From 2e178b5475b156e1876e4e6971c0abd3bdf6c889 Mon Sep 17 00:00:00 2001
From: Edwin Cheng <edwin0cheng@gmail.com>
Date: Sat, 7 Mar 2020 13:02:54 +0800
Subject: Fix test and add more comment

---
 crates/ra_hir_expand/src/builtin_macro.rs | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

(limited to 'crates/ra_hir_expand')

diff --git a/crates/ra_hir_expand/src/builtin_macro.rs b/crates/ra_hir_expand/src/builtin_macro.rs
index 51d54331e..a57e9285f 100644
--- a/crates/ra_hir_expand/src/builtin_macro.rs
+++ b/crates/ra_hir_expand/src/builtin_macro.rs
@@ -142,6 +142,9 @@ fn env_expand(
     _tt: &tt::Subtree,
 ) -> Result<tt::Subtree, mbe::ExpandError> {
     // dummy implementation for type-checking purposes
+    // we cannot use an empty string here, because for
+    // `include!(concat!(env!("OUT_DIR"), "/foo.rs"))` will become
+    // `include!("foo.rs"), which maybe infinite loop
     let expanded = quote! { "__RA_UNIMPLEMENTATED__" };
 
     Ok(expanded)
@@ -394,7 +397,7 @@ mod tests {
             "#,
         );
 
-        assert_eq!(expanded, "\"\"");
+        assert_eq!(expanded, "\"__RA_UNIMPLEMENTATED__\"");
     }
 
     #[test]
-- 
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