diff options
| -rw-r--r-- | src/librustc_typeck/check/coercion.rs | 6 |
1 files changed, 5 insertions, 1 deletions
diff --git a/src/librustc_typeck/check/coercion.rs b/src/librustc_typeck/check/coercion.rs index cfcdbcc1195..94422f93e59 100644 --- a/src/librustc_typeck/check/coercion.rs +++ b/src/librustc_typeck/check/coercion.rs @@ -187,7 +187,11 @@ impl<'f, 'gcx, 'tcx> Coerce<'f, 'gcx, 'tcx> { } // Consider coercing the subtype to a DST - let unsize = self.coerce_unsized(a, b); + // + // NOTE: this is wrapped in a `commit_if_ok` because it creates + // a "spurious" type variable, and we don't want to have that + // type variable in memory if the coercion fails. + let unsize = self.commit_if_ok(|_| self.coerce_unsized(a, b)); if unsize.is_ok() { debug!("coerce: unsize successful"); return unsize; |