When I compile code using GNU Make I get multiple warnings like:
clang: warning: -lGui: 'linker' input unused
This is probably because I have messed something up in my Makefile (below). Can anyone point me toward the problem?
CXX=g++
CC=g++
CXXFLAGS=-g -Wall -W -Wshadow -Wcast-qual -Wwrite-strings $(shell root-config --cflags --glibs)
CPPFLAGS+=-MMD -MP
LDFLAGS=-g $(shell root-config --ldflags)
LDLIBS=$(shell root-config --libs)
xSec_x: xSec_x.o xSec.o Analysis.o
-include xSec_x.d xSec.d Analysis.d
xSec.o: xSec.cpp xSec.h Analysis.h Analysis.cpp
xSec_x.o: xSec_x.cpp xSec.h Analysis.h
clean:
rm -f #rm -f $(PROGRAMS) *.o *.d
That message means you are passing linker flags (like -l which tells the linker to pull in a library) to the compiler.
This means that the result of running root-config --cflags --glibs is generating linker flags, and those are going into CXXFLAGS, which is being passed to the compiler. I don't know what root-config is, but you should investigate its command line and invoke it in a way where it doesn't generate linker flags. Probably removing the --glibs option will do it.
ETA: you really want to be using := to assign these flags variables if you're going to run $(shell ...) there. It will work either way, but if you use = then the shell command will be run every time make expands the variable, which is once per compilation. If you use := it will only be run once, when the makefile is parsed.
I got this same error and the reason was that I forgot to add -I in front of my included paths for cflags in makefile. For example:
CFLAGS += $(path)/dir/subdir/include -> Got the above mentioned error.
CFLAGS += -I$(path)/dir/subdir/include -> Fixed the issue.
Related
Im a Windows dev who has no expirience on building C/C++ programs on Linux, but now I need to. Right way would be to go and learn Make and g++ compiler, but before I commit to that I want to figure out some basic stuff.
So I have .c program which is compiled with this makefile:
CUDA_VER=11.5
ifeq ($(CUDA_VER),)
$(error "CUDA_VER is not set")
endif
APP:= deepstream-test3-app
TARGET_DEVICE = $(shell gcc -dumpmachine | cut -f1 -d -)
NVDS_VERSION:=6.0
LIB_INSTALL_DIR?=/opt/nvidia/deepstream/deepstream-$(NVDS_VERSION)/lib/
APP_INSTALL_DIR?=/opt/nvidia/deepstream/deepstream-$(NVDS_VERSION)/bin/
ifeq ($(TARGET_DEVICE),aarch64)
CFLAGS:= -DPLATFORM_TEGRA
endif
SRCS:= $(wildcard *.c)
$(info info is $(SRCS))
INCS:= $(wildcard *.h)
PKGS:= gstreamer-1.0
OBJS:= $(SRCS:.c=.o)
CFLAGS+= -I../../../includes \
-I /usr/local/cuda-$(CUDA_VER)/include
CFLAGS+= $(shell pkg-config --cflags $(PKGS))
LIBS:= $(shell pkg-config --libs $(PKGS))
LIBS+= -L/usr/local/cuda-$(CUDA_VER)/lib64/ -lcudart -lnvdsgst_helper -lm \
-L$(LIB_INSTALL_DIR) -lnvdsgst_meta -lnvds_meta \
-lcuda -Wl,-rpath,$(LIB_INSTALL_DIR)
$(info info is $(CFLAGS))
all: $(APP)
%.o: %.c $(INCS) Makefile
gcc -c -o $# $(CFLAGS) $<
$(APP): $(OBJS) Makefile
gcc -o $(APP) $(OBJS) $(LIBS)
install: $(APP)
cp -rv $(APP) $(APP_INSTALL_DIR)
clean:
rm -rf $(OBJS) $(APP)
First thing I tried is to change this Makefile to compile it as C++ program. I changed .c file into .cpp, in makefile I change gcc to g++ everywhere and .c to .cpp everywhere. It gave me error that it couldnt find "main" entry point.
