From 4409b33145bb0a53a2480bf81f39941197c304ff Mon Sep 17 00:00:00 2001
From: Nico Weber <thakis@chromium.org>
Date: Thu, 8 Feb 2024 18:52:03 -0500
Subject: [PATCH] AK: Make IndexSequence use size_t

This makes it possible to use MakeIndexSequqnce in functions like:

    template<typename T, size_t N>
    constexpr auto foo(T (&a)[N])

This means AK/StdLibExtraDetails.h must now include AK/Types.h
for size_t, which means AK/Types.h can no longer include
AK/StdLibExtras.h (which arguably it shouldn't do anyways),
which requires rejiggering some things.

(IMHO Types.h shouldn't use AK::Details metaprogramming at all.
FlatPtr doesn't necessarily have to use Conditional<> and ssize_t could
maybe be in its own header or something. But since it's tangential to
this PR, going with the tried and true "lift things that cause the
cycle up to the top" approach.)
---
 AK/FloatingPoint.h                            |  1 +
 AK/Forward.h                                  |  1 +
 AK/StdLibExtraDetails.h                       | 80 ++-----------------
 AK/Tuple.h                                    | 24 +++---
 AK/TypeList.h                                 |  4 +-
 AK/Types.h                                    | 80 ++++++++++++++++++-
 AK/Variant.h                                  |  6 +-
 Kernel/API/Syscall.h                          |  1 +
 Kernel/Arch/aarch64/PageDirectory.h           |  1 +
 Kernel/Arch/aarch64/RegisterState.h           |  2 +
 Kernel/Arch/aarch64/TrapFrame.h               |  1 +
 Kernel/Arch/riscv64/CSR.h                     |  1 +
 Kernel/Arch/riscv64/RegisterState.h           |  2 +
 Kernel/Arch/riscv64/SBI.h                     |  1 +
 Kernel/Arch/riscv64/TrapFrame.h               |  2 +
 Kernel/Devices/Storage/SD/Commands.h          |  1 +
 Tests/AK/TestIndexSequence.cpp                |  2 +-
 Userland/Libraries/LibC/arch/aarch64/fenv.cpp |  1 +
 Userland/Libraries/LibC/arch/riscv64/fenv.cpp |  1 +
 Userland/Libraries/LibJS/Runtime/VM.cpp       |  4 +-
 20 files changed, 120 insertions(+), 96 deletions(-)

diff --git a/AK/FloatingPoint.h b/AK/FloatingPoint.h
index 1f3346dcfa..d615d25d6a 100644
--- a/AK/FloatingPoint.h
+++ b/AK/FloatingPoint.h
@@ -7,6 +7,7 @@
 #pragma once
 
 #include <AK/BitCast.h>
+#include <AK/StdLibExtras.h>
 #include <AK/Types.h>
 
 namespace AK {
diff --git a/AK/Forward.h b/AK/Forward.h
index 24f18de69f..997ae19549 100644
--- a/AK/Forward.h
+++ b/AK/Forward.h
@@ -8,6 +8,7 @@
 
 #include <AK/DefaultDelete.h>
 #include <AK/SinglyLinkedListSizePolicy.h>
+#include <AK/StdLibExtras.h>
 #include <AK/Types.h>
 
 namespace AK {
diff --git a/AK/StdLibExtraDetails.h b/AK/StdLibExtraDetails.h
index e856e3e684..6790de3f9c 100644
--- a/AK/StdLibExtraDetails.h
+++ b/AK/StdLibExtraDetails.h
@@ -9,6 +9,7 @@
 #pragma once
 
 #include <AK/Platform.h>
+#include <AK/Types.h>
 
 namespace AK::Detail {
 
@@ -175,19 +176,6 @@ inline constexpr bool IsSame = false;
 template<typename T>
 inline constexpr bool IsSame<T, T> = true;
 
