2 ms·

I'm not sure that this particular example can ever use some_string outside the if without hitting a type error, but I see what you mean. That seems like a reas

I'm not sure that this particular example can ever use some_string outside the if without hitting a type error, but I see what you mean. That seems like a reasonable case to raise a type error. That defines the cases quite neatly: if it's temporary on both branches then it can work, and if it has different lifetimes then the values can't be merged and should be rejected. If the programmer really meant for this to work then they need to copy the global, and copies should be written explicitly.

dbaupp 12y ago
There's no type error at all, we're talking about delaying the destruction of some_string so that the `s` (which is a &str) is valid outside the if. The string literal is a &str with a infinite lifetime, and so can of course be safely restricted to have the same lifetime as the other branch (done implicitly). However, it's easily possible to have the &str come from temporaries of different types in the two branches. This would restrict the static destruction case to only working through an `if` when the "parent" values have exactly the same types; which doesnt seem nearly as valuable and possibly not worth the effort.