Store span of method receiver colon tokens
diff --git a/syntax/parse.rs b/syntax/parse.rs
index fe18832..a06affc 100644
--- a/syntax/parse.rs
+++ b/syntax/parse.rs
@@ -562,6 +562,7 @@
                         lifetime: lifetime.clone(),
                         mutable: arg.mutability.is_some(),
                         var: arg.self_token,
+                        colon_token: Token![:](arg.self_token.span),
                         ty: NamedType::new(Ident::new("Self", arg.self_token.span)),
                         shorthand: true,
                         pin_tokens: None,
@@ -607,6 +608,7 @@
                             lifetime: reference.lifetime,
                             mutable: reference.mutable,
                             var: Token![self](ident.rust.span()),
+                            colon_token: arg.colon_token,
                             ty: ident,
                             shorthand: false,
                             pin_tokens: reference.pin_tokens,