Annotate matcher combinators with CATCH_ATTR_LIFETIMEBOUND

The matcher combinators do not take ownership of the matchers
being combined, which can catch the users off-guard, when code like
this

```cpp
using Catch::Matchers::EndsWith;
using Catch::Matchers::ContainsSubstring;

auto combinedMatcher = EndsWith("as a service")
                       && ContainsSubstring("web scale");

REQUIRE_THAT( getSomeString(), combinedMatcher );
```

leads to use-after-free, as the `combinedMatcher` refers to matcher
temporaries that no longer exists. With this commit, users of Clang,
MSVC or other compiler that understands the `lifetimebound` attribute,
should get a warning.

src/CMakeLists.txt

@@ -98,6 +98,7 @@ set(IMPL_HEADERS
   ${SOURCES_DIR}/internal/catch_jsonwriter.hpp
   ${SOURCES_DIR}/internal/catch_lazy_expr.hpp
   ${SOURCES_DIR}/internal/catch_leak_detector.hpp
+  ${SOURCES_DIR}/internal/catch_lifetimebound.hpp
   ${SOURCES_DIR}/internal/catch_list.hpp
   ${SOURCES_DIR}/internal/catch_logical_traits.hpp
   ${SOURCES_DIR}/internal/catch_message_info.hpp

src/catch2/catch_all.hpp

@@ -79,6 +79,7 @@
 #include <catch2/internal/catch_jsonwriter.hpp>
 #include <catch2/internal/catch_lazy_expr.hpp>
 #include <catch2/internal/catch_leak_detector.hpp>
+#include <catch2/internal/catch_lifetimebound.hpp>
 #include <catch2/internal/catch_list.hpp>
 #include <catch2/internal/catch_logical_traits.hpp>
 #include <catch2/internal/catch_message_info.hpp>

src/catch2/internal/catch_lifetimebound.hpp

@@ -0,0 +1,24 @@
+
+//              Copyright Catch2 Authors
+// Distributed under the Boost Software License, Version 1.0.
+//   (See accompanying file LICENSE.txt or copy at
+//        https://www.boost.org/LICENSE_1_0.txt)
+
+// SPDX-License-Identifier: BSL-1.0
+
+#ifndef CATCH_LIFETIMEBOUND_HPP_INCLUDED
+#define CATCH_LIFETIMEBOUND_HPP_INCLUDED
+
+#if !defined( __has_cpp_attribute )
+#    define CATCH_ATTR_LIFETIMEBOUND
+#elif __has_cpp_attribute( msvc::lifetimebound )
+#    define CATCH_ATTR_LIFETIMEBOUND [[msvc::lifetimebound]]
+#elif __has_cpp_attribute( clang::lifetimebound )
+#    define CATCH_ATTR_LIFETIMEBOUND [[clang::lifetimebound]]
+#elif __has_cpp_attribute( lifetimebound )
+#    define CATCH_ATTR_LIFETIMEBOUND [[lifetimebound]]
+#else
+#    define CATCH_ATTR_LIFETIMEBOUND
+#endif
+
+#endif // CATCH_LIFETIMEBOUND_HPP_INCLUDED

src/catch2/matchers/catch_matchers.hpp

@@ -10,6 +10,7 @@
 
 #include <catch2/matchers/internal/catch_matchers_impl.hpp>
 #include <catch2/internal/catch_move_and_forward.hpp>
+#include <catch2/internal/catch_lifetimebound.hpp>
 
 #include <string>
 #include <vector>
@@ -79,11 +80,15 @@ namespace Matchers {
                 return description;
             }
 
