fix(frontends/lean/structure_cmd): fixes #968

src/frontends/lean/structure_cmd.cpp

@@ -605,6 +605,7 @@ struct structure_cmd_fn {
         expr tmp   = Pi(m_params, Pi(m_fields, dummy));
         collected_locals local_set;
         ::lean::collect_locals(tmp, local_set);
+        collect_annonymous_inst_implicit(m_p, local_set);
         sort_locals(local_set.get_collected(), m_p, locals);
     }
 

tests/lean/run/968.lean

@@ -0,0 +1,15 @@
+variables (A : Type) [inhabited A]
+
+definition f (a : A) : A := a
+
+check @f nat nat.is_inhabited
+
+structure foo :=
+(a : A)
+
+check @foo nat nat.is_inhabited
+
+inductive bla :=
+| mk : A → bla
+
+check @bla nat nat.is_inhabited