[libc][NFC] Use RemoveCVType to implement IsIntegral and IsPointerType.

[sivachandra]

Summary

Added IsSameV as a convenience variable and used it where convenient.

[abrachet]

libc/utils/CPP/TypeTraits.h

44

Maybe we could have:

template <typename Type> struct IsIntegral {
  using NoCV = RemoveCVType<Type>;
  static constexpr bool Value = IsSame<char, NoCV>::Value ||
    ...

It also might make sense to make an std::is_same_v so we don't need to keep adding ::Value

60–61

This needs RemoveCV too. As a nit, this and the IsFloatingPointType shouldn't have Type at the end because that sounds like it would be analogous to the type definitions which end in _t like std::remove_cv_t. Although these templates have a Value not Type I think it is still better to leave it off. Especially because the type_traits version of these are just be called std::is_pointer and std::is_floating_point

[sivachandra]

• Add IsSameV
• Use RemoveCV for IsPointerType as well.

[sivachandra]

Add a convenience nested type TypeNoCV in IsInteger and IsFloatingPointType.

[sivachandra]

Add static to a global var.

[sivachandra]

libc/utils/CPP/TypeTraits.h

34

Using inline on variables is a C++ 17 feature. Does static make sense until then? I would expect this var to get optimized out anyway.

60–61

Using RemoveCV here now. Will do the renaming in a different pass as obvious. It touches a whole bunch of places.

libc/utils/CPP/TypeTraits.h

 struct TrueValue {
   static constexpr bool Value = true;
 };
 
 struct FalseValue {
   static constexpr bool Value = false;
 };
 
-template <typename Type> struct IsIntegral : public FalseValue {};
-template <> struct IsIntegral<char> : public TrueValue {};
-template <> struct IsIntegral<signed char> : public TrueValue {};
-template <> struct IsIntegral<unsigned char> : public TrueValue {};
-template <> struct IsIntegral<short> : public TrueValue {};
-template <> struct IsIntegral<unsigned short> : public TrueValue {};
-template <> struct IsIntegral<int> : public TrueValue {};
-template <> struct IsIntegral<unsigned int> : public TrueValue {};
-template <> struct IsIntegral<long> : public TrueValue {};
-template <> struct IsIntegral<unsigned long> : public TrueValue {};
-template <> struct IsIntegral<long long> : public TrueValue {};
-template <> struct IsIntegral<unsigned long long> : public TrueValue {};
-template <> struct IsIntegral<bool> : public TrueValue {};
-
-template <typename T> struct IsPointerType : public FalseValue {};
-template <typename T> struct IsPointerType<T *> : public TrueValue {};
+template <typename T> struct TypeIdentity { typedef T Type; };
 
 template <typename T1, typename T2> struct IsSame : public FalseValue {};
 template <typename T> struct IsSame<T, T> : public TrueValue {};
-
-template <typename T> struct TypeIdentity { typedef T Type; };
+template <typename T1, typename T2>
+static constexpr bool IsSameV = IsSame<T1, T2>::Value;
 
 template <typename T> struct RemoveCV : public TypeIdentity<T> {};
 template <typename T> struct RemoveCV<const T> : public TypeIdentity<T> {};
 template <typename T> struct RemoveCV<volatile T> : public TypeIdentity<T> {};
 template <typename T>
 struct RemoveCV<const volatile T> : public TypeIdentity<T> {};
 
 template <typename T> using RemoveCVType = typename RemoveCV<T>::Type;
 
+template <typename Type> struct IsIntegral {
+  using TypeNoCV = RemoveCVType<Type>;
+  static constexpr bool Value =
+      IsSameV<char, TypeNoCV> || IsSameV<signed char, TypeNoCV> ||
+      IsSameV<unsigned char, TypeNoCV> || IsSameV<short, TypeNoCV> ||
+      IsSameV<unsigned short, TypeNoCV> || IsSameV<int, TypeNoCV> ||
+      IsSameV<unsigned int, TypeNoCV> || IsSameV<long, TypeNoCV> ||
+      IsSameV<unsigned long, TypeNoCV> || IsSameV<long long, TypeNoCV> ||
+      IsSameV<unsigned long long, TypeNoCV> || IsSameV<bool, TypeNoCV>;
+};
+
+template <typename T> struct IsPointerTypeNoCV : public FalseValue {};
+template <typename T> struct IsPointerTypeNoCV<T *> : public TrueValue {};
+template <typename T> struct IsPointerType {
+  static constexpr bool Value = IsPointerTypeNoCV<RemoveCVType<T>>::Value;
+};
+
 template <typename Type> struct IsFloatingPointType {
-  static constexpr bool Value = IsSame<float, RemoveCVType<Type>>::Value ||
-                                IsSame<double, RemoveCVType<Type>>::Value ||
-                                IsSame<long double, RemoveCVType<Type>>::Value;
+  using TypeNoCV = RemoveCVType<Type>;
+  static constexpr bool Value = IsSame<float, TypeNoCV>::Value ||
+                                IsSame<double, TypeNoCV>::Value ||
+                                IsSame<long double, TypeNoCV>::Value;
 };
 
 } // namespace cpp
 } // namespace __llvm_libc
 
 #endif // LLVM_LIBC_UTILS_CPP_TYPETRAITS_H