Is there a way to use the native Makefile if-else conditional and also have it respects target-specific variables re-assignments?
Example Makefile:
#!/usr/bin/make
CONFIG = Debug
.PHONY: test printme
test: override CONFIG=Release
test: printme
#echo "Done."
printme:
ifeq "$(CONFIG)" "Debug"
#echo "should be DEBUG -> $(CONFIG)"
else
#echo "should be RELEASE -> $(CONFIG)"
endif
Running make test prints the following output:
should be DEBUG -> Release
Done.
The output I'm looking for is should be RELEASE -> Release how can I achieve that? Do I need to use shell conditionals instead?
This behavior seems logical to me: At the time of parsing the Makefile, CONFIG is defined as Debug. The ifeq conditional uses the value of CONFIG it knows at that time. Therefore it chooses the ifeq branch that outputs "Should be DEBUG".
The target-specific variable is only defined as Release with the target test. Its prerequisite printme also knows the target-specific variable and ouputs Release.
May I suggest that you set variable to make on the command line for the purpose you want. It's not many more characters to write when invoking make but brings all you seem to be willing.
make CONFIG=Release
Related
I have the following Makefile where the all make target depends on a separate setup make target that also takes an argument. However when I make all the setup target is not invoked with the argument
setup:
...command
clean:
...command
all: setup myarg=value clean myarg=value
#echo "setup & clean"
I think what you're asking is if a prerequisite can inherit a target-specific variable. In which case, yes it can -- Note, in your example you tried to intersperse the target specific variables and the prerequisites, which you can't do. But beware -- this has sharp sticks attached. Consider the following makefile:
all:
setup:
#echo "building $#: myarg=$(myarg)"
all: myarg:=value
all: setup
#echo "building $#: myarg=$(myarg)"
blah: setup
#echo "building $#: myarg=$(myarg)"
If I do make all, I get:
tmp> make all
building setup: myarg=value
building all: myarg=value
Which is what you want. But if I do make blah, then setup is run as a prerequisite of blah, and does not have the value set as you might expect. It will not be rebuilt for main, even though the variable is different:
tmp> make blah all
building setup: myarg=
building blah: myarg=
building all: myarg=value
See the make manual for more details
The command line of the make program is not free-form. You can't just pass it a bunch of stuff and have that "stuff" passed through make to appear somehow inside your recipes. make can only take arguments that it's defined to take: all arguments (not options) are either targets or variable assignments. See the documentation or the man page.
It is not possible in general to pass arbitrary values on the make command line. However, as I said, make does allow variables to be set on its command line.
If you run make setup myarg=value then this will set the make variable myarg to have the value value, and ask make to build the setup target.
So, if you write your makefile:
setup:
...command $(myarg)
referencing the make variable myarg, then it will "work" (I guess, you haven't made clear exactly what you want to run using myarg).
I tried to write this dynamic target to check the variable before running the actual target:
.PHONY: check-env-%
check-env-%:
ifeq ($(${*}),)
$(error not found ${*})
endif
so that I can use it like:
build: check-env-VERSION
But looks like it cannot compare it and even when I supply the required variable, it errors: Makefile:16: *** not found VERSION. Stop.
I believe I'm using the ifeq correctly but not sure why it cannot compare it?
From the docs: "Conditionals control what make actually “sees” in the makefile, so they cannot be used to control recipes at the time of execution." So your access to $* always yields an empty string at the time of makefile analysis, leaving your $(error) as recipe instruction.
Vroomfondel is right. What you can do instead is this:
check-env-%:
test $($*) || (echo $* not found; exit 1;)
...
test shall stop when there is no variable defined.
I've written a fairly simple test Makefile where I define two targets, all & clean. I've got two different conditional statements. One checks for the existence of the $(MAKECMDGOALS) special variable and the other detects whether any of the command line targets matched those listed in a variable (NODEPS). The problem I'm having is that none of the branches within my conditionals get executed. Ultimately I want to use a conditional to decide whether the target I'm supplying should include some autogenerated dependency files but at the moment I'm struggling to get either expression to even evaluate. I'm running GNU make version 3.81 and I've tried it under Ubuntu and Mac OS X to no avail.
