From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <gcc-bugs-return-294609-listarch-gcc-bugs=gcc.gnu.org@gcc.gnu.org>
Received: (qmail 22451 invoked by alias); 21 Sep 2009 12:51:12 -0000
Received: (qmail 22416 invoked by uid 48); 21 Sep 2009 12:51:02 -0000
Date: Mon, 21 Sep 2009 12:51:00 -0000
Subject: [Bug c++/41426]  New: User defined conversion on return ignores array types
X-Bugzilla-Reason: CC
Message-ID: <bug-41426-17480@http.gcc.gnu.org/bugzilla/>
Reply-To: gcc-bugzilla@gcc.gnu.org
To: gcc-bugs@gcc.gnu.org
From: "roger dot ferrer at bsc dot es" <gcc-bugzilla@gcc.gnu.org>
Mailing-List: contact gcc-bugs-help@gcc.gnu.org; run by ezmlm
Precedence: bulk
List-Id: <gcc-bugs.gcc.gnu.org>
List-Archive: <http://gcc.gnu.org/ml/gcc-bugs/>
List-Post: <mailto:gcc-bugs@gcc.gnu.org>
List-Help: <mailto:gcc-bugs-help@gcc.gnu.org>
Sender: gcc-bugs-owner@gcc.gnu.org
X-SW-Source: 2009-09/txt/msg01988.txt.bz2

I think g++ simplifies too early array types into pointers when looking for a
conversion sequence in a return statement.

---
struct B
{
    B (int (&v)[10]);
    B();
};

B g2()
{
    int c[10];
    return c;
}
---

results in

test.cc: In function ‘B g2()’:
test.cc:10: error: conversion from ‘int*’ to non-scalar type ‘B’ requested

while at least the conversion constructor B::B(int (&)[10]) should be given a
chance.

For another (slightly) more elaborated example

---
template <typename _T>
struct A
{
    template <int _N>
        A(_T (&V)[_N]);
    A();
};

A<float> g1()
{
    float f[] = {1.1f, 2.3f};
    return f;
}
---

which gives

prova.cc: In function ‘A<float> g1()’:
prova.cc:12: error: conversion from ‘float*’ to non-scalar type ‘A<float>’
requested

Again, at least the 'A<T>::A<_N>(T (&)[_N])' constructor should be given a
chance (which eventually should succeed).

Using an explicit-conversion can be used as workaround.


-- 
           Summary: User defined conversion on return ignores array types
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: roger dot ferrer at bsc dot es


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41426