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From: "bruno-gcc at defraine dot net" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug c++/54359] New: [C++0x][N3282] decltype in member function's trailing return type when defined outside of class Date: Thu, 23 Aug 2012 13:42:00 -0000 [thread overview] Message-ID: <bug-54359-4@http.gcc.gnu.org/bugzilla/> (raw) http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54359 Bug #: 54359 Summary: [C++0x][N3282] decltype in member function's trailing return type when defined outside of class Classification: Unclassified Product: gcc Version: 4.7.2 Status: UNCONFIRMED Severity: normal Priority: P3 Component: c++ AssignedTo: unassigned@gcc.gnu.org ReportedBy: bruno-gcc@defraine.net Even after closing bug #49003, there remain problems regarding the handling of N3282 (resolution of DR 1207). Specifically, the problems have to do with a definition of a member function outside of the class. Consider these test cases: int& ref(int& x) { return x; } const int& ref(const int& x) { return x; } class A { int x; int f() const; auto test1() const -> decltype(this); auto test2() const -> decltype(ref(x)); auto test3() const -> decltype(f()); }; auto A::test1() const -> decltype(this) { return this; } auto A::test2() const -> decltype(ref(x)) { return ref(x); } auto A::test3() const -> decltype(f()) { return f(); } This gives the following compiler errors in the C++0x mode of gcc 4.7.1: - test1(): invalid use of 'this' at top level - test2(): prototype for 'int& A::test2() const' does not match any in class 'A' (candidate is: const int& A::test2() const); additionally, 'int A::x' is private - test3(): cannot call member function 'int A::f() const' without object; additionally, 'int A::f() const' is private In summary, in the trailing return type of a const member function definition outside of a class declaration, it seems: 1. I cannot explicitly reference 'this' 2. I can reference data members, but not private ones, and they are not const 3. I cannot invoke member functions I believe all three function definitions should compile. Similarly, inline definitions of the same member functions have no such problems: class B { int x; int f() const; auto test1() const -> decltype(this) { return this; } auto test2() const -> decltype(ref(x)) { return ref(x); } auto test3() const -> decltype(f()) { return f(); } }; It seems that issue #2 is a regression compared to gcc 4.6, which seemed to allow some access to data members. Consider test4(): template<typename X> class C { const X& x; auto test4() const -> decltype(x); }; template<typename X> auto C<X>::test4() const -> decltype(x) { return x; } This test compiles without problems under gcc 4.6.3. Whereas gcc 4.7.1 gives: prototype for 'decltype (((C<X>*)0)->C<X>::x) C<X>::test4() const' does not match any in class 'C<X>' (candidate is: decltype (((const C<X>*)this)->C<X>::x) C<X>::test4() const)
next reply other threads:[~2012-08-23 13:42 UTC|newest] Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top 2012-08-23 13:42 bruno-gcc at defraine dot net [this message] 2012-08-24 0:30 ` [Bug c++/54359] " paolo.carlini at oracle dot com 2012-08-24 12:10 ` [Bug c++/54359] [C++0x] " redi at gcc dot gnu.org 2012-08-24 12:21 ` paolo.carlini at oracle dot com 2013-03-11 3:05 ` jason at gcc dot gnu.org 2013-03-17 2:40 ` jason at gcc dot gnu.org 2013-03-18 3:41 ` jason at gcc dot gnu.org 2013-03-26 14:28 ` jason at gcc dot gnu.org 2014-03-04 22:16 ` jason at gcc dot gnu.org
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