presto-main/src/main/java/io/prestosql/sql/analyzer/StatementAnalyzer.java/StatementAnalyzer/validateColumnAliasesCount
class StatementAnalyzer:        private void validateColumnAliasesCount(List<Identifier> columnAliases, int sourceColumnSize)
        {
            if (columnAliases.size() != sourceColumnSize) {
                throw semanticException(
                        MISMATCHED_COLUMN_ALIASES,
                        columnAliases.get(0),
                        "Column alias list has %s entries but relation has %s columns",
                        columnAliases.size(),
                        sourceColumnSize);
            }
        }