Add option to skip forward to the generator interface

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.

docs/generators.md

@@ -252,9 +252,23 @@ struct IGenerator : GeneratorUntypedBase {
     // Returns user-friendly string showing the current generator element
     // Does not have to be overridden, IGenerator provides default implementation
     virtual std::string stringifyImpl() const;
+
+    /**
+     * Customization point for `skipToNthElement`
+     *
+     * Does not have to be overridden, there is a default implementation.
+     * Can be overridden for better performance.
+     *
+     * If there are not enough elements, shall throw an error.
+     *
+     * Going backwards is not supported.
+     */
+    virtual void skipToNthElementImpl( std::size_t n );
 };
 ```
 
+> `skipToNthElementImpl` was added in Catch2 vX.Y.Z
+
 However, to be able to use your custom generator inside `GENERATE`, it
 will need to be wrapped inside a `GeneratorWrapper<T>`.
 `GeneratorWrapper<T>` is a value wrapper around a

examples/300-Gen-OwnGenerator.cpp

@@ -39,6 +39,22 @@ public:
         current_number = m_dist(m_rand);
         return true;
     }
+
+    // Note: this improves the performance only a bit, but it is here
+    //       to show how you can override the skip functionality.
+    void skipToNthElementImpl( std::size_t n ) override {
+        auto current_index = currentElementIndex();
+        assert(current_index <= n);
+        // We cannot jump forward the underlying generator directly,
+        // because we do not know how many bits each distributed number
+        // would consume to be generated.
+        for (; current_index < n; ++current_index) {
+            (void)m_dist(m_rand);
+        }
+
+        // We do not have to touch the current element index; it is handled
+        // by the base class.
+    }
 };
 
 // Avoids -Wweak-vtables

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/interfaces/catch_interfaces_generatortracker.cpp

@@ -7,6 +7,8 @@
 // SPDX-License-Identifier: BSL-1.0
 
 #include <catch2/interfaces/catch_interfaces_generatortracker.hpp>
+#include <catch2/generators/catch_generators.hpp>
+
 #include <string>
 
 namespace Catch {
@@ -21,6 +23,30 @@ namespace Catch {
             return ret;
         }
 
+        void GeneratorUntypedBase::skipToNthElementImpl( std::size_t n ) {
+            for ( size_t i = m_currentElementIndex; i < n; ++i ) {
+                bool isValid = next();
+                if ( !isValid ) {
+                    Detail::throw_generator_exception(
+                        "Coud not jump to Nth element: not enough elements" );
+                }
+            }
+        }
+
+        void GeneratorUntypedBase::skipToNthElement( std::size_t n ) {
+            if ( n < m_currentElementIndex ) {
+                Detail::throw_generator_exception(
+                    "Tried to jump generator backwards" );
+            }
+            skipToNthElementImpl(n);
+
+            // Fixup tracking after moving the generator forward
+            //  * Ensure that the correct element index is set after skipping
+            //  * Invalidate cache
+            m_currentElementIndex = n;
+            m_stringReprCache.clear();
+        }
+
         StringRef GeneratorUntypedBase::currentElementAsString() const {
             if ( m_stringReprCache.empty() ) {
                 m_stringReprCache = stringifyImpl();

src/catch2/interfaces/catch_interfaces_generatortracker.hpp

@@ -35,6 +35,15 @@ namespace Catch {
             //! Customization point for `currentElementAsString`
             virtual std::string stringifyImpl() const = 0;
 
+            /**
+             * Customization point for skipping to the n-th element
+             *
+             * Defaults to successively calling `countedNext`. If there
+             * are not enough elements to reach the nth one, will throw
+             * an error.
+             */
+            virtual void skipToNthElementImpl( std::size_t n );
+
         public:
             GeneratorUntypedBase() = default;
             // Generation of copy ops is deprecated (and Clang will complain)
@@ -58,6 +67,13 @@ namespace Catch {
 
             std::size_t currentElementIndex() const { return m_currentElementIndex; }
 
+            /**
+             * Moves the generator forward **to** the n-th element
+             *
+             * Cannot move backwards.
+             */
+            void skipToNthElement( std::size_t n );
+
             /**
              * Returns generator's current element as user-friendly string.
