https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81188
Bug ID: 81188
Summary: decltype(this->member()) raises invalid prototype
Product: gcc
Version: 7.1.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: serge.guel...@telecom-bretagne.eu
Target Milestone: ---
Compiling the following test case
```
template <class F>
struct C {
F fast(long i) const;
auto operator[](long i) const -> decltype(this->fast(i));
};
template <class F>
auto C<F>::operator[](long i) const -> decltype(this->fast(i)) {
return fast(i);
}
```
with
```
g++ -std=c++11 -c a.cpp
```
raises the following unexpected error message
```
a.cpp:8:6: error: prototype for ‘decltype (((const C<F>*)this)->C<F>::fast(i))
C<F>::operator[](long int) const’ does not match any in class ‘C<F>’
auto C<F>::operator[](long i) const -> decltype(this->fast(i)) {
^~~~
a.cpp:4:8: error: candidate is: decltype (((const C<F>*)this)->C<F>::fast(i))
C<F>::operator[](long int) const
auto operator[](long i) const -> decltype(this->fast(i));
```
Removing the ``this->`` in the decltype fixes the issue, but this is a
regression compared to g++-6 and clang++.