-            friend MatchAllOf operator&& (MatchAllOf&& lhs, MatcherBase<ArgT> const& rhs) {
+            friend MatchAllOf operator&&( MatchAllOf&& lhs,
+                                          MatcherBase<ArgT> const& rhs
+                                              CATCH_ATTR_LIFETIMEBOUND ) {
                 lhs.m_matchers.push_back(&rhs);
                 return CATCH_MOVE(lhs);
             }
-            friend MatchAllOf operator&& (MatcherBase<ArgT> const& lhs, MatchAllOf&& rhs) {
+            friend MatchAllOf
+            operator&&( MatcherBase<ArgT> const& lhs CATCH_ATTR_LIFETIMEBOUND,
+                        MatchAllOf&& rhs ) {
                 rhs.m_matchers.insert(rhs.m_matchers.begin(), &lhs);
                 return CATCH_MOVE(rhs);
             }
@@ -131,11 +136,15 @@ namespace Matchers {
                 return description;
             }
 
-            friend MatchAnyOf operator|| (MatchAnyOf&& lhs, MatcherBase<ArgT> const& rhs) {
+            friend MatchAnyOf operator||( MatchAnyOf&& lhs,
+                                          MatcherBase<ArgT> const& rhs
+                                              CATCH_ATTR_LIFETIMEBOUND ) {
                 lhs.m_matchers.push_back(&rhs);
                 return CATCH_MOVE(lhs);
             }
-            friend MatchAnyOf operator|| (MatcherBase<ArgT> const& lhs, MatchAnyOf&& rhs) {
+            friend MatchAnyOf
+            operator||( MatcherBase<ArgT> const& lhs CATCH_ATTR_LIFETIMEBOUND,
+                        MatchAnyOf&& rhs ) {
                 rhs.m_matchers.insert(rhs.m_matchers.begin(), &lhs);
                 return CATCH_MOVE(rhs);
             }
@@ -155,7 +164,8 @@ namespace Matchers {
             MatcherBase<ArgT> const& m_underlyingMatcher;
 
         public:
-            explicit MatchNotOf( MatcherBase<ArgT> const& underlyingMatcher ):
+            explicit MatchNotOf( MatcherBase<ArgT> const& underlyingMatcher
+                                     CATCH_ATTR_LIFETIMEBOUND ):
                 m_underlyingMatcher( underlyingMatcher )
             {}
 
@@ -171,16 +181,22 @@ namespace Matchers {
     } // namespace Detail
 
     template <typename T>
-    Detail::MatchAllOf<T> operator&& (MatcherBase<T> const& lhs, MatcherBase<T> const& rhs) {
+    Detail::MatchAllOf<T>
+    operator&&( MatcherBase<T> const& lhs CATCH_ATTR_LIFETIMEBOUND,
+                MatcherBase<T> const& rhs CATCH_ATTR_LIFETIMEBOUND ) {
         return Detail::MatchAllOf<T>{} && lhs && rhs;
     }
+
     template <typename T>
-    Detail::MatchAnyOf<T> operator|| (MatcherBase<T> const& lhs, MatcherBase<T> const& rhs) {
+    Detail::MatchAnyOf<T>
+    operator||( MatcherBase<T> const& lhs CATCH_ATTR_LIFETIMEBOUND,
+                MatcherBase<T> const& rhs CATCH_ATTR_LIFETIMEBOUND ) {
         return Detail::MatchAnyOf<T>{} || lhs || rhs;
     }
 
     template <typename T>
-    Detail::MatchNotOf<T> operator! (MatcherBase<T> const& matcher) {
+    Detail::MatchNotOf<T>
+    operator!( MatcherBase<T> const& matcher CATCH_ATTR_LIFETIMEBOUND ) {
         return Detail::MatchNotOf<T>{ matcher };
     }
 

src/catch2/matchers/catch_matchers_templated.hpp

@@ -11,6 +11,7 @@
 #include <catch2/matchers/catch_matchers.hpp>
 #include <catch2/internal/catch_stringref.hpp>
 #include <catch2/internal/catch_move_and_forward.hpp>
+#include <catch2/internal/catch_lifetimebound.hpp>
 #include <catch2/internal/catch_logical_traits.hpp>
 
 #include <array>
@@ -114,7 +115,8 @@ namespace Matchers {
             MatchAllOfGeneric(MatchAllOfGeneric&&) = default;
             MatchAllOfGeneric& operator=(MatchAllOfGeneric&&) = default;
 
