My clang now doesn't complain about !"foo".

src/gpu/GrAtlas.cpp

Index: src/gpu/GrAtlas.cpp
diff --git a/src/gpu/GrAtlas.cpp b/src/gpu/GrAtlas.cpp
index 9184929efc9e1bc034b3f7028989d766b57cd96c..9776326f953c71fa03e8b0486ac7d6ea694c3ee7 100644
--- a/src/gpu/GrAtlas.cpp
+++ b/src/gpu/GrAtlas.cpp
@@ -189,7 +189,7 @@ static GrPixelConfig maskformat2pixelconfig(GrMaskFormat format) {
         case kA888_GrMaskFormat:
             return kSkia8888_GrPixelConfig;
         default:
-            SkASSERT(!"unknown maskformat");
+            SkDEBUGFAIL("unknown maskformat");
     }
     return kUnknown_GrPixelConfig;
 }