-template<bool condition, class TrueType, class FalseType>
-struct __Conditional {
-    using Type = TrueType;
-};
-
-template<class TrueType, class FalseType>
-struct __Conditional<false, TrueType, FalseType> {
-    using Type = FalseType;
-};
-
-template<bool condition, class TrueType, class FalseType>
-using Conditional = typename __Conditional<condition, TrueType, FalseType>::Type;
-
 template<typename T>
 inline constexpr bool IsNullPointer = IsSame<decltype(nullptr), RemoveCV<T>>;
 
@@ -284,64 +272,6 @@ struct __MakeUnsigned<wchar_t> {
 template<typename T>
 using MakeUnsigned = typename __MakeUnsigned<T>::Type;
 
-template<typename T>
-struct __MakeSigned {
-    using Type = void;
-};
-template<>
-struct __MakeSigned<signed char> {
-    using Type = signed char;
-};
-template<>
-struct __MakeSigned<short> {
-    using Type = short;
-};
-template<>
-struct __MakeSigned<int> {
-    using Type = int;
-};
-template<>
-struct __MakeSigned<long> {
-    using Type = long;
-};
-template<>
-struct __MakeSigned<long long> {
-    using Type = long long;
-};
-template<>
-struct __MakeSigned<unsigned char> {
-    using Type = char;
-};
-template<>
-struct __MakeSigned<unsigned short> {
-    using Type = short;
-};
-template<>
-struct __MakeSigned<unsigned int> {
-    using Type = int;
-};
-template<>
-struct __MakeSigned<unsigned long> {
-    using Type = long;
-};
-template<>
-struct __MakeSigned<unsigned long long> {
-    using Type = long long;
-};
-template<>
-struct __MakeSigned<char> {
-    using Type = char;
-};
-#if ARCH(AARCH64)
-template<>
-struct __MakeSigned<wchar_t> {
-    using Type = void;
-};
-#endif
-
-template<typename T>
-using MakeSigned = typename __MakeSigned<T>::Type;
-
 template<typename T>
 auto declval() -> T;
 
@@ -451,8 +381,8 @@ struct IntegerSequence {
     static constexpr unsigned size() noexcept { return sizeof...(Ts); }
 };
 
-template<unsigned... Indices>
-using IndexSequence = IntegerSequence<unsigned, Indices...>;
+template<size_t... Indices>
+using IndexSequence = IntegerSequence<size_t, Indices...>;
 
 #if __has_builtin(__make_integer_seq)
 template<typename T, T N>
@@ -474,8 +404,8 @@ template<typename T, T N>
 using MakeIntegerSequence = decltype(make_integer_sequence_impl<T, N>());
 #endif
 
-template<unsigned N>
-using MakeIndexSequence = MakeIntegerSequence<unsigned, N>;
+template<size_t N>
+using MakeIndexSequence = MakeIntegerSequence<size_t, N>;
 
 template<typename T>
 struct __IdentityType {
diff --git a/AK/Tuple.h b/AK/Tuple.h
index 46c3ba4113..df8a3d26fc 100644
--- a/AK/Tuple.h
+++ b/AK/Tuple.h
@@ -41,14 +41,14 @@ struct Tuple<T> {
         return const_cast<Tuple<T>&>(*this).get<U>();
     }
 
-    template<typename U, unsigned index>
+    template<typename U, size_t index>
     U& get_with_index()
     {
         static_assert(IsSame<T, U> && index == 0, "Invalid tuple access");
         return value;
     }
 
-    template<typename U, unsigned index>
+    template<typename U, size_t index>
     U const& get_with_index() const
     {
         return const_cast<Tuple<T>&>(*this).get_with_index<U, index>();
@@ -89,7 +89,7 @@ struct Tuple<T, TRest...> : Tuple<TRest...> {
         return const_cast<Tuple<T, TRest...>&>(*this).get<U>();
     }
 
-    template<typename U, unsigned index>
+    template<typename U, size_t index>
     U& get_with_index()
     {
         if constexpr (IsSame<T, U> && index == 0)
@@ -98,7 +98,7 @@ struct Tuple<T, TRest...> : Tuple<TRest...> {
             return Tuple<TRest...>::template get_with_index<U, index - 1>();
     }
 
