Add test for missing cfg propagation for reexport

src/test/rustdoc/cfg_doc_reexport.rs

@@ -0,0 +1,33 @@
+#![feature(doc_cfg)]
+#![feature(no_core)]
+
+#![crate_name = "foo"]
+#![no_core]
+
+// @has 'foo/index.html'
+// @has - '//*[@class="item-left module-item"]/*[@class="stab portability"]' 'foobar'
+// @has - '//*[@class="item-left module-item"]/*[@class="stab portability"]' 'bar'
+
+#[doc(cfg(feature = "foobar"))]
+mod imp_priv {
+    // @has 'foo/struct.BarPriv.html'
+    // @has - '//*[@id="main-content"]/*[@class="item-info"]/*[@class="stab portability"]' \
+    //    'Available on crate feature foobar only.'
+    pub struct BarPriv {}
+    impl BarPriv {
+        pub fn test() {}
+    }
+}
+#[doc(cfg(feature = "foobar"))]
+pub use crate::imp_priv::*;
+
+pub mod bar {
+    // @has 'foo/bar/struct.Bar.html'
+    // @has - '//*[@id="main-content"]/*[@class="item-info"]/*[@class="stab portability"]' \
+    //    'Available on crate feature bar only.'
+    #[doc(cfg(feature = "bar"))]
+    pub struct Bar;
+}
+
+#[doc(cfg(feature = "bar"))]
+pub use bar::Bar;