              *

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/internal/catch_string_manip.hpp

@@ -8,6 +8,7 @@
 #ifndef CATCH_STRING_MANIP_HPP_INCLUDED
 #define CATCH_STRING_MANIP_HPP_INCLUDED
 
+#include <catch2/internal/catch_lifetimebound.hpp>
 #include <catch2/internal/catch_stringref.hpp>
 
 #include <cstdint>
@@ -28,10 +29,10 @@ namespace Catch {
     //! Returns a new string without whitespace at the start/end
     std::string trim( std::string const& str );
     //! Returns a substring of the original ref without whitespace. Beware lifetimes!
-    StringRef trim(StringRef ref);
+    StringRef trim( StringRef ref CATCH_ATTR_LIFETIMEBOUND );
 
     // !!! Be aware, returns refs into original string - make sure original string outlives them
-    std::vector<StringRef> splitStringRef( StringRef str, char delimiter );
+    std::vector<StringRef> splitStringRef( StringRef str CATCH_ATTR_LIFETIMEBOUND, char delimiter );
     bool replaceInPlace( std::string& str, std::string const& replaceThis, std::string const& withThis );
 
     /**
@@ -49,7 +50,7 @@ namespace Catch {
         StringRef m_label;
 
     public:
-        constexpr pluralise(std::uint64_t count, StringRef label):
+        constexpr pluralise(std::uint64_t count, StringRef label CATCH_ATTR_LIFETIMEBOUND):
             m_count(count),
             m_label(label)
         {}

src/catch2/internal/catch_stringref.hpp

@@ -8,11 +8,12 @@
 #ifndef CATCH_STRINGREF_HPP_INCLUDED
 #define CATCH_STRINGREF_HPP_INCLUDED
 
+#include <catch2/internal/catch_lifetimebound.hpp>
+
 #include <cstddef>
 #include <string>
 #include <iosfwd>
 #include <cassert>
-
 #include <cstring>
 
 namespace Catch {
@@ -36,14 +37,16 @@ namespace Catch {
     public: // construction
         constexpr StringRef() noexcept = default;
 
-        StringRef( char const* rawChars ) noexcept;
+        StringRef( char const* rawChars CATCH_ATTR_LIFETIMEBOUND ) noexcept;
 
-        constexpr StringRef( char const* rawChars, size_type size ) noexcept
+        constexpr StringRef( char const* rawChars CATCH_ATTR_LIFETIMEBOUND,
+                             size_type size ) noexcept
         :   m_start( rawChars ),
             m_size( size )
         {}
 
-        StringRef( std::string const& stdString ) noexcept
+        StringRef(
+            std::string const& stdString CATCH_ATTR_LIFETIMEBOUND ) noexcept
         :   m_start( stdString.c_str() ),
             m_size( stdString.size() )
         {}
@@ -89,7 +92,7 @@ namespace Catch {
         }
 
         // Returns the current start pointer. May not be null-terminated.
-        constexpr char const* data() const noexcept {
+        constexpr char const* data() const noexcept CATCH_ATTR_LIFETIMEBOUND {
             return m_start;
         }
 

src/catch2/internal/catch_test_case_tracker.hpp

@@ -8,6 +8,7 @@
 #ifndef CATCH_TEST_CASE_TRACKER_HPP_INCLUDED
 #define CATCH_TEST_CASE_TRACKER_HPP_INCLUDED
 
+#include <catch2/internal/catch_lifetimebound.hpp>
 #include <catch2/internal/catch_source_line_info.hpp>
 #include <catch2/internal/catch_unique_ptr.hpp>
 #include <catch2/internal/catch_stringref.hpp>
@@ -48,7 +49,7 @@ namespace TestCaseTracking {
         StringRef name;
         SourceLineInfo location;
 
-        constexpr NameAndLocationRef( StringRef name_,
+        constexpr NameAndLocationRef( StringRef name_ CATCH_ATTR_LIFETIMEBOUND,
                                       SourceLineInfo location_ ):
             name( name_ ), location( location_ ) {}
 

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',

tests/SelfTest/Baselines/automake.sw.approved.txt

@@ -168,6 +168,7 @@ Nor would this
 :test-result: PASS GENERATE can combine literals and generators
 :test-result: PASS Generators -- adapters
 :test-result: PASS Generators -- simple
+:test-result: PASS Generators can be skipped forward
 :test-result: PASS Generators internals
 :test-result: PASS Greater-than inequalities with different epsilons
 :test-result: PASS Hashers with different seed produce different hash with same test case

tests/SelfTest/Baselines/automake.sw.multi.approved.txt

@@ -166,6 +166,7 @@
