Rollup merge of rust-lang#65307 - Phosphorus15:master, r=varkor

Try fix incorrect "explicit lifetime name needed"

This pr is trying to fixes rust-lang#65285 .

Author: tmandry

src/librustc/hir/lowering.rs

@@ -3291,10 +3291,14 @@ impl<'a> LoweringContext<'a> {
                 let id = self.sess.next_node_id();
                 self.new_named_lifetime(id, span, hir::LifetimeName::Error)
             }
-            // This is the normal case.
-            AnonymousLifetimeMode::PassThrough => self.new_implicit_lifetime(span),
-
-            AnonymousLifetimeMode::ReportError => self.new_error_lifetime(None, span),
+            // `PassThrough` is the normal case.
+            // `new_error_lifetime`, which would usually be used in the case of `ReportError`,
+            // is unsuitable here, as these can occur from missing lifetime parameters in a
+            // `PathSegment`, for which there is no associated `'_` or `&T` with no explicit
+            // lifetime. Instead, we simply create an implicit lifetime, which will be checked
+            // later, at which point a suitable error will be emitted.
+          | AnonymousLifetimeMode::PassThrough
+          | AnonymousLifetimeMode::ReportError => self.new_implicit_lifetime(span),
         }
     }
 

src/test/ui/generics/issue-65285-incorrect-explicit-lifetime-name-needed.rs

@@ -0,0 +1,14 @@
+#![crate_type="lib"]
+
+struct Nested<K>(K);
+
+fn should_error<T>() where T : Into<&u32> {}
+//~^ ERROR `&` without an explicit lifetime name cannot be used here [E0637]
+
+trait X<'a, K: 'a> {
+    fn foo<'b, L: X<&'b Nested<K>>>();
+    //~^ ERROR missing lifetime specifier [E0106]
+}
+
+fn bar<'b, L: X<&'b Nested<i32>>>(){}
+//~^ ERROR missing lifetime specifier [E0106]

src/test/ui/generics/issue-65285-incorrect-explicit-lifetime-name-needed.stderr

@@ -0,0 +1,21 @@
+error[E0637]: `&` without an explicit lifetime name cannot be used here
+  --> $DIR/issue-65285-incorrect-explicit-lifetime-name-needed.rs:5:37
+   |
+LL | fn should_error<T>() where T : Into<&u32> {}
+   |                                     ^ explicit lifetime name needed here
+
+error[E0106]: missing lifetime specifier
+  --> $DIR/issue-65285-incorrect-explicit-lifetime-name-needed.rs:9:19
+   |
+LL |     fn foo<'b, L: X<&'b Nested<K>>>();
+   |                   ^^^^^^^^^^^^^^^^ expected lifetime parameter
+
+error[E0106]: missing lifetime specifier
+  --> $DIR/issue-65285-incorrect-explicit-lifetime-name-needed.rs:13:15
+   |
+LL | fn bar<'b, L: X<&'b Nested<i32>>>(){}
+   |               ^^^^^^^^^^^^^^^^^^ expected lifetime parameter
+
+error: aborting due to 3 previous errors
+
+For more information about this error, try `rustc --explain E0106`.