[Bug c++/44138] New: Cannot call template method from derived template class

[klenze at mpp dot mpg dot de]

If a template class whose parent is a template class tries to call a template
method using the normal this->methodname<T>() syntax, g++ fails to parse the
source file (details below).

-- begin test case file bug.cpp --
#define BUG_HERE
class T1;

//class A declares a template method
class A
{
public:
  template <class X>
  void test()
  {
  }
};

//class B is derived from class A
template<class Y> 
class B : public A
{
public:
  void works()
  {
    //class B can still call the template method from class A
    this->test<T1>();
  }
};


template<class Y> 
class C : public B<Y>
{
public:
  void does_not_work()
  {
#ifdef BUG_HERE
    this->test<T1>();
    //unlike for class B, for class C, this does not work
    // with g++ (Ubuntu 4.4.3-4ubuntu5) 4.4.3
#endif

    A::test<T1>();  //this seems to compile
  }
};
-- end --

$ g++ -v -save-temps -c bug.cpp 
Using built-in specs.
Target: x86_64-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Ubuntu 4.4.3-4ubuntu5'
--with-bugurl=file:///usr/share/doc/gcc-4.4/README.Bugs
--enable-languages=c,c++,fortran,objc,obj-c++ --prefix=/usr --enable-shared
--enable-multiarch --enable-linker-build-id --with-system-zlib
--libexecdir=/usr/lib --without-included-gettext --enable-threads=posix
--with-gxx-include-dir=/usr/include/c++/4.4 --program-suffix=-4.4 --enable-nls
--enable-clocale=gnu --enable-libstdcxx-debug --enable-plugin --enable-objc-gc
--disable-werror --with-arch-32=i486 --with-tune=generic
--enable-checking=release --build=x86_64-linux-gnu --host=x86_64-linux-gnu
--target=x86_64-linux-gnu
Thread model: posix
gcc version 4.4.3 (Ubuntu 4.4.3-4ubuntu5) 
COLLECT_GCC_OPTIONS='-v' '-save-temps' '-c' '-shared-libgcc' '-mtune=generic'
 /usr/lib/gcc/x86_64-linux-gnu/4.4.3/cc1plus -E -quiet -v -D_GNU_SOURCE bug.cpp
-D_FORTIFY_SOURCE=2 -mtune=generic -fpch-preprocess -fstack-protector -o bug.ii
ignoring nonexistent directory "/usr/local/include/x86_64-linux-gnu"
ignoring nonexistent directory
"/usr/lib/gcc/x86_64-linux-gnu/4.4.3/../../../../x86_64-linux-gnu/include"
ignoring nonexistent directory "/usr/include/x86_64-linux-gnu"
#include "..." search starts here:
#include <...> search starts here:
 /usr/include/c++/4.4
 /usr/include/c++/4.4/x86_64-linux-gnu
 /usr/include/c++/4.4/backward
 /usr/local/include
 /usr/lib/gcc/x86_64-linux-gnu/4.4.3/include
 /usr/lib/gcc/x86_64-linux-gnu/4.4.3/include-fixed
 /usr/include
End of search list.
COLLECT_GCC_OPTIONS='-v' '-save-temps' '-c' '-shared-libgcc' '-mtune=generic'
 /usr/lib/gcc/x86_64-linux-gnu/4.4.3/cc1plus -fpreprocessed bug.ii -quiet
-dumpbase bug.cpp -mtune=generic -auxbase bug -version -fstack-protector -o
bug.s
GNU C++ (Ubuntu 4.4.3-4ubuntu5) version 4.4.3 (x86_64-linux-gnu)
        compiled by GNU C version 4.4.3, GMP version 4.3.2, MPFR version
2.4.2-p1.
GGC heuristics: --param ggc-min-expand=98 --param ggc-min-heapsize=128001
GNU C++ (Ubuntu 4.4.3-4ubuntu5) version 4.4.3 (x86_64-linux-gnu)
        compiled by GNU C version 4.4.3, GMP version 4.3.2, MPFR version
2.4.2-p1.
GGC heuristics: --param ggc-min-expand=98 --param ggc-min-heapsize=128001
Compiler executable checksum: 88858f45841827736473e527a4e9ab10
bug.cpp: In member function ‘void C<Y>::does_not_work()’:
bug.cpp:34: error: expected primary-expression before ‘>’ token
bug.cpp:34: error: expected primary-expression before ‘)’ token

While there are workarounds for this bug, it is certainly unexpected behavior.
Note that this bug does not occur for class B or for cases where class C is not
a template class.


-- 
           Summary: Cannot call template method from derived template class
           Product: gcc
           Version: 4.4.3
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: klenze at mpp dot mpg dot de
 GCC build triplet: x86_64-linux-gnu
  GCC host triplet: x86_64-linux-gnu
GCC target triplet: x86_64-linux-gnu


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44138