Merge #8398

8398: Fix inference with conditionally compiled tails r=flodiebold a=DJMcNab

Fixes #8378

Co-authored-by: Daniel McNab <[email protected]>

3 files changed, 51 insertions, 2 deletions

diff --git a/crates/hir_ty/src/diagnostics/expr.rs b/crates/hir_ty/src/diagnostics/expr.rs
index 79602c3dd..47709c1e8 100644
--- a/crates/hir_ty/src/diagnostics/expr.rs
+++ b/crates/hir_ty/src/diagnostics/expr.rs
@@ -83,7 +83,7 @@ impl<'a, 'b> ExprValidator<'a, 'b> {
         if let Expr::Block { statements, tail, .. } = body_expr {
             if let Some(t) = tail {
                 self.validate_results_in_tail_expr(body.body_expr, *t, db);
-            } else if let Some(Statement::Expr(id)) = statements.last() {
+            } else if let Some(Statement::Expr { expr: id, .. }) = statements.last() {
                 self.validate_missing_tail_expr(body.body_expr, *id, db);
             }
         }
diff --git a/crates/hir_ty/src/infer/expr.rs b/crates/hir_ty/src/infer/expr.rs
index 50497eecb..9476e6297 100644
--- a/crates/hir_ty/src/infer/expr.rs
+++ b/crates/hir_ty/src/infer/expr.rs
@@ -809,7 +809,7 @@ impl<'a> InferenceContext<'a> {
                     let ty = self.resolve_ty_as_possible(ty);
                     self.infer_pat(*pat, &ty, BindingMode::default());
                 }
-                Statement::Expr(expr) => {
+                Statement::Expr { expr, .. } => {
                     self.infer_expr(*expr, &Expectation::none());
                 }
             }
diff --git a/crates/hir_ty/src/tests/regression.rs b/crates/hir_ty/src/tests/regression.rs
index d14f5c9bb..e23bd4da9 100644
--- a/crates/hir_ty/src/tests/regression.rs
+++ b/crates/hir_ty/src/tests/regression.rs
@@ -1050,3 +1050,52 @@ fn test() {
         "#]],
     );
 }
+
+#[test]
+fn cfg_tail() {
+    // https://github.com/rust-analyzer/rust-analyzer/issues/8378
+    check_infer(
+        r#"
+        fn fake_tail(){
+            { "first" }
+            #[cfg(never)] 9
+        }
+        fn multiple_fake(){
+            { "fake" }
+            { "fake" }
+            { "second" }
+            #[cfg(never)] { 11 }
+            #[cfg(never)] 12;
+            #[cfg(never)] 13
+        }
+        fn no_normal_tail(){
+            { "third" }
+            #[cfg(never)] 14;
+            #[cfg(never)] 15;
+        }
+        fn no_actual_tail(){
+            { "fourth" };
+            #[cfg(never)] 14;
+            #[cfg(never)] 15
+        }
+        "#,
+        expect![[r#"
+            14..53 '{     ...)] 9 }': &str
+            20..31 '{ "first" }': &str
+            22..29 '"first"': &str
+            72..190 '{     ...] 13 }': &str
+            78..88 '{ "fake" }': &str
+            80..86 '"fake"': &str
+            93..103 '{ "fake" }': &str
+            95..101 '"fake"': &str
+            108..120 '{ "second" }': &str
+            110..118 '"second"': &str
+            210..273 '{     ... 15; }': &str
+            216..227 '{ "third" }': &str
+            218..225 '"third"': &str
+            293..357 '{     ...] 15 }': ()
+            299..311 '{ "fourth" }': &str
+            301..309 '"fourth"': &str
+        "#]],
+    )
+}