$$ in parse.y question(c++)

[Andreas Schwab]

"Dave Raggett" <dave_raggett@hotmail.com> writes:

|> In parse.y(gcc/cp/parse.y),I find such code:
|> expr_no_commas:
|> | expr_no_commas '+' expr_no_commas
|> 		{ $$ = build_x_binary_op ($2, $$, $3); }
|> 
|> why not { $$ = build_x_binary_op ($2, $1, $3); }??

Because Bison implicitly prepends "$$ = $1" to every action.

Andreas.

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