Re: [boost] [function] type conversion ambiguity?

On 15 July 2013 02:16, Andrew Ho wrote:

Consider the overloaded functions foo and bar:

typedef boost::function function_type1; typedef boost::function function_type2;

typedef std::function function_type3; typedef std::function function_type4;

void foo(const function_type1 &a) { // blah }

void foo(const function_type2 &a) { // blah }

void bar(const function_type3 &a) { // blah }

void bar(const function_type4 &a) { // blah }

calling foo with a function pointer is ambiguous, but calling bar is not:

void doit1(void) {}

void doit2(int) {}

foo(&doit1); // ambiguous bar(&doit2); // compiles and runs fine

This occurs despite the fact that boost::function(&doit2) can be caught at compile time.

Actually they should both be ambiguous according to the C++11 standard, but it looks as though your standard library already implements the proposed resolution to http://cplusplus.github.io/LWG/lwg-active.html#2132 (I implemented it for libstdc++ and I know libc++ implements it too.)

Is there some way to fix the definition of boost::function such that this is no longer ambiguous?

Implement the resolution to LWG 2132.