From 8168dd904d3682305114e371814bc41fbb70ada3 Mon Sep 17 00:00:00 2001
From: Avril <flanchan@cumallover.me>
Date: Sat, 12 Mar 2022 20:19:51 +0000
Subject: [PATCH] Added opaque_handle::ptr_cast(): Use `try_cast()` for
 complete types, and `unsafe_cast()` for incomplete types. This is used *only*
 for `operator [const] T*()`, since this is intended for C interop.
 `operator->` and `operator*` will only work with complete types, as they
 should.
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Fortune for opaque_handle's current commit: Curse − 凶
---
 include/opaque.hh | 21 +++++++++++++++++----
 1 file changed, 17 insertions(+), 4 deletions(-)

diff --git a/include/opaque.hh b/include/opaque.hh
index 77cef48..7b3e7c3 100644
--- a/include/opaque.hh
+++ b/include/opaque.hh
@@ -100,6 +100,19 @@ struct opaque_handle final {
 	template<typename T>
 	constexpr T* try_cast() noexcept { return _impl ? _impl->try_cast<T>() : nullptr; }
 
+	
+	/// ptr_cast(): use try_cast() for complete types, and unsafe_cast() for incomplete types.
+	template<typename T>
+	constexpr T* ptr_cast() noexcept { 
+		if constexpr(opaque_is_incomplete<T>) return unsafe_cast<T>();
+		else return try_cast<T>(); 
+	}
+	template<typename T>
+	constexpr const T* ptr_cast() const noexcept { 
+		if constexpr(opaque_is_incomplete<T>) return unsafe_cast<T>();
+		else return try_cast<T>(); 
+	}
+
 	template<typename T, cast_kind Kind = CAST_SAFE>
 	inline const T& cast() const { 
 		if constexpr(Kind >= CAST_UNSAFE)
@@ -118,6 +131,8 @@ struct opaque_handle final {
 	constexpr bool has_value() const noexcept { return bool(_impl); }
 	constexpr explicit operator bool() const noexcept { return has_value(); }
 
+	// XXX: NOTE: operator-> and operator* do not, and SHOULD NOT, work for incomplete types. only `ptr_cast()` and `operator [const] T*()` should consider the completeness of the type.
+
 	//TODO: Test these, we may need to do the same thing we did for `operator*`, but with a shim that has `operator T*` and `operator->` instead of `operator T&`.
 	template<typename T>
 	constexpr const T* operator->() const noexcept(std::is_void_v<T>) { 
@@ -147,13 +162,11 @@ struct opaque_handle final {
 */
 	template<typename T>
 	constexpr operator T*() noexcept { 
-		if constexpr(opaque_is_incomplete<T>) return unsafe_cast<T>();
-		else return try_cast<T>(); 
+		return ptr_cast<T>();
 	}
 	template<typename T>
 	constexpr operator const T*() const noexcept { 
-		if constexpr(opaque_is_incomplete<T>) return unsafe_cast<T>();
-		else return try_cast<T>(); 
+		return ptr_cast<T>();
 	}
 
 private: