pgsql-server/src backend/optimizer/plan/create ...

CVSROOT:    /cvsroot
Module name:    pgsql-server
Changes by:    tgl@svr1.postgresql.org    04/01/17 20:50:03

Modified files:
    src/backend/optimizer/plan: createplan.c planner.c
    src/backend/optimizer/prep: prepunion.c
    src/include/optimizer: planmain.h

Log message:
    When testing whether a sub-plan can do projection, use a general-purpose
    check instead of hardwiring assumptions that only certain plan node types
    can appear at the places where we are testing.  This was always a pretty
    fragile assumption, and it turns out to be broken in 7.4 for certain cases
    involving IN-subselect tests that need type coercion.
    Also, modify code that builds finished Plan tree so that node types that
    don't do projection always copy their input node's targetlist, rather than
    having the tlist passed in from the caller.  The old method makes it too
    easy to write broken code that thinks it can modify the tlist when it
    cannot.