fix ADT hover considering only type or const len not lifetimes

crates/hir/src/lib.rs

@@ -1418,7 +1418,8 @@ pub fn has_non_default_type_params(self, db: &dyn HirDatabase) -> bool {
     }
 
     pub fn layout(self, db: &dyn HirDatabase) -> Result<Layout, LayoutError> {
-        if db.generic_params(self.into()).iter().count() != 0 {
+        let generic_params = &db.generic_params(self.into());
+        if generic_params.iter().next().is_some() || generic_params.iter_lt().next().is_some() {
             return Err(LayoutError::HasPlaceholder);
         }
         let krate = self.krate(db).id;

crates/ide/src/hover/tests.rs

@@ -7856,3 +7856,25 @@ impl Iterator for S {
         "#]],
     );
 }
+
+#[test]
+fn hover_lifetime_regression_16963() {
+    check(
+        r#"
+struct Pedro$0<'a> {
+    hola: &'a str
+}
+"#,
+        expect![[r#"
+            *Pedro*
+
+            ```rust
+            test
+            ```
+
+            ```rust
+            struct Pedro<'a>
+            ```
+        "#]],
+    )
+}