5 files changed, 50 insertions, 2 deletions

diff --git a/crates/hir_ty/src/infer.rs b/crates/hir_ty/src/infer.rs
index 8f9cf7480..e4407ff50 100644
--- a/crates/hir_ty/src/infer.rs
+++ b/crates/hir_ty/src/infer.rs
@@ -45,6 +45,11 @@ use crate::{
     to_assoc_type_id, to_chalk_trait_id, AliasEq, AliasTy, Interner, TyKind,
 };
 
+// This lint has a false positive here. See the link below for details.
+//
+// https://github.com/rust-lang/rust/issues/57411
+#[allow(unreachable_pub)]
+pub use unify::could_unify;
 pub(crate) use unify::unify;
 
 mod unify;
diff --git a/crates/hir_ty/src/infer/expr.rs b/crates/hir_ty/src/infer/expr.rs
index 3f3187ea2..e6ede05ca 100644
--- a/crates/hir_ty/src/infer/expr.rs
+++ b/crates/hir_ty/src/infer/expr.rs
@@ -767,6 +767,7 @@ impl<'a> InferenceContext<'a> {
                     None => self.table.new_float_var(),
                 },
             },
+            Expr::MacroStmts { tail } => self.infer_expr(*tail, expected),
         };
         // use a new type variable if we got unknown here
         let ty = self.insert_type_vars_shallow(ty);
diff --git a/crates/hir_ty/src/infer/unify.rs b/crates/hir_ty/src/infer/unify.rs
index 75250a369..6e7b0f5a6 100644
--- a/crates/hir_ty/src/infer/unify.rs
+++ b/crates/hir_ty/src/infer/unify.rs
@@ -157,6 +157,10 @@ impl<T> Canonicalized<T> {
     }
 }
 
+pub fn could_unify(t1: &Ty, t2: &Ty) -> bool {
+    InferenceTable::new().unify(t1, t2)
+}
+
 pub(crate) fn unify(tys: &Canonical<(Ty, Ty)>) -> Option<Substitution> {
     let mut table = InferenceTable::new();
     let vars = Substitution(
diff --git a/crates/hir_ty/src/lib.rs b/crates/hir_ty/src/lib.rs
index 69265286f..6f9c698e6 100644
--- a/crates/hir_ty/src/lib.rs
+++ b/crates/hir_ty/src/lib.rs
@@ -41,7 +41,7 @@ use crate::{
 };
 
 pub use autoderef::autoderef;
-pub use infer::{InferenceResult, InferenceVar};
+pub use infer::{could_unify, InferenceResult, InferenceVar};
 pub use lower::{
     associated_type_shorthand_candidates, callable_item_sig, CallableDefId, ImplTraitLoweringMode,
     TyDefId, TyLoweringContext, ValueTyDefId,
diff --git a/crates/hir_ty/src/tests/macros.rs b/crates/hir_ty/src/tests/macros.rs
index 7eda51866..01935ec99 100644
--- a/crates/hir_ty/src/tests/macros.rs
+++ b/crates/hir_ty/src/tests/macros.rs
@@ -226,12 +226,49 @@ fn expr_macro_expanded_in_stmts() {
         "#,
         expect![[r#"
             !0..8 'leta=();': ()
+            !0..8 'leta=();': ()
+            !3..4 'a': ()
+            !5..7 '()': ()
             57..84 '{     ...); } }': ()
         "#]],
     );
 }
 
 #[test]
+fn recurisve_macro_expanded_in_stmts() {
+    check_infer(
+        r#"
+        macro_rules! ng {
+            ([$($tts:tt)*]) => {
+                $($tts)*;
+            };
+            ([$($tts:tt)*] $head:tt $($rest:tt)*) => {
+                ng! {
+                    [$($tts)* $head] $($rest)*
+                }
+            };
+        }
+        fn foo() {
+            ng!([] let a = 3);
+            let b = a;
+        }
+        "#,
+        expect![[r#"
+            !0..7 'leta=3;': {unknown}
+            !0..7 'leta=3;': {unknown}
+            !0..13 'ng!{[leta=3]}': {unknown}
+            !0..13 'ng!{[leta=]3}': {unknown}
+            !0..13 'ng!{[leta]=3}': {unknown}
+            !3..4 'a': i32
+            !5..6 '3': i32
+            196..237 '{     ...= a; }': ()
+            229..230 'b': i32
+            233..234 'a': i32
+        "#]],
+    );
+}
+
+#[test]
 fn recursive_inner_item_macro_rules() {
     check_infer(
         r#"
@@ -246,7 +283,8 @@ fn recursive_inner_item_macro_rules() {
         "#,
         expect![[r#"
             !0..1 '1': i32
-            !0..7 'mac!($)': {unknown}
+            !0..26 'macro_...>{1};}': {unknown}
+            !0..26 'macro_...>{1};}': {unknown}
             107..143 '{     ...!(); }': ()
             129..130 'a': i32
         "#]],