[GenericSignatureBuilder] Rewrite sanity check to avoid warning in no-asserts builds.

Author: DougGregor

lib/AST/GenericSignatureBuilder.cpp

@@ -2280,34 +2280,24 @@ Type EquivalenceClass::getAnchor(
     return substAnchor();
   }
 
-  // Form the anchor.
-  bool updatedAnchor = false;
+  // Record the cache miss and update the cache.
+  ++NumArchetypeAnchorCacheMisses;
+  archetypeAnchorCache.anchor =
+    builder.getCanonicalTypeParameter(
+      members.front()->getDependentType(genericParams));
+  archetypeAnchorCache.lastGeneration = builder.Impl->Generation;
+
+#ifndef NDEBUG
+  // All members must produce the same anchor.
   for (auto member : members) {
     auto anchorType =
       builder.getCanonicalTypeParameter(
                                     member->getDependentType(genericParams));
-
-#ifndef NDEBUG
-    // Check that we get consistent results from all of the anchors.
-    if (updatedAnchor) {
-      assert(anchorType->isEqual(archetypeAnchorCache.anchor) &&
-             "Inconsistent anchor computation");
-      continue;
-    }
-#endif
-
-    // Record the cache miss and update the cache.
-    ++NumArchetypeAnchorCacheMisses;
-    archetypeAnchorCache.anchor = anchorType;
-    archetypeAnchorCache.lastGeneration = builder.Impl->Generation;
-    updatedAnchor = true;
-
-#if NDEBUG
-    break;
-#endif
+    assert(anchorType->isEqual(archetypeAnchorCache.anchor) &&
+           "Inconsistent anchor computation");
   }
+#endif
 
-  assert(updatedAnchor && "Couldn't update anchor?");
   return substAnchor();
 }