[mpl] int_<INT_MIN> fails to compile under gcc 4.6
I'm not actually sure if this is a gcc regression, or a bug in mpl, but the following code, which compiles under gcc 4.5, doesn't do so under gcc 4.6: #include <climits> #include <boost/mpl/int.hpp> typedef boost::mpl::int_<INT_MIN> Foo; Foo f; It produces the errors: /usr/local/include/boost/mpl/aux_/integral_wrapper.hpp: In instantiation of ‘mpl_::int_<-0x00000000080000000>’: test_test.cpp:8:27: instantiated from here /usr/local/include/boost/mpl/aux_/integral_wrapper.hpp:73:96: error: ‘2147483647’ is not a valid template argument for type ‘int’ because it is a non-constant expression /usr/local/include/boost/mpl/aux_/integral_wrapper.hpp:73:96: error: overflow in constant expression [-fpermissive] I've already created a trak ticket for this (#5268), but was wondering if anyone had any insights as to its cause and/or any workarounds. My guess is that its related to gcc rewriting parts of its constant folding code to support constexpr. -- Stirling Westrup Programmer, Entrepreneur. https://www.linkedin.com/e/fpf/77228 http://www.linkedin.com/in/swestrup http://technaut.livejournal.com http://sourceforge.net/users/stirlingwestrup
Stirling Westrup wrote:
I'm not actually sure if this is a gcc regression, or a bug in mpl, but the following code, which compiles under gcc 4.5, doesn't do so under gcc 4.6:
#include <climits> #include <boost/mpl/int.hpp> typedef boost::mpl::int_<INT_MIN> Foo; Foo f;
It produces the errors:
/usr/local/include/boost/mpl/aux_/integral_wrapper.hpp: In instantiation of ‘mpl_::int_<-0x00000000080000000>’: test_test.cpp:8:27: instantiated from here /usr/local/include/boost/mpl/aux_/integral_wrapper.hpp:73:96: error: ‘2147483647’ is not a valid template argument for type ‘int’ because it is a non-constant expression /usr/local/include/boost/mpl/aux_/integral_wrapper.hpp:73:96: error: overflow in constant expression [-fpermissive]
I've already created a trak ticket for this (#5268), but was wondering if anyone had any insights as to its cause and/or any workarounds. My guess is that its related to gcc rewriting parts of its constant folding code to support constexpr.
I can confirm that. INT_MIN isn't the only problem, it fails for a lot of other values as well. Can you please raise this issue on the gcc bugtracker because the release is very close. Cheers, Philipp
On Sun, Mar 6, 2011 at 5:50 AM, Philipp Reh <sefi@s-e-f-i.de> wrote:
Stirling Westrup wrote:
I'm not actually sure if this is a gcc regression, or a bug in mpl, but the following code, which compiles under gcc 4.5, doesn't do so under gcc 4.6:
#include <climits> #include <boost/mpl/int.hpp> typedef boost::mpl::int_<INT_MIN> Foo; Foo f;
It produces the errors:
/usr/local/include/boost/mpl/aux_/integral_wrapper.hpp: In instantiation of ‘mpl_::int_<-0x00000000080000000>’: test_test.cpp:8:27: instantiated from here /usr/local/include/boost/mpl/aux_/integral_wrapper.hpp:73:96: error: ‘2147483647’ is not a valid template argument for type ‘int’ because it is a non-constant expression /usr/local/include/boost/mpl/aux_/integral_wrapper.hpp:73:96: error: overflow in constant expression [-fpermissive]
I've already created a trak ticket for this (#5268), but was wondering if anyone had any insights as to its cause and/or any workarounds. My guess is that its related to gcc rewriting parts of its constant folding code to support constexpr.
I can confirm that. INT_MIN isn't the only problem, it fails for a lot of other values as well. Can you please raise this issue on the gcc bugtracker because the release is very close.
Okay, I have done so. Its bug #48003 on the GCC bugtracker. -- Stirling Westrup Programmer, Entrepreneur. https://www.linkedin.com/e/fpf/77228 http://www.linkedin.com/in/swestrup http://technaut.livejournal.com http://sourceforge.net/users/stirlingwestrup
Stirling Westrup wrote:
On Sun, Mar 6, 2011 at 5:50 AM, Philipp Reh <sefi@s-e-f-i.de> wrote:
Stirling Westrup wrote:
I'm not actually sure if this is a gcc regression, or a bug in mpl, but the following code, which compiles under gcc 4.5, doesn't do so under gcc 4.6:
#include <climits> #include <boost/mpl/int.hpp> typedef boost::mpl::int_<INT_MIN> Foo; Foo f;
It produces the errors:
/usr/local/include/boost/mpl/aux_/integral_wrapper.hpp: In instantiation of ‘mpl_::int_<-0x00000000080000000>’: test_test.cpp:8:27: instantiated from here /usr/local/include/boost/mpl/aux_/integral_wrapper.hpp:73:96: error: ‘2147483647’ is not a valid template argument for type ‘int’ because it is a non-constant expression /usr/local/include/boost/mpl/aux_/integral_wrapper.hpp:73:96: error: overflow in constant expression [-fpermissive]
I've already created a trak ticket for this (#5268), but was wondering if anyone had any insights as to its cause and/or any workarounds. My guess is that its related to gcc rewriting parts of its constant folding code to support constexpr.
