[Bug driver/12448] -MT / -MQ don't behave as documented.

["taylor at candd dot org" <gcc-bugzilla at gcc dot gnu dot org>]

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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=12448



------- Additional Comments From taylor at candd dot org  2003-10-03 14:34 -------
To reproduce the problem, consider the following Makefile:

CC = gcc
CFLAGS = -MD -MT foo.o -MF foo.d
MV = mv

foo.o: bar.c
        ${CC} bar.c -o - > xfoo.o
        ${MV} xfoo.o foo.o

Suppose bar.c includes no files, then the resulting foo.d
file will contain:

    foo.o -: bar.c

But, it should contain:

    foo.o: bar.c

The - should NOT be present.  You could argue about whether - should ever
be a target within the .d file, but regardless -- if the user specified one
or more targets with -MT / -MQ, then the *DEFAULT* target should *NOT* be used.

Eliminating or editing the cpp_unique_options line, as mentioned, fixes
the problem.

Deleting the line (my preferred fix) bootstraps just fine.  There do not
appear to be any tests within the testsuite that test the -MT / -MQ / -MD /
-MMD / -MF / -M<whatever> options.  If someone will give me a pointer on
how to have the testsuite compare two files -- the generated .d file against
the correct .d file, I will gladly write a test case for this bug.