Quick item: parse_clause.h fails cpluspluscheck because it has a C++ keyword as a function argument name:
./src/include/parser/parse_clause.h:26:14: error: expected ‘,’ or ‘...’ before ‘namespace’ List **namespace); ^~~~~~~~~ -- Álvaro Herrera https://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services