regex.c not found, but it clearly exists

[NightStrike <nightstrike at gmail dot com>]

When compiling binutils in a cygwin shell using the mingw binary
release of gcc, I see the following confusing thing:

NightStrike@coolermaster1 /tmp/b6/bu/libiberty
$ make
if [ x"" != x ]; then \
          i686-pc-mingw32-gcc -c -DHAVE_CONFIG_H -g -O2 -I.
-I/tmp/build/binutils/src/libiberty/../include  -W -Wall
-Wwrite-strings -Wstrict-prototypes -pedantic
/tmp/build/binutils/src/libiberty/regex.c -o pic/regex.o; \
        else true; fi
i686-pc-mingw32-gcc -c -DHAVE_CONFIG_H -g -O2 -I.
-I/tmp/build/binutils/src/libiberty/../include  -W -Wall
-Wwrite-strings -Wstrict-prototypes -pedantic
/tmp/build/binutils/src/libiberty/regex.c -o regex.o
gcc.exe: /tmp/build/binutils/src/libiberty/regex.c: No such file or directory
gcc.exe: no input files
make: *** [regex.o] Error 1

NightStrike@coolermaster1 /tmp/b6/bu/libiberty
$ ls -la /tmp/build/binutils/src/libiberty/regex.c
-rw-r--r-- 1 NightStrike None 253K Jul 22  2005
/tmp/build/binutils/src/libiberty/regex.c



As you can see, the file does exist and is nonzero.  It is readable by
user, group, and world.  Why would gcc say it does not exist?