On 07/27/2015 03:39 PM, Paul Smith wrote: > On Mon, 2015-07-27 at 13:50 -0500, Larry Evans wrote: >> Thanks Paul. It works; however, what I really >> want is to use the compiler to compile a source file to >> and object file. > > Well, it usually works best to ask the question you want the answer to, > rather than a different question :-). > >> How should I modify this 2nd version of the Makefile to make it compile >> to produce the .o and not the a.out file? BTW, I'd rather not >> hardcode the -c into compile command because the actual args to the >> compile command depend on the compiler. Also, I'd like the output >> object file name to be $(MAIN).gcc.o instead of just $(MAIN).o. > > I don't really understand this, at all. Why do you have a loop in your > recipe? Can you provide a more realistic example? Or else maybe > provide some higher-level explanation of what you're trying to do? > > In your original question I thought maybe you have multiple compilers > and you wanted to write a "show info" type rule to show the paths to all > of them. But in this version of the makefile you're actually trying to > compile code, so I don't understand why you're trying to loop through > multiple compilers...? > > Are you trying to compile the same file with different compilers, or > something? > Yes.
The attached Makefile summarizes methods tried and the reason they failed or succeeded. The last method, the one with target=compiles.def, uses define..endef and succeeds. -regards, Larry
COMPILE.gcc=g++ -c COMPILE.clang=clang -c MAIN=test COMPILERS=gcc clang #The following fails because $(COMPILE.$HOW_CXX) #doesn't have value defined in this Makefile #for reason pointed out by Paul Smith here: # # http://lists.gnu.org/archive/html/help-make/2015-07/msg00016.html # compiles.for_compilers: for HOW_CXX in $(COMPILERS) ; do \ $(COMPILE.$$HOW_CXX) $(MAIN).cpp -o $(MAIN).$$HOW_CXX.o ; \ done ; #The following fails because $(COMPILE.$C) #has multiple space delimited tokens. compiles.for_each: @echo "COMPILE.gcc=" $(COMPILE.gcc) for HOW_CXX in $(foreach C,$(COMPILERS),$(COMPILE.$C)) ; do \ echo "HOW_CXX=" $$HOW_CXX ; \ rm -f a.out $(MAIN).o ; \ date ; \ $$HOW_CXX $(MAIN).cpp ; \ ls -l a.out $(MAIN).o ; \ done ; #The following does work by duplicating code #for each compiler using define...endef: define COMPILE.MAIN compile.$(1): $$(COMPILE.$(1)) -c $(MAIN).cpp -o $(MAIN).$(1).o endef $(foreach compiler, $(COMPILERS),$(eval $(call COMPILE.MAIN,$(compiler)))) compiles.def: $(addprefix compile.,$(COMPILERS))
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