Ideas for improving mismatched_lifetime_syntaxes wording?

[jieyouxu]

Yes... on the other hand, it's possible we were just used to the old one. The new main warning here does match the lang model that we adopted (though I'm not sure if the "flowing from..." is the best possible wording). That model derives from what @nikomatsakis had proposed in #120808 (comment) to boil most of this down to things being mismatched, and we ended up adopting the form specifically described in #120808 (comment).

Originally posted by @traviscross in #138677 (comment)

[yarrow]

I wonder if the message below should refer to hidden_lifetimes_in_output_paths instead of mismatched_lifetime_syntaxes.

warning: lifetime flowing from input to output with different syntax can be confusing
  --> src/help.rs:66:16
   |
66 | fn parse(text: &str) -> Vec<HelpItem> {
   |                ^^^^         -------- the lifetime gets resolved as `'_`
   |                |
   |                this lifetime flows to the output
   |
   = note: `#[warn(mismatched_lifetime_syntaxes)]` on by default
help: one option is to remove the lifetime for references and use the anonymous lifetime for paths
   |
66 | fn parse(text: &str) -> Vec<HelpItem<'_>> {
   |                                     ++++

The message is a bit confusing because the lifetime syntaxes in &str and HelpItem seem to be identical (both empty), and also because there is no lifetime to remove from the &str reference.