From f89e935f7d311b0e7dd4100639b77bf5e04dd03e Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Vladim=C3=ADr=20Vondru=C5=A1?= <mosra@centrum.cz>
Date: Thu, 6 Jun 2019 18:21:12 +0200
Subject: [PATCH] Ensure Resource operator== doesn't work with different types.

Otherwise it could in some circumstances compare the actual
resource values giving false positives.
---
 src/Magnum/Resource.h                   |  6 ++++++
 src/Magnum/Test/ResourceManagerTest.cpp | 14 ++++++++++++++
 2 files changed, 20 insertions(+)

diff --git a/src/Magnum/Resource.h b/src/Magnum/Resource.h
index 4f6790d9c..f3f936646 100644
--- a/src/Magnum/Resource.h
+++ b/src/Magnum/Resource.h
@@ -156,11 +156,17 @@ class Resource {
             return manager == other.manager && _key == other._key;
         }
 
+        /** @brief Equality comparison with other types is explicitly disallowed */
+        template<class V, class W> bool operator==(const Resource<V, W>&) const = delete;
+
         /** @brief Non-equality comparison */
         bool operator!=(const Resource<T, U>& other) const {
             return !operator==(other);
         }
 
+        /** @brief Non-equality comparison with other types is explicitly disallowed */
+        template<class V, class W> bool operator!=(const Resource<V, W>&) const = delete;
+
         /** @brief Resource key */
         ResourceKey key() const { return _key; }
 
diff --git a/src/Magnum/Test/ResourceManagerTest.cpp b/src/Magnum/Test/ResourceManagerTest.cpp
index c325b4095..acc23710c 100644
--- a/src/Magnum/Test/ResourceManagerTest.cpp
+++ b/src/Magnum/Test/ResourceManagerTest.cpp
@@ -98,6 +98,20 @@ void ResourceManagerTest::compare() {
     CORRADE_VERIFY(resA1 == resA1);
     CORRADE_VERIFY(resA1 == resA2);
     CORRADE_VERIFY(resA1 != resB);
+
+    Magnum::ResourceManager<Int, Float> rm2;
+    rm2.set(resKeyA, 1);
+    rm2.set(resKeyA, 1.0f);
+
+    Resource<Int> resAOther = rm2.get<Int>(resKeyA);
+    Resource<Float> resADifferentType = rm2.get<Float>(resKeyA);
+    /* Verify it checks for manager equality as well */
+    CORRADE_VERIFY(resA1 != resAOther);
+    /* If the comparison operator wouldn't be deleted, the implicit conversion
+       would kick in and then 1.0f == 1.0f, which is wrong. With the deleted
+       operator this doesn't compile. */
+    //CORRADE_VERIFY(resA1 != resADifferentType);
+    //CORRADE_VERIFY(!(resA1 == resADifferentType));
 }
 
 void ResourceManagerTest::state() {