-            MatchAllOfGeneric(MatcherTs const&... matchers) : m_matchers{ {std::addressof(matchers)...} } {}
+            MatchAllOfGeneric(MatcherTs const&... matchers CATCH_ATTR_LIFETIMEBOUND)
+                : m_matchers{ {std::addressof(matchers)...} } {}
             explicit MatchAllOfGeneric(std::array<void const*, sizeof...(MatcherTs)> matchers) : m_matchers{matchers} {}
 
             template<typename Arg>
@@ -136,8 +138,8 @@ namespace Matchers {
             template<typename... MatchersRHS>
             friend
             MatchAllOfGeneric<MatcherTs..., MatchersRHS...> operator && (
-                    MatchAllOfGeneric<MatcherTs...>&& lhs,
-                    MatchAllOfGeneric<MatchersRHS...>&& rhs) {
+                MatchAllOfGeneric<MatcherTs...>&& lhs CATCH_ATTR_LIFETIMEBOUND,
+                MatchAllOfGeneric<MatchersRHS...>&& rhs CATCH_ATTR_LIFETIMEBOUND ) {
                 return MatchAllOfGeneric<MatcherTs..., MatchersRHS...>{array_cat(CATCH_MOVE(lhs.m_matchers), CATCH_MOVE(rhs.m_matchers))};
             }
 
@@ -145,8 +147,8 @@ namespace Matchers {
             template<typename MatcherRHS>
             friend std::enable_if_t<is_matcher_v<MatcherRHS>,
             MatchAllOfGeneric<MatcherTs..., MatcherRHS>> operator && (
-                    MatchAllOfGeneric<MatcherTs...>&& lhs,
-                    MatcherRHS const& rhs) {
+                MatchAllOfGeneric<MatcherTs...>&& lhs CATCH_ATTR_LIFETIMEBOUND,
+                MatcherRHS const& rhs CATCH_ATTR_LIFETIMEBOUND ) {
                 return MatchAllOfGeneric<MatcherTs..., MatcherRHS>{array_cat(CATCH_MOVE(lhs.m_matchers), static_cast<void const*>(&rhs))};
             }
 
@@ -154,8 +156,8 @@ namespace Matchers {
             template<typename MatcherLHS>
             friend std::enable_if_t<is_matcher_v<MatcherLHS>,
             MatchAllOfGeneric<MatcherLHS, MatcherTs...>> operator && (
-                    MatcherLHS const& lhs,
-                    MatchAllOfGeneric<MatcherTs...>&& rhs) {
+                MatcherLHS const& lhs CATCH_ATTR_LIFETIMEBOUND,
+                MatchAllOfGeneric<MatcherTs...>&& rhs CATCH_ATTR_LIFETIMEBOUND ) {
                 return MatchAllOfGeneric<MatcherLHS, MatcherTs...>{array_cat(static_cast<void const*>(std::addressof(lhs)), CATCH_MOVE(rhs.m_matchers))};
             }
         };
@@ -169,7 +171,8 @@ namespace Matchers {
             MatchAnyOfGeneric(MatchAnyOfGeneric&&) = default;
             MatchAnyOfGeneric& operator=(MatchAnyOfGeneric&&) = default;
 
-            MatchAnyOfGeneric(MatcherTs const&... matchers) : m_matchers{ {std::addressof(matchers)...} } {}
+            MatchAnyOfGeneric(MatcherTs const&... matchers CATCH_ATTR_LIFETIMEBOUND)
+                : m_matchers{ {std::addressof(matchers)...} } {}
             explicit MatchAnyOfGeneric(std::array<void const*, sizeof...(MatcherTs)> matchers) : m_matchers{matchers} {}
 
