From f31bd190b0f746a8e304a4eeb79ce9c002e656d0 Mon Sep 17 00:00:00 2001
From: Timothy Flynn <trflynn89@pm.me>
Date: Thu, 2 Feb 2023 10:48:11 -0500
Subject: [PATCH] AK: Ensure string types are actually considered
 hash-compatible

The AnyString concept is currently broken because it checks whether a
StringView is constructible from a type T. The StringView constructors,
however, only accept constant rvalue references - i.e. `T const&`.

This also adds a test to ensure this continues to work.
---
 AK/Concepts.h                |  2 +-
 Tests/AK/TestStringUtils.cpp | 24 ++++++++++++++++++++++++
 2 files changed, 25 insertions(+), 1 deletion(-)

diff --git a/AK/Concepts.h b/AK/Concepts.h
index f3966a1e84c..5b753050d9f 100644
--- a/AK/Concepts.h
+++ b/AK/Concepts.h
@@ -49,7 +49,7 @@ template<typename T, typename S>
 concept DerivedFrom = IsBaseOf<S, T>;
 
 template<typename T>
-concept AnyString = IsConstructible<StringView, T>;
+concept AnyString = IsConstructible<StringView, RemoveCVReference<T> const&>;
 
 template<typename T, typename U>
 concept HashCompatible = IsHashCompatible<Detail::Decay<T>, Detail::Decay<U>>;
diff --git a/Tests/AK/TestStringUtils.cpp b/Tests/AK/TestStringUtils.cpp
index 93b4c451573..90090acf106 100644
--- a/Tests/AK/TestStringUtils.cpp
+++ b/Tests/AK/TestStringUtils.cpp
@@ -6,9 +6,33 @@
 
 #include <LibTest/TestCase.h>
 
+#include <AK/ByteBuffer.h>
+#include <AK/Concepts.h>
+#include <AK/FlyString.h>
+#include <AK/String.h>
 #include <AK/StringUtils.h>
 #include <AK/Vector.h>
 
+TEST_CASE(hash_compatible)
+{
+    static_assert(AK::Concepts::HashCompatible<String, StringView>);
+    static_assert(AK::Concepts::HashCompatible<String, FlyString>);
+    static_assert(AK::Concepts::HashCompatible<StringView, String>);
+    static_assert(AK::Concepts::HashCompatible<StringView, FlyString>);
+    static_assert(AK::Concepts::HashCompatible<FlyString, String>);
+    static_assert(AK::Concepts::HashCompatible<FlyString, StringView>);
+
+    static_assert(AK::Concepts::HashCompatible<DeprecatedString, StringView>);
+    static_assert(AK::Concepts::HashCompatible<DeprecatedString, DeprecatedFlyString>);
+    static_assert(AK::Concepts::HashCompatible<StringView, DeprecatedString>);
+    static_assert(AK::Concepts::HashCompatible<StringView, DeprecatedFlyString>);
+    static_assert(AK::Concepts::HashCompatible<DeprecatedFlyString, DeprecatedString>);
+    static_assert(AK::Concepts::HashCompatible<DeprecatedFlyString, StringView>);
+
+    static_assert(AK::Concepts::HashCompatible<StringView, ByteBuffer>);
+    static_assert(AK::Concepts::HashCompatible<ByteBuffer, StringView>);
+}
+
 TEST_CASE(matches_null)
 {
     EXPECT(AK::StringUtils::matches(StringView(), StringView()));