[Bug c++/18161] New: [4.0 regression] typeof(1==1) is now int instead of bool

[bangerth at dealii dot org]

For this code 
----------------- 
template <typename = typeof(1==1)> struct X { X(){} }; 
template struct X<>; 
----------------- 
I would expect an instantiation of X<bool>, and indeed got it up to 
3.4. However, since 4.0 we get X<int>: 
 
g/x> /home/bangerth/bin/gcc-3.4*/bin/c++ -c x.cc ; nm -C x.o 
00000000 W X<bool>::X() 
00000000 W X<bool>::X() 
g/x> /home/bangerth/bin/gcc-4*/bin/c++ -c x.cc ; nm -C x.o 
00000000 W X<int>::X() 
00000000 W X<int>::X() 
 
 
This is somehow odd, since for a related piece of code 
------------------- 
template <typename> struct X {}; 
void foo(X<typeof(1==1)>) {} 
------------------- 
there is no regression: 
 
g/x> /home/bangerth/bin/gcc-3.4*/bin/c++ -c y.cc ; nm -C y.o 
00000000 T foo(X<bool>) 
g/x> /home/bangerth/bin/gcc-4*/bin/c++ -c y.cc ; nm -C y.o 
00000000 T foo(X<bool>) 
 
W.

-- 
           Summary: [4.0 regression] typeof(1==1) is now int instead of bool
           Product: gcc
           Version: 4.0.0
            Status: UNCONFIRMED
          Keywords: wrong-code
          Severity: normal
          Priority: P2
         Component: c++
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: bangerth at dealii dot org
                CC: gcc-bugs at gcc dot gnu dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=18161