-    template<typename U, unsigned index>
+    template<typename U, size_t index>
     U const& get_with_index() const
     {
         return const_cast<Tuple<T, TRest...>&>(*this).get_with_index<U, index>();
@@ -146,7 +146,7 @@ struct Tuple : Detail::Tuple<Ts...> {
         return Detail::Tuple<Ts...>::template get<T>();
     }
 
-    template<unsigned index>
+    template<size_t index>
     auto& get()
     {
         return Detail::Tuple<Ts...>::template get_with_index<typename Types::template Type<index>, index>();
@@ -158,7 +158,7 @@ struct Tuple : Detail::Tuple<Ts...> {
         return Detail::Tuple<Ts...>::template get<T>();
     }
 
-    template<unsigned index>
+    template<size_t index>
     auto& get() const
     {
         return Detail::Tuple<Ts...>::template get_with_index<typename Types::template Type<index>, index>();
@@ -179,37 +179,37 @@ struct Tuple : Detail::Tuple<Ts...> {
     static constexpr auto size() { return sizeof...(Ts); }
 
 private:
-    template<unsigned... Is>
+    template<size_t... Is>
     Tuple(Tuple&& other, IndexSequence<Is...>)
         : Detail::Tuple<Ts...>(move(other.get<Is>())...)
     {
     }
 
-    template<unsigned... Is>
+    template<size_t... Is>
     Tuple(Tuple const& other, IndexSequence<Is...>)
         : Detail::Tuple<Ts...>(other.get<Is>()...)
     {
     }
 
-    template<unsigned... Is>
+    template<size_t... Is>
     void set(Tuple&& other, IndexSequence<Is...>)
     {
         ((get<Is>() = move(other.get<Is>())), ...);
     }
 
-    template<unsigned... Is>
+    template<size_t... Is>
     void set(Tuple const& other, IndexSequence<Is...>)
     {
         ((get<Is>() = other.get<Is>()), ...);
     }
 
-    template<typename F, unsigned... Is>
+    template<typename F, size_t... Is>
     auto apply_as_args(F&& f, IndexSequence<Is...>)
     {
         return forward<F>(f)(get<Is>()...);
     }
 
-    template<typename F, unsigned... Is>
+    template<typename F, size_t... Is>
     auto apply_as_args(F&& f, IndexSequence<Is...>) const
     {
         return forward<F>(f)(get<Is>()...);
diff --git a/AK/TypeList.h b/AK/TypeList.h
index e2f3d13e8f..ef49f8ae7f 100644
--- a/AK/TypeList.h
+++ b/AK/TypeList.h
@@ -46,7 +46,7 @@ struct TypeWrapper {
     using Type = T;
 };
 
-template<typename List, typename F, unsigned... Indices>
+template<typename List, typename F, size_t... Indices>
 constexpr void for_each_type_impl(F&& f, IndexSequence<Indices...>)
 {
     (forward<F>(f)(TypeWrapper<typename List::template Type<Indices>> {}), ...);
@@ -58,7 +58,7 @@ constexpr void for_each_type(F&& f)
     for_each_type_impl<List>(forward<F>(f), MakeIndexSequence<List::size> {});
 }
 
-template<typename ListA, typename ListB, typename F, unsigned... Indices>
+template<typename ListA, typename ListB, typename F, size_t... Indices>
 constexpr void for_each_type_zipped_impl(F&& f, IndexSequence<Indices...>)
 {
     (forward<F>(f)(TypeWrapper<typename ListA::template Type<Indices>> {}, TypeWrapper<typename ListB::template Type<Indices>> {}), ...);
diff --git a/AK/Types.h b/AK/Types.h
index c60a5ed183..80adcfbf80 100644
--- a/AK/Types.h
+++ b/AK/Types.h
@@ -7,7 +7,6 @@
 #pragma once
 
 #include <AK/Platform.h>
-#include <AK/StdLibExtras.h>
 
 using u64 = __UINT64_TYPE__;
 using u32 = __UINT32_TYPE__;
@@ -34,6 +33,85 @@ using f128 = long double;
 #    endif
 #endif
 
