Merge #3509

3509: Prevent include! macro include itself r=matklad a=edwin0cheng

This PR prevent `include` macro including itself. 

Note: It **does not** prevent a cyclic include: 
```rust
// foo.rs
include!("bar.rs")

// bar.rs
include!("foo.rs")
```

Co-authored-by: Edwin Cheng <[email protected]>

1 files changed, 6 insertions, 1 deletions

diff --git a/crates/ra_hir_expand/src/builtin_macro.rs b/crates/ra_hir_expand/src/builtin_macro.rs
index a57e9285f..9bc33cfa8 100644
--- a/crates/ra_hir_expand/src/builtin_macro.rs
+++ b/crates/ra_hir_expand/src/builtin_macro.rs
@@ -279,7 +279,12 @@ fn relative_file(db: &dyn AstDatabase, call_id: MacroCallId, path: &str) -> Opti
     let call_site = call_id.as_file().original_file(db);
     let path = RelativePath::new(&path);
 
-    db.resolve_relative_path(call_site, &path)
+    let res = db.resolve_relative_path(call_site, &path)?;
+    // Prevent include itself
+    if res == call_site {
+        return None;
+    }
+    Some(res)
 }
 
 fn include_expand(