATCH, libstdc++/61166] overflow when parse number in std::duration operator
On 05/15/2014 03:03 PM, Jonathan Wakely wrote: Here's a finished patch to simplify bits/parse_numbers.h Tested x86_64-linux. Ed, any objection to this version? This looks great, thanks! Having done that should we actually stop using it as suggested in the bug trail? ;-)
[PATCH, libstdc++/61166] overflow when parse number in std::duration operator
Make the machinery in bits/parse_number.h unsigned long long.
I had actually noticed this a while back but we were in stage 4. Then I
forgot.. :-/
Built and tested on x84_64-linux.
OK?
2014-05-14 Ed Smith-Rowland 3dw...@verizon.net
libstdc++/61166 overflow when parse number in std::duration operator
* include/bits/parse_numbers.h: Make the machinery unsigned long long.
* testsuite/20_util/duration/literals/pr61166.cc: New.
Index: include/bits/parse_numbers.h
===
--- include/bits/parse_numbers.h(revision 210315)
+++ include/bits/parse_numbers.h(working copy)
@@ -27,8 +27,8 @@
* Do not attempt to use it directly. @headername{chrono}
*/
-#ifndef _PARSE_NUMBERS_H
-#define _PARSE_NUMBERS_H 1
+#ifndef _GLIBCXX_PARSE_NUMBERS_H
+#define _GLIBCXX_PARSE_NUMBERS_H 1
#pragma GCC system_header
@@ -36,262 +36,278 @@
#if __cplusplus 201103L
+#include limits
+
namespace std _GLIBCXX_VISIBILITY(default)
{
_GLIBCXX_BEGIN_NAMESPACE_VERSION
-namespace __parse_int {
+namespace __parse_int
+{
- templateunsigned _Base, char _Dig
+ templateunsigned long long _Base, char _Dig
struct _Digit;
- templateunsigned _Base
+ templateunsigned long long _Base
struct _Digit_Base, '0'
{
static constexpr bool valid{true};
- static constexpr unsigned value{0};
+ static constexpr unsigned long long value{0};
};
- templateunsigned _Base
+ templateunsigned long long _Base
struct _Digit_Base, '1'
{
static constexpr bool valid{true};
- static constexpr unsigned value{1};
+ static constexpr unsigned long long value{1};
};
- templateunsigned _Base
+ templateunsigned long long _Base
struct _Digit_Base, '2'
{
static_assert(_Base 2, invalid digit);
static constexpr bool valid{true};
- static constexpr unsigned value{2};
+ static constexpr unsigned long long value{2};
};
- templateunsigned _Base
+ templateunsigned long long _Base
struct _Digit_Base, '3'
{
static_assert(_Base 3, invalid digit);
static constexpr bool valid{true};
- static constexpr unsigned value{3};
+ static constexpr unsigned long long value{3};
};
- templateunsigned _Base
+ templateunsigned long long _Base
struct _Digit_Base, '4'
{
static_assert(_Base 4, invalid digit);
static constexpr bool valid{true};
- static constexpr unsigned value{4};
+ static constexpr unsigned long long value{4};
};
- templateunsigned _Base
+ templateunsigned long long _Base
struct _Digit_Base, '5'
{
static_assert(_Base 5, invalid digit);
static constexpr bool valid{true};
- static constexpr unsigned value{5};
+ static constexpr unsigned long long value{5};
};
- templateunsigned _Base
+ templateunsigned long long _Base
struct _Digit_Base, '6'
{
static_assert(_Base 6, invalid digit);
static constexpr bool valid{true};
- static constexpr unsigned value{6};
+ static constexpr unsigned long long value{6};
};
- templateunsigned _Base
+ templateunsigned long long _Base
struct _Digit_Base, '7'
{
static_assert(_Base 7, invalid digit);
static constexpr bool valid{true};
- static constexpr unsigned value{7};
+ static constexpr unsigned long long value{7};
};
- templateunsigned _Base
+ templateunsigned long long _Base
struct _Digit_Base, '8'
{
static_assert(_Base 8, invalid digit);
static constexpr bool valid{true};
- static constexpr unsigned value{8};
+ static constexpr unsigned long long value{8};
};
- templateunsigned _Base
+ templateunsigned long long _Base
struct _Digit_Base, '9'
{
static_assert(_Base 9, invalid digit);
static constexpr bool valid{true};
- static constexpr unsigned value{9};
+ static constexpr unsigned long long value{9};
};
- templateunsigned _Base
+ templateunsigned long long _Base
struct _Digit_Base, 'a'
{
static_assert(_Base 0xa, invalid digit);
static constexpr bool valid{true};
- static constexpr unsigned value{0xa};
+ static constexpr unsigned long long value{0xa};
};
- templateunsigned _Base
+ templateunsigned long long _Base
struct _Digit_Base, 'A'
{
static_assert(_Base 0xa, invalid digit);
static constexpr bool valid{true};
- static constexpr unsigned value{0xa};
+ static constexpr unsigned long long value{0xa};
};
- templateunsigned _Base
+ templateunsigned long long _Base
struct _Digit_Base, 'b'
{
static_assert(_Base 0xb, invalid digit);
