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From: sebor@roguewave.com To: gcc-gnats@gcc.gnu.org Subject: c++/10690: bogus ambiguity on templates overloaded on return type Date: Thu, 08 May 2003 18:46:00 -0000 [thread overview] Message-ID: <20030508183848.26535.qmail@sources.redhat.com> (raw) >Number: 10690 >Category: c++ >Synopsis: bogus ambiguity on templates overloaded on return type >Confidential: no >Severity: serious >Priority: medium >Responsible: unassigned >State: open >Class: sw-bug >Submitter-Id: net >Arrival-Date: Thu May 08 18:46:00 UTC 2003 >Closed-Date: >Last-Modified: >Originator: sebor@roguewave.com >Release: 3.2.2 >Organization: >Environment: >Description: The attached well-formed program inspired by the CUJ 6/03 article "Function Overloading Based on Arbitrary Properties of Types," fails to compile with gcc 3.2.2. The errors after replacing the dependency on <typeinfo> with __PRETTY_FUNCTION__ are: t.cpp:24: new declaration `template<class T> select<(!is_int<T>::value), T>::type foo(T)' t.cpp:17: ambiguates old declaration `template<class T> select<is_int<T>::value, T>::type foo(T)' Regards Martin >How-To-Repeat: $ cat t.cpp && g++ --version && g++ t.cpp #include <typeinfo> template <bool B, class T> struct select { typedef T type; }; template <class T> struct select<false, T> { }; template <class T> struct is_int { enum { value }; }; template <> struct is_int<int> { enum { value = 1 }; }; extern "C" int printf (const char*, ...); template <class T> typename select<is_int<T>::value, T>::type foo (T t) { printf ("%s:%d: %s\n", __FILE__, __LINE__, typeid (foo<T>).name ()); return t; } template <class T> typename select<!is_int<T>::value, T>::type foo (T t) { printf ("%s:%d: %s\n", __FILE__, __LINE__, typeid (foo<T>).name ()); return t; } int main () { foo (bool ()); foo (short ()); foo (int ()); } g++ (GCC) 3.2.2 20030222 (Red Hat Linux 3.2.2-5) Copyright (C) 2002 Free Software Foundation, Inc. This is free software; see the source for copying conditions. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. t.cpp:26: new declaration `template<class T> select<(!is_int<T>::value), T>::type foo(T)' t.cpp:19: ambiguates old declaration `template<class T> select<is_int<T>::value, T>::type foo(T)' t.cpp: In function `select<(!is_int<T>::value), T>::type foo(T) [with T = bool]': t.cpp:33: instantiated from here t.cpp:27: insufficient contextual information to determine type t.cpp: In function `select<(!is_int<T>::value), T>::type foo(T) [with T = short int]': t.cpp:34: instantiated from here t.cpp:27: insufficient contextual information to determine type t.cpp: In function `select<is_int<T>::value, T>::type foo(T) [with T = int]': t.cpp:35: instantiated from here t.cpp:20: insufficient contextual information to determine type >Fix: >Release-Note: >Audit-Trail: >Unformatted:
next reply other threads:[~2003-05-08 18:46 UTC|newest] Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top 2003-05-08 18:46 sebor [this message] 2003-05-08 19:56 giovannibajo 2003-05-08 20:56 Martin Sebor
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