I gave up on that pretty fast and decided just to use lines output of original makefile, ending up with this:
g++ -c -o deepstream_test3_app.o -I../../../includes -I /usr/local/cuda-11.5/include -pthread -I/usr/include/gstreamer-1.0 -I/usr/include/glib-2.0 -I/usr/lib/x86_64-linux-gnu/glib-2.0/include ./deepstream_test3_app.cpp
g++ -o deepstream-test3-app deepstream_test3_app.o -lgstreamer-1.0 -lgobject-2.0 -lglib-2.0 -L/usr/local/cuda-11.5/lib64/ -lcudart -lnvdsgst_helper -lm -L/opt/nvidia/deepstream/deepstream-6.0/lib/ -lnvdsgst_meta -lnvds_meta -lcuda -Wl,-rpath,/opt/nvidia/deepstream/deepstream-6.0/lib/
First question, can I combine this 2 launches of g++ into one?
Second, when I make changes to "./deepstream_test3_app.cpp" they are not noticed by compiler. I added
#include <iostream>
...
std::cout << "hello!" << std::endl;
and they are ignored. Its like g++ gets as input some other copy/older version of the file and I dont understand how to go about it.
Hope for any help, sorry if it's all sounds stupid.
Ignoring for the moment the issues surrounding compiling C code with a C++ compiler,
g++ -c -o deepstream_test3_app.o -I../../../includes -I /usr/local/cuda-11.5/include -pthread -I/usr/include/gstreamer-1.0 -I/usr/include/glib-2.0 -I/usr/lib/x86_64-linux-gnu/glib-2.0/include ./deepstream_test3_app.cpp
g++ -o deepstream-test3-app deepstream_test3_app.o -lgstreamer-1.0 -lgobject-2.0 -lglib-2.0 -L/usr/local/cuda-11.5/lib64/ -lcudart -lnvdsgst_helper -lm -L/opt/nvidia/deepstream/deepstream-6.0/lib/ -lnvdsgst_meta -lnvds_meta -lcuda -Wl,-rpath,/opt/nvidia/deepstream/deepstream-6.0/lib/
First question, can I combine this 2 launches of g++ into one?
Yes. It is a common practice in makefiles to separate the compilation and linking steps, but that is not mandatory. When there are multiple sources, the separation makes it possible to limit recompilations to only the source files that have changed, but it doesn't make much difference, makefile or not, when there is only one source file.
The one-command version would be mostly a concatenation of the two commands you gave. One would omit the -c option, which instructs g++ to compile but not link, and one would omit the -o deepstream_test3_app.o, which specifies the name of the object file that we are no longer going to create. One would also omit the appearance of deepstream_test3_app.o drawn from the link (second) command, as we are going straight from source file to program. The rest of the options can be reordered to some extent, but all the -l options need to remain in the same order relative to each other and to any object files among the inputs. Here is how I would write it:
g++ -c -o deepstream_test3_app -I../../../includes -I /usr/local/cuda-11.5/include -pthread -I/usr/include/gstreamer-1.0 -I/usr/include/glib-2.0 -I/usr/lib/x86_64-linux-gnu/glib-2.0/include -Wl,-rpath,/opt/nvidia/deepstream/deepstream-6.0/lib/ ./deepstream_test3_app.cpp -lgstreamer-1.0 -lgobject-2.0 -lglib-2.0 -L/usr/local/cuda-11.5/lib64/ -lcudart -lnvdsgst_helper -lm -L/opt/nvidia/deepstream/deepstream-6.0/lib/ -lnvdsgst_meta -lnvds_meta -lcuda
Second, when I make changes to "./deepstream_test3_app.cpp" they are not noticed by compiler.
The compiler compiles the source file(s) you tell it to.
