Chromium contains at least 2 ways of array size calculation:

base/stl_util.h contains:
[[[
namespace base {
...
template <typename T, size_t N>
constexpr size_t size(const T (&array)[N]) noexcept {
  return N;
}
...
}
]]]

third_party/blink/renderer/platform/text/character_property_data_generator.cc contains:
[[[
#define ARRAY_LENGTH(a) (sizeof(a) / sizeof((a)[0]))
]]]


In C++, zero-length arrays can be defined, but some operations on them are not permitted
(by either Clang or GCC, even in GNU mode (-std=gnu++...)):
[[[
$ cat test.h
#include <cstddef>

namespace base {

template <typename T, size_t N>
constexpr size_t size(const T (&array)[N]) noexcept {
  return N;
}

}

#define ARRAY_LENGTH(a) (sizeof(a) / sizeof((a)[0]))

int non_empty_array[] = {1, 3, 5, 7, 9};
int empty_array[] = {};
$ cat test_base::size_1.cpp
#include "test.h"

int main() {
  size_t x = base::size(non_empty_array);
}
$ cat test_base::size_2.cpp
#include "test.h"

int main() {
  size_t x = base::size(empty_array);
}
$ cat test_ARRAY_LENGTH_1.cpp
#include "test.h"

int main() {
  size_t x = ARRAY_LENGTH(non_empty_array);
}
$ cat test_ARRAY_LENGTH_2.cpp
#include "test.h"

int main() {
  size_t x = ARRAY_LENGTH(empty_array);
}
$ g++-8.3.0 -std=gnu++17 test_base::size_1.cpp
$ clang++-8 -std=gnu++17 test_base::size_1.cpp
$ g++-8.3.0 -std=gnu++17 test_base::size_2.cpp
test_base::size_2.cpp: In function ‘int main()’:
test_base::size_2.cpp:4:36: error: no matching function for call to ‘size(int [0])’
   size_t x = base::size(empty_array);
                                    ^
In file included from test_base::size_2.cpp:1:
test.h:6:18: note: candidate: ‘template<class T, long unsigned int N> constexpr size_t base::size(const T (&)[N])’
 constexpr size_t size(const T (&array)[N]) noexcept {
                  ^~~~
test.h:6:18: note:   template argument deduction/substitution failed:
$ clang++-8 -std=gnu++17 test_base::size_2.cpp
test_base::size_2.cpp:4:14: error: no matching function for call to 'size'
  size_t x = base::size(empty_array);
             ^~~~~~~~~~
./test.h:6:18: note: candidate template ignored: substitution failure [with T = int, N = 0]: zero-length arrays are not permitted in C++
constexpr size_t size(const T (&array)[N]) noexcept {
                 ^                     ~
1 error generated.
$ g++-8.3.0 -std=gnu++17 test_ARRAY_LENGTH_1.cpp
$ clang++-8 -std=gnu++17 test_ARRAY_LENGTH_1.cpp
$ g++-8.3.0 -std=gnu++17 test_ARRAY_LENGTH_2.cpp
$ clang++-8 -std=gnu++17 test_ARRAY_LENGTH_2.cpp
]]]

As seen above, base::size() works with non-zero-length arrays and fails with zero-length arrays,
while ARRAY_LENGTH() works with both non-zero-length arrays and zero-length arrays.


third_party/blink/renderer/platform/text/character_property_data.h defines several arrays.
kIsHangulArray is a zero-length array.

When Chromium is being built with bundled ICU, then array size calculation occurs
in third_party/blink/renderer/platform/text/character_property_data_generator.cc
in GenerateCharacterPropertyData() function,
which (through SET macro) uses ARRAY_LENGTH(), which works with zero-length arrays.

When Chromium is being built with system ICU, then array size calculation occurs
in third_party/blink/renderer/platform/text/character.cc in several functions,
which (through RETURN_HAS_PROPERTY and CREATE_UNICODE_SET macros) use base::size(), which fails with zero-length arrays.

The minimalistic fix is to make third_party/blink/renderer/platform/text/character.cc also use ARRAY_LENGTH() instead of base::size().

--- /third_party/blink/renderer/platform/text/character.cc
+++ /third_party/blink/renderer/platform/text/character.cc
@@ -63,9 +63,13 @@
   return unicodeSet;
 }
 
-#define CREATE_UNICODE_SET(name)                                       \
-  createUnicodeSet(name##Array, base::size(name##Array), name##Ranges, \
-                   base::size(name##Ranges))
+// base::size (from base/stl_util.h) causes compilation errors
+// with zero-length arrays.
+#define ARRAY_LENGTH(a) (sizeof(a) / sizeof((a)[0]))
+
+#define CREATE_UNICODE_SET(name)                             \
+  createUnicodeSet(name##Array, ARRAY_LENGTH(name##Array),   \
+                   name##Ranges, ARRAY_LENGTH(name##Ranges))
 
 #define RETURN_HAS_PROPERTY(c, name)            \
   static icu::UnicodeSet* unicodeSet = nullptr; \
--- /third_party/blink/renderer/platform/text/character_property_data_generator.cc
+++ /third_party/blink/renderer/platform/text/character_property_data_generator.cc
@@ -22,6 +22,9 @@
 #else
 
 const UChar32 kMaxCodepoint = 0x10FFFF;
+
+// base::size (from base/stl_util.h) causes compilation errors
+// with zero-length arrays.
 #define ARRAY_LENGTH(a) (sizeof(a) / sizeof((a)[0]))
 
 static void SetRanges(CharacterProperty* values,