2 files changed, 35 insertions, 14 deletions

diff --git a/crates/hir_def/src/nameres/collector.rs b/crates/hir_def/src/nameres/collector.rs
index 221a5a556..be645a25d 100644
--- a/crates/hir_def/src/nameres/collector.rs
+++ b/crates/hir_def/src/nameres/collector.rs
@@ -367,6 +367,8 @@ impl DefCollector<'_> {
     /// This improves UX when proc macros are turned off or don't work, and replicates the behavior
     /// before we supported proc. attribute macros.
     fn reseed_with_unresolved_attributes(&mut self) -> ReachedFixedPoint {
+        cov_mark::hit!(unresolved_attribute_fallback);
+
         let mut added_items = false;
         let unexpanded_macros = std::mem::replace(&mut self.unexpanded_macros, Vec::new());
         for directive in &unexpanded_macros {
@@ -391,7 +393,9 @@ impl DefCollector<'_> {
                 added_items = true;
             }
         }
-        self.unexpanded_macros = unexpanded_macros;
+
+        // The collection above might add new unresolved macros (eg. derives), so merge the lists.
+        self.unexpanded_macros.extend(unexpanded_macros);
 
         if added_items {
             // Continue name resolution with the new data.
@@ -948,20 +952,17 @@ impl DefCollector<'_> {
         // incrementality).
         let err = self.db.macro_expand_error(macro_call_id);
         if let Some(err) = err {
-            if let MacroCallId::LazyMacro(id) = macro_call_id {
-                let loc: MacroCallLoc = self.db.lookup_intern_macro(id);
+            let loc: MacroCallLoc = self.db.lookup_intern_macro(macro_call_id);
 
-                let diag = match err {
-                    hir_expand::ExpandError::UnresolvedProcMacro => {
-                        // Missing proc macros are non-fatal, so they are handled specially.
-                        DefDiagnostic::unresolved_proc_macro(module_id, loc.kind)
-                    }
-                    _ => DefDiagnostic::macro_error(module_id, loc.kind, err.to_string()),
-                };
+            let diag = match err {
+                hir_expand::ExpandError::UnresolvedProcMacro => {
+                    // Missing proc macros are non-fatal, so they are handled specially.
+                    DefDiagnostic::unresolved_proc_macro(module_id, loc.kind)
+                }
+                _ => DefDiagnostic::macro_error(module_id, loc.kind, err.to_string()),
+            };
 
-                self.def_map.diagnostics.push(diag);
-            }
-            // FIXME: Handle eager macros.
+            self.def_map.diagnostics.push(diag);
         }
 
         // Then, fetch and process the item tree. This will reuse the expansion result from above.
diff --git a/crates/hir_def/src/nameres/tests/macros.rs b/crates/hir_def/src/nameres/tests/macros.rs
index c37f915ab..b34ba885d 100644
--- a/crates/hir_def/src/nameres/tests/macros.rs
+++ b/crates/hir_def/src/nameres/tests/macros.rs
@@ -686,6 +686,27 @@ pub trait Clone {}
 }
 
 #[test]
+fn builtin_derive_with_unresolved_attributes_fall_back() {
+    // Tests that we still resolve derives after ignoring an unresolved attribute.
+    cov_mark::check!(unresolved_attribute_fallback);
+    let map = compute_crate_def_map(
+        r#"
+        //- /main.rs crate:main deps:core
+        use core::Clone;
+
+        #[derive(Clone)]
+        #[unresolved]
+        struct Foo;
+
+        //- /core.rs crate:core
+        #[rustc_builtin_macro]
+        pub macro Clone {}
+        "#,
+    );
+    assert_eq!(map.modules[map.root].scope.impls().len(), 1);
+}
+
+#[test]
 fn macro_expansion_overflow() {
     cov_mark::check!(macro_expansion_overflow);
     check(
@@ -842,7 +863,6 @@ fn collects_derive_helpers() {
 fn resolve_macro_def() {
     check(
         r#"
-//- /lib.rs
 pub macro structs($($i:ident),*) {
     $(struct $i { field: u32 } )*
 }