From b87b335e6859ead3baa7fde20e3ea2ac69f63d85 Mon Sep 17 00:00:00 2001
From: Benjamin Coenen <5719034+bnjjj@users.noreply.github.com>
Date: Sat, 25 Apr 2020 15:48:04 +0200
Subject: add support for cfg feature attributes on expression #4063

Signed-off-by: Benjamin Coenen <5719034+bnjjj@users.noreply.github.com>
---
 crates/ra_hir_def/src/body/lower.rs |  4 ++++
 crates/ra_hir_ty/src/tests.rs       | 32 ++++++++++++++++++++++++++++++++
 2 files changed, 36 insertions(+)

diff --git a/crates/ra_hir_def/src/body/lower.rs b/crates/ra_hir_def/src/body/lower.rs
index 0caedd8d8..571603854 100644
--- a/crates/ra_hir_def/src/body/lower.rs
+++ b/crates/ra_hir_def/src/body/lower.rs
@@ -141,6 +141,10 @@ impl ExprCollector<'_> {
 
     fn collect_expr(&mut self, expr: ast::Expr) -> ExprId {
         let syntax_ptr = AstPtr::new(&expr);
+        let attrs = self.expander.parse_attrs(&expr);
+        if !self.expander.is_cfg_enabled(&attrs) {
+            return self.missing_expr();
+        }
         match expr {
             ast::Expr::IfExpr(e) => {
                 let then_branch = self.collect_block_opt(e.then_branch());
diff --git a/crates/ra_hir_ty/src/tests.rs b/crates/ra_hir_ty/src/tests.rs
index b6a96bb5c..588d81282 100644
--- a/crates/ra_hir_ty/src/tests.rs
+++ b/crates/ra_hir_ty/src/tests.rs
@@ -390,6 +390,38 @@ fn no_such_field_with_feature_flag_diagnostics_on_struct_lit() {
     assert_snapshot!(diagnostics, @r###""###);
 }
 
+#[test]
+fn no_such_field_with_feature_flag_diagnostics_on_block_expr() {
+    let diagnostics = TestDB::with_files(
+        r#"
+        //- /lib.rs crate:foo cfg:feature=foo
+        struct S {
+            #[cfg(feature = "foo")]
+            foo: u32,
+            #[cfg(not(feature = "foo"))]
+            bar: u32,
+        }
+
+        impl S {
+            fn new(bar: u32) -> Self {
+                #[cfg(feature = "foo")]
+                {
+                Self { foo: bar }
+                }
+                #[cfg(not(feature = "foo"))]
+                {
+                Self { bar }
+                }
+            }
+        }
+        "#,
+    )
+    .diagnostics()
+    .0;
+
+    assert_snapshot!(diagnostics, @r###""###);
+}
+
 #[test]
 fn no_such_field_with_feature_flag_diagnostics_on_struct_fields() {
     let diagnostics = TestDB::with_files(
-- 
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