Vk: properly test std::lower_bound() corner cases.

Like, no wonder C++ codebases are so bug-ridden, given all APIs in the
standard library are weird like this, requiring the user to completely
understand their inner workings in order to be able to use them safely.

A fix for this got made in 390d3fc06f
(2022) already, but somehow the corresponding tests were living in a
half-done stash ever since. I should probably also just do my own binary
search thing so I don't need to test everything so extensively.

src/Magnum/Vk/Device.cpp

@@ -846,6 +846,10 @@ void Device::initialize(Instance& instance, const Version version, const Contain
             const auto found = std::lower_bound(knownExtensions.begin(), knownExtensions.end(), extension, [](const Extension& a, Containers::StringView b) {
                 return a.string() < b;
             });
+            /* Thanks, C++, for forcing me to have a larger bug surface instead
+               of providing a library helper to find the damn thing. See
+               DeviceVkTest::wrapExtensionNotFound() for verification of both
+               cases. */
             if(found == knownExtensions.end() || found->string() != extension) continue;
             _enabledExtensions.set(found->index(), true);
         }

src/Magnum/Vk/Instance.cpp

@@ -346,6 +346,10 @@ void Instance::initialize(const Version version, const Containers::StringIterabl
             const auto found = std::lower_bound(knownExtensions.begin(), knownExtensions.end(), extension, [](const InstanceExtension& a, Containers::StringView b) {
                 return a.string() < b;
             });
+            /* Thanks, C++, for forcing me to have a larger bug surface instead
+               of providing a library helper to find the damn thing. See
+               InstanceVkTest::wrapExtensionNotFound() for verification of both
+               cases. */
             if(found == knownExtensions.end() || found->string() != extension) continue;
             _extensionStatus.set(found->index(), true);
         }

src/Magnum/Vk/Test/DeviceVkTest.cpp

@@ -95,6 +95,7 @@ struct DeviceVkTest: VulkanTester {
     void tryCreateUnknownExtension();
 
     void wrap();
+    void wrapExtensionNotFound();
     void wrapAlreadyCreated();
 
     void populateGlobalFunctionPointers();
@@ -233,6 +234,7 @@ DeviceVkTest::DeviceVkTest(): VulkanTester{NoCreate} {
               &DeviceVkTest::tryCreateUnknownExtension,
 
               &DeviceVkTest::wrap,
+              &DeviceVkTest::wrapExtensionNotFound,
               &DeviceVkTest::wrapAlreadyCreated,
 
               &DeviceVkTest::populateGlobalFunctionPointers});
@@ -1189,6 +1191,45 @@ void DeviceVkTest::wrap() {
     wrapped->DestroyDevice(device, nullptr);
 }
 
+void DeviceVkTest::wrapExtensionNotFound() {
+    if(std::getenv("MAGNUM_DISABLE_EXTENSIONS"))
+        CORRADE_SKIP("Can't test with the MAGNUM_DISABLE_EXTENSIONS environment variable set");
+
+    /* Creating a dedicated instance so we can enable device extensions
+       independently */
+    Instance instance2;
+
+    DeviceProperties deviceProperties = pickDevice(instance2);
+    ExtensionProperties extensions = deviceProperties.enumerateExtensionProperties({});
+    if(!extensions.isSupported<Extensions::KHR::bind_memory2>())
+        CORRADE_SKIP(Extensions::KHR::bind_memory2::string() << "not supported, can't test");
+
+    Queue queue{NoCreate};
+    Device device{instance2, DeviceCreateInfo{deviceProperties}
+        .addQueues(0, {0.0f}, {queue})
+        .addEnabledExtensions<Extensions::KHR::bind_memory2>()
+    };
+
+    /* Verify that we don't dereference garbage when std::lower_bound() ... */
+    Device wrapped{NoCreate};
+    wrapped.wrap(instance2, deviceProperties, device, device.version(), {
+        /* ... returns `last` for an unknown extension, */
+        "VK_ZZZ_this_does_not_exist",
+        Extensions::KHR::bind_memory2::string(),
+        /* ... or returns an extension that isn't actually the one we're
+           looking for, in this case being right before VK_KHR_maintenance1
+           because of this here
+         -----------------v  */
+        "VK_KHR_maintenancd1",
+    }, {}, {});
+
+    /* This one shouldn't be listed */
+    CORRADE_VERIFY(!wrapped.isExtensionEnabled<Extensions::KHR::maintenance1>());
+
+    /* The valid extension should be */
+    CORRADE_VERIFY(wrapped.isExtensionEnabled<Extensions::KHR::bind_memory2>());
+}
+
 void DeviceVkTest::wrapAlreadyCreated() {
     CORRADE_SKIP_IF_NO_ASSERT();
 

src/Magnum/Vk/Test/InstanceVkTest.cpp

@@ -64,6 +64,7 @@ struct InstanceVkTest: TestSuite::Tester {
     void tryCreateUnknownExtension();
 
     void wrap();
+    void wrapExtensionNotFound();
     void wrapAlreadyCreated();
 
     void populateGlobalFunctionPointers();
@@ -172,6 +173,7 @@ InstanceVkTest::InstanceVkTest() {
               &InstanceVkTest::tryCreateUnknownExtension,
 
               &InstanceVkTest::wrap,
+              &InstanceVkTest::wrapExtensionNotFound,
               &InstanceVkTest::wrapAlreadyCreated,
 
               &InstanceVkTest::populateGlobalFunctionPointers});
@@ -526,6 +528,38 @@ void InstanceVkTest::wrap() {
     wrapped->DestroyInstance(instance, nullptr);
 }
 
+void InstanceVkTest::wrapExtensionNotFound() {
+    if(std::getenv("MAGNUM_DISABLE_EXTENSIONS"))
+        CORRADE_SKIP("Can't test with the MAGNUM_DISABLE_EXTENSIONS environment variable set");
+
+    InstanceExtensionProperties properties = enumerateInstanceExtensionProperties();
+    if(!properties.isSupported<Extensions::EXT::debug_report>())
+        CORRADE_SKIP(Extensions::EXT::debug_report::string() << "not supported, can't test");
+
+    Instance instance{InstanceCreateInfo{}
+        .addEnabledExtensions<Extensions::EXT::debug_report>()
+    };
+
+    /* Verify that we don't dereference garbage when std::lower_bound() ... */
+    Instance wrapped{NoCreate};
+    wrapped.wrap(instance, Version::Vk11, {
+        /* ... returns `last` for an unknown extension, */
+        "VK_ZZZ_this_does_not_exist",
+        Extensions::EXT::debug_report::string(),
+        /* ... or returns an extension that isn't actually the one we're
+           looking for, in this case being right before
+           VK_KHR_get_physical_device_properties2 because of this here
+         ------------------------------------v  */
+        "VK_KHR_get_physical_device_propertier2",
+    }, {});
+
+    /* This one shouldn't be listed */
+    CORRADE_VERIFY(!wrapped.isExtensionEnabled<Extensions::KHR::get_physical_device_properties2>());
+
+    /* The valid extension should be */
+    CORRADE_VERIFY(wrapped.isExtensionEnabled<Extensions::EXT::debug_report>());
+}
+
 void InstanceVkTest::wrapAlreadyCreated() {
     CORRADE_SKIP_IF_NO_ASSERT();