Re: [PATCH] Revert 'Fix logic error in _AC_PROG_LEX_YYTEXT_DECL (#109320)'

[Paul Eggert]

On 7/16/20 12:42 PM, Ross Burton wrote:
> checking for flex... flex
> checking for lex output file root... lex.yy
> checking for lex library... not found
> configure: WARNING: required lex library not found; giving up on flex
> ...
> configure: error: readline works only with flex.
>
> Again, bc's scanner has its own yywrap implementation, so it doesn't
> need to link to libfl.

In that case, why did 'configure' fail to build the little test program? The 
test program also has its own yywrap implementation, so it should be just like 
bc. 'configure' should successfully link the test program, set ac_cv_lib_lex to 
'none needed', and break out of the loop, and the warning you mentioned should 
not occur.

Are you using an old shell where 'ac_cv_lib_lex="${ac_lib:-none needed}' doesn't 
work? That might explain the problem.