+namespace AK::Detail {
+
+// MakeSigned<> is here instead of in StdLibExtras.h because it's used in the definition of size_t and ssize_t
+// and Types.h must not include StdLibExtras.h to avoid circular dependencies.
+template<typename T>
+struct __MakeSigned {
+    using Type = void;
+};
+template<>
+struct __MakeSigned<signed char> {
+    using Type = signed char;
+};
+template<>
+struct __MakeSigned<short> {
+    using Type = short;
+};
+template<>
+struct __MakeSigned<int> {
+    using Type = int;
+};
+template<>
+struct __MakeSigned<long> {
+    using Type = long;
+};
+template<>
+struct __MakeSigned<long long> {
+    using Type = long long;
+};
+template<>
+struct __MakeSigned<unsigned char> {
+    using Type = char;
+};
+template<>
+struct __MakeSigned<unsigned short> {
+    using Type = short;
+};
+template<>
+struct __MakeSigned<unsigned int> {
+    using Type = int;
+};
+template<>
+struct __MakeSigned<unsigned long> {
+    using Type = long;
+};
+template<>
+struct __MakeSigned<unsigned long long> {
+    using Type = long long;
+};
+template<>
+struct __MakeSigned<char> {
+    using Type = char;
+};
+#if ARCH(AARCH64)
+template<>
+struct __MakeSigned<wchar_t> {
+    using Type = void;
+};
+#endif
+
+template<typename T>
+using MakeSigned = typename __MakeSigned<T>::Type;
+
+// Conditional<> is here instead of in StdLibExtras.h because it's used in the definition of FlatPtr
+// and Types.h must not include StdLibExtras.h to avoid circular dependencies.
+template<bool condition, class TrueType, class FalseType>
+struct __Conditional {
+    using Type = TrueType;
+};
+
+template<class TrueType, class FalseType>
+struct __Conditional<false, TrueType, FalseType> {
+    using Type = FalseType;
+};
+
+template<bool condition, class TrueType, class FalseType>
+using Conditional = typename __Conditional<condition, TrueType, FalseType>::Type;
+
+}
+
 #ifdef AK_OS_SERENITY
 
 using size_t = __SIZE_TYPE__;
diff --git a/AK/Variant.h b/AK/Variant.h
index 307c41a27e..d8dad49623 100644
--- a/AK/Variant.h
+++ b/AK/Variant.h
@@ -182,14 +182,14 @@ inline constexpr bool IsTypeInPack<T, ParameterPack<Ts...>> = (IsSame<T, Ts> ||
 template<typename T, typename... Qs>
 using BlankIfDuplicate = Conditional<(IsTypeInPack<T, Qs> || ...), Blank<T>, T>;
 
-template<unsigned I, typename...>
+template<size_t I, typename...>
 struct InheritFromUniqueEntries;
 
 // InheritFromUniqueEntries will inherit from both Qs and Ts, but only scan entries going *forwards*
 // that is to say, if it's scanning from index I in Qs, it won't scan for duplicates for entries before I
 // as that has already been checked before.
 // This makes sure that the search is linear in time (like the 'merge' step of merge sort).
-template<unsigned I, typename... Ts, unsigned... Js, typename... Qs>
+template<size_t I, typename... Ts, size_t... Js, typename... Qs>
 struct InheritFromUniqueEntries<I, ParameterPack<Ts...>, IndexSequence<Js...>, Qs...>
     : public BlankIfDuplicate<Ts, Conditional<Js <= I, ParameterPack<>, Qs>...>... {
 
@@ -201,7 +201,7 @@ struct InheritFromPacks;
 
 // InheritFromPacks will attempt to 'merge' the pack 'Ps' with *itself*, but skip the duplicate entries
 // (via InheritFromUniqueEntries).
-template<unsigned... Is, typename... Ps>
+template<size_t... Is, typename... Ps>
 struct InheritFromPacks<IndexSequence<Is...>, Ps...>
     : public InheritFromUniqueEntries<Is, Ps, IndexSequence<Is...>, Ps...>... {
 
diff --git a/Kernel/API/Syscall.h b/Kernel/API/Syscall.h
index 4e4bdc03b1..8d00db0315 100644
--- a/Kernel/API/Syscall.h
+++ b/Kernel/API/Syscall.h
@@ -6,6 +6,7 @@
 
