On 07/27/2015 12:59 PM, Paul Smith wrote:
> On Mon, 2015-07-27 at 12:47 -0500, Larry Evans wrote:
>> How should the which command within the for loop script be
>> modified to produce the same output as the which command
>> before the for loop script?
>
> The recipe is run by the shell, not by make. Make simply expands the
> make variables and functions one time before the shell is started, then
> sends the results to the shell to be run, then waits for the exit code
> to see if it worked. The shell, being a separate shell process, cannot
> access make's database of variables. So, you cannot write a _shell_
> loop that uses _make_ computed variables.
>
> If you want to use make variables, you have to use a make loop via
> $(foreach ...) or similar.
>
> compiles:
> make -version
> @echo "COMPILE.gcc=" $(COMPILE.gcc)
> which $(COMPILE.gcc)
> for HOW_CXX in $(foreach C,gcc,$(COMPILE.$C)) ; do \
> which $$HOW_CXX ; \
> done ;
>
Thanks Paul. It works; however, what I really
want is to use the compiler to compile a source file to
and object file.
When I tried to modify the Makefile as shown in 1st attachment,
I get the output shown in 2nd attachment. Apparently, it's
not globbing the gcc and the -c together. Instead, it's using
gcc to produce the a.out file, which is not what I want and
during the 2nd loop, it's trying to use -c is a shell command.
How should I modify this 2nd version of the Makefile to make it compile
to produce the .o and not the a.out file? BTW, I'd rather not
hardcode the -c into compile command because the actual args to the
compile command depend on the compiler. Also, I'd like the output
object file name to be $(MAIN).gcc.o instead of just $(MAIN).o.
TIA.
-Larry
COMPILE.gcc=g++ -c
COMPILE.clang=clang -c
MAIN=test
compiles:
@echo "COMPILE.gcc=" $(COMPILE.gcc)
for HOW_CXX in $(foreach C,gcc,$(COMPILE.$C)) ; do \
echo "HOW_CXX=" $$HOW_CXX ; \
rm -f a.out $(MAIN).o ; \
date ; \
$$HOW_CXX $(MAIN).cpp ; \
ls -l a.out $(MAIN).o ; \
done ;
Compilation started at Mon Jul 27 13:46:17
make
COMPILE.gcc= g++ -c
for HOW_CXX in g++ -c ; do \
echo "HOW_CXX=" $HOW_CXX ; \
rm -f a.out test.o ; \
date ; \
$HOW_CXX test.cpp ; \
ls -l a.out test.o ; \
done ;
HOW_CXX= g++
Mon Jul 27 13:46:17 CDT 2015
ls: cannot access test.o: No such file or directory
-rwxrwxr-x 1 evansl evansl 6654 Jul 27 13:46 a.out
HOW_CXX= -c
Mon Jul 27 13:46:17 CDT 2015
/bin/sh: 5: -c: not found
ls: cannot access a.out: No such file or directory
ls: cannot access test.o: No such file or directory
make: *** [compiles] Error 2
Compilation exited abnormally with code 2 at Mon Jul 27 13:46:17
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