NODEPS := clean
INCLUDE = $(filter $(NODEPS),$(MAKECMDGOALS))
.PHONY : all clean
ifndef $(MAKECMDGOALS)
#echo "$$(MAKECMDGOALS) is not defined"
else
#echo "$(MAKECMDGOALS) is defined"
endif
ifneq (0, $(words $(INCLUDE)))
#echo "INCLUDE = $(INCLUDE) != 0"
else
#echo "INCLUDE = $(INCLUDE) == 0"
endif
all :
#echo "all : $(MAKECMDGOALS)"
clean :
#echo "clean : $(MAKECMDGOALS)"
I eventually managed to work out what was wrong. #eriktous was right, pointing out that I should be using $(info) rather than #echo. More subtly though, part of the problem was that I'd indented the #echos with a tab. It seems that tabs are mandatory for rules but not allowed in conditionals. The other mistake was I'd expanded the $(MAKECMDGOALS) variable in the test condition when it should have been written as just ifndef MAKECMDGOALS.
https://www.gnu.org/software/make/manual/html_node/Make-Control-Functions.html
A makefile is not a shell script. You can not "randomly" place executable statements anywhere you like and expect them to be executed.
There are various ways of communicating with the outside world from within a makefile: $(info ...), $(warning ...), $(error ...) and $(shell #echo ...) (some or all of these may be GNU make extensions).
Ps: you misspelled PHONY.
There is a Makefile that I am using, which I got from somewhere, and which is quite big. I have also found some things that I'd like changed occasionally in the makefile - and the easiest way to do that for me is to define (or not) a (switch) variable (say, OVWRCHOICE) at the start of the makefile; and then later on in the makefile code, do something like:
ifdef OVWRCHOICE
MYOPT = override
....
endif
... which is all dandy and fine.
The thing is, eventually I also need to change parts in the "override" part as well, so I'd like to have it at the start of the file. So, as this "override" part contains several make commands -- I tried to use define, to have a variable which will contain the commands (which would be executed at the ifdef OVWRCHOICE... part).
So I arrived at this simple example:
# uncomment as needed;
OVWRCHOICE = YES
define SET_OVWRCHOICE
MYOPT = override
endef
export SET_OVWRCHOICE
# ... many lines of code ...
MYOPT = default
# ... many lines of code...
# without indent: Makefile:18: *** missing separator. Stop.
# with tab indent: Makefile:18: *** commands commence before first target. Stop.
ifdef OVWRCHOICE
$(SET_OVWRCHOICE)
endif
all:
#echo $(MYOPT)
... which fails with the errors noted. Of course, if I use the first snippet in the post instead, all runs fine, and make prints out the expected result: "override".
How would I go about in achieving something like this? Not sure if "inclusion" or "execution" of "Makefile commands" are even the right terms in this context; so I have a hard time in finding a starting point for a search :)
Got it - it is described in Eval Function - GNU `make'; the right construct is:
ifdef OVWRCHOICE
$(eval $(call SET_OVWRCHOICE))
endif
Hope this helps someone,
Cheers!
Oh well, didn't really know where to archive this snippet, so back to this old question of mine :) this is off topic for OP; but here goes:
To test how environment variables are processed by a makefile, here is a simple example:
Foo=something
all :
ifdef DEBUG
#echo "Debug defined"
else
#echo "Debug NOT defined"
endif
... and here is the test for it:
$ make
Debug NOT defined
$ make DEBUG
make: *** No rule to make target `DEBUG'. Stop.
$ DEBUG make
DEBUG: command not found
$ DEBUG= make
Debug NOT defined
$ DEBUG=1 make
Debug defined
... so obviously, the right syntax to set that variable inside the makefile from the command line is: "DEBUG=1 make"
Can I pass variables to a GNU Makefile as command line arguments? In other words, I want to pass some arguments which will eventually become variables in the Makefile.
