Auto merge of #95779 - cjgillot:ast-lifetimes-undeclared, r=petrochenkov

Report undeclared lifetimes during late resolution.

First step in https://github.com/rust-lang/rust/pull/91557

We reuse the rib design of the current resolution framework. Specific `LifetimeRib` and `LifetimeRibKind` types are introduced. The most important variant is `LifetimeRibKind::Generics`, which happens each time we encounter something which may introduce generic lifetime parameters. It can be an item or a `for<...>` binder. The `LifetimeBinderKind` specifies how this rib behaves with respect to in-band lifetimes.

r? `@petrochenkov`

compiler/rustc_hir/src/hir.rs

@@ -95,7 +95,7 @@ pub enum LifetimeName {
     /// User wrote nothing (e.g., the lifetime in `&u32`).
     ///
     /// The bool indicates whether the user should have written something.
-    Implicit(bool),
+    Implicit,
 
     /// Implicit lifetime in a context like `dyn Foo`. This is
     /// distinguished from implicit lifetimes elsewhere because the
@@ -125,7 +125,7 @@ impl LifetimeName {
     pub fn ident(&self) -> Ident {
         match *self {
             LifetimeName::ImplicitObjectLifetimeDefault
-            | LifetimeName::Implicit(_)
+            | LifetimeName::Implicit
             | LifetimeName::Error => Ident::empty(),
             LifetimeName::Underscore => Ident::with_dummy_span(kw::UnderscoreLifetime),
             LifetimeName::Static => Ident::with_dummy_span(kw::StaticLifetime),
@@ -136,7 +136,7 @@ impl LifetimeName {
     pub fn is_elided(&self) -> bool {
         match self {
             LifetimeName::ImplicitObjectLifetimeDefault
-            | LifetimeName::Implicit(_)
+            | LifetimeName::Implicit
             | LifetimeName::Underscore => true,
 
             // It might seem surprising that `Fresh(_)` counts as

compiler/rustc_hir/src/intravisit.rs

@@ -528,7 +528,7 @@ pub fn walk_lifetime<'v, V: Visitor<'v>>(visitor: &mut V, lifetime: &'v Lifetime
         | LifetimeName::Param(ParamName::Error)
         | LifetimeName::Static
         | LifetimeName::Error
-        | LifetimeName::Implicit(_)
+        | LifetimeName::Implicit
         | LifetimeName::ImplicitObjectLifetimeDefault
         | LifetimeName::Underscore => {}
     }