[Bug other/46268] New: gengtype warning when GTY(()) markers have no effect

[dnovillo at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46268

           Summary: gengtype warning when GTY(()) markers have no effect
           Product: gcc
           Version: 4.6.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: other
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: dnovillo@gcc.gnu.org


Recently I was adding GTY markers to new structures but had forgotten to
declare a GC root variable.  This was causing gengtype to ignore the structure,
which meant that no ggc_alloc_cleared_XXX function was generated.  This caused
a failure during stage 2 when the compiler warned that no such function had
been declared.

The warning is removed from the immediate cause.  If gengtype had warned me
that I was adding a useless GTY marker, it would have made it easier to fix.

Additionally, the automatic generation of the ggc_... function family is not
very clearly documented in doc/gty.texi.