 #pragma once
 
+#include <AK/StdLibExtras.h>
 #include <AK/Types.h>
 #include <AK/Userspace.h>
 #include <Kernel/API/POSIX/sched.h>
diff --git a/Kernel/Arch/aarch64/PageDirectory.h b/Kernel/Arch/aarch64/PageDirectory.h
index c464229167..6683808e40 100644
--- a/Kernel/Arch/aarch64/PageDirectory.h
+++ b/Kernel/Arch/aarch64/PageDirectory.h
@@ -12,6 +12,7 @@
 #include <AK/HashMap.h>
 #include <AK/IntrusiveRedBlackTree.h>
 #include <AK/RefPtr.h>
+#include <AK/StdLibExtras.h>
 #include <AK/Types.h>
 #include <Kernel/Forward.h>
 #include <Kernel/Locking/Spinlock.h>
diff --git a/Kernel/Arch/aarch64/RegisterState.h b/Kernel/Arch/aarch64/RegisterState.h
index efbca3e8e7..4f0caf90b8 100644
--- a/Kernel/Arch/aarch64/RegisterState.h
+++ b/Kernel/Arch/aarch64/RegisterState.h
@@ -11,6 +11,8 @@
 #include <Kernel/Security/ExecutionMode.h>
 
 #include <AK/Platform.h>
+#include <AK/StdLibExtras.h>
+
 VALIDATE_IS_AARCH64()
 
 namespace Kernel {
diff --git a/Kernel/Arch/aarch64/TrapFrame.h b/Kernel/Arch/aarch64/TrapFrame.h
index cd97a9ed4d..a72986e0e1 100644
--- a/Kernel/Arch/aarch64/TrapFrame.h
+++ b/Kernel/Arch/aarch64/TrapFrame.h
@@ -8,6 +8,7 @@
 #pragma once
 
 #include <AK/Platform.h>
+#include <AK/StdLibExtras.h>
 #include <AK/Types.h>
 #include <Kernel/Arch/RegisterState.h>
 
diff --git a/Kernel/Arch/riscv64/CSR.h b/Kernel/Arch/riscv64/CSR.h
index 3a5a6c046f..a1f3cff971 100644
--- a/Kernel/Arch/riscv64/CSR.h
+++ b/Kernel/Arch/riscv64/CSR.h
@@ -8,6 +8,7 @@
 
 #include <AK/BitCast.h>
 #include <AK/Format.h>
+#include <AK/StdLibExtras.h>
 #include <AK/Types.h>
 
 #include <AK/Platform.h>
diff --git a/Kernel/Arch/riscv64/RegisterState.h b/Kernel/Arch/riscv64/RegisterState.h
index da5b45f1ae..9480051c74 100644
--- a/Kernel/Arch/riscv64/RegisterState.h
+++ b/Kernel/Arch/riscv64/RegisterState.h
@@ -12,6 +12,8 @@
 #include <Kernel/Security/ExecutionMode.h>
 
 #include <AK/Platform.h>
+#include <AK/StdLibExtras.h>
+
 VALIDATE_IS_RISCV64()
 
 namespace Kernel {
diff --git a/Kernel/Arch/riscv64/SBI.h b/Kernel/Arch/riscv64/SBI.h
index e08c0d933e..827dea472f 100644
--- a/Kernel/Arch/riscv64/SBI.h
+++ b/Kernel/Arch/riscv64/SBI.h
@@ -8,6 +8,7 @@
 
 #include <AK/Error.h>
 #include <AK/Format.h>
+#include <AK/StdLibExtras.h>
 
 // Documentation about the SBI:
 // RISC-V Supervisor Binary Interface Specification (https://github.com/riscv-non-isa/riscv-sbi-doc)
diff --git a/Kernel/Arch/riscv64/TrapFrame.h b/Kernel/Arch/riscv64/TrapFrame.h
index 69de942984..6e01b3fe4c 100644
--- a/Kernel/Arch/riscv64/TrapFrame.h
+++ b/Kernel/Arch/riscv64/TrapFrame.h
@@ -9,6 +9,8 @@
 #include <Kernel/Arch/RegisterState.h>
 
