[Bug c++/23914] New: [4.0 Regression] further 'non-constant' template argument case exposed by Boost

[mail at michael-stevens dot de]

Failing case comes from regression testing using Boost uBLAS with gcc4.0.2 
prerelease: 
Using built-in specs. 
Target: x86_64-unknown-linux-gnu 
Configured with: ../gcc-4.0.2-20050913/configure 
--prefix=/home/michael/locacc402 
Thread model: posix 
gcc version 4.0.2 20050913 (prerelease) 
  
The failure in this case is caused by 
 
    BOOST_STATIC_ASSERT (foo_template<int>::complexity == 0); 
where foo_template is defined thus: 
 
  template <class T> 
  struct foo_template { 
      public: 
          static const unsigned complexity = 0; 
  }; 
N.B. failure only occurs if foo_template is a template class. 
 
Suggestive is that if 'foo_template::complexity' encountered anyware by the 
compiler prior to the failing instantiation then problem disappers. Therefore 
    const unsigned a = foo_template<int>::complexity; 
    BOOST_STATIC_ASSERT (foo_template<int>::complexity == 0); 
is instantiated without error! 
 
 
Minimal test case without Boost headers is: 
 
template <class T> 
struct foo_template { 
  static const unsigned complexity = 0; 
}; 
 
template <int x> struct STATIC_ASSERTION {}; 
 
void gcc_402_problem_minimal() 
{ 
  sizeof(STATIC_ASSERTION< foo_template<int>::complexity >); 
} 
 
cc402.cpp: In function ‘void gcc_402_problem_minimal()’: 
gcc402.cpp:10: error: ‘foo_template<int>::complexity’ is not a valid template 
argument for type ‘int’ because it is a non-constant expression

-- 
           Summary: [4.0 Regression] further 'non-constant' template
                    argument case exposed by Boost
           Product: gcc
           Version: 4.0.2
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: c++
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: mail at michael-stevens dot de
                CC: gcc-bugs at gcc dot gnu dot org
GCC target triplet: x86_64-unknown-linux-gnu


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23914