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
