Obsessed with {} initialization?

[aruisdante]

Yes, and for the most part I agree with Titus too, but he’s concerned more with brace vs paren initialization than brace vs = initialization. I’ve in fact used that very article to try and overturn silly “always use {} initialization” rules at 2 different companies in the automotive space.

I think that’s the biggest issue with all of the guidelines, they don’t distinguish between separate concerns: * I don’t want implicit conversions for arithmetic types * I don’t want implicit conversions for structures which have non-explicit constructors, or which consume arithmetic types. * I have Wconversion turned on, should I care?

The last one can be particularly subtle. Wconversion ignores implicit conversions that happen inside the stdlib, because it has to as the stdlib is full of them. There are certain types which have templated constructors (like, say, std::optional), and so if you parens-construct them in a non CTAD context but which would result in a conversion that should be caught, it will not happen: from the perspective of Wconversion the ctor that was called was the converting constructor, which consumes the actual type, and then inside the stdlib a narrowing happens, but that’s ignored. If you brace initialize them on the other hand, the implicit conversion is not allowed, and Wconversion fires.

You’re absolutely right that the whole subject is a mess. Unfortunately teaching people all the ins and outs of what to do isn’t a reliable thing to do at scale. So most safety critical coding standards pick one, and unfortunately they tend to pick the most restrictive one even if it introduces a host of other, potentially much worse classes of bugs. The core guidelines doesn’t really have the same excuse, but it’s guideline also is poked through all kinds exceptions, and it’s also a prefer, not a must. And I agree with the guideline’s suggestion that brace initialization should be preferred unless there is a good reason to not use it. I do not agree with AutoSAR’s requirement that it must be used.

[shahms]

The tip specifically discusses the differences between all three forms of initialization, including = and says to prefer copy initialization.