Subject: [Boost-bugs] [Boost C++ Libraries] #4566: Binding to a class member with lambda::bind() can cause const qualifier mismatch.
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2010-08-18 17:52:52
#4566: Binding to a class member with lambda::bind() can cause const qualifier
mismatch.
-------------------------------------------------------+--------------------
Reporter: David Larsson <david.larsson@â¦> | Owner: no-maintainer
Type: Bugs | Status: new
Milestone: To Be Determined | Component: lambda
Version: Boost 1.44.0 | Severity: Problem
Keywords: |
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The following code (omitting namespaces) would compile correctly in Boost
1.43.0, but now fails with error
''boost/lambda/detail/function_adaptors.hpp(264) : error C2440
: 'return' : cannot convert from 'const int' to 'int &''':
{{{
bind( &pair<int,int>::first, _1 )( make_pair( 1, 0 ) );
}}}
The `boost::lambda::bind()` expression creates a function that returns the
first element of a pair, and then applies this to a `const pair<int,int>`.
The following will work, because the argument is not constant:
{{{
pair<int,int> x(1,0);
bind( &pair<int,int>::first, _1 )( x );
}}}
A workaround for this issue is to specify the return value of `bind()`
explicitly, but it shouldn't be necessary for this simple case:
{{{
bind<int>( &pair<int,int>::first, _1 )( make_pair( 1, 0 ) );
}}}
I have tested this on VC8 and VC10 with identical results.
Thanks for a great library,
''/David''
-- Ticket URL: <https://svn.boost.org/trac/boost/ticket/4566> Boost C++ Libraries <http://www.boost.org/> Boost provides free peer-reviewed portable C++ source libraries.
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