Make concrete matchers final

Outside of `MatcherBase` and `GenericMatcherBase`, matchers are not
designed to be overriden. This means that doing so can easily lead
to errors, and matchers are generally fairly simple functionality-wise.
so there is not much code reuse to be gained anyway.

Thus, Catch2-provided concrete matchers are now final.

src/catch2/matchers/catch_matchers_exception.hpp

@@ -13,7 +13,7 @@ namespace Catch {
 namespace Matchers {
 namespace Exception {
 
-class ExceptionMessageMatcher : public MatcherBase<std::exception> {
+class ExceptionMessageMatcher final : public MatcherBase<std::exception> {
     std::string m_message;
 public:
 

src/catch2/matchers/catch_matchers_floating.hpp

@@ -16,7 +16,7 @@ namespace Matchers {
 
         enum class FloatingPointKind : uint8_t;
 
-        struct WithinAbsMatcher : MatcherBase<double> {
+        struct WithinAbsMatcher final : MatcherBase<double> {
             WithinAbsMatcher(double target, double margin);
             bool match(double const& matchee) const override;
             std::string describe() const override;
@@ -25,7 +25,7 @@ namespace Matchers {
             double m_margin;
         };
 
-        struct WithinUlpsMatcher : MatcherBase<double> {
+        struct WithinUlpsMatcher final : MatcherBase<double> {
             WithinUlpsMatcher(double target, uint64_t ulps, FloatingPointKind baseType);
             bool match(double const& matchee) const override;
             std::string describe() const override;
@@ -41,7 +41,7 @@ namespace Matchers {
         // |lhs - rhs| <= epsilon * max(fabs(lhs), fabs(rhs)), then we get
         // the same result if we do this for floats, as if we do this for
         // doubles that were promoted from floats.
-        struct WithinRelMatcher : MatcherBase<double> {
+        struct WithinRelMatcher final : MatcherBase<double> {
             WithinRelMatcher(double target, double epsilon);
             bool match(double const& matchee) const override;
             std::string describe() const override;

src/catch2/matchers/catch_matchers_generic.hpp

@@ -23,7 +23,7 @@ namespace Detail {
 }
 
 template <typename T, typename Predicate>
-class PredicateMatcher : public MatcherBase<T> {
+class PredicateMatcher final : public MatcherBase<T> {
     Predicate m_predicate;
     std::string m_description;
 public:

src/catch2/matchers/catch_matchers_string.hpp

@@ -35,24 +35,24 @@ namespace Matchers {
             std::string m_operation;
         };
 
-        struct EqualsMatcher : StringMatcherBase {
+        struct EqualsMatcher final : StringMatcherBase {
             EqualsMatcher( CasedString const& comparator );
             bool match( std::string const& source ) const override;
         };
-        struct ContainsMatcher : StringMatcherBase {
+        struct ContainsMatcher final : StringMatcherBase {
             ContainsMatcher( CasedString const& comparator );
             bool match( std::string const& source ) const override;
         };
-        struct StartsWithMatcher : StringMatcherBase {
+        struct StartsWithMatcher final : StringMatcherBase {
             StartsWithMatcher( CasedString const& comparator );
             bool match( std::string const& source ) const override;
         };
-        struct EndsWithMatcher : StringMatcherBase {
+        struct EndsWithMatcher final : StringMatcherBase {
             EndsWithMatcher( CasedString const& comparator );
             bool match( std::string const& source ) const override;
         };
 
-        struct RegexMatcher : MatcherBase<std::string> {
+        struct RegexMatcher final : MatcherBase<std::string> {
             RegexMatcher( std::string regex, CaseSensitive::Choice caseSensitivity );
             bool match( std::string const& matchee ) const override;
             std::string describe() const override;

src/catch2/matchers/catch_matchers_vector.hpp

@@ -18,7 +18,7 @@ namespace Matchers {
 
     namespace Vector {
         template<typename T>
-        struct ContainsElementMatcher : MatcherBase<std::vector<T>> {
+        struct ContainsElementMatcher final : MatcherBase<std::vector<T>> {
 
             ContainsElementMatcher(T const &comparator) : m_comparator( comparator) {}
 
@@ -39,7 +39,7 @@ namespace Matchers {
         };
 
         template<typename T>
-        struct ContainsMatcher : MatcherBase<std::vector<T>> {
+        struct ContainsMatcher final : MatcherBase<std::vector<T>> {
 
             ContainsMatcher(std::vector<T> const &comparator) : m_comparator( comparator ) {}
 
@@ -69,7 +69,7 @@ namespace Matchers {
         };
 
         template<typename T>
-        struct EqualsMatcher : MatcherBase<std::vector<T>> {
+        struct EqualsMatcher final : MatcherBase<std::vector<T>> {
 
             EqualsMatcher(std::vector<T> const &comparator) : m_comparator( comparator ) {}
 
@@ -92,7 +92,7 @@ namespace Matchers {
         };
 
         template<typename T>
-        struct ApproxMatcher : MatcherBase<std::vector<T>> {
+        struct ApproxMatcher final : MatcherBase<std::vector<T>> {
 
             ApproxMatcher(std::vector<T> const& comparator) : m_comparator( comparator ) {}
 
@@ -128,7 +128,7 @@ namespace Matchers {
         };
 
         template<typename T>
-        struct UnorderedEqualsMatcher : MatcherBase<std::vector<T>> {
+        struct UnorderedEqualsMatcher final : MatcherBase<std::vector<T>> {
             UnorderedEqualsMatcher(std::vector<T> const& target) : m_target(target) {}
             bool match(std::vector<T> const& vec) const override {
                 // Note: This is a reimplementation of std::is_permutation,