Bug 1625138 - Part 21: Replace mozilla::IsFunction with std::is_function. r=froydnj

Differential Revision: https://phabricator.services.mozilla.com/D68376

--HG--
extra : moz-landing-system : lando

mfbt/Assertions.h

@@ -426,7 +426,7 @@ struct AssertionConditionType {
   static_assert(!IsArray<ValueT>::value,
                 "Expected boolean assertion condition, got an array or a "
                 "string!");
-  static_assert(!IsFunction<ValueT>::value,
+  static_assert(!std::is_function_v<ValueT>,
                 "Expected boolean assertion condition, got a function! Did "
                 "you intend to call that function?");
   static_assert(!std::is_floating_point_v<ValueT>,

mfbt/TypeTraits.h

@@ -103,34 +103,6 @@ struct IsArrayHelper<T[]> : TrueType {};
 template <typename T>
 struct IsArray : detail::IsArrayHelper<typename RemoveCV<T>::Type> {};
 
-namespace detail {
-
-template <typename T>
-struct IsFunPtr;
-
-template <typename>
-struct IsFunPtr : public FalseType {};
-
-template <typename Result, typename... ArgTypes>
-struct IsFunPtr<Result (*)(ArgTypes...)> : public TrueType {};
-
-};  // namespace detail
-
-/**
- * IsFunction determines whether a type is a function type. Function pointers
- * don't qualify here--only the type of an actual function symbol. We do not
- * correctly handle varags function types because of a bug in MSVC.
- *
- * Given the function:
- *   void f(int) {}
- *
- * mozilla::IsFunction<void(int)> is true;
- * mozilla::IsFunction<void(*)(int)> is false;
- * mozilla::IsFunction<decltype(f)> is true.
- */
-template <typename T>
-struct IsFunction : public detail::IsFunPtr<typename RemoveCV<T>::Type*> {};
-
 /* 20.9.4.3 Type properties [meta.unary.prop] */
 
 /**

mfbt/tests/TestTypeTraits.cpp

@@ -12,15 +12,9 @@ using mozilla::DeclVal;
 using mozilla::IsArray;
 using mozilla::IsConvertible;
 using mozilla::IsDestructible;
-using mozilla::IsFunction;
 using mozilla::IsSame;
 using mozilla::RemovePointer;
 
-static_assert(!IsFunction<int>::value, "int is not a function type");
-static_assert(IsFunction<void(int)>::value, "void(int) is a function type");
-static_assert(!IsFunction<void (*)(int)>::value,
-              "void(*)(int) is not a function type");
-
 static_assert(!IsArray<bool>::value, "bool not an array");
 static_assert(IsArray<bool[]>::value, "bool[] is an array");
 static_assert(IsArray<bool[5]>::value, "bool[5] is an array");