 :test-result: PASS GENERATE can combine literals and generators
 :test-result: PASS Generators -- adapters
 :test-result: PASS Generators -- simple
+:test-result: PASS Generators can be skipped forward
 :test-result: PASS Generators internals
 :test-result: PASS Greater-than inequalities with different epsilons
 :test-result: PASS Hashers with different seed produce different hash with same test case

tests/SelfTest/Baselines/compact.sw.approved.txt

@@ -787,6 +787,13 @@ Generators.tests.cpp:<line number>: passed: j < i for: -1 < 3
 Generators.tests.cpp:<line number>: passed: 4u * i > str.size() for: 12 > 1
 Generators.tests.cpp:<line number>: passed: 4u * i > str.size() for: 12 > 2
 Generators.tests.cpp:<line number>: passed: 4u * i > str.size() for: 12 > 3
+GeneratorsImpl.tests.cpp:<line number>: passed: generator.currentElementIndex() == 0 for: 0 == 0
+GeneratorsImpl.tests.cpp:<line number>: passed: generator.currentElementIndex() == 3 for: 3 == 3
+GeneratorsImpl.tests.cpp:<line number>: passed: generator.get() == 3 for: 3 == 3
+GeneratorsImpl.tests.cpp:<line number>: passed: generator.currentElementIndex() == 5 for: 5 == 5
+GeneratorsImpl.tests.cpp:<line number>: passed: generator.get() == 5 for: 5 == 5
+GeneratorsImpl.tests.cpp:<line number>: passed: generator.skipToNthElement( 3 )
+GeneratorsImpl.tests.cpp:<line number>: passed: generator.skipToNthElement( 6 )
 GeneratorsImpl.tests.cpp:<line number>: passed: gen.get() == 123 for: 123 == 123
 GeneratorsImpl.tests.cpp:<line number>: passed: !(gen.next()) for: !false
 GeneratorsImpl.tests.cpp:<line number>: passed: gen.get() == 1 for: 1 == 1
@@ -2888,7 +2895,7 @@ InternalBenchmark.tests.cpp:<line number>: passed: med == 18. for: 18.0 == 18.0
 InternalBenchmark.tests.cpp:<line number>: passed: q3 == 23. for: 23.0 == 23.0
 Misc.tests.cpp:<line number>: passed:
 Misc.tests.cpp:<line number>: passed:
-test cases:  435 |  317 passed |  95 failed | 6 skipped | 17 failed as expected
-assertions: 2303 | 2105 passed | 157 failed | 41 failed as expected
+test cases:  436 |  318 passed |  95 failed | 6 skipped | 17 failed as expected
+assertions: 2310 | 2112 passed | 157 failed | 41 failed as expected
 
 

tests/SelfTest/Baselines/compact.sw.multi.approved.txt

@@ -785,6 +785,13 @@ Generators.tests.cpp:<line number>: passed: j < i for: -1 < 3
 Generators.tests.cpp:<line number>: passed: 4u * i > str.size() for: 12 > 1
 Generators.tests.cpp:<line number>: passed: 4u * i > str.size() for: 12 > 2
 Generators.tests.cpp:<line number>: passed: 4u * i > str.size() for: 12 > 3
+GeneratorsImpl.tests.cpp:<line number>: passed: generator.currentElementIndex() == 0 for: 0 == 0
+GeneratorsImpl.tests.cpp:<line number>: passed: generator.currentElementIndex() == 3 for: 3 == 3
+GeneratorsImpl.tests.cpp:<line number>: passed: generator.get() == 3 for: 3 == 3
+GeneratorsImpl.tests.cpp:<line number>: passed: generator.currentElementIndex() == 5 for: 5 == 5
+GeneratorsImpl.tests.cpp:<line number>: passed: generator.get() == 5 for: 5 == 5
+GeneratorsImpl.tests.cpp:<line number>: passed: generator.skipToNthElement( 3 )
+GeneratorsImpl.tests.cpp:<line number>: passed: generator.skipToNthElement( 6 )
 GeneratorsImpl.tests.cpp:<line number>: passed: gen.get() == 123 for: 123 == 123
 GeneratorsImpl.tests.cpp:<line number>: passed: !(gen.next()) for: !false
 GeneratorsImpl.tests.cpp:<line number>: passed: gen.get() == 1 for: 1 == 1
@@ -2877,7 +2884,7 @@ InternalBenchmark.tests.cpp:<line number>: passed: med == 18. for: 18.0 == 18.0
 InternalBenchmark.tests.cpp:<line number>: passed: q3 == 23. for: 23.0 == 23.0
 Misc.tests.cpp:<line number>: passed:
 Misc.tests.cpp:<line number>: passed:
-test cases:  435 |  317 passed |  95 failed | 6 skipped | 17 failed as expected
-assertions: 2303 | 2105 passed | 157 failed | 41 failed as expected
+test cases:  436 |  318 passed |  95 failed | 6 skipped | 17 failed as expected
+assertions: 2310 | 2112 passed | 157 failed | 41 failed as expected
 
 

tests/SelfTest/Baselines/console.std.approved.txt

@@ -1719,6 +1719,6 @@ due to unexpected exception with message:
   Why would you throw a std::string?
