Add the span of attributes of the lhs to the span of the assignment expression

Author: topecongiro

src/libsyntax/parse/parser.rs

@@ -3455,6 +3455,14 @@ impl<'a> Parser<'a> {
                 }),
             }?;
 
+            // Make sure that the span of the parent node is larger than the span of lhs and rhs,
+            // including the attributes.
+            let lhs_span = lhs
+                .attrs
+                .iter()
+                .filter(|a| a.style == AttrStyle::Outer)
+                .next()
+                .map_or(lhs_span, |a| a.span);
             let span = lhs_span.to(rhs.span);
             lhs = match op {
                 AssocOp::Add | AssocOp::Subtract | AssocOp::Multiply | AssocOp::Divide |