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

src/gpu/gl/GrGLUtil.cpp

Index: src/gpu/gl/GrGLUtil.cpp
diff --git a/src/gpu/gl/GrGLUtil.cpp b/src/gpu/gl/GrGLUtil.cpp
index 99efeaf6a6e84d075f8db0f54e8a60e9ea45e842..422f0c321a8be913b0bcbdef2051c2dacbb6a25d 100644
--- a/src/gpu/gl/GrGLUtil.cpp
+++ b/src/gpu/gl/GrGLUtil.cpp
@@ -93,7 +93,7 @@ bool get_gl_version_for_mesa(int mesaMajorVersion, int* major, int* minor) {
 
 GrGLBinding GrGLGetBindingInUseFromString(const char* versionString) {
     if (NULL == versionString) {
-        SkASSERT(!"NULL GL version string.");
+        SkDEBUGFAIL("NULL GL version string.");
         return kNone_GrGLBinding;
     }
 
@@ -129,7 +129,7 @@ bool GrGLIsMesaFromVersionString(const char* versionString) {
 
 GrGLVersion GrGLGetVersionFromString(const char* versionString) {
     if (NULL == versionString) {
-        SkASSERT(!"NULL GL version string.");
+        SkDEBUGFAIL("NULL GL version string.");
         return 0;
     }
 
@@ -168,7 +168,7 @@ GrGLVersion GrGLGetVersionFromString(const char* versionString) {
 
 GrGLSLVersion GrGLGetGLSLVersionFromString(const char* versionString) {
     if (NULL == versionString) {
-        SkASSERT(!"NULL GLSL version string.");
+        SkDEBUGFAIL("NULL GLSL version string.");
         return 0;
     }