🚀 go-pugleaf

I don't quite understand why the compiler complains about one line of C:

(My CFLAGS):
CFLAGS=-Wall -Wshadow -Wpointer-arith -Wcast-qual -Wcast-align \
-Wwrite-strings -Wtraditional -Wstrict-prototypes \
-Wnested-externs -O3 -ggdb3 -DPATH_MAX=255 -pipe

(gc-2.7.1):
genstamm.c: In function `exported_filename':
genstamm.c:99: warning: suggest parentheses around && within ||

(genstamm.c#99):
	if ( PATIENTNO[0] != ' ' && PATIENTNO[0] != '0' ||
	     PATIENTNO[1] != ' ' && PATIENTNO[1] != '0' )
		return(-1);

I think here the situation is rather clear ("&&" is stronger than "||"). 
On the other hand the compiler does not warn about "v & 3 == 1". 
Something like "expression is const" or "code has no effect" would not 
bee too bad. I've found the example above in the Linux-1.2.13 pci.c file 
(not literally). Obviously that kind of error is still made.

Anything to be done?

Ulrich