http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54318
Bug #: 54318
Summary: [C++11] Bogus "template instantiation depth exceeds
maximum" error + segfault
Classification: Unclassified
Product: gcc
Version: 4.8.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
AssignedTo: [email protected]
ReportedBy: [email protected]
The following code:
template <typename T>
struct wrapped
{
typedef T type;
};
template <typename T>
typename T::type unwrap1(T);
int unwrap(int);
template <typename T>
auto unwrap(T t) -> decltype(unwrap(unwrap1(t)))
{
return unwrap(unwrap1(t));
}
int main()
{
unwrap(wrapped<wrapped<int>>());
}
Seems to produce an infinite loop in GCC, as it displays the same error message
over and over again, and eventualy segfaults.
Here is the error message:
test.cpp:13:6: error: template instantiation depth exceeds maximum of 900 (use
-ftemplate-depth= to increase the maximum) substituting 'template<class T>
typename T::type unwrap1(T) [with T = wrapped<wrapped<int> >]'
auto unwrap(T t) -> decltype(unwrap(unwrap1(t)))
^
test.cpp:13:6: recursively required by substitution of 'template<class T>
decltype (unwrap(unwrap1(t))) unwrap(T) [with T = wrapped<int>]'
test.cpp:13:6: required by substitution of 'template<class T> decltype
(unwrap(unwrap1(t))) unwrap(T) [with T = wrapped<int>]'
test.cpp:15:29: template instantiation depth exceeds maximum of 900 (use
-ftemplate-depth= to increase the maximum) substituting 'template<class T>
typename T::type unwrap1(T) [with T = wrapped<wrapped<int> >]'
The last 3 lines are repeated thousands of times until finally:
g++: internal compiler error: Segmentation fault (program cc1plus)
Please submit a full bug report,
with preprocessed source if appropriate.
See <http://gcc.gnu.org/bugs.html> for instructions.
I believe the code is valid. Clang compiles it without errors.
