What actually is causing `The System Can not find the file specified` problem in make?

Question

Here is my Simple Makefile:

run.exe: link
 gcc link.o -o run
link.o: main.o fun.o
 ld -r main.o fun.o -o link.o
main.o: main.c
 gcc -c main.c -o main.o
fun.o: functionfile.c
 gcc -c functionfile.c -o fun.o
clean:
 del *.o
 del *.exe

The question is not really about creating `run.exe` I know several ways to create this. But while I was writing my **Makefile**, I accidently forget to write `.o` after `link` in dependency of `run.exe`( which I know when I found following error after running `make`):

gcc -c main.c -o main.o
gcc -c functionfile.c -o fun.o
ld -r main.o fun.o -o link.o
cc link.o -o link
process_begin: CreateProcess(NULL, cc link.o -o link, ...) failed.
make (e=2): The system cannot find the file specified.
<builtin>: recipe for target 'link' failed
make: *** [link] Error 2

I guess the file it is saying which it can not find is link because it doesn't previously exists and none of Makefile commands create it. My question is if link can not be found how the commands of targets 2,3 and 4 runs successfully and able to create respective .o files? Why does not it return at the same time when it does not find link i.e without executing any of the commands? Help me to sort it if my guess is correct or if it is wrong tell me the actual thing which is happening and problem too!!? And what is this recipe for target 'link' failed as I don't have any target named link??

Answer 1

The problem comes from the very first line in your Makefile:

run.exe: link

This causes Make to try to figure out how to create link. It knows how to build link from link.o, so it uses the rules provided to create link.o, and then tries to create link using its built-in rule, which references cc. But you don’t have a cc.exe command, so it fails — that’s the missing file. All this explains the "<builtin>: recipe for target 'link' failed" error message: Make failed in its attempt to create link using a built-in rule.

To fix this, specify the correct prerequisites:

run.exe: link.o
 gcc $^ -o $@

This uses automatic variables to avoid repeating information from the rule: $^ stands for "all the prerequisites" (link.o), $@ stands for "the file name of the target" (run.exe).

• John Doe: so, actually it could not find cc.exe. Can we create it or? And how it knows to make link from link.o? It means file extention doesn't matter or else??
• Stephen Kitt: File extensions do matter, and that’s what’s wrong with your Makefile. If you fix the extensions as indicated in my answer, you won’t need to create cc.exe because Make will stop looking for it. The link in my answer explains why Make "knows" how to build link — but its knowledge isn’t great on Windows because it doesn’t know about .exe extensions.
• John Doe: If I named it anything instead of link then it does not run even single command? It means same name matters?
• Stephen Kitt: Yes, the names matter. The name before a : is the file that is produced, the names after a : are the files that are used. You want to build run.exe using link.o, so the rule needs to be run.exe: link.o, and the gcc command needs to produce run.exe, i.e. gcc link.o -o run.exe (or gcc $^ -o $@ using automatic variables).
• Stephen Kitt: Specifying link causes commands to run because there’s a link.o rule. Make has a built-in rule to build executables with no extension using a .o file; in this case that’s cc link.o -o link. You’d get the same effect with main or fun, since there are rules for main.o and fun.o. Anything else won’t trigger the built-in rule.