diff options
| -rw-r--r-- | src/libsyntax_pos/hygiene.rs | 9 |
1 files changed, 8 insertions, 1 deletions
diff --git a/src/libsyntax_pos/hygiene.rs b/src/libsyntax_pos/hygiene.rs index 6cf6f6f17c1..64cd31a485c 100644 --- a/src/libsyntax_pos/hygiene.rs +++ b/src/libsyntax_pos/hygiene.rs @@ -85,7 +85,14 @@ impl Mark { #[inline] pub fn set_expn_info(self, info: ExpnInfo) { - HygieneData::with(|data| data.marks[self.0 as usize].expn_info = Some(info)) + HygieneData::with(|data| { + let old_info = &mut data.marks[self.0 as usize].expn_info; + if let Some(old_info) = old_info { + panic!("expansion info is reset for the mark {}\nold: {:#?}\nnew: {:#?}", + self.0, old_info, info); + } + *old_info = Some(info); + }) } pub fn modern(mut self) -> Mark { |