c )make error& link problem: i386:x86-64 architecture of input file, incompatible with i386 output

Question

I have this output with error message when i type "make" in terminal!!

gcc test1.o dispatchQueue.o -o test1 -pthread
/usr/bin/ld: i386:x86-64 architecture of input file `test1.o' is incompatible with i386     output
/usr/bin/ld: final link failed: Invalid operation
collect2: ld returned 1 exit status
make: *** [test1] Error 1

Is there anyone who can explain why and how to fix it? :(

I'm attaching makefile just in case

# Comment out the targets you don't want.

# Runs all of the tests.
all: test1 test2 test3 test4 test5 testFor
    ./test1
    ./test2
    ./test3
    ./test4
    ./test5
    ./testFor

test1: test1.o dispatchQueue.o
    gcc test1.o dispatchQueue.o -o test1 -pthread

test1.o: test1.c
    gcc -c test1.c

test2: test2.o dispatchQueue.o
    gcc test2.o dispatchQueue.o -o test2 -pthread

test2.o: test2.c
    gcc -c test2.c

test3: test3.o dispatchQueue.o
    gcc test3.o dispatchQueue.o -o test3 -pthread

test3.o: test3.c
    gcc -c test3.c

test4: test4.o dispatchQueue.o
    gcc test4.o dispatchQueue.o -o test4 -pthread

test4.o: test4.c
    gcc -c test4.c

test5: test5.o dispatchQueue.o
    gcc test5.o dispatchQueue.o -o test5 -pthread

test5.o: test5.c
    gcc -c test5.c

testFor: testFor.o dispatchQueue.o
    gcc testFor.o dispatchQueue.o -o testFor -pthread

testFor.o: testFor.c
    gcc -c testFor.c

dispatchQueue.o: dispatchQueue.c dispatchQueue.h
    gcc -c dispatchQueue.c

Answer 1

You probably have some old files (at least test1.o) compiled for i386-x64. You can remove these old files and run make again. If you can modify the Makefile try adding a line such as:

clean:
    rm *.o test1 test2 test3 test4 test5 testFor

Then when you run make clean it'll remove the old stuff, at which point you can run make again.