Rollup merge of #103414 - compiler-errors:rpit-print-lt, r=cjgillot

Pretty print lifetimes captured by RPIT

This specifically makes the output in #103409 change from:

```diff
  error: `impl` item signature doesn't match `trait` item signature
    --> $DIR/signature-mismatch.rs:15:5
     |
  LL |     fn async_fn(&self, buff: &[u8]) -> impl Future<Output = Vec<u8>>;
     |     ----------------------------------------------------------------- expected `fn(&'1 Struct, &'2 [u8]) -> impl Future<Output = Vec<u8>>`
  ...
  LL |     fn async_fn<'a>(&self, buff: &'a [u8]) -> impl Future<Output = Vec<u8>> + 'a {
-  |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ found `fn(&'1 Struct, &'2 [u8]) -> impl Future<Output = Vec<u8>>`
+  |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ found `fn(&'1 Struct, &'2 [u8]) -> impl Future<Output = Vec<u8>> + '2`
     |
     = note: expected `fn(&'1 Struct, &'2 [u8]) -> impl Future<Output = Vec<u8>>`
-               found `fn(&'1 Struct, &'2 [u8]) -> impl Future<Output = Vec<u8>>`
+               found `fn(&'1 Struct, &'2 [u8]) -> impl Future<Output = Vec<u8>> + '2`
     = help: the lifetime requirements from the `impl` do not correspond to the requirements in the `trait`
     = help: verify the lifetime relationships in the `trait` and `impl` between the `self` argument, the other inputs and its output

  error: aborting due to previous error
```

Along with the UI tests in this PR, which I think are all improvements!

r? `@oli-obk` though feel free to re-roll

1 files changed, 10 insertions, 0 deletions

diff --git a/compiler/rustc_middle/src/ty/print/pretty.rs b/compiler/rustc_middle/src/ty/print/pretty.rs
index f18c95a61d4..b8ee2b994b1 100644
--- a/compiler/rustc_middle/src/ty/print/pretty.rs
+++ b/compiler/rustc_middle/src/ty/print/pretty.rs
@@ -16,6 +16,7 @@ use rustc_session::cstore::{ExternCrate, ExternCrateSource};
 use rustc_span::symbol::{kw, Ident, Symbol};
 use rustc_target::abi::Size;
 use rustc_target::spec::abi::Abi;
+use smallvec::SmallVec;
 
 use std::cell::Cell;
 use std::char;
@@ -794,6 +795,7 @@ pub trait PrettyPrinter<'tcx>:
         let mut traits = FxIndexMap::default();
         let mut fn_traits = FxIndexMap::default();
         let mut is_sized = false;
+        let mut lifetimes = SmallVec::<[ty::Region<'tcx>; 1]>::new();
 
         for (predicate, _) in bounds.subst_iter_copied(tcx, substs) {
             let bound_predicate = predicate.kind();
@@ -824,6 +826,9 @@ pub trait PrettyPrinter<'tcx>:
                         &mut fn_traits,
                     );
                 }
+                ty::PredicateKind::TypeOutlives(outlives) => {
+                    lifetimes.push(outlives.1);
+                }
                 _ => {}
             }
         }
@@ -977,6 +982,11 @@ pub trait PrettyPrinter<'tcx>:
             write!(self, "Sized")?;
         }
 
+        for re in lifetimes {
+            write!(self, " + ")?;
+            self = self.print_region(re)?;
+        }
+
         Ok(self)
     }