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Re: Make things it's time to link when it should compile


On Fri, 20 Jan 2006, Eric Lilja wrote:

> Hello, I'm having trouble with make for one simple program.
> mikael@mindcooler ~/coding/C/extract_acodes
> $ ls -al
> total 33K
> drwxrwxrwx+  2 mikael None    0 Jan 20 22:15 ./
> drwxrwxrwx+ 22 mikael None    0 Dec  7 16:12 ../
> -rwxrwxrwx   1 mikael None  264 Oct 14 13:54 Makefile*
> -rw-r--r--   1 mikael None  25K Jan 20 22:15 cygcheck.out
> -rwxrwxrwx   1 mikael None 1.7K Oct 14 14:03 extract_acodes.c*
>
> mikael@mindcooler ~/coding/C/extract_acodes
> $ cat Makefile
> CC = gcc
> CFLAGS = -Wall -W -ansi -pedantic -g -O0 -c -o
> LDFLAGS = -o $(EXEC)
> EXEC = extract_acodes.exe
> OBJECTS = extract_acodes.o
>
> all: $(OBJECTS)
>         $(CC) $^ $(LDFLAGS)
>
> %.o: %.c
>         $(CC) $(CLFAGS) $@ $<
>
> clean:
>         rm -f $(OBJECTS) $(EXEC) *~ *.stackdump
>
> mikael@mindcooler ~/coding/C/extract_acodes
> $ make
> gcc  extract_acodes.o extract_acodes.c
> gcc: extract_acodes.o: No such file or directory
> make: *** [extract_acodes.o] Error 1
>
> Compiling and linking the program manually works just fine:
> $ gcc -Wall -W -ansi -pedantic -g -O0 -c extract_acodes.c
>
> mikael@mindcooler ~/coding/C/extract_acodes
> $ gcc extract_acodes.o -o extract_acodes.exe
>
> But when I try to use the make, it seems to think it's time for the
> final linking stage...and it's just a problem with this particular
> "project". Any ideas what's wrong? I'm sure the Makefile is the culprit,
> but I can't see the error. cygcheck.out attached (I would have used
> cygwin 1.5.19-4 but I couln't find it on my local mirrors yet).

Actually, make does exactly what you told it to do in line 11: invoke gcc
with the empty value (of an uninitialized CLFAGS variable) after it,
followed by the object file target, followed by the prerequisite source
file.  That's not a linking step.  FWIW, you'd have the same exact trouble
on Linux.

For that reason, the "-o" option usually isn't part of CFLAGS.  Aside from
fixing the typo, I'd rewrite your Makefile as follows:

$ cat Makefile
CC = gcc
CFLAGS = -Wall -W -ansi -pedantic -g -O0
LDFLAGS =
EXEC = extract_acodes.exe
OBJECTS = extract_acodes.o

all: $(OBJECTS)
	$(CC) $(LDFLAGS) -o $(EXEC) $^ $(LDLIBS)

%.o: %.c
	$(CC) $(CLFAGS) -c -o $@ $<

clean:
	rm -f $(OBJECTS) $(EXEC) *~ *.stackdump
$

Considering that most of your actions directly reflect the implicit make
rules anyway, I'd even go for

$ cat Makefile
CC = gcc
CFLAGS = -Wall -W -ansi -pedantic -g -O0
LDFLAGS =
EXEC = extract_acodes.exe
OBJECTS = extract_acodes.o

all: $(EXEC)

$(EXEC): $(OBJECTS)

clean:
	rm -f $(OBJECTS) $(EXEC) *~ *.stackdump
$

HTH,
	Igor
-- 
				http://cs.nyu.edu/~pechtcha/
      |\      _,,,---,,_	    pechtcha@cs.nyu.edu | igor@watson.ibm.com
ZZZzz /,`.-'`'    -.  ;-;;,_		Igor Peshansky, Ph.D. (name changed!)
     |,4-  ) )-,_. ,\ (  `'-'		old name: Igor Pechtchanski
    '---''(_/--'  `-'\_) fL	a.k.a JaguaR-R-R-r-r-r-.-.-.  Meow!

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"But no -- you are no fool; you call yourself a fool, there's proof enough in
that!" -- Rostand, "Cyrano de Bergerac"

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