gmake: a target completes but $(realpath ...) doesn't find it - solaris

Question

Environment stuff:
Solaris NFS file servers running NFS 3
Errors occur in Linux or Solaris environments
Using GNU Make 3.82
Using Sun Studio compilers, if that matters
This is a vastly simplified example of the build I'm looking at:
all: ${list of shared objects to build}
#do whatever
lib1.so: ${1s objects}
lib2.so: ${2s objects}
lib3.so: ${3s objects}
#...
%.so:
$(call CHECK_DEPENDENCIES_EXIST)
#${LD} ${LDFLAGS} ${^} -o ${#}
%.o : %.c
#do stuff
%.o : %.cc
#do stuff
define CHECK_DEPENDENCIES_EXIST =
$(if $(realpath ${^}),,$(warning No dependencies specified for ${#})false)
endef
The short & sweet: $(realpath x y z) (x/y/z get returned if they exist; returns an absolute path including no symlinks) is removing files from the list under some circumstances, and I think it has to do with NFS. It isn't predictable which target will fail. Sometimes a target will fail when it's succeeded the last 10 times. If I take #false out of the macro, the build continues without error -- that is, the linker does not complain about the supposedly missing file(s).
I'll spare you the drawn-out explanation; suffice it to say, the macro is helpful for debugging.

Answer 1

Turns out there's a bug in gmake. From the GNU Make 3.82 source, function.c, on or about line 2026:
while ((path = find_next_token (&p, &len)) != 0 ) {
/* ... */
if (
#ifdef HAVE_REALPATH
realpath (in, out)
#else
abspath (in, out) && stat (out, &st) == 0
#endif
)
{
/* ... */
}
}
}
/* ... */
Ocasionally, various calls to realpath would get interrupted (EINTR); nothing in this code checks errno, so it just silently fails.
So, it wasn't that the file didn't exist, it was that $(realpath ...) was being interrupted by a signal (presumably a child instance of gmake signaling its completion or something similar) and this function wasn't designed to recover from that sort of event.
To fix the problem:
while ((path = find_next_token (&p, &len)) != 0 ) {
... becomes:
while ( errno == EINTR || (path = find_next_token (&p, &len)) != 0 ) {
The || will shortcut & prevent it from marching on to the next token.