Remove skstd::is_function.

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
@@ skipping 15 matching lines @@
 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(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) && (_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.
@@ skipping 49 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