Re: Bison/flex compatibility revisited

[Bruce Lilly]

Paul Eggert wrote:

> So, not only is Bison is within its rights to use local variables
> beginning with yy, it's _required_ to use yy (or YY).
>
> It is a tricky situation, since POSIX also places constraints on lex
> about yy symbols.  Anyway, I've worked around this particular instance
> of the problem by renaming yylineno to yylno in the Bison CVS.

Thanks.

Yes, it's indeed tricky.

OK, so for future use, how about something less likely to clash,
e.g. yy_bison_ as a prefix?

FYI, as of now the complete list (unless I missed some) of yy and
YY prefixed names used by the flex-generated header is:

YYFARGS0 YYFARGS1 YYFARGS2 YYFARGS3 YYLMAX YYLTYPE YYLTYPE_IS_DECLARED
YYSTATE YYSTYPE YY_ALWAYS_INTERACTIVE YY_AT_BOL YY_BISON_BRIDGE
YY_BREAK YY_BUFFER_EOF_PENDING YY_BUFFER_NEW YY_BUFFER_NORMAL
YY_BUFFER_STATE YY_BUF_SIZE YY_CALL_LAST_ARG YY_CALL_ONLY_ARG
YY_CURRENT_BUFFER YY_DECL YY_DECL_LAST_ARG YY_DEF_LAST_ARG YY_DEF_ONLY_ARG
YY_DO_BEFORE_ACTION YY_END_OF_BUFFER YY_END_OF_BUFFER_CHAR YY_EXIT_FAILURE
YY_HEADER_EXPORT_START_CONDITIONS YY_EXTRA_TYPE YY_FATAL_ERROR
YY_FLEX_DEFINED_ECHO YY_FLEX_LEX_COMPAT YY_FLEX_MAJOR_VERSION
YY_FLEX_MINOR_VERSION YY_FLEX_SUBMINOR_VERSION YY_FLUSH_BUFFER YY_G
YY_HEADER_NO_UNDEFS YY_INPUT YY_INTERACTIVE YY_INT_ALIGNED YY_LAST_ARG
YY_LESS_LINENO YY_LEX_ARGS YY_LEX_DECLARATION YY_LEX_PROTO YY_MAIN YY_MORE_ADJ
YY_NEED_STRLEN YY_NEW_FILE YY_NO_DESTROY YY_NO_FLEX_ALLOC YY_NO_FLEX_FREE
YY_NO_FLEX_REALLOC YY_NO_GET_DEBUG YY_NO_GET_EXTRA YY_NO_GET_IN YY_NO_GET_LENG
YY_NO_GET_LINENO YY_NO_GET_LLOC YY_NO_GET_LVAL YY_NO_GET_OUT YY_NO_GET_TEXT
YY_NO_INPUT YY_NO_POP_STATE YY_NO_PROTOS YY_NO_PUSH_STATE YY_NO_SCAN_BUFFER
YY_NO_SCAN_BYTES YY_NO_SCAN_STRING YY_NO_SET_DEBUG YY_NO_SET_EXTRA
YY_NO_SET_IN YY_NO_SET_LINENO YY_NO_SET_LLOC YY_NO_SET_LVAL YY_NO_SET_OUT
YY_NO_TOP_STATE YY_NO_UNISTD_H YY_NO_UNPUT YY_NULL YY_NUM_RULES YY_ONLY_ARG
YY_PARAMS YY_PROTO YY_PROTO_LAST_ARG YY_PROTO_ONLY_ARG YY_READ_BUF_SIZE
YY_REENTRANT YY_RESTORE_YY_MORE_OFFSET YY_RULE_SETUP YY_SC_TO_UI
YY_SKIP_YYWRAP YY_STACK_USED YY_START YY_START_STACK_INCR YY_STATE_EOF
YY_STDINIT YY_STRUCT_YY_BUFFER_STATE YY_TABLES_VERIFY YY_TEXT_IS_ARRAY
YY_TRADITIONAL_FUNC_DEFS YY_TRAILING_HEAD_MASK YY_TRAILING_MASK
YY_TYPEDEF_YY_BUFFER_STATE YY_TYPEDEF_YY_SIZE_T YY_USER_ACTION YY_USES_REJECT
YY_USE_CONST YY_USE_LINENO YY_USE_PROTOS yy_buffer_state yy_create_buffer
yy_current_buffer yy_delete_buffer yy_flex_debug yy_flex_strlen
yy_flex_strncpy yy_flush_buffer yy_init_buffer yy_load_buffer_state
yy_new_buffer yy_scan_buffer yy_scan_bytes yy_scan_string yy_set_bol
yy_set_interactive yy_size_t yy_switch_to_buffer yyalloc yyconst yyextra
yyfree yyget_debug yyget_extra yyget_in yyget_leng yyget_lineno yyget_lloc
yyget_lval yyget_out yyget_text yyin yyleng yyless yylex yylex_destroy
yylex_init yylineno yylloc yyllocp yylval yylvalp yymore yyout yyrealloc
yyrestart yyscan_t yyscanner yyset_debug yyset_extra yyset_in yyset_lineno
yyset_lloc yyset_lval yyset_out yyterminate yytext yytext_ptr yywrap

Of those, certainly the yylex prototype and yylex macro (in case
flex uses a prefix to change that to something like foolex) are
necessary since bison calls yylex (or whatever prefix-altered
name is used), and the others come along for the ride.

Best regards,
  Bruce Lilly