 
 ===============================================================================
-test cases:  435 |  335 passed |  76 failed | 7 skipped | 17 failed as expected
-assertions: 2282 | 2105 passed | 136 failed | 41 failed as expected
+test cases:  436 |  336 passed |  76 failed | 7 skipped | 17 failed as expected
+assertions: 2289 | 2112 passed | 136 failed | 41 failed as expected
 

tests/SelfTest/Baselines/console.sw.approved.txt

@@ -5831,6 +5831,43 @@ Generators.tests.cpp:<line number>: PASSED:
 with expansion:
   12 > 3
 
+-------------------------------------------------------------------------------
+Generators can be skipped forward
+-------------------------------------------------------------------------------
+GeneratorsImpl.tests.cpp:<line number>
+...............................................................................
+
+GeneratorsImpl.tests.cpp:<line number>: PASSED:
+  REQUIRE( generator.currentElementIndex() == 0 )
+with expansion:
+  0 == 0
+
+GeneratorsImpl.tests.cpp:<line number>: PASSED:
+  REQUIRE( generator.currentElementIndex() == 3 )
+with expansion:
+  3 == 3
+
+GeneratorsImpl.tests.cpp:<line number>: PASSED:
+  REQUIRE( generator.get() == 3 )
+with expansion:
+  3 == 3
+
+GeneratorsImpl.tests.cpp:<line number>: PASSED:
+  REQUIRE( generator.currentElementIndex() == 5 )
+with expansion:
+  5 == 5
+
+GeneratorsImpl.tests.cpp:<line number>: PASSED:
+  REQUIRE( generator.get() == 5 )
+with expansion:
+  5 == 5
+
+GeneratorsImpl.tests.cpp:<line number>: PASSED:
+  REQUIRE_THROWS( generator.skipToNthElement( 3 ) )
+
+GeneratorsImpl.tests.cpp:<line number>: PASSED:
+  REQUIRE_THROWS( generator.skipToNthElement( 6 ) )
+
 -------------------------------------------------------------------------------
 Generators internals
   Single value
@@ -19295,6 +19332,6 @@ Misc.tests.cpp:<line number>
 Misc.tests.cpp:<line number>: PASSED:
 
 ===============================================================================
-test cases:  435 |  317 passed |  95 failed | 6 skipped | 17 failed as expected
-assertions: 2303 | 2105 passed | 157 failed | 41 failed as expected
+test cases:  436 |  318 passed |  95 failed | 6 skipped | 17 failed as expected
+assertions: 2310 | 2112 passed | 157 failed | 41 failed as expected
 

tests/SelfTest/Baselines/console.sw.multi.approved.txt

@@ -5829,6 +5829,43 @@ Generators.tests.cpp:<line number>: PASSED:
 with expansion:
   12 > 3
 
+-------------------------------------------------------------------------------
+Generators can be skipped forward
+-------------------------------------------------------------------------------
+GeneratorsImpl.tests.cpp:<line number>
+...............................................................................
