[Bug c++/49292] New: [c++0x] non_const_var_error ICE for error when mixing static_assert, template, and constexpr

[Bug c++/49292] New: [c++0x] non_const_var_error ICE for error when mixing static_assert, template, and constexpr

[lankyleggy at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49292

           Summary: [c++0x] non_const_var_error ICE for error when mixing
                    static_assert, template, and constexpr
           Product: gcc
           Version: 4.7.0
            Status: UNCONFIRMED
          Severity: minor
          Priority: P3
         Component: c++
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: lankyleggy@gmail.com


Created attachment 24439
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=24439
Preprocessed code

When trying to compile this code with SVN trunk revision 174633:

template <int n, int min, int max>
struct no_divisors_between
{
        static constexpr bool v()
        {
                return (n % min) && no_divisors_between<n, min + 1, max>::v();
        }
};
template <int n, int k>
struct no_divisors_between<n, k, k>
{
        static constexpr bool v()
        {
                return n % random_undefined_symbol_which_should_be_k;
        }
};

template <int size>
class SillyHashTable
{
public:
        static constexpr bool get_good_size()
        {
                return m_good_size;
        }
private:
        static const bool m_good_size = no_divisors_between<size, 2,
size-1>::v();
};

int main()
{
        const int hash_table_size = 5;
        static_assert(SillyHashTable<hash_table_size>::get_good_size(),
"hash_table_size should be a prime.");
}



I get an internal compiler error:

james@ubuntu:~/Desktop$ /home/james/programs/other/gcc_install/bin/g++ -v
-save-temps -std=c++0x test.cc
Using built-in specs.
COLLECT_GCC=/home/james/programs/other/gcc_install/bin/g++
COLLECT_LTO_WRAPPER=/home/james/programs/other/gcc_install/libexec/gcc/x86_64-unknown-linux-gnu/4.7.0/lto-wrapper
Target: x86_64-unknown-linux-gnu
Configured with: ../gcc/configure
--prefix=/home/james/programs/other/gcc_install/
--with-local-prefix=/home/james/programs/other/gcc_install/ --disable-bootstrap
Thread model: posix
gcc version 4.7.0 20110604 (experimental) (GCC) 
COLLECT_GCC_OPTIONS='-v' '-save-temps' '-std=c++0x' '-shared-libgcc'
'-mtune=generic' '-march=x86-64'

/home/james/programs/other/gcc_install/libexec/gcc/x86_64-unknown-linux-gnu/4.7.0/cc1plus
-E -quiet -v -D_GNU_SOURCE test.cc -mtune=generic -march=x86-64 -std=c++0x
-fpch-preprocess -o test.ii
ignoring duplicate directory "/home/james/programs/other/gcc_install/include"
ignoring nonexistent directory
"/home/james/programs/other/gcc_install/lib/gcc/x86_64-unknown-linux-gnu/4.7.0/../../../../x86_64-unknown-linux-gnu/include"
#include "..." search starts here:
#include <...> search starts here:

/home/james/programs/other/gcc_install/lib/gcc/x86_64-unknown-linux-gnu/4.7.0/../../../../include/c++/4.7.0

/home/james/programs/other/gcc_install/lib/gcc/x86_64-unknown-linux-gnu/4.7.0/../../../../include/c++/4.7.0/x86_64-unknown-linux-gnu

/home/james/programs/other/gcc_install/lib/gcc/x86_64-unknown-linux-gnu/4.7.0/../../../../include/c++/4.7.0/backward

/home/james/programs/other/gcc_install/lib/gcc/x86_64-unknown-linux-gnu/4.7.0/include
 /home/james/programs/other/gcc_install//include

/home/james/programs/other/gcc_install/lib/gcc/x86_64-unknown-linux-gnu/4.7.0/include-fixed
 /usr/include
End of search list.
COLLECT_GCC_OPTIONS='-v' '-save-temps' '-std=c++0x' '-shared-libgcc'
'-mtune=generic' '-march=x86-64'

