From 624ee2314798573d9df93be860cf10aa629a0e0e Mon Sep 17 00:00:00 2001
From: Giacomo Stevanato <giaco.stevanato@gmail.com>
Date: Wed, 29 Sep 2021 21:06:37 +0200
Subject: [PATCH 1/2] Use the right HirFileId for LowerCtx when expanding
 macros in fn parameter types

---
 crates/hir_def/src/generics.rs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/crates/hir_def/src/generics.rs b/crates/hir_def/src/generics.rs
index 8c5313fa45..8622357cd4 100644
--- a/crates/hir_def/src/generics.rs
+++ b/crates/hir_def/src/generics.rs
@@ -299,7 +299,7 @@ impl GenericParams {
                 let macro_call = mc.to_node(db.upcast());
                 match expander.enter_expand::<ast::Type>(db, macro_call) {
                     Ok(ExpandResult { value: Some((mark, expanded)), .. }) => {
-                        let ctx = LowerCtx::new(db, mc.file_id);
+                        let ctx = LowerCtx::new(db, expander.current_file_id());
                         let type_ref = TypeRef::from_ast(&ctx, expanded);
                         self.fill_implicit_impl_trait_args(db, expander, &type_ref);
                         expander.exit(db, mark);

From 034dd41ea81264a6cb3f4e84d49a99ecd4a96406 Mon Sep 17 00:00:00 2001
From: Giacomo Stevanato <giaco.stevanato@gmail.com>
Date: Wed, 29 Sep 2021 21:06:44 +0200
Subject: [PATCH 2/2] Add regression test

---
 crates/hir_ty/src/tests/regression.rs | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/crates/hir_ty/src/tests/regression.rs b/crates/hir_ty/src/tests/regression.rs
index 2f38d584a1..67952edca3 100644
--- a/crates/hir_ty/src/tests/regression.rs
+++ b/crates/hir_ty/src/tests/regression.rs
@@ -1198,3 +1198,26 @@ fn bar() {
     "#,
     )
 }
+
+#[test]
+fn nested_macro_in_fn_params() {
+    check_no_mismatches(
+        r#"
+macro_rules! U32Inner {
+    () => {
+        u32
+    };
+}
+
+macro_rules! U32 {
+    () => {
+        U32Inner!()
+    };
+}
+
+fn mamba(a: U32!(), p: u32) -> u32 {
+    a
+}
+    "#,
+    )
+}