Makefile: CreateProcess(...) failed. The system cannot find the file specified - makefile

Question

I'm trying to deal with Makefiles and wrote a simple "program":
DELETE_COMMAND := del
COMPILER := gcc
SOME_TEXT := lalalalalalalalalalalal!!!
all: sum.o even.o main.o pi.o
#$(COMPILER) -o output.exe sum.o even.o main.o pi.o
SOME_TEXT_2 := $(subst la,La,$(SOME_TEXT))
#echo $(SOME_TEXT_2)
clean:
#$(DELETE_COMMAND) *.o
#$(DELETE_COMMAND) output.exe
sum.o: sum.c sum.h
#$(COMPILER) -c sum.c
main.o: main.c sum.h pi.h
#$(COMPILER) -c main.c
pi.o: pi.c pi.h even.h
#$(COMPILER) -c pi.c
even.o: even.c even.h
#$(COMPILER) -c even.c
But I get the following error:
SOME_TEXT_2 := LaLaLaLaLaLaLaLaLaLaLal!!!
process_begin: CreateProcess(NULL, SOME_TEXT_2 := LaLaLaLaLaLaLaLaLaLaLal!!!, ...) failed.
make (e=2): The system cannot find the file specified.
make: *** [Makefile:7: all] Error 2
The problem is caused by this line:
SOME_TEXT_2 := $(subst la,La,$(SOME_TEXT))
but I have no idea what the problem is.
I'm using make from mingw-w64 on Windows.

Answer 1

Consider the rule...
all: sum.o even.o main.o pi.o
#$(COMPILER) -o output.exe sum.o even.o main.o pi.o
SOME_TEXT_2 := $(subst la,La,$(SOME_TEXT))
#echo $(SOME_TEXT_2)
Assuming all lines except the first begin with a tab character then each command will be run in a separate shell. But...
SOME_TEXT_2 := $(subst la,La,$(SOME_TEXT))
is not valid shell syntax -- it looks like it's supposed to be interpreted by make.
If the intent is simply to modify the variable SOME_TEXT and print the result then you can have either...
all: sum.o even.o main.o pi.o
#$(COMPILER) -o output.exe sum.o even.o main.o pi.o
#echo $(subst la,La,$(SOME_TEXT))
or, let make assign to SOME_TEXT_2...
SOME_TEXT_2 := $(subst la,La,$(SOME_TEXT))
all: sum.o even.o main.o pi.o
#$(COMPILER) -o output.exe sum.o even.o main.o pi.o
#echo $(SOME_TEXT_2)