Its like g++ gets as input some other copy/older version of the file
It is possible that you are indeed telling it to compile a different version than the one you modified. It is also possible that compilation fails, so you don't get a new executable. And it is possible that when you try to run the result, you are not running the program you think you are running. We don't have enough information to know.
With regard to the last, however, do be aware that on Linux, unlike on Windows, the working directory is not automatically in the executable search path. If you want to run the compiled result from the above command, you would want to specify the path to it, which you could most easily do by prepending ./ to its simple name: ./deepstream-test3-app.
I want to assemble and link some code for a 32-bit target from a 64-bit host, and I'm trying to use make's implicit rules as much as possible.
If I put -m32 in ASFLAGS it works fine for linking and assembling in one step, as make will use gcc for this. But if one of my executables needs separate linking, everything breaks, because make will then use as for assembling, and as doesn't understand -m32. To solve this I can use --32 instead, but this will of course not work with gcc.
$ cat Makefile
ASFLAGS = -m32
all: prog1 prog2
prog2: prog2.o
$ make
cc -m32 prog1.s -o prog1
as -m32 -o prog2.o prog2.s
as: unrecognized option '-m32'
<builtin>: recipe for target 'prog2.o' failed
make: *** [prog2.o] Error 1
Why does make use ASFLAGS for both gcc and as when their flags aren't compatible? Am I not supposed to specify the architecture this way? Do I really have to hack my way around this (i.e. actually write something in my Makefile), or is there something I've missed?
Since ASFLAGS is used by both LINK.s (gcc) and COMPILE.s (as) as you mentioned, one possible solution is to add following in the Makefile for compiling %.s with $(AS),
EXTRA_ASFLAGS = --32
%.o : %.s
$(AS) $(ASFLAGS) $(EXTRA_ASFLAGS) $(TARGET_MACH) -o $# $<
, or
COMPILE.s += --32
Well, you lied to make and as. If you put in ASFLAGS something that is not an assembler option, you're doing something out of spec.
make cannot know what options the compiler and assembler understand. To deal with this, make provides a way to specify the options for each tool separately: use CFLAGS for the compiler, ASFLAGS for the assembler, LDFLAGS for the link step.
I suggest using make CFLAGS=-m32 ASFLAGS=--32.
I've got a problem with the way I am shelling out. I'm working with Bash, but its on Debian Sid (Unstable) in a ARM64 Chroot. (I'm doing this because its our Debian package maintainer. Otherwise, I run away from the unstable, bleeding edge stuff)...
# echo $0
/bin/bash
It appears one of my shell commands is creating an -o2 rather than an -O2. I suspect memory is being trashed while shelling out, and the -o2 is just a symptom.
# make cryptlib.o
g++ -DNDEBUG -g3 -o2 -pipe -c cryptlib.cpp
Here's the same command under Remake:
# remake -X -f GNUmakefile cryptlib.o
GNU Make 3.82+dbg0.9
Built for aarch64-unknown-linux-gnu
Copyright (C) 2010 Free Software Foundation, Inc.
...
Updating goal targets....
File `cryptlib.o' does not exist.
Must remake target `cryptlib.o'.
Invoking recipe from GNUmakefile:449 to update target `cryptlib.o'.
##>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
g++ -DNDEBUG -g3 -o2 -pipe -c cryptlib.cpp
##<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
++ (/cryptopp-git/GNUmakefile:448)
cryptlib.o
remake<0>
As can be seen, the stuff I am interested in has already passed. Line 449 is very uninteresting. Its just a standard recipe that uses CXX, CXXFLAGS and $<.
Unfortunately, I don't really see what I should be doing to debug this issue. According to 1.1.6 Debugging Shell Commands, there's a step, but it does not really tell me how to use it. When I attempt to add it to the command:
remake -X step -f GNUmakefile cryptlib.o
It results in No rule to make target 'step'.
How do I debug this makefile with Remake? Or even without it?
The recipe's in your makefile aren't involved with setting that variable's value.
That's is a make variable. It is set at make-parse time by make itself (and the make-level contents of your makefile).
