[Bug c++/71182] [6/7 Regression] parser.c cp_lexer_previous_token sanitizer detects member call on null pointer

[trippels at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71182

--- Comment #2 from Markus Trippelsdorf <trippels at gcc dot gnu.org> ---
  760 static inline cp_token *                                                  
  761 cp_lexer_previous_token (cp_lexer *lexer)                                 
  762 {                                                                         
  763   cp_token_position tp = cp_lexer_previous_token_position (lexer);        
  764                                                                           
  765   /* Skip past purged tokens.  */                                         
  766   while (tp->purged_p)                                                    
  767     {                                                                     
  768       gcc_assert (tp != lexer->buffer->address ());                       
  769       tp--;                                                               
  770     }                                                                     
  771                                                                           
  772   return cp_lexer_token_at (lexer, tp);                                   
  773 }