[ConstraintSystem] Implement simplication of PatternMatch element

Author: xedin

lib/Sema/ConstraintSystem.cpp

@@ -4758,6 +4758,12 @@ void constraints::simplifyLocator(ASTNode &anchor,
         path = path.slice(1);
         continue;
       }
+
+      if (anchor.is<Pattern *>()) {
+        path = path.slice(1);
+        continue;
+      }
+
       break;
 
     case ConstraintLocator::SubscriptMember:
@@ -4851,6 +4857,13 @@ void constraints::simplifyLocator(ASTNode &anchor,
       continue;
     }
 
+    case ConstraintLocator::PatternMatch: {
+      auto patternElt = path[0].castTo<LocatorPathElt::PatternMatch>();
+      anchor = patternElt.getPattern();
+      path = path.slice(1);
+      continue;
+    }
+
     default:
       // FIXME: Lots of other cases to handle.
       break;