I don't see anything in the linked GNUMakefile that says either -o2 or -g3 both of which are in the make-run compilation command.
That makefile does include a GNUMakefile.deps file if it exists. I suppose that might have the erroneous value in it. Do you have a GNUMakefile.deps file?
Does grep find -g3 or -o2 anywhere in your source directory? (In case there's some other included makefile?)
The last place that make might be getting this value from is the process environment (because CXXFLAGS is defined with the ?= operator).
Do you have CXXFLAGS defined incorrectly in your environment?
I'm following Zed Shaw's tutorial "Learn C the Hard Way" and trying to teach myself c programming language.
On my ubuntu desktop, I encountered the linking problem he mentioned in the note of this post.
That is, when linking a static library with gcc, using a command like this:
gcc -Wall -g -DNDEBUG -lmylib ex29.c -o ex29
The linker fails to find the functions in the lib. To link correctly, I have to change the order of source file and lib to this:
gcc -Wall -g -DNDEBUG ex29.c -lmylib -o ex29
And I'm trying to use the makefile offered by Zed to automate unit test. The makefile looks like this:
TEST_SRC=$(wildcard tests/*_tests.c)
TESTS=$(patsubst %.c,%,$(TEST_SRC))
TARGET=build/libYOUR_LIBRARY.a
tests: CFLAGS += $(TARGET)
tests: $(TESTS)
sh ./tests/runtests.sh
The rest part of the makefile that isn't listed here can build the $(TARGET) lib flawlessly.
The problem is Zed append the lib to the $(CFLAGS) and use the implicit rule to compile the test files which leads to a command like this:
gcc -g -O2 -Wall -Wextra -Isrc -rdynamic -DNDEBUG tests/hashmap_tests.c build/mylib.a -o tests/list_tests
The command fails because of the link problem mentioned before as expected.
The solution I came up with was to write the compilation command explicitly like this so I can change the order:
$(TESTS): $(TARGET)
$(CC) $(CFLAGS) $^ $(TARGET) -o $#
This works fine if there is only one main source file. Unfortunately, I have several out there under the ./tests directory, and a command like this is a total disaster.
My question is, how should I change my makefile to make it work or is there any other way I can do the same work as elegant as expected?
CFLAGS holds compiler flags, like -g -O2. You should not add linker flags to it. CPPFLAGS holds preprocessor flags like -Isrc -DNDEBUG. LDFLAGS holds linker flags, which would include things like -L (capital L) if you need it to find libraries, and -rdynamic. And the LDLIBS variable holds libraries, so you should do this:
CPPFLAGS = -Isrc -DNDEBUG
CFLAGS = -g -O2 -Wall -Wextra
LDFLAGS = -rdynamic
LDLIBS = -lmylib
Now you can use the built-in rules for GNU make to build your program. You can see a list of the build-in rules by running make -p -f/dev/null.
Of course the above are just the default variables make defines and uses with its default rules. You don't have to use them, but in general it's better to follow conventions rather than flaunt them.
I'm compiling a SDL program using a Makefile. Typically I can compile my SDL projects with gcc like so:
# gcc -c test.c `sdl-config --cflags`
# gcc -o test test.o `sdl-config --libs`
# ./test
I'm having trouble executing sdl-config in my Makefile however. This is what I have:
CFLAGS := $(shell sdl-config --cflags)
LDFLAGS := $(shell sdl-config --libs)
test : test.o
gcc $(CFLAGS) $(LDFLAGS) -o test test.o
test.o:
But I keep getting the sdl-config usage line back rather than the respective output. I suspect the arguments (--cflags and --libs) are not being passed to sdl-config.
How do I pass arguments to the shell function? Is there a better way to achieve my end goal?
What you're doing is correct. If you run "sdl-config --cflags" from the command line, does it work or do you get the usage line? The best way to debug scripting problems is to run the script from your shell prompt. If it works there, it will work in make, too.