Thread: Makefile Problem: None rule to make target

Hello guys,

Instead of opening a new subject, I rather continue with this subject.
Anyway, I compile/build a project with Autotools and have an issue with it.
GCC seems to use some default flags like: -g -O2
In the Makefile.am I have the following:
AM_CFLAGS = -Wall
When it compiles I see output like that "gcc somefile.c -Wall -g -O2"
If I modify AM_CFLAGS to "-Wall -g3 -O0" I assume to get an executable for best debugging. But the output is like this: "gcc somefile.c -Wall -g3 O0 -g -O2"
So I guess the source files will finally be compiled according to -g -O2 flags.

The problem is when debugging, some parts of the source are optimized away and so can't see what happens.

How can I turn off the gcc default flag or modify it?

Thanks in advance.

Originally Posted by Andaluz

Hello guys,

Instead of opening a new subject, I rather continue with this subject.
Anyway, I compile/build a project with Autotools and have an issue with it.
GCC seems to use some default flags like: -g -O2
In the Makefile.am I have the following:
AM_CFLAGS = -Wall
When it compiles I see output like that "gcc somefile.c -Wall -g -O2"
If I modify AM_CFLAGS to "-Wall -g3 -O0" I assume to get an executable for best debugging. But the output is like this: "gcc somefile.c -Wall -g3 O0 -g -O2"
So I guess the source files will finally be compiled according to -g -O2 flags.

The problem is when debugging, some parts of the source are optimized away and so can't see what happens.

How can I turn off the gcc default flag or modify it?

Thanks in advance.

Have you tried re-configuring?

Code:

$ CFLAGS='-g -O0' ./configure

If that doesn't work, open Makefile.in, search for where those flags are being set, remove them, and re-configure.

(I despise autoconf, by the way)

Originally Posted by Kennedy

Sorry, couldn't resist.

Well, it's more of an emotion than an opinion

But I admit to being one of the wrongest people alive.

Oh my gosh. I can't believe I put $(SOURCES) in the clean target! I'm very sorry . . . .

I knew I should have copied a working Makefile rather than try to type one up on the spot. Sigh.

Here's a real makefile, for my project nort. You should be able to modify it as necessary, if you still trust me after all this.

Code:

# Makefile for nort

CXX = g++
CXXFLAGS = -W -Wall -ansi -pedantic -g -I /usr/include/SDL
LDFLAGS = -lSDL -lSDLmain
SOURCES = $(wildcard *.cpp)
OBJECTS = $(SOURCES:.cpp=.o)
TARGET = nort

# Default target: all
.PHONY: all
all: $(TARGET)

# Executable files
$(TARGET): $(OBJECTS)
	$(CXX) $^ -o $@ $(LDFLAGS)

# Dependencies
include depend

.PHONY: depend
depend: $(SOURCES)
	$(CXX) $(CXXFLAGS) -MM $(SOURCES) > depend

# Other targets
.PHONY: clean
clean:
	-$(RM) $(OBJECTS) $(TARGET)

(I despise autoconf, by the way)

I don't much like it either. Here's one good reason: when I was creating xuni, I originally used autoconf and friends to make a build system, and then I tried making the build system in CMake. CMake compiled the whole project faster than autoconf did, and I don't think that was including the time to run ./configure.

Hi guys,

Thanks for your replies.
Brewbuck, I don't think ./configure would affect the compiler options. Cause, AFAIK, ./configure is just to check which compilers, libraries etc... are available to use to get the same result on another platform (Linux, FreeBSD, x86, Motorola 68xxx whatever). But the make is actually compiling (first automake to generate Makefile out of Makefile.am) the sources with the right compiler (determined by ./configure). In Makefile you can add the compiler flags, like the following example:

Code:

INCLUDES = $(all_includes) -I$(top_srcdir)/include
AM_CFLAGS=-Wall -g3 -O0         # O0 turns off optimization

sbin_PROGRAMS = babewatch
noinst_LIBRARIES = libabc.a libxyz.a
noinst_HEADERS = vty/cardshell.h

libabc_a_SOURCES = bisa.c babes.c...

When build the project I get this after executing make:

Code:

I../include   -Wall     -g3 -O0          -g -O2 -MT gsm.o -MD -MP -MF .deps/gsm.Tpo -c -o gsm_u.o gsm_u.c
mv -f .deps/gsm_u.Tpo .deps/gsm_u.Po
gcc -DPACKAGE_NAME=\"\" -DPACKAGE_TARNAME=\"\" -DPACKAGE_VERSION=\"\"
-DPACKAGE_STRING=\"\" -DPACKAGE_BUGREPORT=\"\" -DPACKAGE=\"projectname\"
-DVERSION=\"0.0alpha1\" -DSTDC_HEADERS=1 -I.  -I../include   -Wall     -g3 -O0          -g -O2 -MT

As you can see there is -g3 -O0 as well as -g -O2, so what overrules what?

Thank you.

Originally Posted by Andaluz

Brewbuck, I don't think ./configure would affect the compiler options. Cause, AFAIK, ./configure is just to check which compilers, libraries etc... are available to use to get the same result on another platform (Linux, FreeBSD, x86, Motorola 68xxx whatever).

I've done it hundreds of times with no problem.

As you can see there is -g3 -O0 as well as -g -O2, so what overrules what?

-g and -O are independent -- both will be active. Whichever -g is listed last takes effect. Whichever -O is listed last takes effect. In your case, you are getting "-g -O2"

Originally Posted by EVOEx

@dwks:
May I advise you to use, in stead of making the actual compiler and linker flags for SDL, doing something like:
CXXFLAGS=[...] `sdl-config --cflags`
LDFLAGS=[...] `sdl-config --libs`
That should be more portable at least .

I suppose so. I'll have to consider it.

Code:

CXXFLAGS=[...] $(shell sdl-config --cflags)

Brewbuck, I don't think ./configure would affect the compiler options. Cause, AFAIK, ./configure is just to check which compilers, libraries etc... are available to use to get the same result on another platform (Linux, FreeBSD, x86, Motorola 68xxx whatever). But the make is actually compiling (first automake to generate Makefile out of Makefile.am) the sources with the right compiler (determined by ./configure). In Makefile you can add the compiler flags, like the following example:

Remember that ./configure generates the Makefile in the first place. So you can tell it how to generate the Makefile if you like.