+
+GeneratorsImpl.tests.cpp:<line number>: PASSED:
+  REQUIRE( generator.currentElementIndex() == 0 )
+with expansion:
+  0 == 0
+
+GeneratorsImpl.tests.cpp:<line number>: PASSED:
+  REQUIRE( generator.currentElementIndex() == 3 )
+with expansion:
+  3 == 3
+
+GeneratorsImpl.tests.cpp:<line number>: PASSED:
+  REQUIRE( generator.get() == 3 )
+with expansion:
+  3 == 3
+
+GeneratorsImpl.tests.cpp:<line number>: PASSED:
+  REQUIRE( generator.currentElementIndex() == 5 )
+with expansion:
+  5 == 5
+
+GeneratorsImpl.tests.cpp:<line number>: PASSED:
+  REQUIRE( generator.get() == 5 )
+with expansion:
+  5 == 5
+
+GeneratorsImpl.tests.cpp:<line number>: PASSED:
+  REQUIRE_THROWS( generator.skipToNthElement( 3 ) )
+
+GeneratorsImpl.tests.cpp:<line number>: PASSED:
+  REQUIRE_THROWS( generator.skipToNthElement( 6 ) )
+
 -------------------------------------------------------------------------------
 Generators internals
   Single value
@@ -19284,6 +19321,6 @@ Misc.tests.cpp:<line number>
 Misc.tests.cpp:<line number>: PASSED:
 
 ===============================================================================
-test cases:  435 |  317 passed |  95 failed | 6 skipped | 17 failed as expected
-assertions: 2303 | 2105 passed | 157 failed | 41 failed as expected
+test cases:  436 |  318 passed |  95 failed | 6 skipped | 17 failed as expected
+assertions: 2310 | 2112 passed | 157 failed | 41 failed as expected
 

tests/SelfTest/Baselines/junit.sw.approved.txt

@@ -1,7 +1,7 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <testsuitesloose text artifact
 >
-  <testsuite name="<exe-name>" errors="17" failures="140" skipped="12" tests="2315" hostname="tbd" time="{duration}" timestamp="{iso8601-timestamp}">
+  <testsuite name="<exe-name>" errors="17" failures="140" skipped="12" tests="2322" hostname="tbd" time="{duration}" timestamp="{iso8601-timestamp}">
     <properties>
       <property name="random-seed" value="1"/>
       <property name="filters" value="&quot;*&quot; ~[!nonportable] ~[!benchmark] ~[approvals]"/>
@@ -837,6 +837,7 @@ at Message.tests.cpp:<line number>
     <testcase classname="<exe-name>.global" name="Generators -- simple" time="{duration}" status="run"/>
     <testcase classname="<exe-name>.global" name="Generators -- simple/one" time="{duration}" status="run"/>
     <testcase classname="<exe-name>.global" name="Generators -- simple/two" time="{duration}" status="run"/>
+    <testcase classname="<exe-name>.global" name="Generators can be skipped forward" time="{duration}" status="run"/>
     <testcase classname="<exe-name>.global" name="Generators internals" time="{duration}" status="run"/>
     <testcase classname="<exe-name>.global" name="Generators internals/Single value" time="{duration}" status="run"/>
     <testcase classname="<exe-name>.global" name="Generators internals/Preset values" time="{duration}" status="run"/>

tests/SelfTest/Baselines/junit.sw.multi.approved.txt

@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <testsuites>
-  <testsuite name="<exe-name>" errors="17" failures="140" skipped="12" tests="2315" hostname="tbd" time="{duration}" timestamp="{iso8601-timestamp}">
+  <testsuite name="<exe-name>" errors="17" failures="140" skipped="12" tests="2322" hostname="tbd" time="{duration}" timestamp="{iso8601-timestamp}">
     <properties>
       <property name="random-seed" value="1"/>
       <property name="filters" value="&quot;*&quot; ~[!nonportable] ~[!benchmark] ~[approvals]"/>
@@ -836,6 +836,7 @@ at Message.tests.cpp:<line number>
     <testcase classname="<exe-name>.global" name="Generators -- simple" time="{duration}" status="run"/>
     <testcase classname="<exe-name>.global" name="Generators -- simple/one" time="{duration}" status="run"/>
     <testcase classname="<exe-name>.global" name="Generators -- simple/two" time="{duration}" status="run"/>
+    <testcase classname="<exe-name>.global" name="Generators can be skipped forward" time="{duration}" status="run"/>
     <testcase classname="<exe-name>.global" name="Generators internals" time="{duration}" status="run"/>
     <testcase classname="<exe-name>.global" name="Generators internals/Single value" time="{duration}" status="run"/>
