Remove unused StringRef argument from MatchExpr

Apart from cleaning up the code, this change also improves the
compilation time of `UsageTests/Matchers.tests.cpp` by about 2%.

src/catch2/internal/catch_assertion_handler.cpp

@@ -76,8 +76,8 @@ namespace Catch {
 
     // This is the overload that takes a string and infers the Equals matcher from it
     // The more general overload, that takes any string matcher, is in catch_capture_matchers.cpp
-    void handleExceptionMatchExpr( AssertionHandler& handler, std::string const& str, StringRef matcherString  ) {
-        handleExceptionMatchExpr( handler, Matchers::Equals( str ), matcherString );
+    void handleExceptionMatchExpr( AssertionHandler& handler, std::string const& str ) {
+        handleExceptionMatchExpr( handler, Matchers::Equals( str ) );
     }
 
 } // namespace Catch

src/catch2/internal/catch_assertion_handler.hpp

@@ -64,7 +64,7 @@ namespace Catch {
         auto allowThrows() const -> bool;
     };
 
-    void handleExceptionMatchExpr( AssertionHandler& handler, std::string const& str, StringRef matcherString );
+    void handleExceptionMatchExpr( AssertionHandler& handler, std::string const& str );
 
 } // namespace Catch
 

src/catch2/internal/catch_test_macro_impl.hpp

@@ -147,7 +147,7 @@
                 catchAssertionHandler.handleUnexpectedExceptionNotThrown(); \
             } \
             catch( ... ) { \
-                Catch::handleExceptionMatchExpr( catchAssertionHandler, matcher, #matcher##_catch_sr ); \
+                Catch::handleExceptionMatchExpr( catchAssertionHandler, matcher ); \
             } \
         else \
             catchAssertionHandler.handleThrowingCallSkipped(); \