compiler construction - Creating a grammar for function prototypes and declaration bison -

i'm build compiler school project. works fine having difficulty defining grammar functions. have detect if there 0 or more parameters , if function either prototype or definition. keep getting shift/reduce and/or reduce/reduce errors. have tried many variations no avail. here have, looking pointers in direction or ideas on how fix this.

function   : parameters ';'   {free_ast($2); $$ = $1;}            | parameters block {$$ = adopt1($1, $2)}            ;  parameters : paramlist ')'   {free_ast($2); $$ = $1;}            | '(' identdecl ')' {free_ast($3); $$ = adopt_func2($1, $2);}            ;  paramlist  : paramlist ',' identdecl {free_ast($2);                                       $$ = adopt1($1, $2);}            | '(' identdecl           {$$ = adopt_func2($1, $2);}  identdecl  : basetype tok_array tok_ident {$$ = adopt2($1, $2,                                            change_symbol(                                            $3, tok_declid));}            | basetype tok_ident           {$$ = adopt1($1,                                            change_symbol(                                            $2, tok_declid));}            ;  block      : stateseq '}'       {free_ast($2); $$ = $1;}            | ';'                {free_ast($1);}            ; 

adopt_func2 adopts definition part of problem adopt_proto. thank time.

as far can see, issue has nothing declaration/definition similarity. problem have special case parameter list 1 parameter, leading ambiguity:

parameters : paramlist ')'            | '(' identdecl ')'            ;  paramlist  : paramlist ',' identdecl             | '(' identdecl            ; 

so (type id) can reduced using either first production parameters, paramlist reduced second production, or can reduced directly using second production parameters. can't see obvious need second production parameters, i'd suggest removing it.

however, (imho) ugly way of writing grammar, since hides symmetry of parentheses. not recognize parameter list 0 parameters. i'd suggest:

parameters : '(' paramlist ')'            | '(' ')'  paramlist  : identdecl            | paramlist ',' identdecl 

which think clearer.