     <testcase classname="<exe-name>.global" name="Generators internals/Preset values" time="{duration}" status="run"/>

tests/SelfTest/Baselines/sonarqube.sw.approved.txt

@@ -144,6 +144,7 @@ at AssertionHandler.tests.cpp:<line number>
   </file>
   <file path="tests/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp">
     <testCase name="Filter generator throws exception for empty generator" duration="{duration}"/>
+    <testCase name="Generators can be skipped forward" duration="{duration}"/>
     <testCase name="Generators internals" duration="{duration}"/>
     <testCase name="Generators internals/Single value" duration="{duration}"/>
     <testCase name="Generators internals/Preset values" duration="{duration}"/>

tests/SelfTest/Baselines/sonarqube.sw.multi.approved.txt

@@ -143,6 +143,7 @@ at AssertionHandler.tests.cpp:<line number>
   </file>
   <file path="tests/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp">
     <testCase name="Filter generator throws exception for empty generator" duration="{duration}"/>
+    <testCase name="Generators can be skipped forward" duration="{duration}"/>
     <testCase name="Generators internals" duration="{duration}"/>
     <testCase name="Generators internals/Single value" duration="{duration}"/>
     <testCase name="Generators internals/Preset values" duration="{duration}"/>

tests/SelfTest/Baselines/tap.sw.approved.txt

@@ -1430,6 +1430,20 @@ ok {test-number} - 4u * i > str.size() for: 12 > 1
 ok {test-number} - 4u * i > str.size() for: 12 > 2
 # Generators -- simple
 ok {test-number} - 4u * i > str.size() for: 12 > 3
+# Generators can be skipped forward
+ok {test-number} - generator.currentElementIndex() == 0 for: 0 == 0
+# Generators can be skipped forward
+ok {test-number} - generator.currentElementIndex() == 3 for: 3 == 3
+# Generators can be skipped forward
+ok {test-number} - generator.get() == 3 for: 3 == 3
+# Generators can be skipped forward
+ok {test-number} - generator.currentElementIndex() == 5 for: 5 == 5
+# Generators can be skipped forward
+ok {test-number} - generator.get() == 5 for: 5 == 5
+# Generators can be skipped forward
+ok {test-number} - generator.skipToNthElement( 3 )
+# Generators can be skipped forward
+ok {test-number} - generator.skipToNthElement( 6 )
 # Generators internals
 ok {test-number} - gen.get() == 123 for: 123 == 123
 # Generators internals
@@ -4627,5 +4641,5 @@ ok {test-number} - q3 == 23. for: 23.0 == 23.0
 ok {test-number} -
 # xmlentitycheck
 ok {test-number} -
-1..2315
+1..2322
 

tests/SelfTest/Baselines/tap.sw.multi.approved.txt

@@ -1428,6 +1428,20 @@ ok {test-number} - 4u * i > str.size() for: 12 > 1
 ok {test-number} - 4u * i > str.size() for: 12 > 2
 # Generators -- simple
 ok {test-number} - 4u * i > str.size() for: 12 > 3
+# Generators can be skipped forward
+ok {test-number} - generator.currentElementIndex() == 0 for: 0 == 0
+# Generators can be skipped forward
+ok {test-number} - generator.currentElementIndex() == 3 for: 3 == 3
+# Generators can be skipped forward
+ok {test-number} - generator.get() == 3 for: 3 == 3
+# Generators can be skipped forward
+ok {test-number} - generator.currentElementIndex() == 5 for: 5 == 5
+# Generators can be skipped forward
+ok {test-number} - generator.get() == 5 for: 5 == 5
+# Generators can be skipped forward
+ok {test-number} - generator.skipToNthElement( 3 )
+# Generators can be skipped forward
+ok {test-number} - generator.skipToNthElement( 6 )
 # Generators internals
 ok {test-number} - gen.get() == 123 for: 123 == 123
 # Generators internals
@@ -4616,5 +4630,5 @@ ok {test-number} - q3 == 23. for: 23.0 == 23.0
 ok {test-number} -
 # xmlentitycheck
 ok {test-number} -
-1..2315
+1..2322
 

tests/SelfTest/Baselines/teamcity.sw.approved.txt

@@ -414,6 +414,8 @@
 ##teamcity[testFinished name='Generators -- adapters' duration="{duration}"]
 ##teamcity[testStarted name='Generators -- simple']
 ##teamcity[testFinished name='Generators -- simple' duration="{duration}"]
+##teamcity[testStarted name='Generators can be skipped forward']
+##teamcity[testFinished name='Generators can be skipped forward' duration="{duration}"]
 ##teamcity[testStarted name='Generators internals']