             template<typename Arg>
@@ -190,8 +193,8 @@ namespace Matchers {
             //! Avoids type nesting for `GenericAnyOf || GenericAnyOf` case
             template<typename... MatchersRHS>
             friend MatchAnyOfGeneric<MatcherTs..., MatchersRHS...> operator || (
-                    MatchAnyOfGeneric<MatcherTs...>&& lhs,
-                    MatchAnyOfGeneric<MatchersRHS...>&& rhs) {
+                MatchAnyOfGeneric<MatcherTs...>&& lhs CATCH_ATTR_LIFETIMEBOUND,
+                MatchAnyOfGeneric<MatchersRHS...>&& rhs CATCH_ATTR_LIFETIMEBOUND ) {
                 return MatchAnyOfGeneric<MatcherTs..., MatchersRHS...>{array_cat(CATCH_MOVE(lhs.m_matchers), CATCH_MOVE(rhs.m_matchers))};
             }
 
@@ -199,8 +202,8 @@ namespace Matchers {
             template<typename MatcherRHS>
             friend std::enable_if_t<is_matcher_v<MatcherRHS>,
             MatchAnyOfGeneric<MatcherTs..., MatcherRHS>> operator || (
-                    MatchAnyOfGeneric<MatcherTs...>&& lhs,
-                    MatcherRHS const& rhs) {
+                    MatchAnyOfGeneric<MatcherTs...>&& lhs CATCH_ATTR_LIFETIMEBOUND,
+                    MatcherRHS const& rhs CATCH_ATTR_LIFETIMEBOUND ) {
                 return MatchAnyOfGeneric<MatcherTs..., MatcherRHS>{array_cat(CATCH_MOVE(lhs.m_matchers), static_cast<void const*>(std::addressof(rhs)))};
             }
 
@@ -208,8 +211,8 @@ namespace Matchers {
             template<typename MatcherLHS>
             friend std::enable_if_t<is_matcher_v<MatcherLHS>,
             MatchAnyOfGeneric<MatcherLHS, MatcherTs...>> operator || (
-                MatcherLHS const& lhs,
-                MatchAnyOfGeneric<MatcherTs...>&& rhs) {
+                MatcherLHS const& lhs CATCH_ATTR_LIFETIMEBOUND,
+                MatchAnyOfGeneric<MatcherTs...>&& rhs CATCH_ATTR_LIFETIMEBOUND) {
                 return MatchAnyOfGeneric<MatcherLHS, MatcherTs...>{array_cat(static_cast<void const*>(std::addressof(lhs)), CATCH_MOVE(rhs.m_matchers))};
             }
         };
@@ -225,7 +228,8 @@ namespace Matchers {
             MatchNotOfGeneric(MatchNotOfGeneric&&) = default;
             MatchNotOfGeneric& operator=(MatchNotOfGeneric&&) = default;
 
-            explicit MatchNotOfGeneric(MatcherT const& matcher) : m_matcher{matcher} {}
+            explicit MatchNotOfGeneric(MatcherT const& matcher CATCH_ATTR_LIFETIMEBOUND)
+                : m_matcher{matcher} {}
 
             template<typename Arg>
             bool match(Arg&& arg) const {
@@ -237,7 +241,9 @@ namespace Matchers {
             }
 
             //! Negating negation can just unwrap and return underlying matcher
-            friend MatcherT const& operator ! (MatchNotOfGeneric<MatcherT> const& matcher) {
+            friend MatcherT const&
+            operator!( MatchNotOfGeneric<MatcherT> const& matcher
+                           CATCH_ATTR_LIFETIMEBOUND ) {
                 return matcher.m_matcher;
             }
         };
@@ -247,20 +253,22 @@ namespace Matchers {
     // compose only generic matchers
     template<typename MatcherLHS, typename MatcherRHS>
     std::enable_if_t<Detail::are_generic_matchers_v<MatcherLHS, MatcherRHS>, Detail::MatchAllOfGeneric<MatcherLHS, MatcherRHS>>
-        operator && (MatcherLHS const& lhs, MatcherRHS const& rhs) {
+    operator&&( MatcherLHS const& lhs CATCH_ATTR_LIFETIMEBOUND,
+                MatcherRHS const& rhs CATCH_ATTR_LIFETIMEBOUND ) {
         return { lhs, rhs };
     }
 
     template<typename MatcherLHS, typename MatcherRHS>
     std::enable_if_t<Detail::are_generic_matchers_v<MatcherLHS, MatcherRHS>, Detail::MatchAnyOfGeneric<MatcherLHS, MatcherRHS>>
-        operator || (MatcherLHS const& lhs, MatcherRHS const& rhs) {
+    operator||( MatcherLHS const& lhs CATCH_ATTR_LIFETIMEBOUND,
+                MatcherRHS const& rhs CATCH_ATTR_LIFETIMEBOUND ) {
         return { lhs, rhs };
     }
 
