For some time compiling pf with ALTQ enabled on CURRENT gives following errors (pf compiles fine without ALTQ) :

#   compile  WIFIBSD_RUN/pf.o
/usr/src/obj/tooldir.NetBSD-3.99.6-i386/bin/i386--netbsdelf-gcc -ffreestanding -Os -mcpu=i486 -Werror -Wall -Wno-main -Wno-format-zero-length -Wpointer-arith -Wmissing-prototypes -Wstrict-prototypes -Wreturn-type -Wswitch -Wshadow -Wcast-qual -Wwrite-strings -Wno-sign-compare -Wno-shadow -fno-zero-initialized-in-bss -Di386 -I. -I/usr/src/sys/arch -I/usr/src/sys -nostdinc -DTIMER_FREQ=1189200 -DDUMMY_NOPS -DMAXUSERS=32 -D_KERNEL -D_KERNEL_OPT -I/usr/src/sys/dist/pf -c /usr/src/sys/dist/pf/net/pf.c
/usr/src/sys/dist/pf/net/pf.c: In function `pf_send_tcp':
/usr/src/sys/dist/pf/net/pf.c:1523: error: dereferencing pointer to incomplete type
/usr/src/sys/dist/pf/net/pf.c:1526: error: dereferencing pointer to incomplete type
/usr/src/sys/dist/pf/net/pf.c:1528: error: dereferencing pointer to incomplete type
/usr/src/sys/dist/pf/net/pf.c:1529: error: dereferencing pointer to incomplete type
/usr/src/sys/dist/pf/net/pf.c: In function `pf_send_icmp':
/usr/src/sys/dist/pf/net/pf.c:1673: error: dereferencing pointer to incomplete type
/usr/src/sys/dist/pf/net/pf.c:1676: error: dereferencing pointer to incomplete type
/usr/src/sys/dist/pf/net/pf.c:1678: error: dereferencing pointer to incomplete type
/usr/src/sys/dist/pf/net/pf.c:1679: error: dereferencing pointer to incomplete type
/usr/src/sys/dist/pf/net/pf.c: In function `pf_test':
/usr/src/sys/dist/pf/net/pf.c:6063: error: dereferencing pointer to incomplete type
/usr/src/sys/dist/pf/net/pf.c:6067: error: dereferencing pointer to incomplete type
/usr/src/sys/dist/pf/net/pf.c:6069: error: dereferencing pointer to incomplete type
/usr/src/sys/dist/pf/net/pf.c:6071: error: dereferencing pointer to incomplete type
/usr/src/sys/dist/pf/net/pf.c:6072: error: dereferencing pointer to incomplete type
/usr/src/sys/dist/pf/net/pf.c: In function `pf_test6':
/usr/src/sys/dist/pf/net/pf.c:6404: error: dereferencing pointer to incomplete type
/usr/src/sys/dist/pf/net/pf.c:6408: error: dereferencing pointer to incomplete type
/usr/src/sys/dist/pf/net/pf.c:6410: error: dereferencing pointer to incomplete type
/usr/src/sys/dist/pf/net/pf.c:6412: error: dereferencing pointer to incomplete type
/usr/src/sys/dist/pf/net/pf.c:6413: error: dereferencing pointer to incomplete type

*** Failed target:  pf.o
*** Failed command: echo '# ' "compile WIFIBSD_RUN/pf.o"; echo /usr/src/obj/tooldir.NetBSD-3.99.6-i386/bin/i386--netbsdelf-gcc -ffreestanding -Os -mcpu=i486 -Werror -Wall -Wno-main -Wno-format-zero-length -Wpointer-arith -Wmissing-prototypes -Wstrict-prototypes -Wreturn-type -Wswitch -Wshadow -Wcast-qual -Wwrite-strings -Wno-sign-compare -Wno-shadow -fno-zero-initialized-in-bss -Di386 -I. -I/usr/src/sys/arch -I/usr/src/sys -nostdinc -DTIMER_FREQ="1189200" -DDUMMY_NOPS -DMAXUSERS=32 -D_KERNEL -D_KERNEL_OPT -I/usr/src/sys/dist/pf -c /usr/src/sys/dist/pf/net/pf.c; /usr/src/obj/tooldir.NetBSD-3.99.6-i386/bin/i386--netbsdelf-gcc -ffreestanding -Os -mcpu=i486 -Werror -Wall -Wno-main -Wno-format-zero-length -Wpointer-arith -Wmissing-prototypes -Wstrict-prototypes -Wreturn-type -Wswitch -Wshadow -Wcast-qual -Wwrite-strings -Wno-sign-compare -Wno-shadow -fno-zero-initialized-in-bss -Di386 -I. -I/usr/src/sys/arch -I/usr/src/sys -nostdinc -DTIMER_FREQ="1189200" -DDUMMY_NOPS -DMAXUSERS=!
 32 -D_KERNEL -D_KERNEL_OPT -I/usr/src/sys/dist/pf -c /usr/src/sys/dist/pf/net/pf.c
*** Error code 1

Stop.
nbmake: stopped in /usr/obj/sys/arch/i386/compile/WIFIBSD_RUN

ERROR: Failed to make all in /usr/src/sys/arch/i386/compile/obj/WIFIBSD_RUN
*** BUILD ABORTED ***