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Make problem with implicit rule

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Join Date: Nov 2006

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Reputation: n.aggel is an unknown quantity at this point

Solved Threads: 11

n.aggel

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Make problem with implicit rule

Jul 10th, 2008

 Help with Code Tags 
 c Syntax (Toggle Plain Text) 
float hey(float a, float b);
float hey(float a, float b);

*func.c

 Help with Code Tags 
 c Syntax (Toggle Plain Text) 
#include "func.h"
 
float hey(float a, float b)
{
	return a+b;
}
#include "func.h"

float hey(float a, float b)
{
	return a+b;
}

*main.c

 Help with Code Tags 
 c Syntax (Toggle Plain Text) 
#include "func.h"
#include <stdio.h>
 
int main()
{
	printf("%f\n", hey(4.4,4.4) );
 
 
	return 0;
}
#include "func.h"
#include <stdio.h>

int main()
{
	printf("%f\n", hey(4.4,4.4) );


	return 0;
}

and here is the makefile, where i try to use builtin rules to
reduce the size of it

 Help with Code Tags 
 C++ Syntax (Toggle Plain Text) 
vpath %.c src
vpath %.h headers
 
CPPFLAGS = -I headers
 
simple: main.o func.o
 
main.o: func.h
 
func.o: func.h
vpath %.c src
vpath %.h headers

CPPFLAGS = -I headers

simple: main.o func.o

main.o: func.h

func.o: func.h

the problem is that when i run gnu-make i only get:

 Help with Code Tags 
 C++ Syntax (Toggle Plain Text) 
cc  -I headers  -c -o main.o src/main.c
cc  -I headers  -c -o func.o src/func.c
cc  -I headers  -c -o main.o src/main.c
cc  -I headers  -c -o func.o src/func.c

so basically the built in rule for simple is never run.

To verify that there is a default rule for such cases,
i type gmake --print-data-base > gmake.database.txt
and when i read gmake.database.txt i find

 Help with Code Tags 
 C++ Syntax (Toggle Plain Text) 
# Implicit Rules
 
%.out:
 
%.a:
 
%.ln:
 
%.o:
 
%: %.o
#  commands to execute (built-in):
	$(LINK.o) $^ $(LOADLIBES) $(LDLIBS) -o $@
# Implicit Rules

%.out:

%.a:

%.ln:

%.o:

%: %.o
#  commands to execute (built-in):
	$(LINK.o) $^ $(LOADLIBES) $(LDLIBS) -o $@

so this should work but it doesn't.....

any ideas will be appreciated
-nicolas

Two roads diverged in a wood, and I— I took the one less traveled by, and that has made all the difference.

by Robert Frost the "The Road Not Taken"

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Join Date: Dec 2006

Posts: 1,089

Reputation: vijayan121 is a name known to all

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vijayan121 vijayan121 is offline

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Re: Make problem with implicit rule

Jul 11th, 2008

•

n is made automatically from n.o by running the linker (usually called ld) via the C compiler. The precise command used is ...

This rule does the right thing for a simple program with only one source file. It will also do the right thing if there are multiple object files (presumably coming from various other source files), one of which has a name matching that of the executable file....

In more complicated cases, such as when there is no object file whose name derives from the executable file name, you must write an explicit command for linking.

from http://www.gnu.org/software/make/man...Implicit-Rules