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Andrey Semashev 24d29e5865 Fix for clang, when adapted type is convertible from other types.

The problem was with copy/move constructors of boost::optional<T>, which invoked
optional_base<T> constructors with a single argument. Since optional_base has
copy/move constructors along with initializing constructors taking a single
argument, the latter may be considered by the compiler for viability. While
doing so, the compiler may instantiate the template constructor of T with
an argument of optional_base<T>, which in turn may fail if the constructor
attempts to inspect the type of its argument (e.g. to constrain the set of
acceptable types). Specifically, this happens with clang in C++03 mode,
when boost::multiprecision::number is wrapped in boost::optional and
a copy constructor of boost::optional is invoked.

This commit fixes the problem by destinguishing copy/move constructors of
optional_base from initializing constructors with an additional tag argument.

2018-11-04 17:35:10 +03:00

doc

docs: updated releasenotes

2018-10-29 22:06:47 +01:00

include/boost

Fix for clang, when adapted type is convertible from other types.

2018-11-04 17:35:10 +03:00

README.md

optional

A library for representing optional (nullable) objects in C++.

optional<int> readInt(); // this function may return either an int or a not-an-int

if (optional<int> oi = readInt()) // did I get a real int
  cout << "my int is: " << *oi;   // use my int
else
  cout << "I have no int";

For more information refer to the documentation provided with this library.