Add a NoAllocate tag.

Will be used by Vulkan.

doc/changelog.dox

@@ -40,6 +40,8 @@ See also:
 
 @subsection changelog-latest-new New features
 
+-   New @ref NoAllocate constructor tag, to be used by the @ref Vk library
+
 @subsubsection changelog-latest-new-debugtools DebugTools library
 
 -   Added @ref DebugTools::ColorMap::coolWarmSmooth() and

src/Magnum/Tags.h

@@ -53,6 +53,21 @@ Vulkan / ... object.
 */
 typedef Corrade::Containers::NoCreateT NoCreateT;
 
+/**
+@brief No allocation tag type
+@m_since_latest
+
+Used to distinguish construction without allocating memory.
+@see @ref NoAllocate
+*/
+/* Explicit constructor to avoid ambiguous calls when using {} */
+struct NoAllocateT {
+    #ifndef DOXYGEN_GENERATING_OUTPUT
+    struct Init{};
+    constexpr explicit NoAllocateT(Init) {}
+    #endif
+};
+
 /**
 @brief No initialization tag
 @m_since{2020,06}
@@ -80,6 +95,14 @@ constexpr NoCreateT NoCreate{};
 using Corrade::Containers::NoCreate;
 #endif
 
+/**
+@brief No allocation tag
+@m_since_latest
+
+Use for construction without allocating memory.
+*/
+constexpr NoAllocateT NoAllocate{NoAllocateT::Init{}};
+
 }
 
 #endif

src/Magnum/Test/TagsTest.cpp

@@ -45,11 +45,13 @@ TagsTest::TagsTest() {
 void TagsTest::noDefaultConstructor() {
     CORRADE_VERIFY(!std::is_default_constructible<NoInitT>::value);
     CORRADE_VERIFY(!std::is_default_constructible<NoCreateT>::value);
+    CORRADE_VERIFY(!std::is_default_constructible<NoAllocateT>::value);
 }
 
 void TagsTest::inlineDefinition() {
     CORRADE_VERIFY((std::is_same<decltype(NoInit), const NoInitT>::value));
     CORRADE_VERIFY((std::is_same<decltype(NoCreate), const NoCreateT>::value));
+    CORRADE_VERIFY((std::is_same<decltype(NoAllocate), const NoAllocateT>::value));
 }
 
 }}}