Add SK_BEGIN_REQUIRE_DENSE / SK_END_REQUIRE_DENSE.

include/core/SkTypes.h

 /*
  * Copyright 2006 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkTypes_DEFINED
 #define SkTypes_DEFINED
 
@@ skipping 269 matching lines @@
 static inline bool SkIsU16(long x) {
     return (uint16_t)x == x;
 }
 
 //////////////////////////////////////////////////////////////////////////////
 
 /** Returns the number of entries in an array (not a pointer) */
 template <typename T, size_t N> char (&SkArrayCountHelper(T (&array)[N]))[N];
 #define SK_ARRAY_COUNT(array) (sizeof(SkArrayCountHelper(array)))
 
+// Can be used to bracket data types that must be dense, e.g. hash keys.
+#if defined(__clang__)  // This should work on GCC too, but GCC diagnostic pop didn't seem to work!
+    #define SK_BEGIN_REQUIRE_DENSE _Pragma("GCC diagnostic push") \
+                                   _Pragma("GCC diagnostic error \"-Wpadded\"")
+    #define SK_END_REQUIRE_DENSE   _Pragma("GCC diagnostic pop")
+#else
+    #define SK_BEGIN_REQUIRE_DENSE
+    #define SK_END_REQUIRE_DENSE
+#endif
+
 #define SkAlign2(x)     (((x) + 1) >> 1 << 1)
 #define SkIsAlign2(x)   (0 == ((x) & 1))
 
 #define SkAlign4(x)     (((x) + 3) >> 2 << 2)
 #define SkIsAlign4(x)   (0 == ((x) & 3))
 
 #define SkAlign8(x)     (((x) + 7) >> 3 << 3)
 #define SkIsAlign8(x)   (0 == ((x) & 7))
 
 #define SkAlignPtr(x)   (sizeof(void*) == 8 ?   SkAlign8(x) :   SkAlign4(x))
@@ skipping 358 matching lines @@
 private:
     void*       fPtr;
     size_t      fSize;  // can be larger than the requested size (see kReuse)
     uint32_t    fStorage[(kSize + 3) >> 2];
 };
 // Can't guard the constructor because it's a template class.
 
 #endif /* C++ */
 
 #endif