imcs: Can't rebuild using make option USE_DISK=1

Hi,

I wanted to test the disk mode so I edited the install.sh file to include the USE_DISK=1 option like below and executed it, but it results in some errors.

PATH=/usr/local/pgsql/bin/:$PATH make USE_PGXS=1 CFLAGS="-O3 -Wall -Wno-format-security"  LDFLAGS="-pthread" USE_DISK=1 install

Errors:

gcc -O3 -Wall -Wno-format-security -fPIC -I. -I./ -I/usr/include/postgresql/12/server -I/usr/include/postgresql/internal  -Wdate-time -D_FORTIFY_SOURCE=2 -D_GNU_SOURCE -I/usr/include/libxml2  -I/usr/include/mit-krb5  -c -o imcs.o imcs.c
gcc -O3 -Wall -Wno-format-security -fPIC -I. -I./ -I/usr/include/postgresql/12/server -I/usr/include/postgresql/internal  -Wdate-time -D_FORTIFY_SOURCE=2 -D_GNU_SOURCE -I/usr/include/libxml2  -I/usr/include/mit-krb5  -c -o func.o func.c
gcc -O3 -Wall -Wno-format-security -fPIC -I. -I./ -I/usr/include/postgresql/12/server -I/usr/include/postgresql/internal  -Wdate-time -D_FORTIFY_SOURCE=2 -D_GNU_SOURCE -I/usr/include/libxml2  -I/usr/include/mit-krb5  -c -o smp.o smp.c
gcc -O3 -Wall -Wno-format-security -fPIC -I. -I./ -I/usr/include/postgresql/12/server -I/usr/include/postgresql/internal  -Wdate-time -D_FORTIFY_SOURCE=2 -D_GNU_SOURCE -I/usr/include/libxml2  -I/usr/include/mit-krb5  -c -o btree.o btree.c
gcc -O3 -Wall -Wno-format-security -fPIC -I. -I./ -I/usr/include/postgresql/12/server -I/usr/include/postgresql/internal  -Wdate-time -D_FORTIFY_SOURCE=2 -D_GNU_SOURCE -I/usr/include/libxml2  -I/usr/include/mit-krb5  -c -o threadpool.o threadpool.c
gcc -O3 -Wall -Wno-format-security -fPIC -I. -I./ -I/usr/include/postgresql/12/server -I/usr/include/postgresql/internal  -Wdate-time -D_FORTIFY_SOURCE=2 -D_GNU_SOURCE -I/usr/include/libxml2  -I/usr/include/mit-krb5  -c -o fileio.o fileio.c
gcc -O3 -Wall -Wno-format-security -fPIC -I. -I./ -I/usr/include/postgresql/12/server -I/usr/include/postgresql/internal  -Wdate-time -D_FORTIFY_SOURCE=2 -D_GNU_SOURCE -I/usr/include/libxml2  -I/usr/include/mit-krb5  -c -o disk.o disk.c
disk.c:31:46: error: unknown type name ‘imcs_page_access_mode_t’
 imcs_page_t* imcs_load_page(imcs_page_t* pg, imcs_page_access_mode_t mode)
                                              ^~~~~~~~~~~~~~~~~~~~~~~
disk.c:134:1: error: expected identifier or ‘(’ before ‘{’ token
 {
 ^
disk.c:160:25: error: macro "imcs_disk_open" passed 1 arguments, but takes just 0
 void imcs_disk_open(void)
                         ^
disk.c:161:1: error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘{’ token
 {
 ^
disk.c:165:26: error: macro "imcs_disk_close" passed 1 arguments, but takes just 0
 void imcs_disk_close(void)
                          ^
disk.c:166:1: error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘{’ token
 {
 ^
disk.c:177:26: error: macro "imcs_disk_flush" passed 1 arguments, but takes just 0
 void imcs_disk_flush(void)
                          ^
disk.c:178:1: error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘{’ token
 {
 ^
disk.c:170:12: warning: ‘compare_page_offset’ defined but not used [-Wunused-function]
 static int compare_page_offset(void const* p, void const* q)
            ^~~~~~~~~~~~~~~~~~~
<builtin>: recipe for target 'disk.o' failed
make: *** [disk.o] Error 1

imcs_page_access_mode_t is present in disk.h but not sure why I’m getting this issue.