Proper indentation for C++11 lambdas

Question

Is there an accepted "standard" way to format lambda-expressions in C++ >= 11 ? Especially when put in generic algorithms for instance.

For instance :

1)

auto it = std::find_if(myVec.begin(),
                       myVec.end(),
                       [id = 42] (const Element& e)
{ return e.id() == id;});

Or 2)

auto it = std::find_if(myVec.begin(),
                       myVec.end(),
                       [id = 42] 
                       (const Element& e)
                       { return e.id() == id;});

Or 3)

auto it = std::find_if(myVec.begin(),
                       myVec.end(),
                       [id = 42] (const Element& e)
                       { 
                           return e.id() == id;
                       });

Or 4)

auto it = std::find_if(myVec.begin(),
                       myVec.end(),
                       [id = 42] (const Element& e)
{ 
    return e.id() == id;
});

Or any other combination of carriage returns, spaces, tabs... Note : I use Allman style in my code, so ideally it would be "fitting in the same style".

Answer 1

I have always preferred to endow relative levels of indent with their own semantic value and vertically align a closing delimiter with the line that contains its matching opening delimiter. This makes complex statements (like those with lambda expressions as arguments) easier to read:

auto it = std::find_if(
  myVec.begin(),
  myVec.end(),
  [id = 42] (const Element& e){ return e.id() == id;}
);

or (if, for example, the lambda body was too long for one line)

auto it = std::find_if(
  myVec.begin(),
  myVec.end(),
  [id = 42] (const Element& e){ 
    return e.id() == id;
  }
);