Re: base_yylex undefined in src/interface/ecpg/preproc/parser.c

=?UTF-8?B?0JTQuNC70Y/QvSDQn9Cw0LvQsNGD0LfQvtCy?= <dpa-postgres(at)aegee(dot)org> writes:
> with the newest flex (v2.6.2-19-g6bea32e, which is newer than 2.6.3) I
> need this patch to compile postgres:

Ugh.

> With previous versions of flex the compilation has worked. But I do not
> find in the code where is supposed yylex to be renamed to base_yylex
> when parser.c is proccessed. pgc.l also does not use %option
> prefix=base_yy, which would be the right way to rename yylex (apart from
> #define YY_DECL).
> What is the purpose to rename yylex to base_yylex?

It's mostly for consistency with the backend, where we have multiple bison
parsers (and multiple flex lexers) so there's a policy of renaming all of
them away from the default name. Since ecpg is a standalone program,
we could in principle not bother to rename its parser; but I'd rather
keep it in as close sync with the corresponding backend code as possible.

The reason for the current hacky approach is explained in pgc.l:

/*
* Change symbol names as expected by preproc.y. It'd be better to do this
* with %option prefix="base_yy", but that affects some other names that
* various files expect *not* to be prefixed with "base_". Cleaning it up
* is not worth the trouble right now.
*/
#define yylex base_yylex
#define yylval base_yylval

Looks like it's time to pay down that technical debt.

regards, tom lane