I can confirm that. INT_MIN isn't the only problem, it fails for a lot of other values as well. Can you please raise this issue on the gcc bugtracker because the release is very close.
Okay, I have done so. Its bug #48003 on the GCC bugtracker.
Thanks. After looking further into this I realized that mpl tries to calculate INT_MIN-1 which, of course, is undefined. But I'm still not sure if this is a gcc bug or not because the typedef isn't used and I don't know if gcc should evaluate this.
On Sun, Mar 6, 2011 at 7:24 AM, Philipp Reh <sefi@s-e-f-i.de> wrote:
Stirling Westrup wrote:
On Sun, Mar 6, 2011 at 5:50 AM, Philipp Reh <sefi@s-e-f-i.de> wrote:
Stirling Westrup wrote:
I'm not actually sure if this is a gcc regression, or a bug in mpl, but the following code, which compiles under gcc 4.5, doesn't do so under gcc 4.6:
#include <climits> #include <boost/mpl/int.hpp> typedef boost::mpl::int_<INT_MIN> Foo; Foo f;
It produces the errors:
/usr/local/include/boost/mpl/aux_/integral_wrapper.hpp: In instantiation of ‘mpl_::int_<-0x00000000080000000>’: test_test.cpp:8:27: instantiated from here /usr/local/include/boost/mpl/aux_/integral_wrapper.hpp:73:96: error: ‘2147483647’ is not a valid template argument for type ‘int’ because it is a non-constant expression /usr/local/include/boost/mpl/aux_/integral_wrapper.hpp:73:96: error: overflow in constant expression [-fpermissive]
I've already created a trak ticket for this (#5268), but was wondering if anyone had any insights as to its cause and/or any workarounds. My guess is that its related to gcc rewriting parts of its constant folding code to support constexpr.
I can confirm that. INT_MIN isn't the only problem, it fails for a lot of other values as well. Can you please raise this issue on the gcc bugtracker because the release is very close.
Okay, I have done so. Its bug #48003 on the GCC bugtracker.
Thanks. After looking further into this I realized that mpl tries to calculate INT_MIN-1 which, of course, is undefined. But I'm still not sure if this is a gcc bug or not because the typedef isn't used and I don't know if gcc should evaluate this.
An equally important questions is what should mpl do if someone DOES ask for the prior of int_<INT_MIN>. Should it generate an error, throw an exception, return INT_MIN, or wrap around to INT_MAX? I can see arguments for most of these. Maybe it needs to be policy-defined somehow? -- Stirling Westrup Programmer, Entrepreneur. https://www.linkedin.com/e/fpf/77228 http://www.linkedin.com/in/swestrup http://technaut.livejournal.com http://sourceforge.net/users/stirlingwestrup
Stirling Westrup wrote:
On Sun, Mar 6, 2011 at 7:24 AM, Philipp Reh wrote:
Stirling Westrup wrote:
On Sun, Mar 6, 2011 at 5:50 AM, Philipp Reh wrote:
Stirling Westrup wrote:
I'm not actually sure if this is a gcc regression, or a bug in mpl, but the following code, which compiles under gcc 4.5, doesn't do so under gcc 4.6:
#include #include typedef boost::mpl::int_ Foo; Foo f;
It produces the errors:
/usr/local/include/boost/mpl/aux_/integral_wrapper.hpp: In instantiation of ‘mpl_::int_<-0x00000000080000000>’: test_test.cpp:8:27: instantiated from here /usr/local/include/boost/mpl/aux_/integral_wrapper.hpp:73:96: error: ‘2147483647’ is not a valid template argument for type ‘int’ because it is a non-constant expression /usr/local/include/boost/mpl/aux_/integral_wrapper.hpp:73:96: error: overflow in constant expression [-fpermissive]
I've already created a trak ticket for this (#5268), but was wondering if anyone had any insights as to its cause and/or any workarounds. My guess is that its related to gcc rewriting parts of its constant folding code to support constexpr.
I can confirm that. INT_MIN isn't the only problem, it fails for a lot of other values as well. Can you please raise this issue on the gcc bugtracker because the release is very close.
Okay, I have done so. Its bug #48003 on the GCC bugtracker.
Thanks. After looking further into this I realized that mpl tries to calculate INT_MIN-1 which, of course, is undefined. But I'm still not sure if this is a gcc bug or not because the typedef isn't used and I don't know if gcc should evaluate this.
An equally important questions is what should mpl do if someone DOES ask for the prior of int_. Should it generate an error, throw an exception, return INT_MIN, or wrap around to INT_MAX?
I can see arguments for most of these. Maybe it needs to be policy-defined somehow?
Hi, I provided a patch for this problem more than a month a go. I hope that it could be included in 1.47. Best, Vicente -- View this message in context: http://boost.2283326.n4.nabble.com/mpl-int-INT-MIN-fails-to-compile-under-gc... Sent from the Boost - Dev mailing list archive at Nabble.com.
participants (4)
-
Joel Falcou -
Philipp Reh -
Stirling Westrup -
Vicente Botet