/home/james/programs/other/gcc_install/libexec/gcc/x86_64-unknown-linux-gnu/4.7.0/cc1plus
-fpreprocessed test.ii -quiet -dumpbase test.cc -mtune=generic -march=x86-64
-auxbase test -std=c++0x -version -o test.s
GNU C++ (GCC) version 4.7.0 20110604 (experimental) (x86_64-unknown-linux-gnu)
    compiled by GNU C version 4.7.0 20110604 (experimental), GMP version 4.3.2,
MPFR version 2.4.2-p1, MPC version 0.8.1
GGC heuristics: --param ggc-min-expand=30 --param ggc-min-heapsize=4096
GNU C++ (GCC) version 4.7.0 20110604 (experimental) (x86_64-unknown-linux-gnu)
    compiled by GNU C version 4.7.0 20110604 (experimental), GMP version 4.3.2,
MPFR version 2.4.2-p1, MPC version 0.8.1
GGC heuristics: --param ggc-min-expand=30 --param ggc-min-heapsize=4096
Compiler executable checksum: ce3a170bafb891f93f6be982ba0564e4
test.cc: In static member function ‘static constexpr bool
no_divisors_between<n, k, k>::v()’:
test.cc:14:28: error: ‘random_undefined_symbol_which_should_be_k’ was not
declared in this scope
test.cc: In static member function ‘static constexpr bool
no_divisors_between<n, k, k>::v() [with int n = 5, int k = 4]’:
test.cc:6:77:   recursively instantiated from ‘static constexpr bool
no_divisors_between<n, min, max>::v() [with int n = 5, int min = 3, int max =
4]’
test.cc:6:77:   instantiated from ‘static constexpr bool no_divisors_between<n,
min, max>::v() [with int n = 5, int min = 2, int max = 4]’
test.cc:27:81:   instantiated from ‘const bool SillyHashTable<5>::m_good_size’
test.cc:24:24:   instantiated from ‘static constexpr bool
SillyHashTable<size>::get_good_size() [with int size = 5]’
test.cc:33:56:   instantiated from here
test.cc:15:9: error: body of constexpr function ‘static constexpr bool
no_divisors_between<n, k, k>::v() [with int n = 5, int k = 4]’ not a
return-statement
test.cc: At global scope:
test.cc: In instantiation of ‘const bool SillyHashTable<5>::m_good_size’:
test.cc:24:24:   instantiated from ‘static constexpr bool
SillyHashTable<size>::get_good_size() [with int size = 5]’
test.cc:33:56:   instantiated from here
test.cc:27:81: error: non-constant in-class initialization invalid for static
member ‘SillyHashTable<5>::m_good_size’
test.cc:27:81: error: (an out of class initialisation is required)
test.cc:27:81: error: ‘SillyHashTable<5>::m_good_size’ cannot be initialised by
a non-constant expression when being declared
test.cc: In function ‘int main()’:
test.cc:33:9: error: non-constant condition for static assertion
test.cc:33:70:   in constexpr expansion of ‘SillyHashTable<size>::get_good_size
[with int size = 5]()’
test.cc:33:9: error: the value of ‘SillyHashTable<5>::m_good_size’ is not
usable in a constant expression
test.cc:33:9: internal compiler error: in non_const_var_error, at
cp/semantics.c:6908
Please submit a full bug report,
with preprocessed source if appropriate.
See <http://gcc.gnu.org/bugs.html> for instructions.

The code should not compile anyway: and the first compiler error explains why.
I can't reproduce this ICE on similar code with the error fixed, so I've set
this bug's severity to minor.

[Bug c++/49292] [c++0x] non_const_var_error ICE for error when mixing static_assert, template, and constexpr

[jason at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49292

Jason Merrill <jason at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |RESOLVED
                 CC|                            |jason at gcc dot gnu.org
         Resolution|                            |FIXED

--- Comment #1 from Jason Merrill <jason at gcc dot gnu.org> 2011-06-15 17:08:23 UTC ---
This works now; I think it was fixed by my 6/9 patch.