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generateSerialExtraStmts() was sloppy about handling the case where SEQUENCE NAME is given with a not-schema-qualified name. It was generating a CreateSeqStmt with an unqualified sequence name, and an AlterSeqStmt whose "owned_by" DefElem contained a T_String Value with a null string pointer in the schema-name position. The generated nextval() argument was also underqualified. This accidentally failed to fail at runtime, but only so long as the current default creation namespace at runtime is the right namespace. That's bogus; the parse-time transformation is supposed to be inserting the right schema name in all cases, so as to avoid any possible skew in that selection. I'm not sure this could fail in pg_dump's usage, but it's still wrong; we have had real bugs in this area before adopting the policy that parse_utilcmd.c should generate only fully-qualified auxiliary commands. A slightly lesser problem, which is what led me to notice this in the first place, is that pprint() dumped core on the AlterSeqStmt because of the bogus T_String. Noted while poking into the open problem with ALTER SEQUENCE breaking pg_upgrade.
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.