static constexpr bool valid{true};
- static constexpr unsigned value{0xb};
+ static constexpr unsigned long long value{0xb};
};
- templateunsigned _Base
+
Re: [PATCH, libstdc++/61166] overflow when parse number in std::duration operator
2014-05-14 15:38 GMT+02:00 Ed Smith-Rowland 3dw...@verizon.net: Make the machinery in bits/parse_number.h unsigned long long. I had actually noticed this a while back but we were in stage 4. Then I forgot.. :-/ Built and tested on x84_64-linux. OK? I understand the reason why the corresponding static members value got type unsigned long long, but why did the template parameter _Base also require the same update? Another question: Presumably value indded requires no uglification, but what about the member valid? I would expect that this is no name reserved by the library. - Daniel -- SavedURI :Show URLShow URLSavedURI : SavedURI :Hide URLHide URLSavedURI : https://mail.google.com/_/scs/mail-static/_/js/k=gmail.main.de.LEt2fN4ilLE.O/m=m_i,t,it/am=OCMOBiHj9kJxhnelj6j997_NLil29vVAOBGeBBRgJwD-m_0_8B_AD-qOEw/rt=h/d=1/rs=AItRSTODy9wv1JKZMABIG3Ak8ViC4kuOWA?random=1395770800154https://mail.google.com/_/scs/mail-static/_/js/k=gmail.main.de.LEt2fN4ilLE.O/m=m_i,t,it/am=OCMOBiHj9kJxhnelj6j997_NLil29vVAOBGeBBRgJwD-m_0_8B_AD-qOEw/rt=h/d=1/rs=AItRSTODy9wv1JKZMABIG3Ak8ViC4kuOWA?random=1395770800154
Re: [PATCH, libstdc++/61166] overflow when parse number in std::duration operator
On 14 May 2014 14:59, Daniel Krügler wrote: 2014-05-14 15:38 GMT+02:00 Ed Smith-Rowland 3dw...@verizon.net: Make the machinery in bits/parse_number.h unsigned long long. I had actually noticed this a while back but we were in stage 4. Then I forgot.. :-/ Built and tested on x84_64-linux. OK? I understand the reason why the corresponding static members value got type unsigned long long, but why did the template parameter _Base also require the same update? Another question: Presumably value indded requires no uglification, but what about the member valid? I would expect that this is no name reserved by the library. Good point. (It's a member function in at least future, but we shouldn't be reserving it elsewhere). Any time I see a static const member of integral type called value I wonder if the type should derive from a specialization of std::integral_constant. You could probably also do: using __valid = true_type;
Re: [PATCH, libstdc++/61166] overflow when parse number in std::duration operator
On 05/14/2014 09:59 AM, Daniel Krügler wrote: 2014-05-14 15:38 GMT+02:00 Ed Smith-Rowland 3dw...@verizon.net: Make the machinery in bits/parse_number.h unsigned long long. I had actually noticed this a while back but we were in stage 4. Then I forgot.. :-/ Built and tested on x84_64-linux. OK? I understand the reason why the corresponding static members value got type unsigned long long, but why did the template parameter _Base also require the same update? Another question: Presumably value indded requires no uglification, but what about the member valid? I would expect that this is no name reserved by the library. - Daniel You're right, _Base doesn't need that - only 2, 8, 10, 16 allowed (could do base64 someday, but still). Change all got me. I should uglify the valid members. But in keeping with, say, our extension type traits and such maybe i should uglify value as well.
Re: [PATCH, libstdc++/61166] overflow when parse number in std::duration operator
On 14 May 2014 15:25, Ed Smith-Rowland wrote: But in keeping with, say, our extension type traits and such maybe i should uglify value as well. No, just derive from std::integral_constant and you get value for free. You already use integral_constant in that file, so the name value is already used.
Re: [PATCH, libstdc++/61166] overflow when parse number in std::duration operator
On 14 May 2014 15:36, Jonathan Wakely wrote: On 14 May 2014 15:25, Ed Smith-Rowland wrote: But in keeping with, say, our extension type traits and such maybe i should uglify value as well. No, just derive from std::integral_constant and you get value for free. You already use integral_constant in that file, so the name value is already used. That also has the advantage that _DigitB, 'f' and _DigitB, 'F' share the same base class, so you don't end up with two different static members with the same value (and if you make __valid a typedef as I suggested you don't have any static members for that either). Do we really need _Digit::value to be unsigned long long, or is it only the results in _Power_help and _Number_help that need to be 64-bit?