     //! Wrap provided generic matcher in generic negator
     template<typename MatcherT>
     std::enable_if_t<Detail::is_generic_matcher_v<MatcherT>, Detail::MatchNotOfGeneric<MatcherT>>
-        operator ! (MatcherT const& matcher) {
+    operator!( MatcherT const& matcher CATCH_ATTR_LIFETIMEBOUND ) {
         return Detail::MatchNotOfGeneric<MatcherT>{matcher};
     }
 
@@ -268,25 +276,29 @@ namespace Matchers {
     // compose mixed generic and non-generic matchers
     template<typename MatcherLHS, typename ArgRHS>
     std::enable_if_t<Detail::is_generic_matcher_v<MatcherLHS>, Detail::MatchAllOfGeneric<MatcherLHS, MatcherBase<ArgRHS>>>
-        operator && (MatcherLHS const& lhs, MatcherBase<ArgRHS> const& rhs) {
+    operator&&( MatcherLHS const& lhs CATCH_ATTR_LIFETIMEBOUND,
+                MatcherBase<ArgRHS> const& rhs CATCH_ATTR_LIFETIMEBOUND ) {
         return { lhs, rhs };
     }
 
     template<typename ArgLHS, typename MatcherRHS>
     std::enable_if_t<Detail::is_generic_matcher_v<MatcherRHS>, Detail::MatchAllOfGeneric<MatcherBase<ArgLHS>, MatcherRHS>>
-        operator && (MatcherBase<ArgLHS> const& lhs, MatcherRHS const& rhs) {
+    operator&&( MatcherBase<ArgLHS> const& lhs CATCH_ATTR_LIFETIMEBOUND,
+                MatcherRHS const& rhs CATCH_ATTR_LIFETIMEBOUND ) {
         return { lhs, rhs };
     }
 
     template<typename MatcherLHS, typename ArgRHS>
     std::enable_if_t<Detail::is_generic_matcher_v<MatcherLHS>, Detail::MatchAnyOfGeneric<MatcherLHS, MatcherBase<ArgRHS>>>
-        operator || (MatcherLHS const& lhs, MatcherBase<ArgRHS> const& rhs) {
+    operator||( MatcherLHS const& lhs CATCH_ATTR_LIFETIMEBOUND,
+                MatcherBase<ArgRHS> const& rhs CATCH_ATTR_LIFETIMEBOUND ) {
         return { lhs, rhs };
     }
 
     template<typename ArgLHS, typename MatcherRHS>
     std::enable_if_t<Detail::is_generic_matcher_v<MatcherRHS>, Detail::MatchAnyOfGeneric<MatcherBase<ArgLHS>, MatcherRHS>>
-        operator || (MatcherBase<ArgLHS> const& lhs, MatcherRHS const& rhs) {
+    operator||( MatcherBase<ArgLHS> const& lhs CATCH_ATTR_LIFETIMEBOUND,
+                MatcherRHS const& rhs CATCH_ATTR_LIFETIMEBOUND ) {
         return { lhs, rhs };
     }
 

src/catch2/meson.build

@@ -105,6 +105,7 @@ internal_headers = [
   'internal/catch_jsonwriter.hpp',
   'internal/catch_lazy_expr.hpp',
   'internal/catch_leak_detector.hpp',
+  'internal/catch_lifetimebound.hpp',
   'internal/catch_list.hpp',
   'internal/catch_logical_traits.hpp',
   'internal/catch_message_info.hpp',