Fix class to function.

Author: Sonny Martin

src/util/invariant.h

@@ -199,8 +199,8 @@ std::string get_backtrace();
 
 void report_exception_to_stderr(const invariant_failedt &);
 
-/// This class is the backbone of all the invariant types. Every instance of an
-/// invariant is ultimately generated by this class, which is at times called
+/// This function is the backbone of all the invariant types. Every instance of an
+/// invariant is ultimately generated by this function template, which is at times called
 /// via a wrapper function.
 /// Takes a backtrace, gives it to the reason structure, then aborts, printing
 /// reason.what() (which therefore includes the backtrace).
@@ -236,7 +236,7 @@ CBMC_NORETURN
   abort();
 }
 
-/// This is a wrapper class used by the macro 'INVARIANT(CONDITION, REASON)'
+/// This is a wrapper function used by the macro 'INVARIANT(CONDITION, REASON)'.
 /// It constructs an invariant_violatedt from reason and the
 /// backtrace, then aborts after printing the invariant's description.
 /// In future this may throw rather than aborting.
@@ -350,7 +350,7 @@ std::string assemble_diagnostics(Diagnostics &&... args)
 } // namespace detail
 
 
-/// This is a wrapper class, used by the macro 'INVARIANT_WITH_DIAGNOSTICS'
+/// This is a wrapper function, used by the macro 'INVARIANT_WITH_DIAGNOSTICS'
 template <typename... Diagnostics>
 CBMC_NORETURN void report_invariant_failure(
   const std::string &file,