Extended Description

When using "clang -MMD" with filenames that contain dollar signs, the dollar signs are not escaped. If this output is used with make it won't be able to find the prerequisites. For example:

$ /bin/ls -l
-rw-r--r-- 1 abbeyj users 75 Apr 1 17:36 Makefile
-rw-r--r-- 1 abbeyj users 0 Apr 1 17:35 dollar$sign.h
-rw-r--r-- 1 abbeyj users 25 Apr 1 17:32 main.c

$ cat Makefile
main.o: main.c
$(CC) -MMD -c main.c
-include main.d
clean:
$(RM) *.o *.d

$ cat main.c
#include "dollar$sign.h"

works fine with gcc

$ make CC=gcc
gcc -MMD -c main.c
$ cat main.d
main.o: main.c dollar$$sign.h
$ make CC=gcc
make: `main.o' is up to date.

$ make clean

fails with clang (once .d file has been created)

$ make CC=clang
clang -MMD -c main.c
$ cat main.d
main.o: main.c dollar$sign.h
$ make CC=clang
make: *** No rule to make target dollarign.h', needed by main.o'. Stop.

Since the dollar sign is not doubled, make tries to expand "$s" and gets an empty string making it think the desired filename is "dollarign.h". Since that file doesn't exist, the make then fails.