Templatize SkToXXX.

include/private/SkTLogic.h

 /*
  * Copyright 2013 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  *
  *
  * This header provides some of the helpers (like std::enable_if_t) which will
  * become available with C++14 in the type_traits header (in the skstd
  * namespace). This header also provides several Skia specific additions such
  * as SK_WHEN and the sknonstd namespace.
  */
 
 #ifndef SkTLogic_DEFINED
 #define SkTLogic_DEFINED
 
-#include "SkTypes.h"
-
 #include <stddef.h>
 #include <stdint.h>
 #include <type_traits>
 #include <utility>
 
 namespace skstd {
 
 template <bool B> using bool_constant = std::integral_constant<bool, B>;
 
 template <bool B, typename T, typename F> using conditional_t = typename std::conditional<B, T, F>::type;
 template <bool B, typename T = void> using enable_if_t = typename std::enable_if<B, T>::type;
 
 template <typename T> using remove_const_t = typename std::remove_const<T>::type;
 template <typename T> using remove_volatile_t = typename std::remove_volatile<T>::type;
 template <typename T> using remove_cv_t = typename std::remove_cv<T>::type;
 template <typename T> using remove_pointer_t = typename std::remove_pointer<T>::type;
 template <typename T> using remove_reference_t = typename std::remove_reference<T>::type;
 template <typename T> using remove_extent_t = typename std::remove_extent<T>::type;
 
 // template<typename R, typename... Args> struct is_function<
 //     R [calling-convention] (Args...[, ...]) [const] [volatile] [&|&&]> : std::true_type {};
 // The cv and ref-qualified versions are strange types we're currently avoiding, so not supported.
 // These aren't supported in msvc either until vs2015u2.
 // On all platforms, variadic functions only exist in the c calling convention.
 // mcvc 2013 introduced __vectorcall, but it wan't until 2015 that it was added to is_function.
 template <typename> struct is_function : std::false_type {};
-#if !defined(SK_BUILD_FOR_WIN)
+#if !defined(WIN32)
 template <typename R, typename... Args> struct is_function<R(Args...)> : std::true_type {};
 #else
 template <typename R, typename... Args> struct is_function<R __cdecl (Args...)> : std::true_type {};
 #if defined(_M_IX86)
 template <typename R, typename... Args> struct is_function<R __stdcall (Args...)> : std::true_type {};
 template <typename R, typename... Args> struct is_function<R __fastcall (Args...)> : std::true_type {};
 #endif
-#if defined(_MSC_VER) && SK_CPU_SSE_LEVEL >= SK_CPU_SSE_LEVEL_SSE2
+#if defined(_MSC_VER) && (_M_IX86_FP >= 2 || defined(_M_AMD64) || defined(_M_X64))
 template <typename R, typename... Args> struct is_function<R __vectorcall (Args...)> : std::true_type {};
 #endif
 #endif
 template <typename R, typename... Args> struct is_function<R(Args..., ...)> : std::true_type {};
 
 template <typename T> using add_const_t = typename std::add_const<T>::type;
 template <typename T> using add_volatile_t = typename std::add_volatile<T>::type;
 template <typename T> using add_cv_t = typename std::add_cv<T>::type;
 template <typename T> using add_pointer_t = typename std::add_pointer<T>::type;
 template <typename T> using add_lvalue_reference_t = typename std::add_lvalue_reference<T>::type;
 
 template <typename... T> using common_type_t = typename std::common_type<T...>::type;
 
+// Chromium currently requires gcc 4.8.2 or a recent clang compiler, but uses libstdc++4.6.4.
+// Note that Precise actually uses libstdc++4.6.3.
+// Unfortunately, libstdc++ STL before libstdc++4.7 do not define std::underlying_type.
+// Newer gcc and clang compilers have __underlying_type which does not depend on runtime support.
+// See https://gcc.gnu.org/onlinedocs/libstdc++/manual/abi.html for __GLIBCXX__ values.
+// Unfortunately __GLIBCXX__ is a date, but no updates to versions before 4.7 are now anticipated.
+#define SK_GLIBCXX_4_7_0 20120322
+// Updates to versions before 4.7 but released after 4.7 was released.
+#define SK_GLIBCXX_4_5_4 20120702
+#define SK_GLIBCXX_4_6_4 20121127
+#if defined(__GLIBCXX__) && (__GLIBCXX__ <  SK_GLIBCXX_4_7_0 || \
+                             __GLIBCXX__ == SK_GLIBCXX_4_5_4 || \
+                             __GLIBCXX__ == SK_GLIBCXX_4_6_4)
+template <typename T> struct underlying_type {
+    using type = __underlying_type(T);
+};
+#else
+template <typename T> using underlying_type = std::underlying_type<T>;
+#endif
+template <typename T> using underlying_type_t = typename skstd::underlying_type<T>::type;
+
 template <typename S, typename D,
           bool=std::is_void<S>::value || is_function<D>::value || std::is_array<D>::value>
 struct is_convertible_detector {
     static const/*expr*/ bool value = std::is_void<D>::value;
 };
 template <typename S, typename D> struct is_convertible_detector<S, D, false> {
     using yes_type = uint8_t;
     using no_type = uint16_t;
 
     template <typename To> static void param_convertable_to(To);
@@ skipping 43 matching lines @@
 template <typename D, typename S> using same_volatile_t = typename same_volatile<D, S>::type;
 template <typename D, typename S> using same_cv = copy_cv<skstd::remove_cv_t<D>, S>;
 template <typename D, typename S> using same_cv_t = typename same_cv<D, S>::type;
 
 }  // namespace sknonstd
 
 // Just a pithier wrapper for enable_if_t.
 #define SK_WHEN(condition, T) skstd::enable_if_t<!!(condition), T>
 
 #endif