Re: [boost] [gil::io_new] Help with gcc compiler

Subject: Re: [boost] [gil::io_new] Help with gcc compiler
From: Nathan Crookston (nathan.crookston_at_[hidden])
Date: 2012-07-03 01:22:20

Hi Christian,

I'm glad to see this is moving forward!

On Mon, Jul 2, 2012 at 8:32 PM, Christian Henning <chhenning_at_[hidden]> wrote:
> Hi there,
>
> I'm in the process of making my gil extension ready for inclusion. The
> code is now stable and I'm trying to get gcc/clang to work. Since I'm
> no expert with gcc I would like to ask for some help with various
> compiler errors.

it looks like the two major areas are problems with VS allowing you to
bind temporaries to mutable references, and missing typenames.  You're
probably familiar with both, but I'll explain the former problem as
well as attach a diff that allows your program to compile.  The
problem is similar to the following:
int make_int(); //returns rvalue
void foo(int&); //standard says this should take a mutable lvalue
...
foo(make_int());//Forbidden by standard, allowed by default with VS.

Options are to have foo take its parameter by value or const&, or to
declare a temporary before the invocation of foo, and pass the
temporary to that.  The diff I'm attaching just passes the reader and
writer by value, though I'm not at all sure that's the right thing
here. . .

> The complete test suite compiles with Visual Studio 2010 without any warnings.

We compile with VC10 and gcc 4.5 at my work.  We've found the boost
guidelines to be very helpful in catching cross-platform problems
early:
https://svn.boost.org/trac/boost/wiki/Guidelines/WarningsGuidelines
(see the 'Defining Warnings as Errors' section, particularly 4239 and
4346, which may have helped in this case).

HTH,
Nate