Re: [PATCH, libstdc++/61166] overflow when parse number in std::duration operator
On 14/05/14 15:41 +0100, Jonathan Wakely wrote:
On 14 May 2014 15:36, Jonathan Wakely wrote:
On 14 May 2014 15:25, Ed Smith-Rowland wrote:
But in keeping with, say, our extension type traits and such maybe i should
uglify value as well.
No, just derive from std::integral_constant and you get value for free.
You already use integral_constant in that file, so the name value is
already used.
That also has the advantage that _DigitB, 'f' and _DigitB, 'F'
share the same base class, so you don't end up with two different
static members with the same value (and if you make __valid a typedef
as I suggested you don't have any static members for that either).
I've attached a first pass at doing it that way, using
integral_constant base classes and working with types not values as
much as possible. This gets rid of all static const members except in
_Digits (where is that used?)
Do we really need _Digit::value to be unsigned long long, or is it
only the results in _Power_help and _Number_help that need to be
64-bit?
Because I made _Digit derive from integral_constantunsigned that
means the partial specialization of _Number_help for single digits has
_Number_help::type as integral_constantunsigned, where the other
specializations have integral_constantunsigned long long. That's
inconsistent, but works. Maybe we'd want to be consistent though, and
use this instead of typename _DigitBase, _Dig::type:
using type = integral_constantunsigned long long,
_Digit_Base, _Dig::value;
(Also, I wonder if we could use std::ratio for the power/base
arithmetic, but it might not help.)
diff --git a/libstdc++-v3/include/bits/parse_numbers.h b/libstdc++-v3/include/bits/parse_numbers.h
index 91a127c..055058e 100644
--- a/libstdc++-v3/include/bits/parse_numbers.h
+++ b/libstdc++-v3/include/bits/parse_numbers.h
@@ -46,185 +46,109 @@ namespace __parse_int {
struct _Digit;
templateunsigned _Base
-struct _Digit_Base, '0'
+struct _Digit_Base, '0' : integral_constantunsigned, 0
{
- static constexpr bool valid{true};
- static constexpr unsigned value{0};
+ using __valid = true_type;
};
templateunsigned _Base
-struct _Digit_Base, '1'
+struct _Digit_Base, '1' : integral_constantunsigned, 1
{
- static constexpr bool valid{true};
- static constexpr unsigned value{1};
+ using __valid = true_type;
};
- templateunsigned _Base
-struct _Digit_Base, '2'
+ templateunsigned _Base, unsigned _Val
+struct _Digit_impl : integral_constantunsigned, _Val
{
- static_assert(_Base 2, invalid digit);
- static constexpr bool valid{true};
- static constexpr unsigned value{2};
+ static_assert(_Base _Val, invalid digit);
+ using __valid = true_type;
};
templateunsigned _Base
-struct _Digit_Base, '3'
-{
- static_assert(_Base 3, invalid digit);
- static constexpr bool valid{true};
- static constexpr unsigned value{3};
-};
+struct _Digit_Base, '2' : _Digit_impl_Base, 2
+{ };
templateunsigned _Base
-struct _Digit_Base, '4'
-{
- static_assert(_Base 4, invalid digit);
- static constexpr bool valid{true};
- static constexpr unsigned value{4};
-};
+struct _Digit_Base, '3' : _Digit_impl_Base, 3
+{ };
templateunsigned _Base
-struct _Digit_Base, '5'
-{
- static_assert(_Base 5, invalid digit);
- static constexpr bool valid{true};
- static constexpr unsigned value{5};
-};
+struct _Digit_Base, '4' : _Digit_impl_Base, 4
+{ };
templateunsigned _Base
-struct _Digit_Base, '6'
-{
- static_assert(_Base 6, invalid digit);
- static constexpr bool valid{true};
- static constexpr unsigned value{6};
-};
+struct _Digit_Base, '5' : _Digit_impl_Base, 5
+{ };
templateunsigned _Base
-struct _Digit_Base, '7'
-{
- static_assert(_Base 7, invalid digit);
- static constexpr bool valid{true};
- static constexpr unsigned value{7};
-};
+struct _Digit_Base, '6' : _Digit_impl_Base, 6
+{ };
templateunsigned _Base
-struct _Digit_Base, '8'
-{
- static_assert(_Base 8, invalid digit);
- static constexpr bool valid{true};
- static constexpr unsigned value{8};
-};
+struct _Digit_Base, '7' : _Digit_impl_Base, 7
+{ };
templateunsigned _Base
-struct _Digit_Base, '9'
-{
- static_assert(_Base 9, invalid digit);
- static constexpr bool valid{true};
- static constexpr unsigned value{9};
-};
+struct _Digit_Base, '8' : _Digit_impl_Base, 8
+{ };
templateunsigned _Base
-struct _Digit_Base, 'a'
-{
- static_assert(_Base 0xa, invalid digit);
- static constexpr bool valid{true};
- static constexpr unsigned value{0xa};
-};
+struct _Digit_Base, '9' : _Digit_impl_Base, 9
+{ };
templateunsigned _Base
-struct _Digit_Base, 'A'
-
