libbase: remove ARRAYSIZE_UNSAFE.

Also fix the indentation of a neighboring comment.

Bug: N/A
Test: builds
Change-Id: Iebe5f518b2ac14718f3cae91007e62b61bed9dc0

1 files changed, 14 insertions, 54 deletions

diff --git a/base/include/android-base/macros.h b/base/include/android-base/macros.h
index 174866570..5abf5141f 100644
--- a/base/include/android-base/macros.h
+++ b/base/include/android-base/macros.h
@@ -75,46 +75,6 @@ char(&ArraySizeHelper(T(&array)[N]))[N];  // NOLINT(readability/casting)
 
 #define arraysize(array) (sizeof(ArraySizeHelper(array)))
 
-// ARRAYSIZE_UNSAFE performs essentially the same calculation as arraysize,
-// but can be used on anonymous types or types defined inside
-// functions.  It's less safe than arraysize as it accepts some
-// (although not all) pointers.  Therefore, you should use arraysize
-// whenever possible.
-//
-// The expression ARRAYSIZE_UNSAFE(a) is a compile-time constant of type
-// size_t.
-//
-// ARRAYSIZE_UNSAFE catches a few type errors.  If you see a compiler error
-//
-//   "warning: division by zero in ..."
-//
-// when using ARRAYSIZE_UNSAFE, you are (wrongfully) giving it a pointer.
-// You should only use ARRAYSIZE_UNSAFE on statically allocated arrays.
-//
-// The following comments are on the implementation details, and can
-// be ignored by the users.
-//
-// ARRAYSIZE_UNSAFE(arr) works by inspecting sizeof(arr) (the # of bytes in
-// the array) and sizeof(*(arr)) (the # of bytes in one array
-// element).  If the former is divisible by the latter, perhaps arr is
-// indeed an array, in which case the division result is the # of
-// elements in the array.  Otherwise, arr cannot possibly be an array,
-// and we generate a compiler error to prevent the code from
-// compiling.
-//
-// Since the size of bool is implementation-defined, we need to cast
-// !(sizeof(a) & sizeof(*(a))) to size_t in order to ensure the final
-// result has type size_t.
-//
-// This macro is not perfect as it wrongfully accepts certain
-// pointers, namely where the pointer size is divisible by the pointee
-// size.  Since all our code has to go through a 32-bit compiler,
-// where a pointer is 4 bytes, this means all pointers to a type whose
-// size is 3 or greater than 4 will be (righteously) rejected.
-#define ARRAYSIZE_UNSAFE(a)     \
-  ((sizeof(a) / sizeof(*(a))) / \
-    static_cast<size_t>(!(sizeof(a) % sizeof(*(a)))))
-
 #define SIZEOF_MEMBER(t, f) sizeof(std::declval<t>().f)
 
 // Changing this definition will cause you a lot of pain.  A majority of
@@ -153,23 +113,23 @@ void UNUSED(const T&...) {
 //    case 42:
 //      ...
 //
-//  As shown in the example above, the FALLTHROUGH_INTENDED macro should be
-//  followed by a semicolon. It is designed to mimic control-flow statements
-//  like 'break;', so it can be placed in most places where 'break;' can, but
-//  only if there are no statements on the execution path between it and the
-//  next switch label.
+// As shown in the example above, the FALLTHROUGH_INTENDED macro should be
+// followed by a semicolon. It is designed to mimic control-flow statements
+// like 'break;', so it can be placed in most places where 'break;' can, but
+// only if there are no statements on the execution path between it and the
+// next switch label.
 //
-//  When compiled with clang, the FALLTHROUGH_INTENDED macro is expanded to
-//  [[clang::fallthrough]] attribute, which is analysed when performing switch
-//  labels fall-through diagnostic ('-Wimplicit-fallthrough'). See clang
-//  documentation on language extensions for details:
-//  http://clang.llvm.org/docs/LanguageExtensions.html#clang__fallthrough
+// When compiled with clang, the FALLTHROUGH_INTENDED macro is expanded to
+// [[clang::fallthrough]] attribute, which is analysed when performing switch
+// labels fall-through diagnostic ('-Wimplicit-fallthrough'). See clang
+// documentation on language extensions for details:
+// http://clang.llvm.org/docs/LanguageExtensions.html#clang__fallthrough
 //
-//  When used with unsupported compilers, the FALLTHROUGH_INTENDED macro has no
-//  effect on diagnostics.
+// When used with unsupported compilers, the FALLTHROUGH_INTENDED macro has no
+// effect on diagnostics.
 //
-//  In either case this macro has no effect on runtime behavior and performance
-//  of code.
+// In either case this macro has no effect on runtime behavior and performance
+// of code.
 #ifndef FALLTHROUGH_INTENDED
 #define FALLTHROUGH_INTENDED [[clang::fallthrough]]  // NOLINT
 #endif