 #include <AK/Platform.h>
+#include <AK/StdLibExtras.h>
+
 VALIDATE_IS_RISCV64()
 
 namespace Kernel {
diff --git a/Kernel/Devices/Storage/SD/Commands.h b/Kernel/Devices/Storage/SD/Commands.h
index f62acc45b7..01164d2b56 100644
--- a/Kernel/Devices/Storage/SD/Commands.h
+++ b/Kernel/Devices/Storage/SD/Commands.h
@@ -6,6 +6,7 @@
 
 #pragma once
 
+#include <AK/StdLibExtras.h>
 #include <AK/Types.h>
 
 namespace Kernel::SD {
diff --git a/Tests/AK/TestIndexSequence.cpp b/Tests/AK/TestIndexSequence.cpp
index 1b897ff6b8..f36bdac3d4 100644
--- a/Tests/AK/TestIndexSequence.cpp
+++ b/Tests/AK/TestIndexSequence.cpp
@@ -37,7 +37,7 @@ TEST_CASE(TestIndexSequence)
     constexpr auto index_seq2 = MakeIndexSequence<3> {};
     static_assert(IsSame<decltype(index_seq1), decltype(index_seq2)>, "");
 
-    verify_sequence(MakeIndexSequence<10> {}, std::initializer_list<unsigned> { 0U, 1U, 2U, 3U, 4U, 5U, 6U, 7U, 8U, 9U });
+    verify_sequence(MakeIndexSequence<10> {}, std::initializer_list<size_t> { 0U, 1U, 2U, 3U, 4U, 5U, 6U, 7U, 8U, 9U });
     verify_sequence(MakeIntegerSequence<long, 16> {}, std::initializer_list<long> { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 });
 }
 
diff --git a/Userland/Libraries/LibC/arch/aarch64/fenv.cpp b/Userland/Libraries/LibC/arch/aarch64/fenv.cpp
index 286fc738a6..d9ef2de799 100644
--- a/Userland/Libraries/LibC/arch/aarch64/fenv.cpp
+++ b/Userland/Libraries/LibC/arch/aarch64/fenv.cpp
@@ -4,6 +4,7 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
+#include <AK/Assertions.h>
 #include <AK/Types.h>
 #include <fenv.h>
 
diff --git a/Userland/Libraries/LibC/arch/riscv64/fenv.cpp b/Userland/Libraries/LibC/arch/riscv64/fenv.cpp
index c406c4ed1c..3aedf717eb 100644
--- a/Userland/Libraries/LibC/arch/riscv64/fenv.cpp
+++ b/Userland/Libraries/LibC/arch/riscv64/fenv.cpp
@@ -4,6 +4,7 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
+#include <AK/Assertions.h>
 #include <AK/Types.h>
 #include <fenv.h>
 
diff --git a/Userland/Libraries/LibJS/Runtime/VM.cpp b/Userland/Libraries/LibJS/Runtime/VM.cpp
index 8e38d4f4ab..af172805f8 100644
--- a/Userland/Libraries/LibJS/Runtime/VM.cpp
+++ b/Userland/Libraries/LibJS/Runtime/VM.cpp
@@ -54,10 +54,10 @@ ErrorOr<NonnullRefPtr<VM>> VM::create(OwnPtr<CustomData> custom_data)
     return vm;
 }
 
-template<u32... code_points>
+template<size_t... code_points>
 static constexpr auto make_single_ascii_character_strings(IndexSequence<code_points...>)
 {
-    return AK::Array { (String::from_code_point(code_points))... };
+    return AK::Array { (String::from_code_point(static_cast<u32>(code_points)))... };
 }
 
 static constexpr auto single_ascii_character_strings = make_single_ascii_character_strings(MakeIndexSequence<128>());