#1 Cygwin compile error: invalid application of `sizeof' to inc

[Jari Aalto]

Compiling under Cygwin gives following error.
Please investigate.

gcc (GCC) 3.4.4 (cygming special, gdc 0.12, using dmd 0.125)
/bin/rm -f ish ishd
ccache gcc -O2 -Wall -o ish ish.c ish_main.c
ish_main.c: In function `ish_send':
ish_main.c:21: error: invalid application of `sizeof' to incomplete type `icmp'
ish_main.c:23: error: invalid application of `sizeof' to incomplete type `icmp'
ish_main.c:24: error: invalid application of `sizeof' to incomplete type `icmp'
ish_main.c:32: error: dereferencing pointer to incomplete type
ish_main.c:33: error: dereferencing pointer to incomplete type
ish_main.c:34: error: dereferencing pointer to incomplete type
ish_main.c:35: error: dereferencing pointer to incomplete type
ish_main.c:36: error: dereferencing pointer to incomplete type
ish_main.c:37: error: dereferencing pointer to incomplete type
ish_main.c: In function `ish_recv':
ish_main.c:48: error: invalid application of `sizeof' to incomplete type `icmp'
ish_main.c:53: error: invalid application of `sizeof' to incomplete type `icmp'
ish_main.c:54: error: invalid application of `sizeof' to incomplete type `icmp'
ish_main.c:59: error: dereferencing pointer to incomplete type
make: *** [cc1] Error 1