Opened 7 years ago
Last modified 8 months ago
#6546 new Bugs
mpl::constant_c does not support min and max values for signed types
Reported by: | Owned by: | Aleksey Gurtovoy | |
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Milestone: | To Be Determined | Component: | mpl |
Version: | Boost Development Trunk | Severity: | Problem |
Keywords: | Cc: | viboes |
Description
Boost.Ratio test fails on debian linux with gcc 4.6.
gcc.compile.c++ ../../../bin.v2/libs/ratio/test/ratio_add_pass.test/gcc-4.6/debug/ratio_add_pass.o In file included from ../../../boost/mpl/integral_c.hpp:32:0, from ../../../boost/ratio/detail/mpl/abs.hpp:15, from ../../../boost/ratio/ratio.hpp:36, from ratio_arithmetic/ratio_add_pass.cpp:16: ../../../boost/mpl/aux_/integral_wrapper.hpp: In instantiation of ‘mpl_::integral_c<long int, 9223372036854775807l>’: ../../../boost/ratio/detail/mpl/abs.hpp:38:29: instantiated from ‘boost::mpl::abs_tag<mpl_::integral_c<long int, 9223372036854775807l> >’ ../../../boost/ratio/detail/mpl/abs.hpp:44:8: instantiated from ‘boost::mpl::abs<mpl_::integral_c<long int, 9223372036854775807l> >’ ../../../boost/ratio/detail/mpl/abs.hpp:58:8: instantiated from ‘boost::mpl::abs_c<long int, 9223372036854775807l>’ ../../../boost/ratio/ratio.hpp:79:74: instantiated from ‘const intmax_t boost::ratio<9223372036854775807l, 1l>::ABS_N’ ../../../boost/ratio/ratio.hpp:81:5: instantiated from ‘boost::ratio<9223372036854775807l, 1l>’ ../../../boost/ratio/detail/overflow_helpers.hpp:227:95: instantiated from ‘const intmax_t boost::ratio_detail::ratio_add<boost::ratio<9223372036854775807l, 1l>, boost::ratio<-0x00000000000000001l, 1l> >::gcd_n1_n2’ ../../../boost/ratio/detail/overflow_helpers.hpp:243:18: instantiated from ‘boost::ratio_detail::ratio_add<boost::ratio<9223372036854775807l, 1l>, boost::ratio<-0x00000000000000001l, 1l> >’ ../../../boost/ratio/ratio.hpp:136:8: instantiated from ‘boost::ratio_add<boost::ratio<9223372036854775807l, 1l>, boost::ratio<-0x00000000000000001l, 1l> >’ ratio_arithmetic/ratio_add_pass.cpp:70:37: instantiated from here ../../../boost/mpl/aux_/integral_wrapper.hpp:72:96: warning: integer overflow in expression [-Woverflow] ../../../boost/mpl/aux_/integral_wrapper.hpp:72:96: error: overflow in constant expression [-fpermissive] ../../../boost/mpl/aux_/integral_wrapper.hpp:72:96: note: in template argument for type ‘long int’
Change History (6)
comment:1 Changed 7 years ago by
comment:2 Changed 7 years ago by
Status: | new → assigned |
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Hi,
this is know issue on the Boost.Mpl which instantiates the next and the previous number. I've proposed a patch long time ago (since I started to use gcc-4.6) but it has not been applied. I will see what can I do.
comment:3 Changed 7 years ago by
Cc: | viboes added |
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Component: | ratio → mpl |
I have found the post. See http://boost.2283326.n4.nabble.com/mpl-integral-c-type-traits-integral-constant-limits-tt3042126.html#a3170972.
Moving this to Boost.Mpl.
comment:4 Changed 7 years ago by
Owner: | changed from viboes to Aleksey Gurtovoy |
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Status: | assigned → new |
comment:5 Changed 8 months ago by
This bug still seems to exist (I tried today's mpl git master). The essence, as indicated in the mailing list thread above, is that mpl::integral_c
cannot support the minimum and maximum values of signed types, since the compiler does not allow defining the prior and next values, since that would cause signed overflow which is undefined.
The error shown in the original report is about using ratio, but this bug can be easily reproduced on by instantiating mpl::integral_c
directly:
#include <boost/mpl/integral_c.hpp> typedef boost::mpl::integral_c<int32_t,0x7fffffff>::type next_ovf_32; typedef boost::mpl::integral_c<int32_t,0x80000000>::type prior_ovf_32; typedef boost::mpl::integral_c<int64_t,0x7fffffffffffffff>::type next_ovf_64; typedef boost::mpl::integral_c<int64_t,0x8000000000000000>::type prior_ovf_64;
Which leads to these errors (only one of four shown).
In file included from foo.cpp:1:0: mpl/include/boost/mpl/aux_/integral_wrapper.hpp: In instantiation of ‘struct mpl_::integral_c<long int, -9223372036854775808l>’: foo.cpp:6:59: required from here mpl/include/boost/mpl/aux_/integral_wrapper.hpp:73:88: warning: integer overflow in expression [-Woverflow] typedef AUX_WRAPPER_INST( BOOST_MPL_AUX_STATIC_CAST(AUX_WRAPPER_VALUE_TYPE, (value - 1)) ) prior; ~~~~~~~^~~~ mpl/include/boost/mpl/integral_c.hpp:31:54: note: in definition of macro ‘AUX_WRAPPER_INST’ #define AUX_WRAPPER_INST(value) AUX_WRAPPER_NAME< T, value > ^~~~~ mpl/include/boost/mpl/aux_/integral_wrapper.hpp:73:31: note: in expansion of macro ‘BOOST_MPL_AUX_STATIC_CAST’ typedef AUX_WRAPPER_INST( BOOST_MPL_AUX_STATIC_CAST(AUX_WRAPPER_VALUE_TYPE, (value - 1)) ) prior; ^~~~~~~~~~~~~~~~~~~~~~~~~ In file included from mpl/include/boost/mpl/integral_c.hpp:32:0, from foo.cpp:1: mpl/include/boost/mpl/aux_/integral_wrapper.hpp:73:96: error: overflow in constant expression [-fpermissive] typedef AUX_WRAPPER_INST( BOOST_MPL_AUX_STATIC_CAST(AUX_WRAPPER_VALUE_TYPE, (value - 1)) ) prior; ^~~~~ mpl/include/boost/mpl/aux_/integral_wrapper.hpp:73:96: error: overflow in constant expression [-fpermissive] mpl/include/boost/mpl/aux_/integral_wrapper.hpp:73:96: note: in template argument for type ‘long int’
Solutions proposed in that thread are:
- Convert to
intmax_t
before doing the +1 or -1. This is easy, but only fixes things for types smaller thanintmax_t
, leaves the problem forintmax_t
and probably introduces the problem foruintmax_t
. Post nr8 from Krzysztof Czainski in the above linked mailing list thread has an example implementation. - Specialize
integral_c
for these limiting values, leaving out thenext
orprior
member. Post nr8 from Krzysztof Czainski in the above linked mailing list thread suggests this. - Remove the
next
andprior
members fromintegral_c
and use tag dispatch for them instead. Post nr4 by Vicente Botet in the above linked mailing list thread has a patch.
#3779 seems to be a duplicate of this bug.
comment:6 Changed 8 months ago by
Summary: | ratio_arithmetic/ratio_add_pass fails to compile → mpl::constant_c does not support min and max values for signed types |
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Version: | Boost Release Branch → Boost Development Trunk |
There are similar failures for a dozen other tests, and it appears on both the Sandia and Debian gcc 4.6 testing systems; see http://www.boost.org/development/tests/release/developer/ratio.html