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The Bison documentation clearly states that a semicolon is required after every grammar rule, and our scripts that generate ecpg's grammar from the backend's implicitly assumed this is true. But it turns out that only ancient versions of Bison actually enforce that. There have been a couple of rules without trailing semicolons in gram.y for some time, and as a consequence, ecpg's grammar was faulty and produced wrong output for the affected statements. To fix, add the missing semis, and add some cross-checks to ecpg's scripts so that they'll bleat if we mess this up again. The cases that were broken were: * "SET variable = DEFAULT" (but not "SET variable TO DEFAULT"), as well as allied syntaxes such as ALTER SYSTEM SET ... DEFAULT. These produced syntactically invalid output that the server would reject. * Multiple type names in DROP TYPE/DOMAIN commands. Only the first type name would be listed in the emitted command. Per report from Daisuke Higuchi. Back-patch to all supported versions. Discussion: https://postgr.es/m/1803D792815FC24D871C00D17AE95905DB51CE@g01jpexmbkw24
src/backend/parser/README Parser ====== This directory does more than tokenize and parse SQL queries. It also creates Query structures for the various complex queries that are passed to the optimizer and then executor. parser.c things start here scan.l break query into tokens scansup.c handle escapes in input strings gram.y parse the tokens and produce a "raw" parse tree analyze.c top level of parse analysis for optimizable queries parse_agg.c handle aggregates, like SUM(col1), AVG(col2), ... parse_clause.c handle clauses like WHERE, ORDER BY, GROUP BY, ... parse_coerce.c handle coercing expressions to different data types parse_collate.c assign collation information in completed expressions parse_cte.c handle Common Table Expressions (WITH clauses) parse_expr.c handle expressions like col, col + 3, x = 3 or x = 4 parse_func.c handle functions, table.column and column identifiers parse_node.c create nodes for various structures parse_oper.c handle operators in expressions parse_param.c handle Params (for the cases used in the core backend) parse_relation.c support routines for tables and column handling parse_target.c handle the result list of the query parse_type.c support routines for data type handling parse_utilcmd.c parse analysis for utility commands (done at execution time) See also src/common/keywords.c, which contains the table of standard keywords and the keyword lookup function. We separated that out because various frontend code wants to use it too.