--- a/src/Pure/type.ML Sat Sep 04 20:01:43 2021 +0200
+++ b/src/Pure/type.ML Sat Sep 04 21:25:08 2021 +0200
@@ -446,7 +446,7 @@
in match end;
fun typ_instance tsig (T, U) =
- (typ_match tsig (U, T) Vartab.empty; true) handle TYPE_MATCH => false;
+ (Vartab.build (typ_match tsig (U, T)); true) handle TYPE_MATCH => false;
(*purely structural matching*)
fun raw_match (TVar (v, S), T) subs =
@@ -474,7 +474,7 @@
fun raw_instance (T, U) =
if could_match (U, T) then
- (raw_match (U, T) Vartab.empty; true) handle TYPE_MATCH => false
+ (Vartab.build (raw_match (U, T)); true) handle TYPE_MATCH => false
else false;