[Octave-bug-tracker] [bug #55347] PVS studio static analysis report

[Rik]

Follow-up Comment #40, bug #55347 (project octave):

@jwe: I crossed off all the bugs in lex.cc since that is an auto-generated
file, but lex.ll is a source-controlled that we own.  Taking the first
warning


lex.ll (391)
        V519    The 'yyg->yy_c_buf_p' variable is assigned values twice 
successively.
Perhaps this is a mistake. Check lines: 391, 391.


I find the code


<COMMAND_START>(\.\.\.){ANY_EXCEPT_NL}*{NL} {
    curr_lexer->lexer_debug
("<COMMAND_START>(\\.\\.\\.){ANY_EXCEPT_NL}*{NL}");

    COMMAND_ARG_FINISH;

    curr_lexer->m_input_line_number++;
    curr_lexer->m_current_input_column = 1;

    HANDLE_STRING_CONTINUATION;
  }


The macro HANDLE_STRING_CONTINUATION is


#define HANDLE_STRING_CONTINUATION                      \
   do                                                   \
     {                                                  \
       curr_lexer->decrement_promptflag ();             \
       curr_lexer->m_input_line_number++;               \
       curr_lexer->m_current_input_column = 1;          \
                                                        \
       if (curr_lexer->is_push_lexer ())                \
         {                                              \
           if (curr_lexer->at_end_of_buffer ())         \
             return -1;                                 \
                                                        \
           if (curr_lexer->at_end_of_file ())           \
             return curr_lexer->handle_end_of_input (); \
         }                                              \
     }                                                  \
   while (0)


I think the static analyzer is suspicious because
curr_lexer->m_input_line_number++ is being called twice in succession, as is
curr_lexer->m_current_input_column = 1;

If this is all correct (which it probably is since the parser seems to work)
then we can cross these off as false positives.





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