In-band lifetime syntax inconsistency?

[HadrienG2]

In the in-band lifetime section, the following syntax is introduced:

fn two_args(foo: &Foo, bar: &'bar Bar) -> &'bar Baz

Later, in the lifetime elision in impl section, it is said that the feature interacts with in-band lifetime syntax in the following way:

fn bar(&self, arg: &str) -> &'arg str

There is a little difference between these two syntaxes, however. The former syntax gives the impression that the lifetime parameter is named "bar" by choice, but could be anything, whereas the latter syntax gives the impression that one can use &'arg as a shorthand to denote the lifetime of reference argument "arg" of a function.

Which syntax is the correct one?

[Nemo157]

The RFC itself appears to be inconsistent. The summary and guide level explanation use the first form (lifetimes must be introduced as part of the arguments, and don't have to use the same name) while the reference level explanation use the second form (lifetimes with the name of an argument binding implicitly refer to that binding).

Testing the feature seems to show that only the first form works.

[HadrienG2]

I guess this ambiguity is one thing to be sorted out before the feature lands, then :)

[Nemo157]

Opened rust-lang/rfcs#2486 to fix the RFC and #38 to fix the docs.

[steveklabnik]

Gonna wait to see what the lang team says before merging this.

[steveklabnik]

actually, we should probably take the other PR as it was first...