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## Motivation LALR parsers with default reductions can report inaccurate syntax error messages. When a default reduction is performed, the parser may consume tokens before detecting an error, leading to confusing "expected token" lists that include tokens not actually acceptable at the error point. Additionally, `%nonassoc` operators can cause similar issues where the parser reports unexpected tokens in error messages. LAC (Lookahead Correction) solves these problems by performing exploratory parsing to verify token acceptability before committing to reductions. refs: https://www.gnu.org/software/bison/manual/html_node/LAC.html
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LALR parsers with default reductions can report inaccurate syntax error messages. When a default reduction is performed, the parser may consume tokens before detecting an error, leading to confusing "expected token" lists that include tokens not actually acceptable at the error point.
Additionally,
%nonassocoperators can cause similar issues where the parser reports unexpected tokens in error messages.LAC (Lookahead Correction) solves these problems by performing exploratory parsing to verify token acceptability before committing to reductions.
refs: https://www.gnu.org/software/bison/manual/html_node/LAC.html