Merge #2365

2365: Make expand-macro more flexible r=matklad a=edwin0cheng

Due to lack of implementation or other types of errors, some macros do not expand correctly in the current situation. The PR attempts to make `expand-macro` more flexible in error situations by ignoring internal failed macro expansion.

Co-authored-by: Edwin Cheng <edwin0cheng@gmail.com>

crates/ra_ide_api/src/expand_macro.rs

@@ -47,8 +47,7 @@ fn expand_macro_recur(
 
     for child in children.into_iter() {
         let node = hir::Source::new(macro_file_id, &child);
-        let new_node = expand_macro_recur(db, source, node)?;
-
+        if let Some(new_node) = expand_macro_recur(db, source, node) {
             // Replace the whole node if it is root
             // `replace_descendants` will not replace the parent node
             // but `SyntaxNode::descendants include itself
@@ -58,6 +57,7 @@ fn expand_macro_recur(
                 replaces.insert(child.syntax().clone().into(), new_node.into());
             }
         }
+    }
 
     Some(replace_descendants(&expanded, &replaces))
 }
@@ -247,4 +247,26 @@ fn some_thing() -> u32 {
         assert_eq!(res.name, "match_ast");
         assert_snapshot!(res.expansion, @r###"{}"###);
     }
+
+    #[test]
+    fn macro_expand_inner_macro_fail_to_expand() {
+        let res = check_expand_macro(
+            r#"
+        //- /lib.rs
+        macro_rules! bar {
+            (BAD) => {};
+        }
+        macro_rules! foo {
+            () => {bar!()};
+        }        
+
+        fn main() {        
+            let res = fo<|>o!();
+        }
+        "#,
+        );
+
+        assert_eq!(res.name, "foo");
+        assert_snapshot!(res.expansion, @r###"bar!()"###);
+    }
 }