 ##teamcity[testFinished name='Generators internals' duration="{duration}"]
 ##teamcity[testStarted name='Greater-than inequalities with different epsilons']

tests/SelfTest/Baselines/teamcity.sw.multi.approved.txt

@@ -414,6 +414,8 @@
 ##teamcity[testFinished name='Generators -- adapters' duration="{duration}"]
 ##teamcity[testStarted name='Generators -- simple']
 ##teamcity[testFinished name='Generators -- simple' duration="{duration}"]
+##teamcity[testStarted name='Generators can be skipped forward']
+##teamcity[testFinished name='Generators can be skipped forward' duration="{duration}"]
 ##teamcity[testStarted name='Generators internals']
 ##teamcity[testFinished name='Generators internals' duration="{duration}"]
 ##teamcity[testStarted name='Greater-than inequalities with different epsilons']

tests/SelfTest/Baselines/xml.sw.approved.txt

@@ -6605,6 +6605,65 @@ Approx( 1.30000000000000004 )
     </Section>
     <OverallResult success="true" skips="0"/>
   </TestCase>
+  <TestCase name="Generators can be skipped forward" tags="[generators]" filename="tests/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp" >
+    <Expression success="true" type="REQUIRE" filename="tests/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp" >
+      <Original>
+        generator.currentElementIndex() == 0
+      </Original>
+      <Expanded>
+        0 == 0
+      </Expanded>
+    </Expression>
+    <Expression success="true" type="REQUIRE" filename="tests/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp" >
+      <Original>
+        generator.currentElementIndex() == 3
+      </Original>
+      <Expanded>
+        3 == 3
+      </Expanded>
+    </Expression>
+    <Expression success="true" type="REQUIRE" filename="tests/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp" >
+      <Original>
+        generator.get() == 3
+      </Original>
+      <Expanded>
+        3 == 3
+      </Expanded>
+    </Expression>
+    <Expression success="true" type="REQUIRE" filename="tests/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp" >
+      <Original>
+        generator.currentElementIndex() == 5
+      </Original>
+      <Expanded>
+        5 == 5
+      </Expanded>
+    </Expression>
+    <Expression success="true" type="REQUIRE" filename="tests/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp" >
+      <Original>
+        generator.get() == 5
+      </Original>
+      <Expanded>
+        5 == 5
+      </Expanded>
+    </Expression>
+    <Expression success="true" type="REQUIRE_THROWS" filename="tests/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp" >
+      <Original>
+        generator.skipToNthElement( 3 )
+      </Original>
+      <Expanded>
+        generator.skipToNthElement( 3 )
+      </Expanded>
+    </Expression>
+    <Expression success="true" type="REQUIRE_THROWS" filename="tests/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp" >
+      <Original>
+        generator.skipToNthElement( 6 )
+      </Original>
+      <Expanded>
+        generator.skipToNthElement( 6 )
+      </Expanded>
+    </Expression>
+    <OverallResult success="true" skips="0"/>
+  </TestCase>
   <TestCase name="Generators internals" tags="[generators][internals]" filename="tests/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp" >
     <Section name="Single value" filename="tests/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp" >
       <Expression success="true" type="REQUIRE" filename="tests/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp" >
@@ -22324,6 +22383,6 @@ Approx( -1.95996398454005449 )
     </Section>
     <OverallResult success="true" skips="0"/>
   </TestCase>
-  <OverallResults successes="2105" failures="157" expectedFailures="41" skips="12"/>
-  <OverallResultsCases successes="317" failures="95" expectedFailures="17" skips="6"/>
+  <OverallResults successes="2112" failures="157" expectedFailures="41" skips="12"/>
+  <OverallResultsCases successes="318" failures="95" expectedFailures="17" skips="6"/>
 </Catch2TestRun>

tests/SelfTest/Baselines/xml.sw.multi.approved.txt

@@ -6605,6 +6605,65 @@ Approx( 1.30000000000000004 )
     </Section>
     <OverallResult success="true" skips="0"/>
   </TestCase>