You have several options to set up variables from outside your makefile:
From environment - each environment variable is transformed into a makefile variable with the same name and value.
You may also want to set -e option (aka --environments-override) on, and your environment variables will override assignments made into makefile (unless these assignments themselves use the override directive . However, it's not recommended, and it's much better and flexible to use ?= assignment (the conditional variable assignment operator, it only has an effect if the variable is not yet defined):
FOO?=default_value_if_not_set_in_environment
Note that certain variables are not inherited from environment:
MAKE is gotten from name of the script
SHELL is either set within a makefile, or defaults to /bin/sh (rationale: commands are specified within the makefile, and they're shell-specific).
From command line - make can take variable assignments as part of his command line, mingled with targets:
make target FOO=bar
But then all assignments to FOO variable within the makefile will be ignored unless you use the override directive in assignment. (The effect is the same as with -e option for environment variables).
Exporting from the parent Make - if you call Make from a Makefile, you usually shouldn't explicitly write variable assignments like this:
# Don't do this!
target:
$(MAKE) -C target CC=$(CC) CFLAGS=$(CFLAGS)
Instead, better solution might be to export these variables. Exporting a variable makes it into the environment of every shell invocation, and Make calls from these commands pick these environment variable as specified above.
# Do like this
CFLAGS=-g
export CFLAGS
target:
$(MAKE) -C target
You can also export all variables by using export without arguments.
The simplest way is:
make foo=bar target
Then in your makefile you can refer to $(foo). Note that this won't propagate to sub-makes automatically.
If you are using sub-makes, see this article: Communicating Variables to a Sub-make
Say you have a makefile like this:
action:
echo argument is $(argument)
You would then call it make action argument=something
From the manual:
Variables in make can come from the environment in which make is run. Every environment variable that make sees when it starts up is transformed into a make variable with the same name and value. However, an explicit assignment in the makefile, or with a command argument, overrides the environment.
So you can do (from bash):
FOOBAR=1 make
resulting in a variable FOOBAR in your Makefile.
It seems command args overwrite environment variable.
Makefile:
send:
echo $(MESSAGE1) $(MESSAGE2)
Example run:
$ MESSAGE1=YES MESSAGE2=NG make send MESSAGE2=OK
echo YES OK
YES OK
There's another option not cited here which is included in the GNU Make book by Stallman and McGrath (see http://www.chemie.fu-berlin.de/chemnet/use/info/make/make_7.html). It provides the example:
archive.a: ...
ifneq (,$(findstring t,$(MAKEFLAGS)))
+touch archive.a
+ranlib -t archive.a
else
ranlib archive.a
endif
It involves verifying if a given parameter appears in MAKEFLAGS. For example .. suppose that you're studying about threads in c++11 and you've divided your study across multiple files (class01, ... , classNM) and you want to: compile then all and run individually or compile one at a time and run it if a flag is specified (-r, for instance). So, you could come up with the following Makefile:
CXX=clang++-3.5
CXXFLAGS = -Wall -Werror -std=c++11
LDLIBS = -lpthread
SOURCES = class01 class02 class03
%: %.cxx
$(CXX) $(CXXFLAGS) -o $#.out $^ $(LDLIBS)
ifneq (,$(findstring r, $(MAKEFLAGS)))
./$#.out
endif
all: $(SOURCES)
.PHONY: clean
clean:
find . -name "*.out" -delete
Having that, you'd:
build and run a file w/ make -r class02;
build all w/ make or make all;
build and run all w/ make -r (suppose that all of them contain some certain kind of assert stuff and you just want to test them all)
If you make a file called Makefile and add a variable like this $(unittest)
then you will be able to use this variable inside the Makefile even with wildcards
example :
make unittest=*
I use BOOST_TEST and by giving a wildcard to parameter --run_test=$(unittest)
then I will be able to use regular expression to filter out the test I want my Makefile
to run
export ROOT_DIR=<path/value>
Then use the variable, $(ROOT_DIR) in the Makefile.