+  <TestCase name="Generators can be skipped forward" tags="[generators]" filename="tests/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp" >
+    <Expression success="true" type="REQUIRE" filename="tests/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp" >
+      <Original>
+        generator.currentElementIndex() == 0
+      </Original>
+      <Expanded>
+        0 == 0
+      </Expanded>
+    </Expression>
+    <Expression success="true" type="REQUIRE" filename="tests/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp" >
+      <Original>
+        generator.currentElementIndex() == 3
+      </Original>
+      <Expanded>
+        3 == 3
+      </Expanded>
+    </Expression>
+    <Expression success="true" type="REQUIRE" filename="tests/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp" >
+      <Original>
+        generator.get() == 3
+      </Original>
+      <Expanded>
+        3 == 3
+      </Expanded>
+    </Expression>
+    <Expression success="true" type="REQUIRE" filename="tests/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp" >
+      <Original>
+        generator.currentElementIndex() == 5
+      </Original>
+      <Expanded>
+        5 == 5
+      </Expanded>
+    </Expression>
+    <Expression success="true" type="REQUIRE" filename="tests/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp" >
+      <Original>
+        generator.get() == 5
+      </Original>
+      <Expanded>
+        5 == 5
+      </Expanded>
+    </Expression>
+    <Expression success="true" type="REQUIRE_THROWS" filename="tests/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp" >
+      <Original>
+        generator.skipToNthElement( 3 )
+      </Original>
+      <Expanded>
+        generator.skipToNthElement( 3 )
+      </Expanded>
+    </Expression>
+    <Expression success="true" type="REQUIRE_THROWS" filename="tests/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp" >
+      <Original>
+        generator.skipToNthElement( 6 )
+      </Original>
+      <Expanded>
+        generator.skipToNthElement( 6 )
+      </Expanded>
+    </Expression>
+    <OverallResult success="true" skips="0"/>
+  </TestCase>
   <TestCase name="Generators internals" tags="[generators][internals]" filename="tests/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp" >
     <Section name="Single value" filename="tests/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp" >
       <Expression success="true" type="REQUIRE" filename="tests/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp" >
@@ -22323,6 +22382,6 @@ Approx( -1.95996398454005449 )
     </Section>
     <OverallResult success="true" skips="0"/>
   </TestCase>
-  <OverallResults successes="2105" failures="157" expectedFailures="41" skips="12"/>
-  <OverallResultsCases successes="317" failures="95" expectedFailures="17" skips="6"/>
+  <OverallResults successes="2112" failures="157" expectedFailures="41" skips="12"/>
+  <OverallResultsCases successes="318" failures="95" expectedFailures="17" skips="6"/>
 </Catch2TestRun>

tests/SelfTest/IntrospectiveTests/GeneratorsImpl.tests.cpp

@@ -85,7 +85,7 @@ TEST_CASE("Generators internals", "[generators][internals]") {
                 filter([](int) { return false; }, values({ 1, 2, 3 })),
                 Catch::GeneratorException);
         }
-        
+
         // Non-trivial usage
         SECTION("Out-of-line predicates are copied into the generator") {
             auto evilNumber = Catch::Detail::make_unique<int>(2);
@@ -586,3 +586,21 @@ TEST_CASE("from_range(container) supports ADL begin/end and arrays", "[generator
     }
 
 }
+
+TEST_CASE( "Generators can be skipped forward", "[generators]" ) {
+    auto generator = Catch::Generators::FixedValuesGenerator<int>( { 0, 1, 2, 3, 4, 5 } );
+    REQUIRE( generator.currentElementIndex() == 0 );
+
+    generator.skipToNthElement( 3 );
+    REQUIRE( generator.currentElementIndex() == 3 );
+    REQUIRE( generator.get() == 3 );
+
+    generator.skipToNthElement( 5 );
+    REQUIRE( generator.currentElementIndex() == 5 );
+    REQUIRE( generator.get() == 5 );
+
+    // Backwards
+    REQUIRE_THROWS( generator.skipToNthElement( 3 ) );
+    // Past the end
+    REQUIRE_THROWS( generator.skipToNthElement( 6 ) );
+}